Anyone know the correct way to hook up two batteries, and what the benefits would be? I did a search and everything I read says its for using your sound system when the car is off. If that is the case why do full out race cars use dual batteries? Thanks

 

Wire them in parallel. If you wire them in series, the voltage will be 24. Maybe that's why the race cars you mentioned have dual batteries? Maybe they are 24v.

 

Race cars have the 2nd as a spare just incase, see you don't want to be changing it when racing.

 

For your daily drive there is no real benefit unless you have a big-block with an ungodly compression ratio. If you want more reserve capacity or higher cold crank amps consider an Optima or some other brand of premium battery. Realistically the stock 75A12 is fine for most cases.

 

i just wanted to add...most full all-out drag race cars dont have alternators, no point, they have the batt to just power the car for the short 1/4 run and the 2nd as a back up so they arent stuck on the line if soemthing goes bad...thats just what i learned