Proper Battery in the Trunk wiring with battery cutoff.

[Cheeseburger]

I want to have my battery set up NHRA legal, i have done a few hours of research and it`s a cointoss as to what is proper and not proper it seems!

I talked to a manufacture`r who suggested this: Battery + to cutoff switch, switch to starter then starter to positive junction box.
Alternator back to battery + side of cutoff switch.
Battery to chassis ground.
He said you do not need a seperate alternator switch or a 4 pole switch, just connect to the two pole cutoff.

Here is another setup which is completely different.

Battery + to 4 pole switch then to +junction box, from there to starter and to alternator.
Battery ground to front of car to negative junction box.
14 gage wire from F terminal on alternator to contact switch and then back to + battery.

I am not sure about the F terminal as there is the brown plug covering it up at the alternator, do you cut the plug off and ad a two pin plug

 

[Cheeseburger]

Here is a copy of the second method.

 

[garyk1970]

how i would do it..

rear;
battery + to switch.
switch to starter 0 ga wire.
any other add ons hook to switch,IE dash,IGN switch,fans,etc don't add anything without a fuse or circuit breakers.

battery ground to body,and jump to rear frame.

front;
alt with correct size and length fuseable link spliced to 8 ga wire to starter.(the battery with charge through your 0 ga starter wire to battery/switch).

ground from block (not heads,or intake) to frame.then make jumper ground from frame to body up front also.

using factory dash? run alt regulator wire off of battery/charge light in cluster.
if not, get a one wire alt....
you can wire your dash at starter like oem,just dont forget to use fuseable links there too.

 

[Nick Micale]

.....
battery ground to body,and jump to rear frame.
.......
ground from block (not heads,or intake) to frame.then make jumper ground from frame to body up front also........

Gary, I know you are an expert when to comes to wiring, but we have found that running a ground from the rear battery through the frame to the engine can give you issues, especially in a race car.

And my guess Mike is building his GN for high performance.

The poor quality steel used in G-body frames is a really bad conductor, and as you know the factory connected the battery directly to the engine. We run another cable from the rear battery as a ground, same size as to power cable to the engine, or at least to a junction block up front that is also connected to the engine.

We see many problems with regular GN's due to bad or improper grounds, however in a race car it can get troublesome, as well as expensive, in a race car.

Items such as the aftermarket computer, boost controller, fuel pump, MSD and others MUST have an excellent ground for proper output.

I have a wiring diagram that shows basic race car wiring, and it is also available on line for those interested.

 

[Cheeseburger]

I have a wiring diagram that shows basic race car wiring, and it is also available on line for those interested.

Hi Nick, can you email me a copy of the diagram or a link to it?
Thanks,

Mike.

 

[HighPSI]

alt with correct size and length fuseable link spliced to 8 ga wire to starter.(the battery with charge through your 0 ga starter wire to battery/switch).

Unless I am misunderstanding how you are doing this, the cutoff will not work. The alternator will keep the car running.

I usually run the alternator to the battery side of switch and a ground from the battery to the starter bolt.

 

[KevinB]

The way I wired up my alt worked great.
Get rid of the factory plug on the back of the alt. Go to an auto store and get the replacement plug which has like 4 wires instead of one. Use the the "I" wire, cut the rest off. Take the I (Which is also the f) and run that to a switched 12 volt source. Make sure that switched 12 volt source is on the cut off side of the main batt switch. Run your alt charge wire to the switch also. My car would shut down immediately and never had any charging issues.

 

[cruzn57]

if you ever plan to run at the strip

with a trunk mounted battery, you will need a trunk fire wall, usually a sheet of metal behind the rear seat back.
or.. a sealed battery box, vented to outside of the trunk.
heres a pic to explain.

 

[Cheeseburger]

I don't really like the idea of feeding the junction box voltage from the alternator (possible noise issues?).
I also don't like the idea running 2 hot wires almost the length of the car.
Anyways, here is a possible plan.......

Battery ground to starter bolt (1 gage)this way i can simply swap out my existing positive battery cable and use it as a ground without rewiring.
Another option is direct to neg junction box which would require new cable.

Neg junction box at firewall, grounded to firewall and grounded to intake manifold bolt with straps.

1/0 gage positive from switch to starter.

4 gage from alternator to battery side of cutoff switch.
I hear some guys have run these under the carpet beside the tunnel with split flex tubing covering them but i'm actually leaning towards outside along the frame as the thought of those inside the car concerns me....

Now the pos junction box which i plan on using for my MSD ign/xfi/inj's etc, feed from starter or??? This is where everything can change!

Feedback appreciated!
T.I.A.

 

[Nick Micale]

Hi Nick, can you email me a copy of the diagram or a link to it?
Thanks,

Mike.

The info I have is a booklet with the diagram and other good material for race car wiring.

Their web site is down, but should be working later today.

I will post a link when that happens.

If you want to call, the number is: 1-218-575-5665, and Bill will be happy to help.

 

[Cheeseburger]

I looked over everything last night, and need to redo some old wiring on the car (fuseable links).
I am thinking about putting the battery back in the stock location, it does nothing to have it in the back of the car other then create a headach and crash hazard it seems.
I say it does nothing to have it in the back because it really does not make a differance for weight transfer i.m.o. and actually you add weight to the car to mount it in the trunk.
Does the track require a cutoff if the battery is in the factory location?

 

[HighPSI]

I say it does nothing to have it in the back because it really does not make a differance for weight transfer i.m.o. and actually you add weight to the car to mount it in the trunk.

I'm not sure how you could say this. Have you ever scaled a car? Moving that much weight 15 feet makes quite a bit of diference, especially when you consider the p/s rear is the lightest corner on the car As far as it being a crash hazard, I would think you are more likely to crash the front of the car over the rear. Do what you want, but I'm not sure of your reasoning.

 

[Cheeseburger]

I'm not sure how you could say this. Have you ever scaled a car? Moving that much weight 15 feet makes quite a bit of diference, especially when you consider the p/s rear is the lightest corner on the car As far as it being a crash hazard, I would think you are more likely to crash the front of the car over the rear. Do what you want, but I'm not sure of your reasoning.

Having two hot cables running 3/4's of the distance of the car is a hazard in my books, although i still may chance it.
I have never scaled a car or thought of scaling a car, i would be more serious about it if i knew i could make a living at it but we know you can't (well most of us)........
I bought my cables, they weigh 12lbs, plus the weight of the battery mount/two cutoffs/nuts+bolts.
Basically your adding up to 20lbs of weight to your car to move the battery to the trunk.

 

[Cheeseburger]

Battery has to go in the trunk as my downpipe is too close to the stock battery location.
Battery weighs 42lbs.
Cables weigh 14lbs.
Hardware and cutoff switch 6lbs.

 

[turbobuick]

Unless I am misunderstanding how you are doing this, the cutoff will not work. The alternator will keep the car running.

I usually run the alternator to the battery side of switch and a ground from the battery to the starter bolt.

You will need this if running an alternator
Painless Wiring 50105 - Painless Performance High Amp Shut Down Relay Kits - Overview - SummitRacing.com

I ran a 4ga welding cable to the alt from the relay. In addition I grounded the battery to the frame, engine to the frame and ran another 4ga welding cable to the front from the neg battery terminal. I used a junction box under the hood and another under the dash and ran ALL grounds to them essentially running all grounds directly from the neg battery terminal.

 

[HighPSI]

Battery has to go in the trunk as my downpipe is too close to the stock battery location.
Battery weighs 42lbs.
Cables weigh 14lbs.
Hardware and cutoff switch 6lbs.

If you scale the car before and after this swap, depending on where you mount everything, I predict you will lose over 50# off the nose and gain over 70# on the rear.

 

[regal81455]

I just did this battery relocation to my car. Used a 74102 moroso battery disconnect. It has the posts for the battery disconnect and another set for the alternator interrupter. We ran a 1ga wire from the switch down the passenger side to the area where the computer used to lie ( carb'd 455 car ) and placed the "hot" junction here. This is where I will continue with a 1ga for the starter and 4ga for the alternator.

The ground was ran from the battery to another junction block and the from there we ran a ground to the body and a ground to the frame. We will then do the same thing upfront. I can attach some pics of it if your interested.

 

[regal81455]

ground had not been hooked up from the frame to the junction yet but here were some pics...

 

[HighPSI]

We ran a 1ga wire from the switch down the passenger side to the area where the computer used to lie ( carb'd 455 car ) and placed the "hot" junction here. This is where I will continue with a 1ga for the starter and 4ga for the alternator.

I may not understand what you posted correctly, but I don't think that will work. The alternator will still keep the car running even after you flip the switch.

 

[regal81455]

I may not understand what you posted correctly, but I don't think that will work. The alternator will still keep the car running even after you flip the switch.

It shouldn't - the field terminal on the alternator will have a wire running back to that switch ( its a double pole'd switch ) that will interrupt the signal, killing the alternator. I didn't have a good picture of the switch but its made exactly for this application. This setup is wired per the Caspers relocation diagram.