on 16/01/2012, Grumps supposed :
I'm not sure what the fuse rating is. Say it's 10A (maybe 16A) and the
charger can only do 6A. Then the fuse can't blow can it?

It should be a direct fused supply from the main battery. What I do is
fuse one large cable at 30amps at the source, run that to a charge
relay in the boot, then split it down to two supplies again fused, but
at 15 or 20amp each for fridge and trailer battery charging. Large
cable to avoid volts drop rather than rated for amps.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk