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Aux battery grounding

hillbilly deluxe

hillbilly deluxe

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I've been reading and reading but I can't quite decide...:confused: I have added a second battery to my 73 burb. I am not running an isolator. I was looking at my diesels 2 battery setups. Both batteries in them ground to the engine (intake manifold, one on each side) and the positives are connected. That sounds good. But I also read that the block should be grounded to the frame. I don't see that anywhere on the burb. The first battery is grounded to the alternator bracket. I found a small wire that grounds the frame to the body under the hood. The winch is run directly to the side posts on battery 1, and I am planning on running an ARB twin compressor off the side terminals of battery 2.

So,
Should I ground the second battery to the frame and block?
Should I ground the second battery to the same place, or choose another spot on the block?
 
If you are just putting the two batteries in parallel, ground them both to the block. No need to be in the same place - I would just pick a convenient spot on the DS of the engine. The block should be grounded to the body via a strap at the back of the engine. They are commonly found on the PS running to the PS cylinder head. These straps are to keep RF noise down and the wire is just to power things like tailights, not big stuff.

The starter motor is grounded to the block and once you put the batteries in parallel, they will both feed the starter. You don't want the winch current or the starter current (500A) trying to go through your ground straps or body ground. Likewise, since the alternator is grounded to the block, the charging current returns most easily when the battery is grounded to the block.
 
You should ground the block to the chassis and cab ,GM did ,and you can never have too many good grounds...since the engine & tranny is mounted in rubber mounts that might insulate it some and prevent a good ground its best to run a ground strap to the firewall and frame rail like they did factory...though the ehaust pipes probably ground the engine fairly well,its not going to harm anything by having some extra grounds to the engine and chassis and cab...

I have also put a ground wire from the altenator case to the negative battery terminal on a few trucks that had intermittent charging troubles and it cured them...sometimes the aluminum case on the altenator gets corroded where it meets steel and current cant flow well thru like it should..
 
I'll have to look again, I can't find any ground straps running from the block to the body or frame. Who knows if they got put back last time the engine was rebuilt. I never had any reason to look before. If these "straps" are missing could I run any old piece of wire? Are the straps designed to burn up at a certain amount of current like fuses? Wouldn't want to run a piece of heavy cable if one is not warranted or if it would become unsafe if problems arise.

It's never had any troubles charging battery that I could see. It's just this second battery that is raising questions. That's why I was thinking of running the second battery negative to the block and the frame, that would make a good path, plus it's a path that it easy to install, inspect and maintain. Or, there's a convenient bolt holding the PS pump on where I was thinking of running the second battery ground. Maybe a cable from the battery to the PS bolt then down to the frame.
 
I grounded my second battery on the bolt where arrow points. Yes that looks like the area I can take picture of the one on my truck.
 
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When we rewired my buddy's truck, we ran the negative cable to the frame then another cable the same size under the bolt on the frame to the cylinder head. We have not had any issues doing it this way.
 
GM used a small braided ,un-insulated ground strap from the rear most valve cover bolt to the firewall,usually a self tapping screw secured it to the firewall....you can use whatever you like,but a ground wire doesn't need insulation,you want it to ground!...they need to be fairly heavy gauge,I'd say 12 or 10 gauge is plenty thick enough...

I've seen vehicles with poor grounds or a badly corroded ground cable cause things like shifter cables and throttle cables to turn orange,when they become the only path to ground!...:eek1:..one car my neighbor had,a old chevette,had its shifter cable glowing orange when I went to jump start it one cold morning--his ground cable rotted off at the frame and the shifter cable took its place...we got it started,but it wouldn't come out of park!--it was welded solid!..:doah:
 
Well I got it done. I ran a 4 gauge wire from the block to the firewall, and another to the frame. I grounded the 2nd battery to the manifold since that's how the batteries are grounded on my diesels.

From battery 2:
100_4754.JPG

Engine to frame:
100_4764.JPG

Engine to firewall:
100_4761.JPG

Dual batteries! Probably burn up the alternator now...
100_4757.JPG

100_4754.JPG

100_4764.JPG

100_4761.JPG

100_4757.JPG
 
I grounded my 2nd battery to the bolt connecting to the power steering pump bracket.
 
I usually run a heavy ground strap from the block to the frame, and a light one from the battery to the body. Then I never bother with that annoying one at the back of the engine to the firewall.

Also I think the valve cover bolt is only use as a ground strap location on the straight sixes. The V8's only use the back of the cylinder head as far as I know.

Martin
 
All the older 60's and early 70's GM cars and trucks I had used the passenger side valve cover rear most bolt to attach the ground strap--they may have changed that in the 70's when the square body trucks came along..most of that vintage had the negative battery cable bolted to the altenator bracket ,so it would be unlikely for the engine not to be grounded good--to the battery anyway..

I think the motor needs a direct ground to the body and battery,in case the rubber mounts insulate it from being fully grounded to the chassis..

I've seen things like throttle and detent cables get fried if they end up being the best path to ground on a few vehicles where engines were swapped in,and whoever did it figured that ground strap wasn't really needed that ripped apart when they pulled the old motor out..
 
I've had this truck for like 13 years and it never occurred to me to look for an engine to body/frame ground until I researched where to ground the aux battery. The wiring in this truck looks like it was attacked by gremlins but the headlights and tach always worked so, I guess, if it ain't broke don't fix it... I went out for a drive just to see if the lights were brighter or if it was faster :laugh: but nothing changed. That's okay though, I did tons of research and looked at other vehicles and all the motors are grounded to the bodies and frames so I figured it was worth doing.
 
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