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Old August 2nd 17, 08:49 PM posted to uk.rec.motorcaravans
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Default Leisure battery flat

In article ,
Whiskers writes
On 2017-08-01, bert wrote:
In article ,
Whiskers writes
On 2017-07-29, Roy wrote:
Whiskers wrote on 28/07/2017 18:19:
Now proud owner of a proper campervan, but I think I may have killed
the leisure battery by letting it run flat. I thought they were meant
to be able to tolerate that sort of thing, but now I'm not so sure.

The present one is rated at 75AH which seems a bit small for a vehicle
with a fridge and likely to have very little time with a mains

I have now got a 6W solar 'battery conditioner' but it
seems to be too late for this battery.

Any advice would be most welcome!

Leaving the battery flat for a length of time will lead to its demise. 6
watts to recharge it is a bit optimistic.



Looks as though a trip to Halfords is in the offing then. I'm sure I'll
make other mistakes too as I learn the way of the campervan.

Well the presence of a fridge is irrelevant to the size of battery or
its charge as the fridge never runs off the battery.

My fridge is a 12v electric compressor fridge, and when the leisure
battery wasn't flat it did work and sounded just like the fridge at

You need to check the spec for current (or power rating) and power usage
but the consumption should be fairly low so 75AH should be OK. Does your
fridge have battery monitoring? If so do a "suck it and see" test.
It has no connection to the bottled gas that makes the cooker
work. It doesn't run off the engine-starter battery either.

Maybe not directly but when the vehicle engine is running it will be
charging the battery supplying the fridge which is effectively the same
6W solar battery chargers are a waste of time IME.

They're sold as 'battery conditioners'; I think the idea is that they
keep a charged battery topped up rather than charge it from flat. A
couple of sunny days did get the charge indicator up from 'flat - red
LED' to 'almost flat - amber LED' but it dropped back to red as soon as
the solar panel was disconnected. There was enough charge to run the
cabin LED strip lights for a short while.

I had a similar one. Didn't produce anything except in bright sunlight.
They should have a diode in the output circuit to prevent the battery
discharging back through the charger when its output falls.
Leisure (deep cycle) batteries are more resilient to discharge than
normal auto batteries so you may get away with it.

That was what I thought.

Charge it up and
leave it disconnected for 24 hours then measure the voltage. Should be
12v. N.B. some modern chargers will not actually work on a totally flat
battery. Alternative is to put it in the campervan and go for a drive.
75ah (same as mine) is adequate unless you are a TV/computer addict.

Any idea how long a drive? 20 miles doesn't seem to have been enough,
but that was in slow moving stop-go urban traffic.

Alternators are capable of charging even when idling. If you don't have
a charger you could take the battery to a dealer and they will test it
for you.
Thanks for responding )