This first post is a place holder in part, so that I don't forget to ask
the question, as I usually do once I get involved in stuff during the day.

The Motor Home has mains powered habitation air conditioning - that is an
ELectrolux slug on the roof.

So for it to work you need to be on a site with mains electricity.

There is also the issue of the power surge on start-up compared to the
power demand on normal running.

What I would like to be able to do:

(1) Run the A/C whilst driving - that would I assume involve an inverter
which could take power through the 12V electrics buffered by the
habitation batteries (unless the demand needs a direct connection to the
alternator charging circuit instead of via the charge controller which
charges the habitation batteries). This also allows starting the engine,
firing up A/C and then stopping the engine and letting the A/C run on
using the habitation batteries.

(2) Run the A/C when away from mains power - using a small Honda generator
which might be able to meet most of the demand apart from start-up. I am
envisaging perhaps the generator pushing power into the system whilst the
A/C takes power out so that the use of habitation battery charge is
slowed. This probably equates to running a UPS (that is, power in to UPS
for charging, power always out of UPS for running the device) and using a
small generator to keep feeding some power into the UPS during a power
cut. The generator may not fully meet the power demand but it slows the
rate of discharge.

This does seem to demand a lot of inefficiency, though, potentially with
the generator input being converted from 240V to 12V then back again. It
would be nicer if the battery 12V power could be used to boost the 240V
input from the generator so that most of the power comes directly in at
240V.


Bottom line is that one way may require blending two 240V inputs into a
single output, with obvious (I think) requirements to lock the wave forms
of the 240V together.

If I can manage ASCII art:

12V - 240V - Blender - A/C
240V -----------^

I think this is probably not realistic because you would have to prevent
back flow which is why there are so many issues with combining power
inputs connected to the grid. Then again, it is only like combining a
solar panel and mains (but that does allow back flow into the grid).

I need to dig out the handbook for the A/C to check all the power demands,
but meanwhile does this sound in any way feasible?

I know (2) could be met by just buying a bigger generator, but I bought
the little Honda because I could just shoehorn it into the available
storage and anything bigger is too tall/wide to fit anywhere usable.

Cheers


Dave R


--
Windows 8.1 on PCSpecialist box

On Friday, February 26, 2016 at 10:59:10 AM UTC, David wrote:
This first post is a place holder in part, so that I don't forget to ask
the question, as I usually do once I get involved in stuff during the day..

The Motor Home has mains powered habitation air conditioning - that is an
ELectrolux slug on the roof.

So for it to work you need to be on a site with mains electricity.

There is also the issue of the power surge on start-up compared to the
power demand on normal running.

What I would like to be able to do:

(1) Run the A/C whilst driving - that would I assume involve an inverter
which could take power through the 12V electrics buffered by the
habitation batteries (unless the demand needs a direct connection to the
alternator charging circuit instead of via the charge controller which
charges the habitation batteries). This also allows starting the engine,
firing up A/C and then stopping the engine and letting the A/C run on
using the habitation batteries.

(2) Run the A/C when away from mains power - using a small Honda generator
which might be able to meet most of the demand apart from start-up. I am
envisaging perhaps the generator pushing power into the system whilst the
A/C takes power out so that the use of habitation battery charge is
slowed. This probably equates to running a UPS (that is, power in to UPS
for charging, power always out of UPS for running the device) and using a
small generator to keep feeding some power into the UPS during a power
cut. The generator may not fully meet the power demand but it slows the
rate of discharge.

This does seem to demand a lot of inefficiency, though, potentially with
the generator input being converted from 240V to 12V then back again. It
would be nicer if the battery 12V power could be used to boost the 240V
input from the generator so that most of the power comes directly in at
240V.


Bottom line is that one way may require blending two 240V inputs into a
single output, with obvious (I think) requirements to lock the wave forms
of the 240V together.

If I can manage ASCII art:

12V - 240V - Blender - A/C
240V -----------^

I think this is probably not realistic because you would have to prevent
back flow which is why there are so many issues with combining power
inputs connected to the grid. Then again, it is only like combining a
solar panel and mains (but that does allow back flow into the grid).

I need to dig out the handbook for the A/C to check all the power demands,
but meanwhile does this sound in any way feasible?

I know (2) could be met by just buying a bigger generator, but I bought
the little Honda because I could just shoehorn it into the available
storage and anything bigger is too tall/wide to fit anywhere usable.

Cheers


Dave R


--
Windows 8.1 on PCSpecialist box

Non starter. Aircon requires an immense amount of energy that you are just not going to get out of the 12V system or a battery.

You possibly could add an aircon compressor to the engine if there is space for one and all the other components of course (many engines just substitute an idler pulley instead of the compressor if the aircon option isn't chosen) but it would be hugely expensive.

Probably better all round to open the window when driving and sit outside in a deckchair when camped without leccy hookup.

Philip

On Fri, 26 Feb 2016 03:31:22 -0800, wrote:

On Friday, February 26, 2016 at 10:59:10 AM UTC, David wrote:
This first post is a place holder in part, so that I don't forget to
ask the question, as I usually do once I get involved in stuff during
the day.

The Motor Home has mains powered habitation air conditioning - that is
an ELectrolux slug on the roof.

So for it to work you need to be on a site with mains electricity.

There is also the issue of the power surge on start-up compared to the
power demand on normal running.

What I would like to be able to do:

(1) Run the A/C whilst driving - that would I assume involve an
inverter which could take power through the 12V electrics buffered by
the habitation batteries (unless the demand needs a direct connection
to the alternator charging circuit instead of via the charge controller
which charges the habitation batteries). This also allows starting the
engine, firing up A/C and then stopping the engine and letting the A/C
run on using the habitation batteries.

(2) Run the A/C when away from mains power - using a small Honda
generator which might be able to meet most of the demand apart from
start-up. I am envisaging perhaps the generator pushing power into the
system whilst the A/C takes power out so that the use of habitation
battery charge is slowed. This probably equates to running a UPS (that
is, power in to UPS for charging, power always out of UPS for running
the device) and using a small generator to keep feeding some power into
the UPS during a power cut. The generator may not fully meet the power
demand but it slows the rate of discharge.

This does seem to demand a lot of inefficiency, though, potentially
with the generator input being converted from 240V to 12V then back
again. It would be nicer if the battery 12V power could be used to
boost the 240V input from the generator so that most of the power comes
directly in at 240V.


Bottom line is that one way may require blending two 240V inputs into a
single output, with obvious (I think) requirements to lock the wave
forms of the 240V together.

If I can manage ASCII art:

12V - 240V - Blender - A/C 240V -----------^

I think this is probably not realistic because you would have to
prevent back flow which is why there are so many issues with combining
power inputs connected to the grid. Then again, it is only like
combining a solar panel and mains (but that does allow back flow into
the grid).

I need to dig out the handbook for the A/C to check all the power
demands,
but meanwhile does this sound in any way feasible?

I know (2) could be met by just buying a bigger generator, but I bought
the little Honda because I could just shoehorn it into the available
storage and anything bigger is too tall/wide to fit anywhere usable.

Cheers


Dave R


--
Windows 8.1 on PCSpecialist box

Non starter. Aircon requires an immense amount of energy that you are
just not going to get out of the 12V system or a battery.

You possibly could add an aircon compressor to the engine if there is
space for one and all the other components of course (many engines just
substitute an idler pulley instead of the compressor if the aircon
option isn't chosen) but it would be hugely expensive.

Probably better all round to open the window when driving and sit
outside in a deckchair when camped without leccy hookup.

Philip

There is already cab aircon which is fine for driving along and can also
cool the interior of the MH unless it is really hot - keeps the cab cool
but the interior of a MH has a lot more volume than a van cab or a car.

Also does not solve the 240V issue as you would have to run the engine all
the time even when you are on a powered site.

Also not good to cool the van when you are out at the beach - which seems
to be one of the favourite reported usages.

Cheers


Dave R



--
Windows 8.1 on PCSpecialist box

David wrote:

What I would like to be able to do:

(1) Run the A/C whilst driving

To get some idea of the overall feasibility, what is the actual
power demand from the aircon?

Chris
--
Chris J Dixon Nottingham UK


Plant amazing Acers.

On Fri, 26 Feb 2016 10:59:07 +0000, David wrote:

This first post is a place holder in part, so that I don't forget to ask
the question, as I usually do once I get involved in stuff during the
day.

The Motor Home has mains powered habitation air conditioning - that is
an ELectrolux slug on the roof.

So for it to work you need to be on a site with mains electricity.

There is also the issue of the power surge on start-up compared to the
power demand on normal running.

What I would like to be able to do:

(1) Run the A/C whilst driving - that would I assume involve an inverter
which could take power through the 12V electrics buffered by the
habitation batteries (unless the demand needs a direct connection to the
alternator charging circuit instead of via the charge controller which
charges the habitation batteries). This also allows starting the engine,
firing up A/C and then stopping the engine and letting the A/C run on
using the habitation batteries.

(2) Run the A/C when away from mains power - using a small Honda
generator which might be able to meet most of the demand apart from
start-up. I am envisaging perhaps the generator pushing power into the
system whilst the A/C takes power out so that the use of habitation
battery charge is slowed. This probably equates to running a UPS (that
is, power in to UPS for charging, power always out of UPS for running
the device) and using a small generator to keep feeding some power into
the UPS during a power cut. The generator may not fully meet the power
demand but it slows the rate of discharge.

This does seem to demand a lot of inefficiency, though, potentially with
the generator input being converted from 240V to 12V then back again. It
would be nicer if the battery 12V power could be used to boost the 240V
input from the generator so that most of the power comes directly in at
240V.


Bottom line is that one way may require blending two 240V inputs into a
single output, with obvious (I think) requirements to lock the wave
forms of the 240V together.

If I can manage ASCII art:

12V - 240V - Blender - A/C 240V -----------^

I think this is probably not realistic because you would have to prevent
back flow which is why there are so many issues with combining power
inputs connected to the grid. Then again, it is only like combining a
solar panel and mains (but that does allow back flow into the grid).

I need to dig out the handbook for the A/C to check all the power
demands,
but meanwhile does this sound in any way feasible?

I know (2) could be met by just buying a bigger generator, but I bought
the little Honda because I could just shoehorn it into the available
storage and anything bigger is too tall/wide to fit anywhere usable.

The handbook is not entirely clear. *shock*

The unit is an Electrolux Blizzard B1500.

The technical data includes:

Cooling consumption 715 watts
Heating capacity 800 watts.

Looking at the manual it seems that the unit is not designed to be used as
a heat pump when blowing warm air (as you might expect) but has a small
heating element - so from the data it looks to be an 800 watt fan heater
(less a small deduction for the power to turn the fan).

The 715 watts may be the maximum start up for the compressor, or may be
the average after the compressor has started.

Google isn't helping me much so far (apart from several links about the
heater giving of a burning smell then stopping working) but there is one
foreign link which related the "1500" in the brand name to 1.5kW. The fuse
recommended is a 10 amp slow blow, so good for up to about 2.5kW, which
may hint at the expected starting load.

I suppose what I really need is a power meter of some sort to accurately
measure the power draw when it is fired up via the mains.

Can anyone recommend a reasonably priced meter which can do this sort of
thing?

Amazon offers plug in meters from about £7 upwards - to about £55.

In this case I won't be looking for milliwatt accuracy, but who knows what
I might need to check in the future.

Oh, and the generator is rated at 450 watts normal 550 watts maximum at
50Hz. It is badged as a 650W generator as this is the maximum output at
60Hz.

Assuming that the real draw from the A/C is 715W then the generator
couldn't run it stand alone, but could supply a reasonable percentage of
the power.

Cheers


Dave R

--
Windows 8.1 on PCSpecialist box

On Friday, 26 February 2016 12:29:55 UTC, David wrote:
Google isn't helping me much so far (apart from several links about the
heater giving of a burning smell then stopping working) but there is one
foreign link which related the "1500" in the brand name to 1.5kW.

That might be for 110 volt? Or it might refer to cooling capacity of 1500 watts, with electrical consumption of 715 watts, which would be a coefficient of performance (COP) of about 2 which sounds reasonable for a small heat pump.

Owain

On Fri, 26 Feb 2016 05:17:40 -0800, spuorgelgoog wrote:

On Friday, 26 February 2016 12:29:55 UTC, David wrote:
Google isn't helping me much so far (apart from several links about the
heater giving of a burning smell then stopping working) but there is
one foreign link which related the "1500" in the brand name to 1.5kW.

That might be for 110 volt? Or it might refer to cooling capacity of
1500 watts, with electrical consumption of 715 watts, which would be a
coefficient of performance (COP) of about 2 which sounds reasonable for
a small heat pump.

Owain

Thanks - another bit of the data says that it is 230 volts at 50Hz.

Cheers

Dave R

--
Windows 8.1 on PCSpecialist box

David wrote:
On Fri, 26 Feb 2016 05:17:40 -0800, spuorgelgoog wrote:

On Friday, 26 February 2016 12:29:55 UTC, David wrote:
Google isn't helping me much so far (apart from several links about the
heater giving of a burning smell then stopping working) but there is
one foreign link which related the "1500" in the brand name to 1.5kW.

That might be for 110 volt? Or it might refer to cooling capacity of
1500 watts, with electrical consumption of 715 watts, which would be a
coefficient of performance (COP) of about 2 which sounds reasonable for
a small heat pump.

Owain

Thanks - another bit of the data says that it is 230 volts at 50Hz.

Cheers

Dave R

Whatever scheme you use you need the VA requirements of the compressor
NOT the watts to get an inverter or genny to power it. You also need to
be able to source the Starting VA of the compressor which will be far
higher than the running figure by several times.

One way to estimate pk current is to look at the rating of the fuse and
knock off a little.

You will soon see the requirements are far too high for a toy genny or a
battery.

Basically this is a non starter. Forget it.

In article ,
David wrote:
(1) Run the A/C whilst driving - that would I assume involve an inverter
which could take power through the 12V electrics buffered by the
habitation batteries (unless the demand needs a direct connection to the
alternator charging circuit instead of via the charge controller which
charges the habitation batteries). This also allows starting the engine,
firing up A/C and then stopping the engine and letting the A/C run on
using the habitation batteries.

Vehicle AC is invariably driven direct from the engine - the compressor
via a belt drive, etc. You'd need a massive alternator to provide anywhere
near enough current. And a massive inverter.

--
*If Barbie is so popular, why do you have to buy her friends? *

Dave Plowman London SW
To e-mail, change noise into sound.

On 26/02/16 10:59, David wrote:
The Motor Home has mains powered habitation air conditioning - that is an
ELectrolux slug on the roof.

So for it to work you need to be on a site with mains electricity.

There is also the issue of the power surge on start-up compared to the
power demand on normal running.

What I would like to be able to do:

Is not possible.

When I took an RV across the Mojave desert, it had aircon that was
powered by a little donkey engine/genny at the back that chewed petrol.
Only used it in anger once, near Lake mead. There was just enough
humidity to make the 40C+ temps unbearable.

It was noisy too.


--
No Apple devices were knowingly used in the preparation of this post.

Dave Plowman (News) wrote:
In ,
wrote:

(1) Run the A/C whilst driving - that would I assume involve an inverter
which could take power through the 12V electrics buffered by the
habitation batteries (unless the demand needs a direct connection to the
alternator charging circuit instead of via the charge controller which
charges the habitation batteries). This also allows starting the engine,
firing up A/C and then stopping the engine and letting the A/C run on
using the habitation batteries.

Vehicle AC is invariably driven direct from the engine - the compressor
via a belt drive, etc. You'd need a massive alternator to provide anywhere
near enough current. And a massive inverter.



Agreed. A big alternator will give you 2.4 Kw, nowhere near enough
to start a locked compressor. Try sourcing a refigerated container heat
pump and see what it takes.

On 26/02/2016 10:59, David wrote:
This first post is a place holder in part, so that I don't forget to ask
the question, as I usually do once I get involved in stuff during the day.

The Motor Home has mains powered habitation air conditioning - that is an
ELectrolux slug on the roof.

As soon as we know the spec, it might be possible to assist.

So for it to work you need to be on a site with mains electricity.

There is also the issue of the power surge on start-up compared to the
power demand on normal running.

What I would like to be able to do:

(1) Run the A/C whilst driving - that would I assume involve an inverter
which could take power through the 12V electrics buffered by the
habitation batteries (unless the demand needs a direct connection to the
alternator charging circuit instead of via the charge controller which
charges the habitation batteries). This also allows starting the engine,
firing up A/C and then stopping the engine and letting the A/C run on
using the habitation batteries.

For a narrow boat I installed a 3kW inverter (with surge capability),
150A alternator and 4 100Ah batteries. It can be done though
challenging. I doubt you'll have the space to fit a second alternator.

(2) Run the A/C when away from mains power - using a small Honda generator
which might be able to meet most of the demand apart from start-up. I am
envisaging perhaps the generator pushing power into the system whilst the
A/C takes power out so that the use of habitation battery charge is
slowed. This probably equates to running a UPS (that is, power in to UPS
for charging, power always out of UPS for running the device) and using a
small generator to keep feeding some power into the UPS during a power
cut. The generator may not fully meet the power demand but it slows the
rate of discharge.

Again without knowing the rating of the air con, and the size of your
portable gen, we're in the dark.

This does seem to demand a lot of inefficiency, though, potentially with
the generator input being converted from 240V to 12V then back again. It
would be nicer if the battery 12V power could be used to boost the 240V
input from the generator so that most of the power comes directly in at
240V.


Bottom line is that one way may require blending two 240V inputs into a
single output, with obvious (I think) requirements to lock the wave forms
of the 240V together.

You cannot "blend" 2 AC voltages.

On Friday, 26 February 2016 11:31:26 UTC, wrote:
On Friday, February 26, 2016 at 10:59:10 AM UTC, David wrote:
This first post is a place holder in part, so that I don't forget to ask
the question, as I usually do once I get involved in stuff during the day.

The Motor Home has mains powered habitation air conditioning - that is an
ELectrolux slug on the roof.

So for it to work you need to be on a site with mains electricity.

There is also the issue of the power surge on start-up compared to the
power demand on normal running.

What I would like to be able to do:

(1) Run the A/C whilst driving - that would I assume involve an inverter
which could take power through the 12V electrics buffered by the
habitation batteries (unless the demand needs a direct connection to the
alternator charging circuit instead of via the charge controller which
charges the habitation batteries). This also allows starting the engine,
firing up A/C and then stopping the engine and letting the A/C run on
using the habitation batteries.

(2) Run the A/C when away from mains power - using a small Honda generator
which might be able to meet most of the demand apart from start-up. I am
envisaging perhaps the generator pushing power into the system whilst the
A/C takes power out so that the use of habitation battery charge is
slowed. This probably equates to running a UPS (that is, power in to UPS
for charging, power always out of UPS for running the device) and using a
small generator to keep feeding some power into the UPS during a power
cut. The generator may not fully meet the power demand but it slows the
rate of discharge.

This does seem to demand a lot of inefficiency, though, potentially with
the generator input being converted from 240V to 12V then back again. It
would be nicer if the battery 12V power could be used to boost the 240V
input from the generator so that most of the power comes directly in at
240V.


Bottom line is that one way may require blending two 240V inputs into a
single output, with obvious (I think) requirements to lock the wave forms
of the 240V together.

If I can manage ASCII art:

12V - 240V - Blender - A/C
240V -----------^

I think this is probably not realistic because you would have to prevent
back flow which is why there are so many issues with combining power
inputs connected to the grid. Then again, it is only like combining a
solar panel and mains (but that does allow back flow into the grid).

I need to dig out the handbook for the A/C to check all the power demands,
but meanwhile does this sound in any way feasible?

I know (2) could be met by just buying a bigger generator, but I bought
the little Honda because I could just shoehorn it into the available
storage and anything bigger is too tall/wide to fit anywhere usable.

Cheers


Dave R


--
Windows 8.1 on PCSpecialist box

Non starter. Aircon requires an immense amount of energy that you are just not going to get out of the 12V system or a battery.

You possibly could add an aircon compressor to the engine if there is space for one and all the other components of course (many engines just substitute an idler pulley instead of the compressor if the aircon option isn't chosen) but it would be hugely expensive.

Probably better all round to open the window when driving and sit outside in a deckchair when camped without leccy hookup.

Philip

+1

Automotive AC runs directly off the engine such is the power required.

Such AC can be retro-fitted but not cheap.

In article ,
Fredxxx wrote:
For a narrow boat I installed a 3kW inverter (with surge capability),
150A alternator and 4 100Ah batteries. It can be done though
challenging. I doubt you'll have the space to fit a second alternator.

Snag is many motors if rated at nominally under 13 amps take a great deal
more when starting. Not a problem for a normal mains supply - but an
inverter or even generator may not like this.

--
*I didn't like my beard at first. Then it grew on me.*

Dave Plowman London SW
To e-mail, change noise into sound.

On Fri, 26 Feb 2016 17:03:13 +0000, Fredxxx wrote:

On 26/02/2016 10:59, David wrote:
This first post is a place holder in part, so that I don't forget to
ask the question, as I usually do once I get involved in stuff during
the day.

The Motor Home has mains powered habitation air conditioning - that is
an ELectrolux slug on the roof.

As soon as we know the spec, it might be possible to assist.

So for it to work you need to be on a site with mains electricity.

There is also the issue of the power surge on start-up compared to the
power demand on normal running.

What I would like to be able to do:

(1) Run the A/C whilst driving - that would I assume involve an
inverter which could take power through the 12V electrics buffered by
the habitation batteries (unless the demand needs a direct connection
to the alternator charging circuit instead of via the charge controller
which charges the habitation batteries). This also allows starting the
engine, firing up A/C and then stopping the engine and letting the A/C
run on using the habitation batteries.

For a narrow boat I installed a 3kW inverter (with surge capability),
150A alternator and 4 100Ah batteries. It can be done though
challenging. I doubt you'll have the space to fit a second alternator.

(2) Run the A/C when away from mains power - using a small Honda
generator which might be able to meet most of the demand apart from
start-up. I am envisaging perhaps the generator pushing power into the
system whilst the A/C takes power out so that the use of habitation
battery charge is slowed. This probably equates to running a UPS (that
is, power in to UPS for charging, power always out of UPS for running
the device) and using a small generator to keep feeding some power into
the UPS during a power cut. The generator may not fully meet the power
demand but it slows the rate of discharge.

Again without knowing the rating of the air con, and the size of your
portable gen, we're in the dark.

This does seem to demand a lot of inefficiency, though, potentially
with the generator input being converted from 240V to 12V then back
again. It would be nicer if the battery 12V power could be used to
boost the 240V input from the generator so that most of the power comes
directly in at 240V.


Bottom line is that one way may require blending two 240V inputs into a
single output, with obvious (I think) requirements to lock the wave
forms of the 240V together.

You cannot "blend" 2 AC voltages.

Can nobody see my post of 12:29 today?
This contains the details, but I keep getting "as soon as we know the
specs" responses much later in the day.

With regards to blending two AC voltages, how does solar from the roof
blend into the UK grid, then? Thought it was pushed out of an inverter and
synced with mains - depending on how much you are drawing at the time you
should get all inverter (plus some pushed back up the wires) or part mains
and part solar. Or all mains if it is night time!

Or am I missing something about how solar power is delivered from the
rooftop?

Cheers

Dave R



--
Windows 8.1 on PCSpecialist box

On 26/02/2016 18:16, David wrote:
On Fri, 26 Feb 2016 17:03:13 +0000, Fredxxx wrote:

On 26/02/2016 10:59, David wrote:
This first post is a place holder in part, so that I don't forget to
ask the question, as I usually do once I get involved in stuff during
the day.

The Motor Home has mains powered habitation air conditioning - that is
an ELectrolux slug on the roof.

As soon as we know the spec, it might be possible to assist.

So for it to work you need to be on a site with mains electricity.

There is also the issue of the power surge on start-up compared to the
power demand on normal running.

What I would like to be able to do:

(1) Run the A/C whilst driving - that would I assume involve an
inverter which could take power through the 12V electrics buffered by
the habitation batteries (unless the demand needs a direct connection
to the alternator charging circuit instead of via the charge controller
which charges the habitation batteries). This also allows starting the
engine, firing up A/C and then stopping the engine and letting the A/C
run on using the habitation batteries.

For a narrow boat I installed a 3kW inverter (with surge capability),
150A alternator and 4 100Ah batteries. It can be done though
challenging. I doubt you'll have the space to fit a second alternator.

(2) Run the A/C when away from mains power - using a small Honda
generator which might be able to meet most of the demand apart from
start-up. I am envisaging perhaps the generator pushing power into the
system whilst the A/C takes power out so that the use of habitation
battery charge is slowed. This probably equates to running a UPS (that
is, power in to UPS for charging, power always out of UPS for running
the device) and using a small generator to keep feeding some power into
the UPS during a power cut. The generator may not fully meet the power
demand but it slows the rate of discharge.

Again without knowing the rating of the air con, and the size of your
portable gen, we're in the dark.

This does seem to demand a lot of inefficiency, though, potentially
with the generator input being converted from 240V to 12V then back
again. It would be nicer if the battery 12V power could be used to
boost the 240V input from the generator so that most of the power comes
directly in at 240V.


Bottom line is that one way may require blending two 240V inputs into a
single output, with obvious (I think) requirements to lock the wave
forms of the 240V together.

You cannot "blend" 2 AC voltages.

Can nobody see my post of 12:29 today?
This contains the details, but I keep getting "as soon as we know the
specs" responses much later in the day.

My apologies.

That sort of power is doable; 4 a 100Ah batteries at 12V at 750W, taking
into inverter efficiencies and battery characteristics might give you 2
or 3 hours at most. Your biggest problem is how to charge them back up!
I believe a generator would be a better solution.

With regards to blending two AC voltages, how does solar from the roof
blend into the UK grid, then? Thought it was pushed out of an inverter and
synced with mains - depending on how much you are drawing at the time you
should get all inverter (plus some pushed back up the wires) or part mains
and part solar. Or all mains if it is night time!

You are converting the DC power from the PVs into AC using an inverter.
They are purpose built. You cannot just join 2 AC sources, it either
requires some form of inverter or "manual" synchronisation of a
generator to a source. I doubt the inverter will survive as it is most
likely a modified sine wave type.

Or am I missing something about how solar power is delivered from the
rooftop?

Cheers

Dave R

On Friday, 26 February 2016 18:16:39 UTC, David wrote:
On Fri, 26 Feb 2016 17:03:13 +0000, Fredxxx wrote:

On 26/02/2016 10:59, David wrote:
This first post is a place holder in part, so that I don't forget to
ask the question, as I usually do once I get involved in stuff during
the day.

The Motor Home has mains powered habitation air conditioning - that is
an ELectrolux slug on the roof.

As soon as we know the spec, it might be possible to assist.

So for it to work you need to be on a site with mains electricity.

There is also the issue of the power surge on start-up compared to the
power demand on normal running.

What I would like to be able to do:

(1) Run the A/C whilst driving - that would I assume involve an
inverter which could take power through the 12V electrics buffered by
the habitation batteries (unless the demand needs a direct connection
to the alternator charging circuit instead of via the charge controller
which charges the habitation batteries). This also allows starting the
engine, firing up A/C and then stopping the engine and letting the A/C
run on using the habitation batteries.

For a narrow boat I installed a 3kW inverter (with surge capability),
150A alternator and 4 100Ah batteries. It can be done though
challenging. I doubt you'll have the space to fit a second alternator.

(2) Run the A/C when away from mains power - using a small Honda
generator which might be able to meet most of the demand apart from
start-up. I am envisaging perhaps the generator pushing power into the
system whilst the A/C takes power out so that the use of habitation
battery charge is slowed. This probably equates to running a UPS (that
is, power in to UPS for charging, power always out of UPS for running
the device) and using a small generator to keep feeding some power into
the UPS during a power cut. The generator may not fully meet the power
demand but it slows the rate of discharge.

Again without knowing the rating of the air con, and the size of your
portable gen, we're in the dark.

This does seem to demand a lot of inefficiency, though, potentially
with the generator input being converted from 240V to 12V then back
again. It would be nicer if the battery 12V power could be used to
boost the 240V input from the generator so that most of the power comes
directly in at 240V.


Bottom line is that one way may require blending two 240V inputs into a
single output, with obvious (I think) requirements to lock the wave
forms of the 240V together.

You cannot "blend" 2 AC voltages.

Can nobody see my post of 12:29 today?
This contains the details, but I keep getting "as soon as we know the
specs" responses much later in the day.

With regards to blending two AC voltages, how does solar from the roof
blend into the UK grid, then? Thought it was pushed out of an inverter and
synced with mains - depending on how much you are drawing at the time you
should get all inverter (plus some pushed back up the wires) or part mains
and part solar. Or all mains if it is night time!

Or am I missing something about how solar power is delivered from the
rooftop?


Solar power is DC.
It is linked to the mains by means of a grid tie inverter.
The mains AC is used to "create" synchronised AC from the DC.
https://en.wikipedia.org/wiki/Grid-tie_inverter

Synchronisng two separate AC supplies is quite another (more difficult) matter.

On Saturday, 27 February 2016 07:46:31 UTC, harry wrote:
On Friday, 26 February 2016 18:16:39 UTC, David wrote:
On Fri, 26 Feb 2016 17:03:13 +0000, Fredxxx wrote:

On 26/02/2016 10:59, David wrote:
This first post is a place holder in part, so that I don't forget to
ask the question, as I usually do once I get involved in stuff during
the day.

The Motor Home has mains powered habitation air conditioning - that is
an ELectrolux slug on the roof.

As soon as we know the spec, it might be possible to assist.

So for it to work you need to be on a site with mains electricity.

There is also the issue of the power surge on start-up compared to the
power demand on normal running.

What I would like to be able to do:

(1) Run the A/C whilst driving - that would I assume involve an
inverter which could take power through the 12V electrics buffered by
the habitation batteries (unless the demand needs a direct connection
to the alternator charging circuit instead of via the charge controller
which charges the habitation batteries). This also allows starting the
engine, firing up A/C and then stopping the engine and letting the A/C
run on using the habitation batteries.

For a narrow boat I installed a 3kW inverter (with surge capability),
150A alternator and 4 100Ah batteries. It can be done though
challenging. I doubt you'll have the space to fit a second alternator.

(2) Run the A/C when away from mains power - using a small Honda
generator which might be able to meet most of the demand apart from
start-up. I am envisaging perhaps the generator pushing power into the
system whilst the A/C takes power out so that the use of habitation
battery charge is slowed. This probably equates to running a UPS (that
is, power in to UPS for charging, power always out of UPS for running
the device) and using a small generator to keep feeding some power into
the UPS during a power cut. The generator may not fully meet the power
demand but it slows the rate of discharge.

Again without knowing the rating of the air con, and the size of your
portable gen, we're in the dark.

This does seem to demand a lot of inefficiency, though, potentially
with the generator input being converted from 240V to 12V then back
again. It would be nicer if the battery 12V power could be used to
boost the 240V input from the generator so that most of the power comes
directly in at 240V.


Bottom line is that one way may require blending two 240V inputs into a
single output, with obvious (I think) requirements to lock the wave
forms of the 240V together.

You cannot "blend" 2 AC voltages.

Can nobody see my post of 12:29 today?
This contains the details, but I keep getting "as soon as we know the
specs" responses much later in the day.

With regards to blending two AC voltages, how does solar from the roof
blend into the UK grid, then? Thought it was pushed out of an inverter and
synced with mains - depending on how much you are drawing at the time you
should get all inverter (plus some pushed back up the wires) or part mains
and part solar. Or all mains if it is night time!

Or am I missing something about how solar power is delivered from the
rooftop?


Solar power is DC.
It is linked to the mains by means of a grid tie inverter.
The mains AC is used to "create" synchronised AC from the DC.
https://en.wikipedia.org/wiki/Grid-tie_inverter

Synchronisng two separate AC supplies is quite another (more difficult) matter.

Chill!

On Fri, 26 Feb 2016 23:46:27 -0800, harry wrote:

On Friday, 26 February 2016 18:16:39 UTC, David wrote:
On Fri, 26 Feb 2016 17:03:13 +0000, Fredxxx wrote:

On 26/02/2016 10:59, David wrote:
This first post is a place holder in part, so that I don't forget to
ask the question, as I usually do once I get involved in stuff
during the day.

The Motor Home has mains powered habitation air conditioning - that
is an ELectrolux slug on the roof.

As soon as we know the spec, it might be possible to assist.

So for it to work you need to be on a site with mains electricity.

There is also the issue of the power surge on start-up compared to
the power demand on normal running.

What I would like to be able to do:

(1) Run the A/C whilst driving - that would I assume involve an
inverter which could take power through the 12V electrics buffered
by the habitation batteries (unless the demand needs a direct
connection to the alternator charging circuit instead of via the
charge controller which charges the habitation batteries). This also
allows starting the engine, firing up A/C and then stopping the
engine and letting the A/C run on using the habitation batteries.

For a narrow boat I installed a 3kW inverter (with surge capability),
150A alternator and 4 100Ah batteries. It can be done though
challenging. I doubt you'll have the space to fit a second
alternator.

(2) Run the A/C when away from mains power - using a small Honda
generator which might be able to meet most of the demand apart from
start-up. I am envisaging perhaps the generator pushing power into
the system whilst the A/C takes power out so that the use of
habitation battery charge is slowed. This probably equates to
running a UPS (that is, power in to UPS for charging, power always
out of UPS for running the device) and using a small generator to
keep feeding some power into the UPS during a power cut. The
generator may not fully meet the power demand but it slows the rate
of discharge.

Again without knowing the rating of the air con, and the size of your
portable gen, we're in the dark.

This does seem to demand a lot of inefficiency, though, potentially
with the generator input being converted from 240V to 12V then back
again. It would be nicer if the battery 12V power could be used to
boost the 240V input from the generator so that most of the power
comes directly in at 240V.


Bottom line is that one way may require blending two 240V inputs
into a single output, with obvious (I think) requirements to lock
the wave forms of the 240V together.

You cannot "blend" 2 AC voltages.

Can nobody see my post of 12:29 today?
This contains the details, but I keep getting "as soon as we know the
specs" responses much later in the day.

With regards to blending two AC voltages, how does solar from the roof
blend into the UK grid, then? Thought it was pushed out of an inverter
and synced with mains - depending on how much you are drawing at the
time you should get all inverter (plus some pushed back up the wires)
or part mains and part solar. Or all mains if it is night time!

Or am I missing something about how solar power is delivered from the
rooftop?


Solar power is DC.
It is linked to the mains by means of a grid tie inverter.
The mains AC is used to "create" synchronised AC from the DC.
https://en.wikipedia.org/wiki/Grid-tie_inverter

Synchronisng two separate AC supplies is quite another (more difficult)
matter.

However, in the scenario I am exploring I was looking at blending a source
of 240V AC with the output of an inverter driven by 12V batteries.

So in this case a "grid tie inverter" might do the trick. That is,
blending the output from an inverter and the output from 240V mains.
However I think that this is likely to be far too expensive (from memory
of solar installation quotes) for the application I was considering.

I know that the power demand from the A/C is likely to rule it out in my
specific case but I am now exploring general principles. For instance if
you want to run a microwave or hair dryer which is just over the power
output of your genny.

It does raise the possibility of a very limited solar system (couple of
panels on the roof of a motor home) being able to boost the output of some
of the more flaky (especially continental) on site power supplies on sunny
days.

Cheers

Dave R


--
Windows 8.1 on PCSpecialist box

On Fri, 26 Feb 2016 18:42:42 +0000, Fredxxx wrote:

On 26/02/2016 18:16, David wrote:
On Fri, 26 Feb 2016 17:03:13 +0000, Fredxxx wrote:

On 26/02/2016 10:59, David wrote:
This first post is a place holder in part, so that I don't forget to
ask the question, as I usually do once I get involved in stuff during
the day.

The Motor Home has mains powered habitation air conditioning - that
is an ELectrolux slug on the roof.

As soon as we know the spec, it might be possible to assist.

So for it to work you need to be on a site with mains electricity.

There is also the issue of the power surge on start-up compared to
the power demand on normal running.

What I would like to be able to do:

(1) Run the A/C whilst driving - that would I assume involve an
inverter which could take power through the 12V electrics buffered by
the habitation batteries (unless the demand needs a direct connection
to the alternator charging circuit instead of via the charge
controller which charges the habitation batteries). This also allows
starting the engine, firing up A/C and then stopping the engine and
letting the A/C run on using the habitation batteries.

For a narrow boat I installed a 3kW inverter (with surge capability),
150A alternator and 4 100Ah batteries. It can be done though
challenging. I doubt you'll have the space to fit a second alternator.

(2) Run the A/C when away from mains power - using a small Honda
generator which might be able to meet most of the demand apart from
start-up. I am envisaging perhaps the generator pushing power into
the system whilst the A/C takes power out so that the use of
habitation battery charge is slowed. This probably equates to running
a UPS (that is, power in to UPS for charging, power always out of UPS
for running the device) and using a small generator to keep feeding
some power into the UPS during a power cut. The generator may not
fully meet the power demand but it slows the rate of discharge.

Again without knowing the rating of the air con, and the size of your
portable gen, we're in the dark.

This does seem to demand a lot of inefficiency, though, potentially
with the generator input being converted from 240V to 12V then back
again. It would be nicer if the battery 12V power could be used to
boost the 240V input from the generator so that most of the power
comes directly in at 240V.


Bottom line is that one way may require blending two 240V inputs into
a single output, with obvious (I think) requirements to lock the wave
forms of the 240V together.

You cannot "blend" 2 AC voltages.

Can nobody see my post of 12:29 today?
This contains the details, but I keep getting "as soon as we know the
specs" responses much later in the day.

My apologies.

That sort of power is doable; 4 a 100Ah batteries at 12V at 750W, taking
into inverter efficiencies and battery characteristics might give you 2
or 3 hours at most. Your biggest problem is how to charge them back up!
I believe a generator would be a better solution.

With regards to blending two AC voltages, how does solar from the roof
blend into the UK grid, then? Thought it was pushed out of an inverter
and synced with mains - depending on how much you are drawing at the
time you should get all inverter (plus some pushed back up the wires)
or part mains and part solar. Or all mains if it is night time!

You are converting the DC power from the PVs into AC using an inverter.
They are purpose built. You cannot just join 2 AC sources, it either
requires some form of inverter or "manual" synchronisation of a
generator to a source. I doubt the inverter will survive as it is most
likely a modified sine wave type.

Or am I missing something about how solar power is delivered from the
rooftop?

Some obvious confusion (see my response to Harry).

When I am talking about blending two AC sources I am talking about having
an external 240V supply to the motor home (generator or mains) and an
internal one from an inverter.

Which seems to be much the same as having solar power and mains joined
together, which also involves an inverter.

In the motor home I have 2 * 110Ah leisure batteries so (assuming the
information from the handbook is correct) I might be able to handle the
running load but possibly not the starting load. Which was more or less
where I came in (I think).

Bottom line is the question "Can you boost the 240V supply to a motor home
by using a grid tied inverter to feed in battery and/or solar power from
on board sources?"

The answer may be "Yes, but too expensive.".

Cheers

Dave R




--
Windows 8.1 on PCSpecialist box

On Friday, February 26, 2016 at 10:59:10 AM UTC, David wrote:
This first post is a place holder in part, so that I don't forget to ask
the question, as I usually do once I get involved in stuff during the day.

The Motor Home has mains powered habitation air conditioning - that is an
ELectrolux slug on the roof.

So for it to work you need to be on a site with mains electricity.

There is also the issue of the power surge on start-up compared to the
power demand on normal running.

What I would like to be able to do:

(1) Run the A/C whilst driving - that would I assume involve an inverter
which could take power through the 12V electrics buffered by the
habitation batteries (unless the demand needs a direct connection to the
alternator charging circuit instead of via the charge controller which
charges the habitation batteries). This also allows starting the engine,
firing up A/C and then stopping the engine and letting the A/C run on
using the habitation batteries.

(2) Run the A/C when away from mains power - using a small Honda generator
which might be able to meet most of the demand apart from start-up. I am
envisaging perhaps the generator pushing power into the system whilst the
A/C takes power out so that the use of habitation battery charge is
slowed. This probably equates to running a UPS (that is, power in to UPS
for charging, power always out of UPS for running the device) and using a
small generator to keep feeding some power into the UPS during a power
cut. The generator may not fully meet the power demand but it slows the
rate of discharge.

This does seem to demand a lot of inefficiency, though, potentially with
the generator input being converted from 240V to 12V then back again. It
would be nicer if the battery 12V power could be used to boost the 240V
input from the generator so that most of the power comes directly in at
240V.


Bottom line is that one way may require blending two 240V inputs into a
single output, with obvious (I think) requirements to lock the wave forms
of the 240V together.

If I can manage ASCII art:

12V - 240V - Blender - A/C
240V -----------^

I think this is probably not realistic because you would have to prevent
back flow which is why there are so many issues with combining power
inputs connected to the grid. Then again, it is only like combining a
solar panel and mains (but that does allow back flow into the grid).

I need to dig out the handbook for the A/C to check all the power demands,
but meanwhile does this sound in any way feasible?

I know (2) could be met by just buying a bigger generator, but I bought
the little Honda because I could just shoehorn it into the available
storage and anything bigger is too tall/wide to fit anywhere usable.

Cheers


Dave R


--
Windows 8.1 on PCSpecialist box


You need to get out more.Really.

Mary

In article ,
David writes:
The handbook is not entirely clear. *shock*

The unit is an Electrolux Blizzard B1500.

The technical data includes:

Cooling consumption 715 watts
Heating capacity 800 watts.

Looking at the manual it seems that the unit is not designed to be used as
a heat pump when blowing warm air (as you might expect) but has a small
heating element - so from the data it looks to be an 800 watt fan heater
(less a small deduction for the power to turn the fan).

The 715 watts may be the maximum start up for the compressor, or may be
the average after the compressor has started.

Startup will be much more.
120W fridge/freezer compressor draws around 3kW starting
(and 3kW for longer when trying to start with a locked rotor
due to trying to start too quickly after stopping).

My home aircon is 1200W power consumption, and that draws
over 4kW (max my power meter reads) when trying to start
against a locked rotor for a few seconds before giving up
and retrying after a timeout. The momentary starting load
when it does start properly will be the same, but for too
short a time for normal power meters to measure.

Assuming that the real draw from the A/C is 715W then the generator
couldn't run it stand alone, but could supply a reasonable percentage of
the power.

You can't combine the output of multiple AC power sources
unless they are explicitly designed to sync their output
waveforms (a bit like solar panel inverters).

Also, when sizing power sources for loads like this, you
need to use the VA rating, not the watts rating. (A decent
power meter will tell you the VA load - it will be more
than the power consumption.) You probably also want a
pure sine wave inverter - inductives load often don't
like the stepped output which most inverters produce.
(Pure sine wave inverters are now much more viable than
they used to be, most being class D amplifier outputs,
i.e. switched-mode power supplies at a much higher
frequency to generate the sine wave output.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On Sat, 27 Feb 2016 05:26:39 -0800, Mary Fisher wrote:

On Friday, February 26, 2016 at 10:59:10 AM UTC, David wrote:
This first post is a place holder in part, so that I don't forget to
ask the question, as I usually do once I get involved in stuff during
the day.

The Motor Home has mains powered habitation air conditioning - that is
an ELectrolux slug on the roof.

So for it to work you need to be on a site with mains electricity.

There is also the issue of the power surge on start-up compared to the
power demand on normal running.

What I would like to be able to do:

(1) Run the A/C whilst driving - that would I assume involve an
inverter which could take power through the 12V electrics buffered by
the habitation batteries (unless the demand needs a direct connection
to the alternator charging circuit instead of via the charge controller
which charges the habitation batteries). This also allows starting the
engine, firing up A/C and then stopping the engine and letting the A/C
run on using the habitation batteries.

(2) Run the A/C when away from mains power - using a small Honda
generator which might be able to meet most of the demand apart from
start-up. I am envisaging perhaps the generator pushing power into the
system whilst the A/C takes power out so that the use of habitation
battery charge is slowed. This probably equates to running a UPS (that
is, power in to UPS for charging, power always out of UPS for running
the device) and using a small generator to keep feeding some power into
the UPS during a power cut. The generator may not fully meet the power
demand but it slows the rate of discharge.

This does seem to demand a lot of inefficiency, though, potentially
with the generator input being converted from 240V to 12V then back
again. It would be nicer if the battery 12V power could be used to
boost the 240V input from the generator so that most of the power comes
directly in at 240V.


Bottom line is that one way may require blending two 240V inputs into a
single output, with obvious (I think) requirements to lock the wave
forms of the 240V together.

If I can manage ASCII art:

12V - 240V - Blender - A/C 240V -----------^

I think this is probably not realistic because you would have to
prevent back flow which is why there are so many issues with combining
power inputs connected to the grid. Then again, it is only like
combining a solar panel and mains (but that does allow back flow into
the grid).

I need to dig out the handbook for the A/C to check all the power
demands,
but meanwhile does this sound in any way feasible?

I know (2) could be met by just buying a bigger generator, but I bought
the little Honda because I could just shoehorn it into the available
storage and anything bigger is too tall/wide to fit anywhere usable.

Cheers


Dave R


--
Windows 8.1 on PCSpecialist box


You need to get out more.Really.

Mary

Good call.
Perhaps I should buy a motor home?
Oh, wait.......



--
Windows 8.1 on PCSpecialist box

On 26/02/2016 17:58, Dave Plowman (News) wrote:


Snag is many motors if rated at nominally under 13 amps take a great deal
more when starting. Not a problem for a normal mains supply - but an
inverter or even generator may not like this.


Yes, indeed - and a 13A fuse will stand a considerable over-load without
blowing provided it doesn't last very long.

I remember doing an experiment a few years ago to see whether my 2kW
Honda generator would power some device or other. [Can't remember
whether it was a compressor, a table saw or a pressure washer - but it
was something rated at way below 2kW]

Whatever, it was, the genny wouldn't start it - it just groaned and went
into some sort of 'limp home' mode, and had to be reset by shutting it
down and re-starting it before it would run normally again.
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

Get an awning and sleep outside.
Enjoy the outdoors and the weather.
Go sightseeing.
Drink wine.
Remember that the more you spend on kit, the more you loose on
depreciation.
Or go in a hotel with air conditioning.

In article 2,
DerbyBorn wrote:
Get an awning and sleep outside.
Enjoy the outdoors and the weather.
Go sightseeing.
Drink wine.
Remember that the more you spend on kit, the more you loose on
depreciation.
Or go in a hotel with air conditioning.

Must admit I don't share the love of AC many have. Perhaps it's because I
was born in the NE of Scotland, where it's more likely cold than hot, so
loved the odd hot day.

Both my cars have AC, but almost never used. I'd rather open the roof and
windows and enjoy a hot day. ;-)

--
*ONE NICE THING ABOUT EGOTISTS: THEY DON'T TALK ABOUT OTHER PEOPLE.

Dave Plowman London SW
To e-mail, change noise into sound.

On Sat, 27 Feb 2016 15:59:27 +0000, Dave Plowman (News) wrote:

In article 2,
DerbyBorn wrote:
Get an awning and sleep outside.
Enjoy the outdoors and the weather.
Go sightseeing.
Drink wine.
Remember that the more you spend on kit, the more you loose on
depreciation.
Or go in a hotel with air conditioning.

Must admit I don't share the love of AC many have. Perhaps it's because
I was born in the NE of Scotland, where it's more likely cold than hot,
so loved the odd hot day.

Both my cars have AC, but almost never used. I'd rather open the roof
and windows and enjoy a hot day. ;-)

Self and partner can't cope with temperatures much above 30C without going
into meltdown.

We don't use the aircon very often (once every year or so) but it is
reassuring to have it.

Some people love high temperatures; others find that they can't cope and
get very unhappy indeed.

Cheers


Dave R

--
Windows 8.1 on PCSpecialist box

On Saturday, 27 February 2016 12:27:16 UTC, David wrote:
On Fri, 26 Feb 2016 23:46:27 -0800, harry wrote:

On Friday, 26 February 2016 18:16:39 UTC, David wrote:
On Fri, 26 Feb 2016 17:03:13 +0000, Fredxxx wrote:

On 26/02/2016 10:59, David wrote:
This first post is a place holder in part, so that I don't forget to
ask the question, as I usually do once I get involved in stuff
during the day.

The Motor Home has mains powered habitation air conditioning - that
is an ELectrolux slug on the roof.

As soon as we know the spec, it might be possible to assist.

So for it to work you need to be on a site with mains electricity.

There is also the issue of the power surge on start-up compared to
the power demand on normal running.

What I would like to be able to do:

(1) Run the A/C whilst driving - that would I assume involve an
inverter which could take power through the 12V electrics buffered
by the habitation batteries (unless the demand needs a direct
connection to the alternator charging circuit instead of via the
charge controller which charges the habitation batteries). This also
allows starting the engine, firing up A/C and then stopping the
engine and letting the A/C run on using the habitation batteries.

For a narrow boat I installed a 3kW inverter (with surge capability),
150A alternator and 4 100Ah batteries. It can be done though
challenging. I doubt you'll have the space to fit a second
alternator.

(2) Run the A/C when away from mains power - using a small Honda
generator which might be able to meet most of the demand apart from
start-up. I am envisaging perhaps the generator pushing power into
the system whilst the A/C takes power out so that the use of
habitation battery charge is slowed. This probably equates to
running a UPS (that is, power in to UPS for charging, power always
out of UPS for running the device) and using a small generator to
keep feeding some power into the UPS during a power cut. The
generator may not fully meet the power demand but it slows the rate
of discharge.

Again without knowing the rating of the air con, and the size of your
portable gen, we're in the dark.

This does seem to demand a lot of inefficiency, though, potentially
with the generator input being converted from 240V to 12V then back
again. It would be nicer if the battery 12V power could be used to
boost the 240V input from the generator so that most of the power
comes directly in at 240V.


Bottom line is that one way may require blending two 240V inputs
into a single output, with obvious (I think) requirements to lock
the wave forms of the 240V together.

You cannot "blend" 2 AC voltages.

Can nobody see my post of 12:29 today?
This contains the details, but I keep getting "as soon as we know the
specs" responses much later in the day.

With regards to blending two AC voltages, how does solar from the roof
blend into the UK grid, then? Thought it was pushed out of an inverter
and synced with mains - depending on how much you are drawing at the
time you should get all inverter (plus some pushed back up the wires)
or part mains and part solar. Or all mains if it is night time!

Or am I missing something about how solar power is delivered from the
rooftop?


Solar power is DC.
It is linked to the mains by means of a grid tie inverter.
The mains AC is used to "create" synchronised AC from the DC.
https://en.wikipedia.org/wiki/Grid-tie_inverter

Synchronisng two separate AC supplies is quite another (more difficult)
matter.

However, in the scenario I am exploring I was looking at blending a source
of 240V AC with the output of an inverter driven by 12V batteries.

So in this case a "grid tie inverter" might do the trick. That is,
blending the output from an inverter and the output from 240V mains.
However I think that this is likely to be far too expensive (from memory
of solar installation quotes) for the application I was considering.

I know that the power demand from the A/C is likely to rule it out in my
specific case but I am now exploring general principles. For instance if
you want to run a microwave or hair dryer which is just over the power
output of your genny.

It does raise the possibility of a very limited solar system (couple of
panels on the roof of a motor home) being able to boost the output of some
of the more flaky (especially continental) on site power supplies on sunny
days.

Cheers

Dave R


--
Windows 8.1 on PCSpecialist box

It's just not technically feasible.
The grid tie inverter runs at 400 odd volts
You need to have conventional AC fitted to the engine of your vehicle.
The only practical solution.

On Sat, 27 Feb 2016 08:38:15 -0800, harry wrote:

On Saturday, 27 February 2016 12:27:16 UTC, David wrote:
On Fri, 26 Feb 2016 23:46:27 -0800, harry wrote:

On Friday, 26 February 2016 18:16:39 UTC, David wrote:
On Fri, 26 Feb 2016 17:03:13 +0000, Fredxxx wrote:

On 26/02/2016 10:59, David wrote:
This first post is a place holder in part, so that I don't forget
to ask the question, as I usually do once I get involved in stuff
during the day.

The Motor Home has mains powered habitation air conditioning -
that is an ELectrolux slug on the roof.

As soon as we know the spec, it might be possible to assist.

So for it to work you need to be on a site with mains
electricity.

There is also the issue of the power surge on start-up compared
to the power demand on normal running.

What I would like to be able to do:

(1) Run the A/C whilst driving - that would I assume involve an
inverter which could take power through the 12V electrics
buffered by the habitation batteries (unless the demand needs a
direct connection to the alternator charging circuit instead of
via the charge controller which charges the habitation
batteries). This also allows starting the engine, firing up A/C
and then stopping the engine and letting the A/C run on using the
habitation batteries.

For a narrow boat I installed a 3kW inverter (with surge
capability),
150A alternator and 4 100Ah batteries. It can be done though
challenging. I doubt you'll have the space to fit a second
alternator.

(2) Run the A/C when away from mains power - using a small Honda
generator which might be able to meet most of the demand apart
from start-up. I am envisaging perhaps the generator pushing
power into the system whilst the A/C takes power out so that the
use of habitation battery charge is slowed. This probably equates
to running a UPS (that is, power in to UPS for charging, power
always out of UPS for running the device) and using a small
generator to keep feeding some power into the UPS during a power
cut. The generator may not fully meet the power demand but it
slows the rate of discharge.

Again without knowing the rating of the air con, and the size of
your portable gen, we're in the dark.

This does seem to demand a lot of inefficiency, though,
potentially with the generator input being converted from 240V to
12V then back again. It would be nicer if the battery 12V power
could be used to boost the 240V input from the generator so that
most of the power comes directly in at 240V.


Bottom line is that one way may require blending two 240V inputs
into a single output, with obvious (I think) requirements to lock
the wave forms of the 240V together.

You cannot "blend" 2 AC voltages.

Can nobody see my post of 12:29 today?
This contains the details, but I keep getting "as soon as we know
the specs" responses much later in the day.

With regards to blending two AC voltages, how does solar from the
roof blend into the UK grid, then? Thought it was pushed out of an
inverter and synced with mains - depending on how much you are
drawing at the time you should get all inverter (plus some pushed
back up the wires) or part mains and part solar. Or all mains if it
is night time!

Or am I missing something about how solar power is delivered from
the rooftop?


Solar power is DC.
It is linked to the mains by means of a grid tie inverter.
The mains AC is used to "create" synchronised AC from the DC.
https://en.wikipedia.org/wiki/Grid-tie_inverter

Synchronisng two separate AC supplies is quite another (more
difficult)
matter.

However, in the scenario I am exploring I was looking at blending a
source of 240V AC with the output of an inverter driven by 12V
batteries.

So in this case a "grid tie inverter" might do the trick. That is,
blending the output from an inverter and the output from 240V mains.
However I think that this is likely to be far too expensive (from
memory of solar installation quotes) for the application I was
considering.

I know that the power demand from the A/C is likely to rule it out in
my specific case but I am now exploring general principles. For
instance if you want to run a microwave or hair dryer which is just
over the power output of your genny.

It does raise the possibility of a very limited solar system (couple of
panels on the roof of a motor home) being able to boost the output of
some of the more flaky (especially continental) on site power supplies
on sunny days.

Cheers

Dave R


--
Windows 8.1 on PCSpecialist box

It's just not technically feasible.
The grid tie inverter runs at 400 odd volts You need to have
conventional AC fitted to the engine of your vehicle.
The only practical solution.

As already stated I have conventional A/C fitted to the engine of my
vehicle.

Additionally, the exhaust pipe exits into the awning area, so running the
engine when the van is set up with the awning is not a good plan.

This is looking at ways to use the habitation A/C which is already fitted.

However the information that it requires a 400 volt grid tie inverter for
a solar system does rule it out for a motor home.

Cheers

Dave R





--
Windows 8.1 on PCSpecialist box

In article ,
David wrote:
Both my cars have AC, but almost never used. I'd rather open the roof
and windows and enjoy a hot day. ;-)

Self and partner can't cope with temperatures much above 30C without
going into meltdown.

Very rare to have a true temperature above 30c in the UK. The inside of a
car in the sun, yes. But opening the windows on the move soon cools it
down to ambient.

We don't use the aircon very often (once every year or so) but it is
reassuring to have it.

I have used it to cool the car down before getting in.

Some people love high temperatures; others find that they can't cope and
get very unhappy indeed.

True. But we're in the UK. ;-)

--
*WHY ARE HEMORRHOIDS CALLED "HEMORRHOIDS" INSTEAD OF "ASTEROIDS"?

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article 2,
DerbyBorn wrote:
Get an awning and sleep outside.
Enjoy the outdoors and the weather.
Go sightseeing.
Drink wine.
Remember that the more you spend on kit, the more you loose on
depreciation.
Or go in a hotel with air conditioning.

Must admit I don't share the love of AC many have. Perhaps it's because I
was born in the NE of Scotland, where it's more likely cold than hot, so
loved the odd hot day.

Both my cars have AC, but almost never used. I'd rather open the roof and
windows and enjoy a hot day. ;-)

I don’t have a roof that opens but do prefer to open the windows.

But when its 110F prefer to use the AC.

On 27/02/2016 16:34, David wrote:
Self and partner can't cope with temperatures much above 30C without going
into meltdown.

Partner has issue which means she gets severe pain in higher
temperatures. Usual maximum in our house is 17 degrees - much more is
not acceptable.

--
Rod

David wrote:
On Sat, 27 Feb 2016 08:38:15 -0800, harry wrote:

On Saturday, 27 February 2016 12:27:16 UTC, David wrote:
On Fri, 26 Feb 2016 23:46:27 -0800, harry wrote:

On Friday, 26 February 2016 18:16:39 UTC, David wrote:
On Fri, 26 Feb 2016 17:03:13 +0000, Fredxxx wrote:

On 26/02/2016 10:59, David wrote:
This first post is a place holder in part, so that I don't forget
to ask the question, as I usually do once I get involved in stuff
during the day.

The Motor Home has mains powered habitation air conditioning -
that is an ELectrolux slug on the roof.

As soon as we know the spec, it might be possible to assist.

So for it to work you need to be on a site with mains
electricity.

There is also the issue of the power surge on start-up compared
to the power demand on normal running.

What I would like to be able to do:

(1) Run the A/C whilst driving - that would I assume involve an
inverter which could take power through the 12V electrics
buffered by the habitation batteries (unless the demand needs a
direct connection to the alternator charging circuit instead of
via the charge controller which charges the habitation
batteries). This also allows starting the engine, firing up A/C
and then stopping the engine and letting the A/C run on using the
habitation batteries.

For a narrow boat I installed a 3kW inverter (with surge
capability),
150A alternator and 4 100Ah batteries. It can be done though
challenging. I doubt you'll have the space to fit a second
alternator.

(2) Run the A/C when away from mains power - using a small Honda
generator which might be able to meet most of the demand apart
from start-up. I am envisaging perhaps the generator pushing
power into the system whilst the A/C takes power out so that the
use of habitation battery charge is slowed. This probably equates
to running a UPS (that is, power in to UPS for charging, power
always out of UPS for running the device) and using a small
generator to keep feeding some power into the UPS during a power
cut. The generator may not fully meet the power demand but it
slows the rate of discharge.

Again without knowing the rating of the air con, and the size of
your portable gen, we're in the dark.

This does seem to demand a lot of inefficiency, though,
potentially with the generator input being converted from 240V to
12V then back again. It would be nicer if the battery 12V power
could be used to boost the 240V input from the generator so that
most of the power comes directly in at 240V.


Bottom line is that one way may require blending two 240V inputs
into a single output, with obvious (I think) requirements to lock
the wave forms of the 240V together.

You cannot "blend" 2 AC voltages.

Can nobody see my post of 12:29 today?
This contains the details, but I keep getting "as soon as we know
the specs" responses much later in the day.

With regards to blending two AC voltages, how does solar from the
roof blend into the UK grid, then? Thought it was pushed out of an
inverter and synced with mains - depending on how much you are
drawing at the time you should get all inverter (plus some pushed
back up the wires) or part mains and part solar. Or all mains if it
is night time!

Or am I missing something about how solar power is delivered from
the rooftop?


Solar power is DC.
It is linked to the mains by means of a grid tie inverter.
The mains AC is used to "create" synchronised AC from the DC.
https://en.wikipedia.org/wiki/Grid-tie_inverter

Synchronisng two separate AC supplies is quite another (more
difficult)
matter.

However, in the scenario I am exploring I was looking at blending a
source of 240V AC with the output of an inverter driven by 12V
batteries.

So in this case a "grid tie inverter" might do the trick. That is,
blending the output from an inverter and the output from 240V mains.
However I think that this is likely to be far too expensive (from
memory of solar installation quotes) for the application I was
considering.

I know that the power demand from the A/C is likely to rule it out in
my specific case but I am now exploring general principles. For
instance if you want to run a microwave or hair dryer which is just
over the power output of your genny.

It does raise the possibility of a very limited solar system (couple of
panels on the roof of a motor home) being able to boost the output of
some of the more flaky (especially continental) on site power supplies
on sunny days.

Cheers

Dave R


--
Windows 8.1 on PCSpecialist box

It's just not technically feasible.
The grid tie inverter runs at 400 odd volts You need to have
conventional AC fitted to the engine of your vehicle.
The only practical solution.

As already stated I have conventional A/C fitted to the engine of my
vehicle.

Additionally, the exhaust pipe exits into the awning area, so running the
engine when the van is set up with the awning is not a good plan.

This is looking at ways to use the habitation A/C which is already fitted.

However the information that it requires a 400 volt grid tie inverter for
a solar system does rule it out for a motor home.

Cheers

Dave R





Add to that, even if you provided the Grid Tie inverter with enough
battery volts, you will possibly be disappointed that it will not give
any output when the grid is not present.

In article ,
polygonum wrote:
On 27/02/2016 16:34, David wrote:
Self and partner can't cope with temperatures much above 30C without
going into meltdown.

Partner has issue which means she gets severe pain in higher
temperatures. Usual maximum in our house is 17 degrees - much more is
not acceptable.

Oh. That must make life pretty difficult.

--
*Real men don't waste their hormones growing hair

Dave Plowman London SW
To e-mail, change noise into sound.

On Saturday, 27 February 2016 16:49:22 UTC, David wrote:
On Sat, 27 Feb 2016 08:38:15 -0800, harry wrote:

On Saturday, 27 February 2016 12:27:16 UTC, David wrote:
On Fri, 26 Feb 2016 23:46:27 -0800, harry wrote:

On Friday, 26 February 2016 18:16:39 UTC, David wrote:
On Fri, 26 Feb 2016 17:03:13 +0000, Fredxxx wrote:

On 26/02/2016 10:59, David wrote:
This first post is a place holder in part, so that I don't forget
to ask the question, as I usually do once I get involved in stuff
during the day.

The Motor Home has mains powered habitation air conditioning -
that is an ELectrolux slug on the roof.

As soon as we know the spec, it might be possible to assist.

So for it to work you need to be on a site with mains
electricity.

There is also the issue of the power surge on start-up compared
to the power demand on normal running.

What I would like to be able to do:

(1) Run the A/C whilst driving - that would I assume involve an
inverter which could take power through the 12V electrics
buffered by the habitation batteries (unless the demand needs a
direct connection to the alternator charging circuit instead of
via the charge controller which charges the habitation
batteries). This also allows starting the engine, firing up A/C
and then stopping the engine and letting the A/C run on using the
habitation batteries.

For a narrow boat I installed a 3kW inverter (with surge
capability),
150A alternator and 4 100Ah batteries. It can be done though
challenging. I doubt you'll have the space to fit a second
alternator.

(2) Run the A/C when away from mains power - using a small Honda
generator which might be able to meet most of the demand apart
from start-up. I am envisaging perhaps the generator pushing
power into the system whilst the A/C takes power out so that the
use of habitation battery charge is slowed. This probably equates
to running a UPS (that is, power in to UPS for charging, power
always out of UPS for running the device) and using a small
generator to keep feeding some power into the UPS during a power
cut. The generator may not fully meet the power demand but it
slows the rate of discharge.

Again without knowing the rating of the air con, and the size of
your portable gen, we're in the dark.

This does seem to demand a lot of inefficiency, though,
potentially with the generator input being converted from 240V to
12V then back again. It would be nicer if the battery 12V power
could be used to boost the 240V input from the generator so that
most of the power comes directly in at 240V.


Bottom line is that one way may require blending two 240V inputs
into a single output, with obvious (I think) requirements to lock
the wave forms of the 240V together.

You cannot "blend" 2 AC voltages.

Can nobody see my post of 12:29 today?
This contains the details, but I keep getting "as soon as we know
the specs" responses much later in the day.

With regards to blending two AC voltages, how does solar from the
roof blend into the UK grid, then? Thought it was pushed out of an
inverter and synced with mains - depending on how much you are
drawing at the time you should get all inverter (plus some pushed
back up the wires) or part mains and part solar. Or all mains if it
is night time!

Or am I missing something about how solar power is delivered from
the rooftop?


Solar power is DC.
It is linked to the mains by means of a grid tie inverter.
The mains AC is used to "create" synchronised AC from the DC.
https://en.wikipedia.org/wiki/Grid-tie_inverter

Synchronisng two separate AC supplies is quite another (more
difficult)
matter.

However, in the scenario I am exploring I was looking at blending a
source of 240V AC with the output of an inverter driven by 12V
batteries.

So in this case a "grid tie inverter" might do the trick. That is,
blending the output from an inverter and the output from 240V mains.
However I think that this is likely to be far too expensive (from
memory of solar installation quotes) for the application I was
considering.

I know that the power demand from the A/C is likely to rule it out in
my specific case but I am now exploring general principles. For
instance if you want to run a microwave or hair dryer which is just
over the power output of your genny.

It does raise the possibility of a very limited solar system (couple of
panels on the roof of a motor home) being able to boost the output of
some of the more flaky (especially continental) on site power supplies
on sunny days.

Cheers

Dave R


--
Windows 8.1 on PCSpecialist box

It's just not technically feasible.
The grid tie inverter runs at 400 odd volts You need to have
conventional AC fitted to the engine of your vehicle.
The only practical solution.

As already stated I have conventional A/C fitted to the engine of my
vehicle.

Additionally, the exhaust pipe exits into the awning area, so running the
engine when the van is set up with the awning is not a good plan.

Well then, the obvious solution is to re-route the exhaust system.
Or dispense with the awning.

On Sat, 27 Feb 2016 16:58:31 +0000, Dave Plowman (News) wrote:

In article ,
David wrote:
Both my cars have AC, but almost never used. I'd rather open the roof
and windows and enjoy a hot day. ;-)

Self and partner can't cope with temperatures much above 30C without
going into meltdown.

Very rare to have a true temperature above 30c in the UK. The inside of
a car in the sun, yes. But opening the windows on the move soon cools it
down to ambient.

We don't use the aircon very often (once every year or so) but it is
reassuring to have it.

I have used it to cool the car down before getting in.

Some people love high temperatures; others find that they can't cope
and get very unhappy indeed.

True. But we're in the UK. ;-)

Ummm...can I tactfully point out the "Mobile" in "Mobile Home"?

This does mean that we are not tied to the UK and can visit the far flung
reaches of mainland Europe.

Where (especially at some distance from the sea) the temperatures can be
more extreme than those normally experienced in the UK.

Mind you, I can remember 30C plus temperatures in the UK - around 2007
IIRC.

Cheers


Dave R


--
Windows 8.1 on PCSpecialist box

On Sat, 27 Feb 2016 22:02:18 +0000, Bob Minchin wrote:

David wrote:
On Sat, 27 Feb 2016 08:38:15 -0800, harry wrote:

On Saturday, 27 February 2016 12:27:16 UTC, David wrote:
On Fri, 26 Feb 2016 23:46:27 -0800, harry wrote:

On Friday, 26 February 2016 18:16:39 UTC, David wrote:
On Fri, 26 Feb 2016 17:03:13 +0000, Fredxxx wrote:

On 26/02/2016 10:59, David wrote:
This first post is a place holder in part, so that I don't forget
to ask the question, as I usually do once I get involved in stuff
during the day.

The Motor Home has mains powered habitation air conditioning -
that is an ELectrolux slug on the roof.

As soon as we know the spec, it might be possible to assist.

So for it to work you need to be on a site with mains
electricity.

There is also the issue of the power surge on start-up compared
to the power demand on normal running.

What I would like to be able to do:

(1) Run the A/C whilst driving - that would I assume involve an
inverter which could take power through the 12V electrics
buffered by the habitation batteries (unless the demand needs a
direct connection to the alternator charging circuit instead of
via the charge controller which charges the habitation
batteries). This also allows starting the engine, firing up A/C
and then stopping the engine and letting the A/C run on using the
habitation batteries.

For a narrow boat I installed a 3kW inverter (with surge
capability),
150A alternator and 4 100Ah batteries. It can be done though
challenging. I doubt you'll have the space to fit a second
alternator.

(2) Run the A/C when away from mains power - using a small Honda
generator which might be able to meet most of the demand apart
from start-up. I am envisaging perhaps the generator pushing
power into the system whilst the A/C takes power out so that the
use of habitation battery charge is slowed. This probably equates
to running a UPS (that is, power in to UPS for charging, power
always out of UPS for running the device) and using a small
generator to keep feeding some power into the UPS during a power
cut. The generator may not fully meet the power demand but it
slows the rate of discharge.

Again without knowing the rating of the air con, and the size of
your portable gen, we're in the dark.

This does seem to demand a lot of inefficiency, though,
potentially with the generator input being converted from 240V to
12V then back again. It would be nicer if the battery 12V power
could be used to boost the 240V input from the generator so that
most of the power comes directly in at 240V.


Bottom line is that one way may require blending two 240V inputs
into a single output, with obvious (I think) requirements to lock
the wave forms of the 240V together.

You cannot "blend" 2 AC voltages.

Can nobody see my post of 12:29 today?
This contains the details, but I keep getting "as soon as we know
the specs" responses much later in the day.

With regards to blending two AC voltages, how does solar from the
roof blend into the UK grid, then? Thought it was pushed out of an
inverter and synced with mains - depending on how much you are
drawing at the time you should get all inverter (plus some pushed
back up the wires) or part mains and part solar. Or all mains if it
is night time!

Or am I missing something about how solar power is delivered from
the rooftop?


Solar power is DC.
It is linked to the mains by means of a grid tie inverter. The mains
AC is used to "create" synchronised AC from the DC.
https://en.wikipedia.org/wiki/Grid-tie_inverter

Synchronisng two separate AC supplies is quite another (more
difficult)
matter.

However, in the scenario I am exploring I was looking at blending a
source of 240V AC with the output of an inverter driven by 12V
batteries.

So in this case a "grid tie inverter" might do the trick. That is,
blending the output from an inverter and the output from 240V mains.
However I think that this is likely to be far too expensive (from
memory of solar installation quotes) for the application I was
considering.

I know that the power demand from the A/C is likely to rule it out in
my specific case but I am now exploring general principles. For
instance if you want to run a microwave or hair dryer which is just
over the power output of your genny.

It does raise the possibility of a very limited solar system (couple
of panels on the roof of a motor home) being able to boost the output
of some of the more flaky (especially continental) on site power
supplies on sunny days.

Cheers

Dave R


--
Windows 8.1 on PCSpecialist box

It's just not technically feasible.
The grid tie inverter runs at 400 odd volts You need to have
conventional AC fitted to the engine of your vehicle.
The only practical solution.

As already stated I have conventional A/C fitted to the engine of my
vehicle.

Additionally, the exhaust pipe exits into the awning area, so running
the engine when the van is set up with the awning is not a good plan.

This is looking at ways to use the habitation A/C which is already
fitted.

However the information that it requires a 400 volt grid tie inverter
for a solar system does rule it out for a motor home.

Cheers

Dave R





Add to that, even if you provided the Grid Tie inverter with enough
battery volts, you will possibly be disappointed that it will not give
any output when the grid is not present.

I was assuming "grid tie" was code for latching onto a 240V AC supply from
an external source.

Ummm...yes, the implication is that you would need an external AC source
to persuade the inverter to run (otherwise the safety lock to prevent
killing people repairing the grid would cut in).

Which brings me to wonder if a solar array can keep the home going if the
grid is down.

This would require a reliable cut out!


Cheers

Dave R
--
Windows 8.1 on PCSpecialist box

On 28/02/2016 00:18, Dave Plowman (News) wrote:
In article ,
polygonum wrote:
On 27/02/2016 16:34, David wrote:
Self and partner can't cope with temperatures much above 30C without
going into meltdown.

Partner has issue which means she gets severe pain in higher
temperatures. Usual maximum in our house is 17 degrees - much more is
not acceptable.

Oh. That must make life pretty difficult.

It does - not for me - but for her. Lots of places are effectively
off-limits - such as theatres, cinemas, many restaurants, pubs, ...
Short periods in some shops are OK (or bearable) but nothing that means
a long time. Hospitals are among the worst...

--
Rod

On Sat, 27 Feb 2016 21:54:01 +0000, polygonum wrote:

On 27/02/2016 16:34, David wrote:
Self and partner can't cope with temperatures much above 30C without
going into meltdown.

Partner has issue which means she gets severe pain in higher
temperatures. Usual maximum in our house is 17 degrees - much more is
not acceptable.

Sounds like she may have inherited "Peace Keeper" genes from an alien
encounter many generations past.

--
Johnny B Good