Wiring multiple batteries for hungry amps

[Spl-Junkie]

When you wire multiply batteries do you wire them

( + --> + --> + ) or is it ( +--> - --> + --> - )

I am really not sure. I plan to install two additional yellow top Optimas batteries in my blazer. (1) in the engine bay and (2) in the rear left side inside the truck although I think I am going to break out the welding machine and make a battery rack to them under the truck on the far left corner then pass the 1Ga wire up to feed amps. Do you really need a relay. Any help would be greatly appreciated !!!!

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[crhye250r 10+ year member]

Relays break the circuit between the front and dedicated batteries when the ignition is turned off. Basically what they do, is keep the front and rear batteries from killing each other, trying to equal out power. I personally prefer having them in all my dual + battery installs. Its your call, but they do come in handy, especially if your ride ever sits for very long undriven.