Electrical Trunk mounted battery and grounds


Active Member
Jun 14, 2007
Hey guys,

I recently bought my car in May of this year. It has a trunk mounted battery. The negative cable is connected to a bolt underneath the car. It looks like it's connected to the rear bumper crash absorber brace, if that makes sense? Should I have another smaller cable coming off the negative battery cable grounded somewhere else as well?

The car has a PA 200 amp alternator and I see it has a 4 gauge ground going from I believe the block to the drivers side frame area. And also a ground strap from drivers side head to the firewall.

I just want to make sure the car is grounded properly and wondering if I should add anymore? When I initially start the car I see 14-14.2 volts. Once my mark iv electric fan turns on it drops down to 13 volts. And if I turn my ac on full with headlights on I see 12.5-12.9 or so.

I just installed a Optima redtop battery. Previous owner used some very hard 1/0 battery cable. I might eventually redo them and use welding cable.
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New Member
Apr 17, 2019
orlando fl
I had a similar issue with my build that I received back from the shop .That is a ground,but its not correct. You should have both cables, ( pos , neg ) the same exact size , and use the vehicles original ground on the block.