Following on from the thread about second use for old electric car
batteries: surely as end of life is reached for any cell the self
discharge increases and thus a higher proportion of the charge gets
expressed as heat?

I need to provide hot washing water in one of our vans, about 10
litres is enough and these basin units are readily available for £250.

I can see a split charge system will only charge the second battery
when the main vehicle battery exceeds 13.5V, and even a facility I'm
told that will only charge it on overrun. This will get the water hot
on the run to work.

During the day how does one prevent the auxiliary battery discharging
below 50% DOD, is it by voltage sensing or do VA have to be
integrated?

AJH

wrote in message
...
Following on from the thread about second use for old electric car
batteries: surely as end of life is reached for any cell the self
discharge increases and thus a higher proportion of the charge gets
expressed as heat?

I need to provide hot washing water in one of our vans, about 10
litres is enough and these basin units are readily available for £250.

I can see a split charge system will only charge the second battery
when the main vehicle battery exceeds 13.5V, and even a facility I'm
told that will only charge it on overrun. This will get the water hot
on the run to work.

I understood that when the engine was running the split charge relay would
energise and connect both batteries in parallel -
https://www.marcleleisure.co.uk/Sund...itCharge01.htm

During the day how does one prevent the auxiliary battery discharging
below 50% DOD, is it by voltage sensing or do VA have to be
integrated?

AJH

On 13/04/2014 10:19, bm wrote:
wrote in message
...
Following on from the thread about second use for old electric car
batteries: surely as end of life is reached for any cell the self
discharge increases and thus a higher proportion of the charge gets
expressed as heat?

I need to provide hot washing water in one of our vans, about 10
litres is enough and these basin units are readily available for £250.

I can see a split charge system will only charge the second battery
when the main vehicle battery exceeds 13.5V, and even a facility I'm
told that will only charge it on overrun. This will get the water hot
on the run to work.

I understood that when the engine was running the split charge relay would
energise and connect both batteries in parallel -
https://www.marcleleisure.co.uk/Sund...itCharge01.htm


What a *really* useful link; I have been thinking about fitting a
leisure battery to my horsebox, and they have done all the work!

On Sunday, April 13, 2014 9:24:29 AM UTC+1, wrote:

Following on from the thread about second use for old electric car
batteries: surely as end of life is reached for any cell the self
discharge increases and thus a higher proportion of the charge gets
expressed as heat?

if thats whats causing its end of life.

I need to provide hot washing water in one of our vans, about 10
litres is enough and these basin units are readily available for £250.
I can see a split charge system will only charge the second battery
when the main vehicle battery exceeds 13.5V, and even a facility I'm
told that will only charge it on overrun. This will get the water hot
on the run to work.

If you mean electric power, you'd get far more heat for far less by harvesting from the exhaust, or even the engine coolant.


NT

On Sun, 13 Apr 2014 02:40:49 -0700 (PDT), wrote:

On Sunday, April 13, 2014 9:24:29 AM UTC+1, wrote:

Following on from the thread about second use for old electric car
batteries: surely as end of life is reached for any cell the self
discharge increases and thus a higher proportion of the charge gets
expressed as heat?

if thats whats causing its end of life.

OK what modes of failure are there and how do they manifest
themselves?


If you mean electric power, you'd get far more heat for far less by harvesting from the exhaust, or even the engine coolant.

I'm talking about 150W element heating 5 litres of water through 45C,
the unit costs ~£250 and requires 27Ahr from cold which takes about an
hour. I don't know how well it is insulated to keep warm during the
shift. So I may get more heat from the exhaust or a diesel heater but
the capital cost wouldn't warrant it.

As it is a tractor battery (644) will easily manage the demand but the
issue is will it get charged enough in the average commute (about 40
minutes). The split charge facility protects the vehicle battery as it
only closes above 13.5V but I need something to inhibit the heater if
the auxiliary battery falls below 50% DoD or about 12.2V.

AJH

wrote:


As it is a tractor battery (644) will easily manage the demand but the
issue is will it get charged enough in the average commute (about 40
minutes).
No it won't.

The split charge facility protects the vehicle battery as it
only closes above 13.5V but I need something to inhibit the heater if
the auxiliary battery falls below 50% DoD or about 12.2V.

Nowadays 'split charge relays' are usually 'voltage sensing relays'. In
other words they are controlled by the voltage available at the vehicle
battery rather than by a connection to the 'sense' wire on the
alternator. This is much more simple and easy than the old method. (Bear
with me by the way). When the alternator is running and working properly
and the main battery is reasonably charged the voltage rises and the
relay senses this and connects the auxiliary battery. It is important
that the relay is connected to the vehicle charging circuit at a point
where there is negligible resistance between it and the vehicle battery,
otherwise it might sense a high voltage and switch when the vehicle
battery is not charging properly. To put it another way, part of the
installation should be a check of the main battery terminals, ground
connection, and wiring.

Some voltage sensing relays also monitor the voltage of the aux battery
before connection, in case it is dangerously low. If it is the relay
won't connect it to the vehicle battery and alternator. This is a good
precaution. If there's a fault on the aux circuit you don't want the
alternator output shorting out just as you leave harbour/ hit the M1.
This might be a problem for your application. Certainly if the heater
was connected and drawing 27A there would be a risk that the relay
wouldn't switch.

I doubt if you'd be able to apply a cut-off at 12.2V because if you were
drawing 27A the battery terminal voltage would very quickly be below
that (although it would recover quite a lot once the load was removed).
If your need to protect the aux battery from total discharge (and you do
if using a voltage sensing relay because most of these won't connect the
aux battery if it is totally flat) I suggest a cut off of about 11.1V
for a high load like 27A. You might be able to get a conventional
voltage sensing relay that will adjust down to that value and use it in
series with the heater supply. Look at the specs. These are the ones I use:
http://www.merlinequipment.com/marke...asp?groupid=37

Alternatively use a purpose made item:
http://www.dg2k.co.uk/xcise.htm
£108 though...

Bill





AJH

On Mon, 14 Apr 2014 01:35:59 +0100, Bill Wright
wrote:

Alternatively use a purpose made item:
http://www.dg2k.co.uk/xcise.htm
£108 though...


Thanks for your concise and complete post Bill, this device still
needs a continuous duty solenoid but looks a good way to go even if
the vehicle may need a bigger alternator.

AJH

On Sunday, April 13, 2014 8:49:24 PM UTC+1, wrote:
On Sun, 13 Apr 2014 02:40:49 -0700 (PDT), wrote:
On Sunday, April 13, 2014 9:24:29 AM UTC+1, wrote:

Following on from the thread about second use for old electric car
batteries: surely as end of life is reached for any cell the self
discharge increases and thus a higher proportion of the charge gets
expressed as heat?

if thats whats causing its end of life.

OK what modes of failure are there and how do they manifest
themselves?

lead deposits shorting plates
ionic contamination causing self discharge
broken lead plate
sulphation
electrolyte too low
electrolyte too weak
electrolyte too strong
electrolyte dried out
terminal corrosion
plate buckled & shorting
likely others I'm not thinking of just now


If you mean electric power, you'd get far more heat for far less by harvesting from the exhaust, or even the engine coolant.

I'm talking about 150W element heating 5 litres of water through 45C,
the unit costs ~£250 and requires 27Ahr from cold which takes about an
hour. I don't know how well it is insulated to keep warm during the
shift. So I may get more heat from the exhaust or a diesel heater but
the capital cost wouldn't warrant it.

Why would one spend 250 on a diesel heater when heat can be harvested from the exhaust with metal & rubber pipe?


As it is a tractor battery (644) will easily manage the demand but the
issue is will it get charged enough in the average commute (about 40
minutes). The split charge facility protects the vehicle battery as it
only closes above 13.5V but I need something to inhibit the heater if
the auxiliary battery falls below 50% DoD or about 12.2V.
AJH

opamp or comparator, relay. If you can do electronics.


NT

On 14/04/2014 20:35, wrote:
On Sunday, April 13, 2014 8:49:24 PM UTC+1, wrote:
I'm talking about 150W element heating 5 litres of water through 45C,
the unit costs ~£250 and requires 27Ahr from cold which takes about an
hour. I don't know how well it is insulated to keep warm during the
shift. So I may get more heat from the exhaust or a diesel heater but
the capital cost wouldn't warrant it.

Why would one spend 250 on a diesel heater when heat can be harvested from the exhaust with metal & rubber pipe?

Because running the engine creates noise and pollution which many people
find annoying. Because it's cheaper to run a diesel powered heater than
the engine used for moving the vehicle. Because the diesel powered
heater starts heating the water immediately without first having to heat
many kilogrammes of metal. Because with today's efficient diesels, they
take ages to start getting warm enough to make a difference to the water
temperature in a calorifier.

However, it's the electric water heater that's costing £250, a diesel
heater costs over £500 fitted. Installing a calorifier run off either
exhaust heat or engine cooling water costs even more.


--
Tciao for Now!

John.

On Mon, 14 Apr 2014 22:07:45 +0100, John Williamson
wrote:

However, it's the electric water heater that's costing £250, a diesel
heater costs over £500 fitted. Installing a calorifier run off either
exhaust heat or engine cooling water costs even more.

In fact the vans already have eberspacher hot air units but as you say
the capital cot of changing to ones that heat water is prohibitive.

AJH

On Monday, April 14, 2014 10:07:45 PM UTC+1, John Williamson wrote:
On 14/04/2014 20:35, wrote:
On Sunday, April 13, 2014 8:49:24 PM UTC+1, wrote:
I'm talking about 150W element heating 5 litres of water through 45C,
the unit costs ~£250 and requires 27Ahr from cold which takes about an
hour. I don't know how well it is insulated to keep warm during the
shift. So I may get more heat from the exhaust or a diesel heater but
the capital cost wouldn't warrant it.

Why would one spend 250 on a diesel heater when heat can be harvested from the exhaust with metal & rubber pipe?

Because running the engine creates noise and pollution which many people
find annoying. Because it's cheaper to run a diesel powered heater than
the engine used for moving the vehicle. Because the diesel powered
heater starts heating the water immediately without first having to heat
many kilogrammes of metal. Because with today's efficient diesels, they
take ages to start getting warm enough to make a difference to the water
temperature in a calorifier.

I wont quibble with the noise. Its the coolant circuit that takes time to heat up though. Most heat is lost via exhaust, not coolant.

However, it's the electric water heater that's costing £250, a diesel
heater costs over £500 fitted. Installing a calorifier run off either
exhaust heat or engine cooling water costs even more.

How would it cost over 500 to bend some pipe and tack it on to the manifold?


NT

On 14/04/2014 22:10, Huge wrote:
On 2014-04-14, John Williamson wrote:
On 14/04/2014 20:35, wrote:
On Sunday, April 13, 2014 8:49:24 PM UTC+1, wrote:
I'm talking about 150W element heating 5 litres of water through 45C,
the unit costs ~£250 and requires 27Ahr from cold which takes about an
hour. I don't know how well it is insulated to keep warm during the
shift. So I may get more heat from the exhaust or a diesel heater but
the capital cost wouldn't warrant it.

Why would one spend 250 on a diesel heater when heat can be harvested from the exhaust with metal & rubber pipe?

Because running the engine creates noise and pollution which many people
find annoying. Because it's cheaper to run a diesel powered heater than
the engine used for moving the vehicle. Because the diesel powered
heater starts heating the water immediately without first having to heat
many kilogrammes of metal. Because with today's efficient diesels, they
take ages to start getting warm enough to make a difference to the water
temperature in a calorifier.

Hell, my diesel *car* has a diesel powered heater.


And I'll bet it needs it for the first ten miles or so.

--
Tciao for Now!

John.

In message ,
writes
On Sun, 13 Apr 2014 02:40:49 -0700 (PDT), wrote:

On Sunday, April 13, 2014 9:24:29 AM UTC+1, wrote:

Following on from the thread about second use for old electric car
batteries: surely as end of life is reached for any cell the self
discharge increases and thus a higher proportion of the charge gets
expressed as heat?

if thats whats causing its end of life.

OK what modes of failure are there and how do they manifest
themselves?


If you mean electric power, you'd get far more heat for far less by
harvesting from the exhaust, or even the engine coolant.

I'm talking about 150W element heating 5 litres of water through 45C,
the unit costs ~£250 and requires 27Ahr from cold which takes about an
hour. I don't know how well it is insulated to keep warm during the
shift. So I may get more heat from the exhaust or a diesel heater but
the capital cost wouldn't warrant it.

As it is a tractor battery (644) will easily manage the demand but the
issue is will it get charged enough in the average commute (about 40
minutes). The split charge facility protects the vehicle battery as it
only closes above 13.5V but I need something to inhibit the heater if
the auxiliary battery falls below 50% DoD or about 12.2V.

AJH
Voltage sensitive relay as used on caravans these days?
--
bert

wrote:
Following on from the thread about second use for old electric car
batteries: surely as end of life is reached for any cell the self
discharge increases and thus a higher proportion of the charge gets
expressed as heat?

I need to provide hot washing water in one of our vans, about 10
litres is enough and these basin units are readily available for £250.

I can see a split charge system will only charge the second battery
when the main vehicle battery exceeds 13.5V, and even a facility I'm
told that will only charge it on overrun.


Really? Why? Surely it'll charge whenever the engine is running?

Tim

On 13/04/2014 12:03, Tim+ wrote:
wrote:
Following on from the thread about second use for old electric car
batteries: surely as end of life is reached for any cell the self
discharge increases and thus a higher proportion of the charge gets
expressed as heat?

I need to provide hot washing water in one of our vans, about 10
litres is enough and these basin units are readily available for £250.

I can see a split charge system will only charge the second battery
when the main vehicle battery exceeds 13.5V, and even a facility I'm
told that will only charge it on overrun.


Really? Why? Surely it'll charge whenever the engine is running?

It depends on the split charge relay in use. Some just connect the
batteries in parallel with the engine running, some sense the charge on
the starter battery, and connect intelligently.

As for how do you stop the leisure battery discharging too far, it's
done by sensing the battery voltage. As all lead acid batteries have the
same (Roughly) discharge curve against the percentage of available
charge used, even ones which are approaching their end of life, there's
no need to calculate amp hours used and put in.

These problems were all solved long ago by the boaters and motorhome owners.

One slightly more expensive way to get quicker hot water is to use a
well insulated calorifier heated by the engine, which has a high power
alternator fitted to run an small immersion heater as well. If you have
room, that is.
--
Tciao for Now!

John.

wrote in message
...
Following on from the thread about second use for old electric car
batteries: surely as end of life is reached for any cell the self
discharge increases and thus a higher proportion of the charge gets
expressed as heat?

I need to provide hot washing water in one of our vans, about 10
litres is enough and these basin units are readily available for £250.

I can see a split charge system will only charge the second battery
when the main vehicle battery exceeds 13.5V, and even a facility I'm
told that will only charge it on overrun. This will get the water hot
on the run to work.

During the day how does one prevent the auxiliary battery discharging
below 50% DOD, is it by voltage sensing or do VA have to be
integrated?

AJH

The amount of power a lead acid battery stores is insignificant compared
with its weight
For any heating load,you wouldn't want to be carting a big enough one
around.
As someone else says, there is far more energy available from the engine
cooling system or exhaust.