> Just searching eBay and I came across this interesting modification.
> Its a microwave oven underneith the westy sink.
> 

That's just crazy, if you ask me. Looks like he's using a Sharp R-120
"Half Pint" model microwave (1100 watts) on a 1200W continuous
inverter. That's all fine, but he's probably drawing 100A outta' that
battery (factoring loss across the inverter) when he runs it. I'm not
sure I'd be satisfied recharging such a heavily used battery through
two FI hose clamps with a length of 12 or 14ga wire attached, running
through the stock relay. He says he's managed to find 125
suckers....er...CUSTOMERS to buy his $25 "kit" consisting of an
instruction sheet and the two aforementioned clamps with wires on, and
lists a number of comments from satisfied customers, so who knows?
Must work well enough.

My own dual battery setup consists of a 200A continuous rated solenoid
type relay fed via 6ga cable, but then again I'm a nut. I've got a 6ga
copper ground cable running fore to aft  around the whole vehicle and
bonded to any major ground point I could reach.