Leisure battery split charging cable sizes.

[Spencer54]

Can anyone steer me in the right direction.

I've added a leisure battery 100ah, and a cyrix-ct relay which is rated to 120a but I'm confused as to what rating/size the cables should be.

I have some strip fuses ala ParkerNorris's set up.

Any idea what cables I'll need to run to the interior fuse holder and between both batteries?

Ta

[g8dhe]

The charging current could exceed 30-40Amps if the LB is really flat and the alternator is really being revved, so I would suggest you fuse both batteries for 40Amps and rate the cable for 50Amps but having said that the distance is very short in most cases and the charging current at those levels is unlikely to last very long at all as it will fall off rapidly, so using lower values is unlikely to lead to problems, provided you don't go under about 30Amp fuses, however I have seen some fused at 20Amps and they seem to get away with it !