Leisure battery wiring advice.

[MrDrizz]

So I'm set to wire in a leisure battery, it'll fit just under the passenger seat. Got the split charge kit. However I'm a little unsure what gauge wire to use from the battery to the fuses. The only thing I'll be running is a all in one deisel heater and maybe a couple lights. The heater will draw around 20amps on start up.

What gauge wire would you recommend for battery to fuse box?

Thanks.

[dumdum]

Enough to pass the current of the alternator if the battery is flat, so if it’s a 100a alt realistically it’s only going to pass max 40a and your rear battery would have to be really flat and charging way too fast, but... as decent cable isn’t too expensive, and fuses are under a quid (you’ll need two!) it’s not worth skimping

I’d go for a run of 25mm^2 cable with 100a fuses at each end (the shorter the run the smaller the cable can be ??) Using smaller will result in lots of heat around connectors (I’ve seen many times 30a cable being used for split charging and the yellow terminals are brown and shrunk down... customer was blissfully unaware that the heat was potentially a fire hazard)

Lots will say 30amp 6mm^2 cable will work... yes it will and fuse it at 30a each end... but for me as an auto electrician it’s a case of do the job once and do it right ?

3m of 25mm^2 cable and a couple of fuse holders is only 20-30 quid and the job is done right ? although I am presuming your relay has bolt on terminals and isn’t a towing relay type designed for just trickling a battery...