Battery Relocation?

Ok everyone I'm not sure if this is the right place to put this or not but I'll give it a shot. I have a 1972 Chevelle that the previous owner relocated to the trunk. There is currently 4AWG power and ground wires running from the battery to the starter/engine. I really think these wires are too small for this so these are my questions.

What gauge should I use for power and ground and where should I ground it? I suspect this long ground wire is killing me for power and stereo issues and I think it should be a short ground to the frame and also a separate short ground from the frame to the block but I'm not sure.

4 gauge sounds small but on a race car I did years ago with some unknown high torque starter and a low cranking compression cam, it turned over fine reusing the previously run 4 gauge. On his we used the 10 point roll cage as a ground path from the battery to the engine and had a short 4 gauge off of the battery negative to the roll cage in the rear above the rear axle then had another short 4 gauge from the roll cage by the firewall going to a bell housing bolt. The 4 gauge too was copper not the cheaper CCA (copper clad aluminum) stuff.

I would run 1/0 copper myself if it was mine and off of the battery positive post, install some type of protection on the wire at the battery before any master cutoff switch, starter solenoid, and such. I've had good luck using ANL style fuses for this sized for the wire. For the grounds, you could run a dedicated 1/0 ground from the battery negative to the engine block and then add some more from the battery negative to the body of the car in the rear and then another from the engine to the firewall.

I came across a website that gives some info about battery fusing.

https://www.pbase.com/mainecruising/battery_fusing

I would also put the trunk mounted battery in a securely mounted sealed battery box that has a vent you can run to the exterior of the car.

With the battery in the trunk and depending on the alternator and cars wiring, you may have to run the alternators voltage sense wire to the trunk battery so it gets what it should.

Jim

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1968 Chevy II Nova Garage Find 2012
1973 Nova Custom
1974 Spirit of America Nova
1973 Nova Pro-Street

Thank you for the reply. I am seriously considering going to 0AWG for power and ground I'm just not sure if I should use a dedicated ground from the battery to the engine or just jumper to the frame.

Also I'm wondering if this will help my alternator whine in my audio system.

I'm also running a well mounted Optima Red Top

On my 73 Nova, I probably did it in a way no one else does but I ran a dedicated ground from my rear battery negative to a bolt on my transmission. For my other grounds like the headlights instead of having them grounded to the radiator support, I ran a dedicated ground back to the rear of the car to a ground connection block. This block has many spots to where I also ran a dedicated ground from the parking lights to it as well as the radio ground, and so on. I then have a cable from the block to my battery negative post. What I was trying to do years ago was not use the body of the car at all. Why escapes my memory but while the car sits most of the time I have not had any issues except a blown wiper fuse once in the last 20 years.

My 73 is still in nice shape in that no major panels have been replaced and the factory spot welds are all in place and I could have used the body for more of a ground path. Some car's I've seen are really rotted out and having the trunk pan spot welded to the back seat metal and this spot welded to the floor, and then this spot welded to the lower firewall, and so on and so forth, the electrical connection from the rear of the car to the firewall may not be as good as it used to be.

Maybe on yours with a full frame, run a 1/0 ground wire from the battery negative to the frame in back and then up front off of the same frame, run a 1/0 cable to the engine block. From the engine to the firewall you could possibly use the braided ground straps that might have been on the car originally and then run something like that in back to the trunk floor or taillight panel.

All of these new connections "may" help the whine but you might have a battery issue, where wires are run, an alternator issue, or who knows but once you get the battery circuit done, then you can troubleshoot the whine issue.

On the frame connections, clean the spot on both sides and use nuts, bolts, lock washers and such to secure the terminal off of the wire and the coat the connection to slow down any corrosion issues.

Jim

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1968 Chevy II Nova Garage Find 2012
1973 Nova Custom
1974 Spirit of America Nova
1973 Nova Pro-Street

Jim,

Thanks for the input. What I left out was the car was working ok (not great but good enough) until I had to pull the motor to fix an oil leak. I fixed it and put it back in and now the motor doesn't want to turn over unless hooked up to another car with jumper cables. Almost like the starter doesn't have enough power to get it to go (starter and battery tested good). I'm going to pull the plugs and turn the motor over by hand and with the starter just to make sure I don't have something binding but other than that it's electrical.

I also have a weird issue where I only have 10.5 volts at my gauge cluster box (Dakota Digital cluster) instead of the 12.5 volts at the battery. Once I get this starting issue figured out I will dig into that one.

It never fails you get the car close to being done and then something happens (just like the motor issue)

Ah, you are on the Chevelle site also. Your last post rung a bell with me.
Anyway, when you pulled to motor to fix the oil leak, double check the connections that were disconnected and reconnected.
Possibly did the distributor get moved to where now the starter is cranking harder from the ignition being too far advanced ?.
Maybe there is an issue with the connection on the bulkhead connector on the firewall. Maybe it got bumped or just a coincident.
On the lower voltage at the dakota box, when you are getting 12 volts at the battery with the key off and then turning the key on to check voltage then at the box ?. If the key has to be on, double check the battery and the box at the same time. In other words, don't do one test like at the battery with the key off and then turn the ignition on and check a circuit in the dash.
What you could do also is make the ground wire off of your meter long and then have that and left attached to the battery negative post then test at the positive post for voltage then test up at the starter, at the bulkhead, inside the car at the fuse block and so on further and further away from the battery positive voltage. You will probably get a lower and lower voltage reading and if there is a big jump between one point and another then this should narrow the issue down.

Jim

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1968 Chevy II Nova Garage Find 2012
1973 Nova Custom
1974 Spirit of America Nova
1973 Nova Pro-Street