jossey
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| posted on 11/2/14 at 06:30 PM |
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Campervan battery voltage health figures help please.
Can someone explain to me about leisure batteries and what volts it should show etc,.
I have a new leisure battery. Just being wired to the led volt meter it was 12.8 volts for the few week or so when I had it. Not connected to anything
else. Now its at 12.0 3 months later.
How do I work out how much power I have used from the battery. I want to leave the volt meter thing on all the time when I have finished wiring the
van but don't have any idea on what it should look like.
Thanks in advance.
DJ
Thanks
David Johnson
Building my tiger avon slowly but surely.
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coyoteboy
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| posted on 11/2/14 at 07:09 PM |
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Leisure batteries are not much different from car batteries, chemically, other than they are designed to withstand deep cycles (i.e. they tolerate
being taken low for longer).
It's not really possible to determine the capacity left (or discharge percentage) from voltage as it will depend on temperature, state of the
plates, rate of current draw when in use etc etc. Just don't let the voltage drop too low for too long, I can't remember the exact
voltage for lead acids, IIRC it was around 11.6v, below that you get sulphate growth on the plates.
Dig around in battery university (google it).
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jossey
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| posted on 11/2/14 at 07:57 PM |
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Cheers
Thanks
David Johnson
Building my tiger avon slowly but surely.
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BenB
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| posted on 11/2/14 at 08:06 PM |
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You can get an approximation as to depth of discharge by looking at volts but it's a rough guesstimate. Good for working when to recharge but
not much else. And if you look at all the volts vs capacity graphs they differ quite considerably. None of the ones I see would suggest taking down to
12v.
Best option is to recharge frequently and often, even a deep discharge battery won't like the experience of being run flat, I try to avoid mine
going below 50%.
I use the table here:
http://www.leisurebatteries.net/
12.4v on the multimeter and mine goes back on the charger.
Also be aware some cheap leisure batteries are just car batteries re-labelled, they won't even like a 50% discharge too often.
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britishtrident
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| posted on 11/2/14 at 08:21 PM |
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As a rough guide even a dead flat battery will read 11.5 volts across the terminals with no load present.
Battery voltage depends a lot on temperature, for fully charge battery at current a few degrees above freezing point UK ambient temperatures I would
expect to see 12.4 volts with no load but at summer temperatures a battery should show about 12.8 volts.
Your battery is about 50% charged as a general guide it is best to not discharge a battery below 65% as each deep discharge and recharge damages the
battery, deep cycle batteries are more forgiving the modern starting batteries but they still suffer damage.
One thing to keep in mind is the more slowly you discharge a battery or the longer you leave it discharged the recharge must also be for longer at a
lower current rate for it to fully recover.
At 12.0 volts it really is due for charge for at least 24 hrs at a low current rate.
If you look on eBay you will very cheap digital panel meters that measure both current and voltage and slightly more expensive ones that measure the
net amp hour in/out.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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austin man
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| posted on 11/2/14 at 09:35 PM |
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Have you not wired your leisure battery in to your charging circuit with a relay in line to prevent discharging the main battery
Life is like a bowl of fruit, funny how all the weird looking ones are left alone
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jossey
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| posted on 11/2/14 at 09:45 PM |
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Not wired the camper up yet. Just doing that as we speak.
I have a split charge relay etc just don't get why the leisure battery is getting lower over a few months with just an led volt meter....
I'll charge her and keep an eye on it...
Thanks
David Johnson
Building my tiger avon slowly but surely.
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froggy
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| posted on 11/2/14 at 10:25 PM |
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I got a meter that does voltage watts and amp /hr rate for £30 . I have two big batteries under the passenger seat and have everything on 12v with one
inverter to power the sattelite receiver . Not having to rely on mains power for 4-5 days has made weekends away a lot cheaper as I always use the non
hook up areas which are cheaper and usually you have more room than on a serviced pitch . Last year in France our stops were around 100-150 miles
apart and the batteries were charged up by the time we got to the next stop .
Best investment so far has been a propex gas heater and one of the later composite type gas gas bottles that holds 10kg of butane . Running the fridge
, heater and cooking lasted twelve months and you can see the gas level through the bottle .
[IMG]http://i144.photobucket.com/albums/r187/froggy_0[IMG]
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britishtrident
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| posted on 12/2/14 at 08:03 AM |
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All lead acid batteries slowly go flat, you should charge once a month.
Also about 0.4 v. is due to ambient temperature change.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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