# Connecting an extra leisure battery



## brightangel (Oct 1, 2012)

I have one existing 110Ah 12 volt leisure battery in my Compass motorhome and want to add another 12v 110Ah battery located in a battery box under one of the bench seats, approx 1m from the existing battery. Can anyone advise me how to wire it in eg in parallel or in series ? size of cable ? any safety device required ? I need to keep the output at 12 volt. Thanks


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## rayrecrok (Nov 21, 2008)

brightangel said:


> I have one existing 110Ah 12 volt leisure battery in my Compass motorhome and want to add another 12v 110Ah battery located in a battery box under one of the bench seats, approx 1m from the existing battery. Can anyone advise me how to wire it in eg in parallel or in series ? size of cable ? any safety device required ? I need to keep the output at 12 volt. Thanks


Hi.

Wire it in parallel red to red and black to black to keep it 12 volts, if you wire it in series it will become 24 volts.

You will need the same diameter wire as the existing installation or the wire to the engine battery will give you an indication of amperage load it has to carry.. As for safety devices you could put an in line fuse, but others will advise if one is actually needed as if a large amperage wire is used I would have thought that wiring it straight from battery to battery would be OK..

ray.


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## joedenise (Jul 20, 2007)

as you wont have any wires on the new battery and contintal vans use brown as live its Positive to Positive and Negative to Negative

+ to + and - to -

joe


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## listerdiesel (Aug 3, 2012)

Wire size of 25mm sq up to 50mm sq will do the job, you're not starting the engine, but it is easier making the terminal connections with heavier wire.

Follow the existing colouring of cables.

Peter


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## Geriatricbackpacker (Aug 21, 2012)

Having had some really good advice from Alan at aandncaravans (07803 072636) regarding the relocation of my leisure batteries I can pass that on. He told me that I needed a minimum of 6mm wiring to prevent any voltage loss (I have an elektroblock fitted in my Hymer). He also suggested putting a 40/50amp heavy duty in-line fuse as close to the battery(ies) as you can. He was a mine of information regarding the various types of chargers on the market that can be retro fitted to give better performance and a greater charging capacity. Just have a pen and paper to hand if you ever call him as you will be deluged with so much good advice half of it will be forgotten before you hang up. 

I should mention that I have no affiliation to aandncaravans, I just want to pass on a good experience. 

Have fun rummaging around the nooks and crannies of your van...probably find things you thought you'd never see again :lol: :lol:


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## aikidomo (Jan 8, 2008)

I thought that I read on here somewhere that the Batteries had to be of the same type, size and age for them to be efficient.
Or not............?
Clive


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## boringfrog (Sep 22, 2006)

*Battery*



aikidomo said:


> I thought that I read on here somewhere that the Batteries had to be of the same type, size and age for them to be efficient.
> Or not............?
> Clive


Yes a good point.


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## Penquin (Oct 15, 2007)

6mm diameter wires have a cross sectional area of 28 sq mm so that would seeem to fulfill what has been already said.

I tried using the search facility to check this but could not find the specific answers, Sallytraffic wrote a very useful guide on 12v systems which is worth referring to;

http://www.motorhomefacts.com/ftoptitle-65110-12-volt-systems.html

I also can recall reading that both batteries should be the same type, size and age for optimal use and that connecting an old one to a new one will reduce the new one to the sae state as the old one instantly - but I cannot find that reference now........

Dave


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## TerryL (Feb 19, 2009)

Yes, the advice is that the batteries should be of the same type, capacity AND AGE, or the "old" one will pull down the new one.

Unfortunately, and I won't go into details, surfice it to say somebody hadn't done what they said they'd done, I have recently had personal experience of this and had to buy another battery.


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## listerdiesel (Aug 3, 2012)

Penquin said:


> 6mm diameter wires have a cross sectional area of 28 sq mm so that would seeem to fulfill what has been already said.
> Dave


Dave & All:

Wires/cables are listed by their cross-sectional area, and while a 6mm solid bar of copper could be 28 sq mm as stated, in practice you cannot use the outer diameter as a guide as the insulation thickness varies with brands and temperature rating.

We use Tri-Rated cable, it conforms to UL, CSA and BS6231 standards, it is flame-retardent and has an operating temperature to 105 Deg C(UL and CSA) or 90 deg C (BS6231) It is also multi-stranded and therefore suitable for installation in moving equipment, which single-strand or solid strand conduit cable is not.

Where extreme flexibility is required, we use welding cable to BS638 with double-sheathing.

A length of car starter cable would do the job, most auto-electrical places carry that, but if you get stuck, drop me a PM, we'll have something we can sort you out with.

Peter


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