# Connecting two leisure batteries



## PIEDODGER (Aug 22, 2008)

. When connecting two leisure batteries together both the same type but one being 85a the other 110a will the increase in amps cause a problem at the unit end will the existing wiring heat up at any point? or best just use them individually so they charge on the move better/quicker. ta PD.


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## DABurleigh (May 9, 2005)

There is plenty of advice on MHF regarding this situation. To maximise battery life, the batteries should be as similar as possible, in type, brand, model, production batch and history.

In particular, connecting an old one and a new one together will lead to a curtailed life of the new one.

Other than that, there is no problem.

Dave


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## CliveMott (Mar 10, 2008)

More on
http://www.motts.dsl.pipex.com/second leisiure battery.htm
.


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## PIEDODGER (Aug 22, 2008)

cheers guys, Ta


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## twinky (Aug 11, 2008)

The extra battery will not overload the existing cabling - the fuses are designed to stop this. They will protect the circuit and limit the current not allowing compromise of the cable.
Provided of course its wired in correctly :roll:


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## 115341 (Aug 9, 2008)

CliveMott said:


> More on
> http://www.motts.dsl.pipex.com/second leisiure battery.htm
> .


Really useful wiring info on your site Clive - been looking for similar for ages. Thanks for sharing.

P.S. nice to finally find info in "Clive's Corner" as I am a Clive!


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## CliveMott (Mar 10, 2008)

You are welcome.


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## DJP (May 9, 2005)

Clive
Thanks for link, if I may quote from that


> If the two batteries to be connected in parallel are mounted directly alongside each other then its OK to fit two short stout cables or copper links to join the negatives together and the positives together. The original single fuse being sufficient.


What amp rating would you suggest for the "stout cables"? Also fuse rating?
Thanks


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## tude (Feb 9, 2008)

*battery*

hi there mate well im just doin same as you exept i was advised to keep the batterys the same ie 110 amp with another 110 amp and dont forget to connect pos with pos and neg to neg otherwise the other way round will result in 24v tude


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## CliveMott (Mar 10, 2008)

"Stout cable" - it all depends.

If you just want to double your ability to camp without hookup then the size of the existing battery cables should be sufficient.
BUT
If you are adding say a large inverter to power something like a microwave oven then its a different ball game! 25 or 35 sqmm cable would then be more appropriate.

Re the warning about not connecting parallel batteries pos to neg and neg to pos, the result is not 24 volts, its a face full of sulphuric acid, burnt fingers, arc eye, melted spanner perhaps if you were very quick and maybe be a burnt out van.

Two 12 volt batteries connected in parallel is always neg to neg and pos to pos.

If however you are able it is better to have two BIG matched 6 volt batteries connected in series.

Battery 1 neg to chassis. Battery 1 pos to battery 2 neg. Battery 2 pos is outgoing 12 volts.

If in any doubt use a professional.

C.


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