two leisure batteries or one?

[Frankkia]

Peter James - 2012-01-06 6:17 PM

 

Frankkia - 2012-01-02 8:36 PM

 

We had 1 pack in (only 7 years old poor thing) whilst we were in Germany but I merely disconnected the duff one and continued the rest of the hols on 2 - batteries are bloomin expensive in Germany .

 

How did you know which one was the duff one? (assuming they were connected in parallel?)

 

Realised that the batteries weren't charging properly so disconnected both and checked with a meter - the voltage on the duff 1 dropped away very quickly.

[OxfordMorgan]

Hmmm... Another Huge topic!,,,,,, During my research on this, some advice from what seemed a very reliable source suggested two things, 1 - don't mix battery types (I.e. Gell & Ca) and don't mix capacity as this can cause issues...

 

I'm sure lots of people far cleverer than I have an opinion, but the 2 people I know who have mixed them report issues with the larger capacity battery

[Clive]

Lead acid batteries are mostly Lead paste so their size and bulk is prety well proportionate to their effective capacity. A Lead Acid battery of half the weight and size will have (under the same test conditions) have half the storage capacity. Change the technology to NiMh or something then it will all change. But lead acid is Lead acid - if you know what I mean.

Now, if you are thinking about fitting two new batteries then you should consider fitting two 6 volt batteries and connect them in series to make 12 volts. My favourite would be a couple of golf buggy batteries. These are TRACTION duty batteries designed for deep cycling so will do a leisure duty very well.

 

More here

http://www.motts.org/second%20leisiure%20battery.htm

 

[Guest Peter James]

Frankkia - 2012-01-06 7:54 PM

 

Peter James - 2012-01-06 6:17 PM

 

Frankkia - 2012-01-02 8:36 PM

 

We had 1 pack in (only 7 years old poor thing) whilst we were in Germany but I merely disconnected the duff one and continued the rest of the hols on 2 - batteries are bloomin expensive in Germany .

 

How did you know which one was the duff one? (assuming they were connected in parallel?)

 

Realised that the batteries weren't charging properly so disconnected both and checked with a meter - the voltage on the duff 1 dropped away very quickly.

 

Yes I guess thats the problem with coupling two in paerallel isn't it. The duff one must have been discharging the others for some time before it got bad enough to discover it?

[buxton-arts]

for multiple batteries they should be matched as closely as possible - ideally AH, type (lead acid acid, gel etc) even manufacturer. THey should be as close as possible joint with a bus bar if practical or very thick cable. The idea is that there is no differential between the batteries so that one does not discharge into the other so maintaining optimal cahrge and longlevity in both. Not always possible to get the ideal tho !!!

[Clive]

Sorry but paralleled batteries should NOT be joined directly with bus bars. The reason is simple, should one battery suffer an internal shorted cell then it will try and discharge the other battery. For maxumum safely each battery must have its own individual fuse to provide protection against this otherwise unregulated fault current. This is why I advotate using bigger 6 volt batteries connected in series as the fault current scenario no longer exists.

 

C.

.

 

[buxton-arts]

good point - altho I have to admit, running a fleet of 6 vehicles, I've never had a battery failure of this type. Interested to know the frequency.

[thirtle26]

thank you all for your useful comments - we have a lot to think about. The use of the cupboard space isn't an issue as we don't use it for anything except accessing the battery and storing the Kenwood sat nav box and wires. The thread about solar panels will also help.