# extra battery fitting



## froggy59 (Jan 18, 2009)

i have just had a new 85ah battery fitted and want to fit an extra battery 110ah, do i just connect pos to pos and neg to neg and can i use the same type of cable that is fitted as standard or do i need a thicker cable.

thanks 

alan


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## clive1821 (Mar 27, 2010)

Hi Alan,

Its advisible to have similar ampre hour batteries and of the similar age... there are various issues in useing a new battery and a old batteries, nothing dangerious just the ageing process of the battery you have compaired with a new one, I have had experence in using a existing battery and a new battery found in a year both the new battery was usless and of course the old battery was faulty with age...

So to answer your question, yes pos to pos and neg to neg, use at least 16mm cable and if not installed side by side I would recomend putting a 50amp fuse at both ends of the positive conecting lead between the batteries...


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## vardy (Sep 1, 2006)

I'm going to get this done too - my 85amp battery is under the driver's seat and has been in for about 4 years. The plan is to put another under the passenger side.

I am wondering if both will need renewing - but my fitter said 'if the old one is working fine, then no.

Q. Do they both HAVE to be wired together, or is there a way to work off one then the other with a switching unit. Or is this not possible due to the need to mess with the charging units and Zig thingy. 

You can tell I'm a girl!


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## weldted (May 1, 2005)

*second battery*

Hi when fitting batteries both should be of same age and type, positive to positive & negative to negative. if you fit a new battery alongside an older one the old one will pull it down to its level. if the batteries are not alongside each other they should be protected by an in-line fuse. on the positive line. if you split the batteries to use singly although it sound a good idea you will actually loose efficiency. every join or switch in the line creates a resistance, far better to link one battery to the other then on to the supply lead. otherwise you will have to put in relays or remember to switch batteries to recharge them. Den't forget the batteries should be vented to outside the van usually by a tube down through the floor.


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## vardy (Sep 1, 2006)

Thank you for the detailed info - very good of you to explain so simply, as it's a bit above me. I have taken it all in!


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