I want to put a second battery in the back(I go to the drive-ins alot)I already have a system with 4g power wire going from the engine compartment to the trunk. Using fuses and an isolator can I get away with running the 4g from battery to battery? I have the dimming light problem as well and need to upgrade my power source, but I'm told that this can void my car warranty. Any ideas? Dual altenator maybe?

Try a bigger alternator and battery.

I want to go with a second battery and a bigger altenator as well, but don't want to void my car warranty

Ya, put the battery in the trunk, run 4 ga. from your alternator to a solenoid switch (instead of an isolater... isolaters have resistance, solenoids do not), then 4 ga. back to the rear battery from the solenoid.

I wouldn't think it would void any warranty, as this is common in pickup trucks that pull or carry RV's. But find out from your auto manufacturer first. Replacing your alternator with an HO one, or even adding a second, would almost definately void your warranty, unless the dealership supplies the HO alternator or second alternator and bracketry themselves.

Myself, I'm running 160lbs. of rear batteries, and a 1 farad capacitor, with a stock 105 amp alternator. My current draw far axceeds that(their respective fuses total 210 amps), but my lights and whatnot are not affected much as the batteries and cap help with that greatly.

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Thanks for the tips Grizz