Trunk-mounted battery grounding.

[409biscayne]

My first post. A lot of great technical info on this site that is not found anywhere else.

A few questions about grounding for trunk-mounted batteries to determine what solutions others may have employed. I used the battery relocation kit from M.A.D. Electrical. Per the instructions, the battery is grounded to the body in the rear. My questions concern the ground at the front of the car:
1. Can I ground from an aluminum head to the body? Or does it have to be from the engine block to the body?
2. If it should be to the engine block, can it be from the body to somewhere on the transmission? I could attach to a bellhousing bolt but they are not easy to access with the engine in the car. And there are no other unused threaded holes on the block that would be a spot for grounding.

Thanks,
Chad

[andrewb70]

Chad,

I always run a large gauge ground from the battery to the engine block, even when the battery is in the trunk. From the block I make sure to have a couple of good grounds going to the body. I like the stainless braided grounds straps. AC Delco sells then in various widths and lengths.

Andrew

[DT69Cam]

1/0 gauge from block to chassis is what I did and recommended by Mark from Mad.

[icemanrd19]

Battery to rear trunk support hinge wire
Battery to jump post mounted on the firewall wire
engine to jump post wire
engine to subframe ground strap
Subframe to passanger firewall ground strap
Drivers side firewall steering column bolt to engine ground strap
Drivers side inner fender to subframe ground strap
passanger side inner fender to subframe ground strap
Core support to subframe

[GoodysGotaCuda]

I have a short 1/0ga ground to the rear frame rail of my car with two short ground straps from the front of the chassis to the back of the cylinder heads [via nutserts]. I do not have voltage drop on the ground side when cranking and my EFI also does not have any issues either. There are a few ground straps for the dash as well as the transmission to frame. I do not have anything directly connected to the ground terminal of the battery, except the single ground cable.

[parsonsj]

In an effort to confuse even more... I ground the battery to the rear framerail, then ground everything else to the framerails/chassis.

[blitzer454]

I think that's the right way to do it. Adding an additional wire from the trunk mounted battery to the engine block may not be a good idea. That wire is not going to be as good as conductor as the body itself and you can actually create a ground loop doing this.

[1989GTA]

For me pretty much the same as the above posters. You have to be aware of the possibility of ground loops. 1/0 ground wire to the engine from the battery. Then a big wire from the engine to the frame and another big wire from the engine to the body. Like in a Y configuration. The engine being the center of the Y.

[Motown 454]

Do you guys put any di electric great on the connection when you install them?

[parsonsj]

Do you guys put any di electric great on the connection when you install them?I do. I've seen voltage gains of .5V on rear-mounted batteries using dialectric grease on the grounds, alternator brackets, and regulator brushes.

[Motown 454]

Thanks John!
I was just wondering if I was doing my over thinking like I always do. I had thought about painting over the connections on the sub frame to keep the clean.