We currently have the stock(still good) battery up front and a kinetik 2400 in the rear. Charged from the stock 125 amp Alt.
A single run of positive (0 awg) between the batteries. Both batts. are grounded near their location. Both ground points currently measure .12 ohms resistance, so no loop. Stock 4 awg from the Alt and a 0 awg engine ground.
We compete bassrace and streetstock, so the van is always running durring comps.

So this week we're getting a new Alt. put in. A DC Power 270 amp unit. The stock Alt. is located under the plenum/fuel lines back behind the cowl. It's gonna take a couple hours of shop time to switch it over. Meaning I myself, can't install or change the Alt wires around on a whim.. This is important to the question

We were thinking that because the front battery is stock (acid)and we probably won't be replacing it anytime real soon. We could run 2- 0 awg from the new Alt.... 1 to the front battery, one to the back. With just the single 0awg in between the batts. , same grounds.

The new systems current draw full tilt is about 300 amps.

There's really only room for 2 runs through the firewall grommet, since we do not want to modify it and we only have enough wire for 2 runs/new grounds etc. right now...(17ft runs!!extended vans...blah)

Would running the 2 Alt wires/ single O awg. provide more current when running to the amps, than a single 0 awg from the Alt to the front battery and then 2 pos runs to the back?

 

which way to go would depend on the distance from the battery in each install. amperage load per distance in relation to the wire guage....hmmmmmmm
you could do a voltage drop test to se which is the better way to go...
i'm sure there is a calculator somewhere for this, as it's used in electrical building code.....