Technical Trunk mounted battery setup

Here is my trunk mounted battery setup for those interested.

aluminum battery box made from scratch.
Hard hydrogen vent line to gas door.
150 Amp slow burn main fuse mounted on side of box.
150 Amp circuit breaker on altenater feed and chassis wiring.
#1 altenator wire
1/0 starter and ground
Remote mounted solenoid and jumped starter.
Ground battery to frame at back.
Second ground from battery to engine block
Ground engine block to frame
Ground connecting both heads, body, then back to frame with block

 

Nice 50 Pontiac. I hear so often that it's imperative to run your ground all the way up to the starter but hell, even my daily drivers have the battery in the back with the ground strap going to the unibody. I maintained a fleet of dump trucks and snow plows for almost 30 years and they used the frame for a ground.
Anyway, nice setup.

 

It's only imperative to use a separate ground cable, if you're not capable of making the connections to the frame properly.

 

I would get a bolt on terminal like the battery's have, then drill a hole through the frame. Clean the metal up by the hole, once installed cover it with grease..

 

I had a good frame ground, but then playing around ran a ground to the starter and it spun much faster, so i kept it.

 

I run a #8 stranded from the battery to the frame then to the engine block and starter bolts...

Get a pair of jumper cables, at idle, turn everything on including wipers and try bonding different parts with the jumper cables and then check the line with the amp probe and see how much current is going through.

At 12 volts there is hardly any pressure, so make all connections very clean and covered with grease..

Even though electrons flow better in copper then steel, the mass of the frame and chassis makes it a worthy conductor.. I use both..

An engineer suggested to me to always use stranded conductors with D.C. (battery) or even pulsating D.C. (alternator / generator)..

 

Never use the frame for the ground, run the ground cable to the engine block then run grounds off the ground cable to the frame. The frame is ok for low current grounds not high current grounds.

 

Who sez?!..........I thought 'a-ground-was-a-ground'!?
6sally6

 

There is in fact a theory that an old frame with perhaps rust or damage may have gone through metallurgical changes over the years that make it more efficient to run a dedicated ground from the battery to the block or at least a clean area of the frame closer to the starter. Others may disagree.

 

Used the frame as a ground on numerous cars, and never an issue. I use 2/0 for my positive and negative cables at both ends, and crimped on cable ends.

I'm puzzled by the mention by the OP of: "Ground connecting both heads, body, then back to frame with block"?? I can sue see grounding the block, and a strap to the body. But since there's no current flow through the heads why a separate ground to each head? Seems like over kill to me.

 

The whole thing looks overly complicated. My Mustang has a ground to the trunk floor, the positive cable running straight to the relay on the fender apron and that's it. Been that way since Nov. 1969.

 

The way you did it makes the most safe installation only having the starter cable hot when cranking. As well as using a 150amp breaker for all other loads. Nice thought!

FWIW: If you use heat shrink over crimped and soldered ring terminals it gives a nice clean look as compared to black tape.

 

why build when you can just buy off craigslist?

 

I never ground to the frame. I do ground to the body. There is nothing electrical on the frame. I ground directly to the engine and then provide some good grounding busses off the negative terminal for the low current stuff. That's just me.

 

Answering a couple of questions.

I made the battery box because I like the challenge. If I just want bolt on stuff I would build a late model Camaro.

grounding both heads, block and chasis came from an installation guide I had from Taylor Wires. Attached

 

I run both battery cables to the front where both connect to remote battery terminals mounted on either an inner fender or the firewall in a accessible location. From the remote terminals, the cables go where ever they need to go.

On the current project I'm considering adding a power kill switch off the battery, but I don't like the idea of a removable key. Lots of debate about the shut off being on the positive or the negative battery terminal. Gene

 

Tuff crowd to build a battery box setup for! Here's mine. Has worked for years. Just recently hacked up an old Harbor Freight parts washer to make a cover for it.

IMG_6426 by y'sguy posted Apr 9, 2021 at 11:47 AM

IMG_6429 by y'sguy posted Apr 9, 2021 at 11:47 AM

 

Disconnecting either positive or negative battery cable has the same effect.....

As far as which is the safest one, well I dont think it males any difference.

I too like to fabricate all my own stuff, even if something is available, for all the same reasons you stated.

Where did you find the 150amp circuit breaker?

 

I like to line my metal battery boxes with a hard cell closed foam. Also, always mount a set of remote battery posts that are easy to get to. Didn`t see a set pictured. Also, an easy place to reach while driving to to have a battery shut off switch while you are at it. Prevents theft. Always use rubber grommets when routing wires and battery cables going thru metal holes.

 

Heat shrink is nice but when making a wiring harness, use the tape designed for harnesses.. It looks like friction tape without sticky glue. You wrap it up nice and tight then use a slip knot at the end..

The fuses used for this have to be special. Frankly I think a self re-setting breaker would be best.. But have a disconnect lever next to the floor shifter so you can pull it after getting to a safe spot to stop.. You never want have that fuse blow while going down one of these crazy super highways we have..

 

You want the battery in between the front and rear tires on the passenger side to get the most out of the weight.. One of the best places for the battery in on the firewall passenger side.. It helps even out the weight of the car.. Chevy was smart, they put the battery, fuel pump, starter and alternator on the passenger side to balance the cars weight. If you look at the Corvette the engine is slightly more to the passenger side.
I read in Herb Adams suspension book you want to keep the weight in between to front and rear tires. I remember when I changed to an aluminum fuel cell and mounted it more towards the center of the car how much better the car handled..

 

All interesting . At least i'm subscribed now . Reason being one of my '32 Fords has a battery way out back and smokey 6V starter stuff up front .

 

Look at almost every Mopar built...the engines are almost all off set to the right side, for steering clearance.

As far as grounds, someone should tell all of the manufacturers that the frame isn’t a suitable place to ground the battery. If it doesn’t work then you don’t have good connections


Sent from my iPhone using H.A.M.B.

 

I've had several '40 Fords and all of them, I put the battery in the trunk. No kit, I used welding cables. I always had a kill switch I could reach from the drivers seat for safety. I had 1 emergency in many years of driving and the kill switch saved the car plus our belongings. It only took about 1/2 an hour on the roadside and I repaired the problem area and never had that problem again. I have tried both ways of having the ground go all the way back to the engine & I feel it provided the best ground to do that. As for handling, I never noticed any problems. I also had 1 = '40 Ford sedan the battery was under the rear seat, that was a pain in my butt. I'd say it's like building a Hot Rod, build it your way. Have Fun!

 

......I agree.

 

If you have to use a wrench to disconnect the cable, then disconnecting the one that goes to ground, is safer. If it's a switch, then it probably doesn't matter...although for drag racing, NHRA requires the disconnect switch be on the side that's not grounded.

 

All my cars have trunk mounted batteries, and all have disconnect switches. But I'm not passing NHRA tech, so my battery switches are not NHRA located at the back bumper. I locate them hidden so if I'm on a trip I can disconnect the battery and remove the key overnight when on the road.
That Taylor wiring schematic is silly and overly complicated grounding. No reason to ever ground the heads as there's no power to the heads. And if 16 head bolts to each head isn't a good ground, then a strap wont help either.

 

I used a tool box from parts truck in my avatar. Extra grounds came into play when I had trouble with tail lights as I was using a 12V source with low amps,,,not the way to install a wiring kit,,use a fully charged battery to eliminate electrical gremlins.

 

Its a usa manufactured breaker, ebay.