Big 3 with 2 batteries and battery isolator.

[txbass97]

If I have two batteries, connected via a battery isolator, would I run the big 3 kit off my starting battery, or accessory battery? (yellow top)

Batteries are both fused between battery and isolator.

Big 3 is currently coming off accessory battery :
1 from positive post to alternator positive
1 from negative post to chassis ground
1 from engine block to chassis ground

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[Popwarhomie 5,000+ posts]

Big three is for your under hood battery. Are you running two batteries under the hood?

 

[txbass97]

Big three is for your under hood battery. Are you running two batteries under the hood?

Yes. O'Reilly battery runs/starts the car, I hooked up big 3 to yellow top optima ( auxiliary battery)