Chevy Nova Forum banner

1 - 17 of 17 Posts

·
Registered
Joined
·
48 Posts
Discussion Starter #1
I want to re-locate my battery to the trunk of my 67. Do most people install a junction box in the engine compartment for 12 volt feed to starter then run a cable to battery in the trunk. What about 12 volt feed from the fuse panel. I know you can buy kits but what is the best one?
 

·
Registered
Joined
·
1,665 Posts
All of the power for inside the car should already come from the positive battery cable post on the starter so you shouldn’t have to do anything with that.

In its most simple form, put the battery in the trunk and run a long continuous positive battery cable to the starter. Re locate the negative cable from the front battery to the frame in the engine compartment and ground the battery in the trunk to the frame.

There are other things to consider such as you will have a large amperage capacity cable running under the car that is not circuit protected. If you go to the drag strip you may have to have a disconnect back there too. There is a lot of discussion around here regarding the “Right” and the “Wrong” way to do all of this. Do some research, use common sense, and don’t burn your car down to the ground.

This is my Main Power Distribution System:


Steve
 

·
Registered
Joined
·
48 Posts
Discussion Starter #3
Re-locate battery

Thanks for the information. Did you make your own junction boxes or buy them somewhere?What about protecting the heavy gauge wire from battery to starter did you run this in conduit or wrap it with soething?
 

·
Registered
Joined
·
1,665 Posts
Thanks for the information. Did you make your own junction boxes or buy them somewhere?What about protecting the heavy gauge wire from battery to starter did you run this in conduit or wrap it with soething?
As I said before, and as you can see, you will get a lot of opinions on this subject. Ideally, you do want the Negative Terminal of the Battery connected directly to the engine block. Some do and some don’t. Some people have problems and some don’t.

My positive battery cable is only hot while I am cranking the engine with the starter. After the engine starts the battery cable is electrically dead so I don’t have to worry about a short in an unprotected circuit.

Here is a web site with some good technical information that is easy to understand.

http://www.madelectrical.com/

Here are some web sites with anything you need to modify your electrical system.

http://terminalsupplyco.com/default.aspx

http://motorsportswiring.com/

http://www.americanautowire.com/

http://www.waytekwire.com/products/

Steve
 

·
Registered
Joined
·
1,665 Posts
What kind of problems?
For every amp that leaves the battery it has to get back there. Copper wire is a much better conductor than the mild steel frame of the car so grounding to the frame introduces resistance into the circuit on the negative side. Resistance creates voltage drop which reduces the efficiency of electrical components. This “PROBLEM” can range from not quite getting the most out of your ignition system to things that just don’t work and everything in between. Mostly you will see reduced efficiency or even a failure in high amperage draw components like starter motors and electric cooling fans.
 

·
Registered
Joined
·
3,601 Posts
For every amp that leaves the battery it has to get back there. Copper wire is a much better conductor than the mild steel frame of the car so grounding to the frame introduces resistance into the circuit on the negative side. Resistance creates voltage drop which reduces the efficiency of electrical components. This “PROBLEM” can range from not quite getting the most out of your ignition system to things that just don’t work and everything in between. Mostly you will see reduced efficiency or even a failure in high amperage draw components like starter motors and electric cooling fans.
Like he said opinions vary. Of all the manufacturers with trunk mounted batteries I can't think of one that doesn't use the frame/body for the ground. There is an exponentially larger current carrying capacity through the frame/body and I haven't put the meter on one to check, but I wouldn't be surprised if the resistance is lower as well.
 

·
Registered
Joined
·
1,665 Posts
I would just like to add that when I wired my sons 67 I ran copper ground straps from the front sub-frame to the adjoining body structure. It was just a loop of battery cable with eyelets on both ends. One went under the bolt head on one side and the other end under the nut on the other side. I used star washers between the steel and the copper for both ends and did this on the left and right sides of the car. If the body and the sub-frame were painted separately, I can see where a ground path may not exist between them. (This is not so much a problem on the 3rd gen if you have weld in sub-frame connectors.) After that we grounded his battery to the frame and have pretty much 14.2 volts everywhere.

Steve
 

·
Registered
Joined
·
2,990 Posts
mine

Well, I was curious cause mine is in the trunk and works great. Wasnt sure if I was missing something. The only time though, you would really be that worried about the loss is is during start. The alternator is at the front and SHOULD be where you're getting running voltage/amperage from anyway. The resistance I'd think should be negligable as I've never seen more than a tenth (MAYBE 2) of loss if the rest of the system is up to par. plan, plan, plan
 

·
Registered
Joined
·
1,665 Posts
If you are curious you can do a voltage drop test which it sounds like you already have. Just in case, and for those that haven’t…

Measure the voltage across the battery posts with the engine running at high idle (1200 rpm or so). Then measure it from the battery cable on the starter to the frame close to the starter. The difference is the voltage drop in the starter motor circuit due to any resistance that may exist. 1/2 of 1 volt is considered acceptable if I recall.

It’s not a bad idea to test it where the main power feeds inside the car also. Just because everything comes on and works doesn’t mean it is working at peak efficiency. You may have 14.2 volts at the battery but if you only have 12.5 at your distributor then your plugs aren’t firing as well as they could be.
 

·
Registered
72 Frame off, bare metal resto-mod. 383, TH350, Eaton Posi, Complete new suspension, disk brakes
Joined
·
1,519 Posts
Use a wire that has lots of strands.I did a rear mount battery in a 72 Land Cruiser with a 283, and normal cables wouldn't spin the engine, I got some used welding cable and it was like the battery was right next to the starter.
Being able to shut the battery down is important. Adding a simple off/on battery switch is not just good for safety, it can also be handy if the car is a sometimes driver. Shut the battery off, and it's always charged.
 

·
Registered
Joined
·
407 Posts
Use a wire that has lots of strands.I did a rear mount battery in a 72 Land Cruiser with a 283, and normal cables wouldn't spin the engine, I got some used welding cable and it was like the battery was right next to the starter.
Being able to shut the battery down is important. Adding a simple off/on battery switch is not just good for safety, it can also be handy if the car is a sometimes driver. Shut the battery off, and it's always charged.
multiple strand wire works better because current flows on the outside of the metal wire. multiple strands twisted into one have more surface area which makes for more current carrying capability. I learned that.:D
 

·
Registered
Joined
·
3,601 Posts
multiple strand wire works better because current flows on the outside of the metal wire. multiple strands twisted into one have more surface area which makes for more current carrying capability. I learned that.:D
This is refered to as the "skin effect" and only aplies to alternating current (not DC like in our cars) and increases with frequency. A single strand wire of equal size will carry more DC current than multi strand due to the area lost between the strands, but it would be hard to bend into the car and would likely fatigue over time from flexing and fail.
 

·
Registered
Joined
·
407 Posts
im sorry

Well please forgive me for thinking I knew something I didnt. I will remember that for next time. gosh, such a dummy:eek:
 
1 - 17 of 17 Posts
Top