ground for battery in trunk.. this tab ok?

I was thinking of using this existing hole (minus paint of course) as a ground for the battery in trunk. Should that work OK?

Alternatively, I could go through the trunk floor and bolt something to the frame, but I'd rather not do that if this area of the body will work. In the engine compartment, I plan to run another cable from engine to body/firewall.

Thanks.

Nope. Factory frame or aftermarket frame in the rear? If factory, I'd run one to the frame AND one all the way up to the engine block. Yes it is over-kill, but you can never have too good of a ground. Also the heaviest cable you can get your hands on.

I wouldn't rely on that to start the engine on.

I made an aluminum bracket that tied to the two tie down hook points on the back of the RH rail on my 'Cuda. I do not have a battery to block ground, I have one solid battery to chassis and two engine to chassis grounds up front.

Will it work ... YES. Been there, done that.

Was checking the plugs one day and dropped the last plug and it hit the starter positive and shorted. I heard a BANG that sounded like a gunshot come from the back of the car. My first though was that the battery had exploded but when I opened the trunk it was intact. A subsequent search revealed the ground had blown off. It was one of those thin stamped copper ends and it had blown off at that contact point. Kinda lucky it did I guess !! So there's something to be said for having weak points in systems !!

I run mine to the trunk latch bolt. Worked fine for years.

Always run a negative wire smaller than the positive wire running to the front. If the positive wire grounds and they are the same size it will burn both wires sparking a fire along the whole car. If the ground is smaller, only the ground burns and it will be limited to the trunk. Kinda like an emergency fuse. I suggest at least 2 sizes smaller.

For those who think it won't happen it did to me. Trunk filled with smoke but the car was OK. There are other methods that help prevent it but even with those in place this method costs nothing to do. One method is to put a solenoid on the positive going to the starter in the trunk so the main battery cable is not live all the time but it still has to go live to crank. If it goes live to turn the starter and the positive wire is grounded it will still burn the car.

We welded a 3/8 bolt to the sub frame beneath the trunk mounted battery and one to the front sub frame
passenger side, (we have welded sub frame connectors). 2/0 size cable.

For the positive, ran a 2/0 from battery to an insulated stud mounted on the firewall,
have a homemade screw on cover for that connection to eliminate any accidental contact

I do like the Idea of a lesser gauge ground to act as a fuse and will change one of the ground cables to have that safer set-up.

Thanks for the input ....Joe

I've used that spot without a problem. Clean both sides and use large washers of both sides to ensure a large contact area. I do have an aircraft circuit breaker on the positive side that also serves as a battery disconnect/anti-theft device.

I've used that location, a similar factory hole at a rear body panel gusset, and similar holes at the trunk latch support.
Worked fine in every case, whether a 512" Duster, various vintage race cars, early B bodies. My car in the avatar's been that way for over 30 years.
I also always add a heavy ground cable from block to chassis.
Fasten all ends as previously noted, and I like star washers to dig in.
On a unibody car, the chassis and parts welded to it become the "frame".
On something with a separate body/frame construction & isolators, I add ground cable frame/subframe to body.

What 70gtxhemi said. I drilled a hole in the trunk floor near the battery & ran the ground wire to the frame. Did that 20 years ago and has been ignored since then.

Yes, that location works for a chassis ground, and it has worked on my Charger for 25 years, but you may get a bit less charging voltage at the battery?
If running EFI, or other computer stuff, it would be good idea to run another ground from the battery to the computer equipment, and not ground it to the chassis ground.

Normally the battery grounds to the block and then to the body. So the current has to travel through a solid block to get to the starter. Whether it runs through an iron block or a steel chassis is neither here nor there, what matters is the connection between each. Typically the ground from block to body was a much thinner gauge than from the battery to block because the starter needed that heavy gauge for the current draw. So grounding first through the body and then to the block you're going to have to use heavy gauge at both ends.

That tab will work just fine for a chassis ground. You'll still need to run another cable up to the engine block for an engine ground. There are a lot of amps that need to flow back and forth between the battery, starter and alternator. Your ground cable running to the engine should be at least a #8 welding cable and something like #4 would be even better. You can get high quality multi-strand welding cable from Amazon. The more strands the better.

It was mentioned to run a smaller ground wire as a "fuse". Why not just go to NAPA and buy a 100 amp ( I think that is what I have in, but not sure.) fuse and put that in the positive cable right at the battery. Much safer than relying on a homemade "fusible link". NAPA has different amp fuses for them. Very nice item. Not real expensive either. Remember even though your ground wire burns off, your positive wire still has power in it, making it a possible arc point. Fusing it right at the battery limits the amount of powered cable to a few inches. I tried to attach a photo of the fuse I used. Don't know if it worked or not.

NAPA part #


BK 7821143

Lists for less than $12.

Oops, I did forger that you still need to run large ground cable from frame to engine block. Thanks for pointing that out guys.

never a good idea to run small cable for the battery ground. doing this, eventually will cause problems you can't imagine, and WILL cause you to loose hair you don't have.
just relaying my experience in fixing wiring problems over the years.
and if you are contemplating new battery cables and even THINKING about those cheep-o bolt on cable ends at the battery, 50 lashes with wet noodles you shall get !

The stuff that we got away with 30 years ago doesn’t work as well as it did back then. Everything is electronically controlled now so do it right and reap the benefits. Good grounds are so important

can you get small gauge (large) molded cable battery terminal ends?

I've used that hole ground to bare steel on both sides and another same size cable to one of the trunk latch bolts ground to bare steel also as well as two #4 wire block to frame grounds up front
I used one of the threaded holes by the starter in the frame and the bottom lower 7/16 bolt through the block to the tranny case and one from a 7/16 engine mount bolt on the block down to one of the k frame engine mount bolts on the passenger side, clean all the surfaces to bare metal first

Starters can pull more than 100 amps. It's not about fusing the auxiliary systems it's about protecting the main power wire to the starter. I have had the starter come loose and when I went to start the car that is when all heck broke loose. Factory trunk mounted cars use a similar method or use non burn wiring covers(like a fusible link has) to prevent the car from burning if the main trunk line gets shorted.


Like you pointed out though. Auxiliary systems should always be fused with a fuse or fusible link.

Just put a Ford starter solenoid in the back near the battery. Use it to switch the power to the starter that way the long wire forward to the starter is only hot when you need it hot and dead all the rest of the time. You will need to run a separate, fused at the battery feed for the fuse box.

try these. just a couple examples of crimp/solder or furl type. available in almost all gauge sizes. WAY better than those cheep-o "bolt on" pieces of $hit !!
use marine grade heat shrink to complete the job, and no problems of corrosion or a bad connection.

https://www.ebay.com/itm/5-Pack-of-...inal-Cable-End-2-0-Negative/173891462814

here is the other style i spoke of.

https://www.ebay.com/itm/Taylor-Cab...ry-Post-Screw-Together-Pair/392351664826

a guy can also use the crimp/solder "eyelet" type that bolts to the battery ala GM side terminal battery. tons of those ends everywhere in any size.

That is the first step and often required by some racing bodies but once you hit crank it's full power to the starter. In my case the starter had worked loose and the main positive wire was grounded at the starter. Hit the key to crank and poof. Big smoke. No real damage. Had the main line been the same as the ground I would have probably lost the car since the power wire was run inside the car along the rocker the same way the factory does it now.

Back to the original question. Some people have mentioned that they have used that tab. I like a little more metal myself. Like I said I ran my ground to the trunk latch bolt but a direct bolt into the frame (like others suggested) would probably been better than my way. I did my way so that if I moved the battery back to under the hood it would be a simple unbolt, but truthfully so would a bolt to the frame.

Also a switch to a modern starter would reduce the load to the main wire. Modern gear reduction starters use less amps than our old Chrysler gear reduction or the GM/Ford direct drive starter. Just look at the size of the battery cables on modern cars compared to the old ones.

Thanks Moparx

I'm contemplating running two batteries, one large in the rear with "Ford" solenoids on BOTH the positive and negative to be used only to start the car. Charge with a thinner gauge wire through a diode to control the current flow. A smaller, lighter battery (like motorcycle or garden tractor) to "run" the car.