http://nooutage.com/vdrop.htm

http://www.powerstream.com/Wire_Size.htm

You said :
>along with wires for dump load,controllers and mate.

What is mate ?.

The Logical placement of the equipment is close to each other to reduce high current losses.

The battery bank should be close to the DC/AC Inverter, and the charge controller.

If the battery is wind mill charged, it is logical to have the cabling going to the battery bank as close as possible and in this case, it seems best to extend the cabling to the NEW battery site.

One should have the equipment close to the electrical panel, logical and lower losses over all, and easier for trouble shooting if necessary.

Do isolate the battery bank if a lot of energy cycles daily, and what some have done is just a plastic casing with a fan to remove any possible hydrogen built up.

The isolation is a hood covering the whole bank with the small fan sucking the air out, and some of the builds have used the current detection to trigger the fan to operate at certain current level.

I think I know exactly what your problem is, because I have been contemplating the same. If you're going to dump a bunch of excess power off a wind turbine, it is much better to be able to heat the space you're actually living in right? The way I did my system, it's impossible using a C40 or equivalent. I'll be heating a shed 50' away from my house.

Everything logical points to keeping the batteries close to the inverter. Have you priced 2/0 wire lately?  One thing to think about... When I visited Dan a few years ago he had an interesting setup where the AUX terminals off his inverter energized a relay and he actually dumped 120V off the inverter into a regular 120V drugstore style space heater. I don't know exactly how he was doing it but it seemed maybe you could use a system like this to get heat into your living space at 120VAC and at lower line losses than 48VDC.

Volvo Farmer