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