B2B input cable size

Adtb89

Hi all,

I hope everyone is well in these strange times.

I'm currently in the process of converting a 2017 LWB Mercedes Sprinter and I'm looking for some advice on a recommended cable size between the starter battery and my B2B charger (60A Sterling Pro Batt Ultra). The linear distance between the starter battery and where the B2B charger location is around 5m however when you include runs up and around things I'm looking at 9m.
The output charge of the B2B charger is limited to 60A however the input is UNLIMITED and seeing that the starter battery is 12v 92AH with a 850A CCA I am a bit unsure what size cable I require. This also raises a question on what size fuse is required.

The manual is recommending a 25mm^2 for up to 9m which, when run in conduit in an insulated wall, which it mostly will be, has a rating 80-73A. This is lower than the recommended fuse.......

Am I going doing the wrong rabbit hole here or am I getting my wires crossed? Any help would be greatly appreciated.

Andrew

Any ideas?
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xsilvergs

xsilvergs

Forum Member
I would say 25mm2 is fine. The lead that runs from the Starter Batter to the B2B should be fuse as close to the Starter Battery as possible. On our Fiat the fuses lives in the Starter Battery box, it can't get any closer.
 

wildebus

Forum Member
With that cable run length and current potential, 25mm2 will work but if you have yet to run it, I would go for 35mm to give a lower voltage drop and therefore better efficiency.

The starter battery is actually pretty irrelevant in the calculation. The core supply component is the alternator, not the starter battery.
 
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