Linking leisure batteries

[The_Lad]

Hi All I’m thinking about adding a second leisure battery into the van but I don’t want to have to rip it all apart.

Currently I have a ctek 250 As the dc-dc charger and also doing solar all linked to a 110a battery under the passenger seat. I also have a victron charger on the 240v side if I’m on hookup.

From the existing battery I have a 6mm cable up the b pillar along the roof, down the rear pillar and then back up to mid way along the van where my fridge used to be.

Now my question is can I re-use the existing cable to add a second battery by the wheel arch in the rear? Is 6mm cable thick enough? I think it was rated at 53amp as long as I fuse it at say 50 or 30 amp at either end? How many amps does the ctek or victron try to push into the battery?

If not I do t think I’ll bother as it will be a pain to do a new cable run.

 

[Dellmassive]

Yes you could do that.

You would need to match both batterys..... So get a second one of what you already have. (Or two new matched battery as a matched pair)

You need to add an additional fuse at the far battery end on the POS post.

You should run the rear battery NEG ground direct to chassis ground.

Provided you loads are low and you don't full to much current you should be ok... (Below say 20A)

The CTEK charger and Victron EHU charger will help charge both batterys.

You will get voltage drop over the run as the cable is long and it's not the fattest.

(Tip.... Fully charge both batterys independently off the van on a bench before joining them together on the van, that will stop large currents flowing between both batterys as they will have different levels of charge if not balanced first.)


Remember your run time will double.... So fridge etc will run longer.....but your charge time will also double.

The CTEK is only 20A, that could mean 10hours of driving to charge both batterys...... So you will need to use EHU to keep the batterys charged.

 

[The_Lad]

Cheers it was the cable thickness I was concerned about if 6mm is ok I’ll give it a try I’ll also check it is 6mm I hope it’s written on the cable to be 100% sure but I think that’s what I fitted

I’ll fuse at both ends at maybe 25amp just to be sure I’m not drawing too much but really it will only be the fridge and a few usb chargers so not a massive draw

 

[Dellmassive]

6.0mm2 shows here at 53A.

But you have a long ish run..

So

25A shoul be ok.

Single Core Thin Wall Cable - 6.0mm² 50A

50A 6.0mm² high performance, single core, thin wall cable for auto, marine & leisure applications. OEM spec. Available in various colours.

www.12voltplanet.co.uk

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