NHRA Approved Battery Disconnect

[white05gt]

Actually, all I want is a video of your face when you hit the kill switch and nothing happens.

I would like to see that too. I think it would look something like this or

 

[CPRsm]

Lol, I don't bet if I'm not 100% sure I will win. Since I have already run the car, watched the switch successfully kill the car, I gotta say, I'm pretty confident I would win. I think my face will look more like LOL

 

[TexasKyle]

Lol, I don't bet if I'm not 100% sure I will win. Since I have already run the car, watched the switch successfully kill the car, I gotta say, I'm pretty confident I would win. I think my face will look more like LOL

Then you dont have it hooked up like you said you were going to hook it up. You have it hooked up like the diagram you posted.

 

[tmcolegr]

finished gathering all the parts to install the battery disconnect switch:

• Flaming River 1003-2 Battery Disconnect Switch w/Remote Lever Kit (includes "Push Off" decal)
• 2 - 1 gage battery lugs with 3/8" hole
• 2 - Battery Terminal Boots (red)
• Heat Shrink Tubing
• 1 gage welding cable
• 3 - 1/4" pop rivets to mount bracket to body

 

[CPRsm]

Then you dont have it hooked up like you said you were going to hook it up. You have it hooked up like the diagram you posted.

Think you're missing what I'm saying. The car is already running, has been for months, wired just like I said, and have tested it successfully. Single bottom terminal you can see goes to the far right to the positive side. The top terminal has the small cable on it along with the 1/0 that goes to the front of the car. Is this not wired exactly like I said it was ?

 

[TexasKyle]

Not gonna mess up the OP's thread any further. Pardon us tmcoleger

 

[05stroker]

Think you're missing what I'm saying. The car is already running, has been for months, wired just like I said, and have tested it successfully. Single bottom terminal you can see goes to the far right to the positive side. The top terminal has the small cable on it along with the 1/0 that goes to the front of the car. Is this not wired exactly like I said it was ?

Are there any other wires then the three large ones attached to the switch. Seems to me the car wouldnt start this way but, would remain running if the switch was engaged

 

[05stroker]

Not gonna mess up the OP's thread any further. Pardon us tmcoleger

I don't think you are , there are clearly two different ways of wiring this switch according to the post here . If they both work, so be it. I don't see how only isolating the battery can kill the car when we all know the alt will run the car with the hot cable disconnected from the battery.

 

[CPRsm]

Are there any other wires then the three large ones attached to the switch. Seems to me the car wouldnt start this way but, would remain running if the switch was engaged

I couldn't find a wiring diagram when I was doing this of the alt. All you have to so it kill the power to the stator, and the alt turns off. I wasn't sure it would work either. But I figured if I was wrong, a few turns of the nut and I could swap terminals. There aren't any other wires to the switch. There are some you see there from the water pump, boost a pump and what not. But eh, it worked so I'll leave it.

 

[05stroker]

Are there any other wires then the three large ones attached to the switch. Seems to me the car wouldnt start this way but, would remain running if the switch was engaged

I don't think you are , there are clearly two different ways of wiring this switch according to the post here . If they both work, so be it. I don't see how only isolating the battery can kill the car when we all know the alt will run the car with the hot cable disconnected from the battery.

I couldn't find a wiring diagram when I was doing this of the alt. All you have to so it kill the power to the stator, and the alt turns off. I wasn't sure it would work either. But I figured if I was wrong, a few turns of the nut and I could swap terminals. There aren't any other wires to the switch. There are some you see there from the water pump, boost a pump and what not. But eh, it worked so I'll leave it.

With all that said is there anyone else who has a set up like this that can confirm either way ? Is there a way that the power to the starter relay could signal a cut in power to the alt. through the SJB or PCM ?


CPRsm, The thinking here is from everything a car guy has ever seen . When the + 12v is disconnected the alt is running the car. If the alt. 12v is disconnected at the same time as the batt. then the car will die. The way you have it the alt. should keep the car running. IMO

 

[tmcolegr]

Not gonna mess up the OP's thread any further. Pardon us tmcolegr

Not a problem. My opening post clearly asked for ALL opinions, pro or con. Be careful what you ask for. But hey, that's how we all learn. Look at the way I was originally intending to move forward - fortunately someone chimed in with another method that is much simpler and cleaner to install.

I am not going to spar with CPRsm and his method, although for the life of me I don't see it working as described, but that's neither here nor there. I'm not there so I can't confirm his setup will or won't work. Nonetheless I will be using GB10s setup as I clearly can see how it will work.

CPRsm no disrespect intended.

PS: I have slightly altered my decision on where to mount the disconnect switch - you'll either like it or hate it. I have spent hours looking at the back of the vehicle trying to find the cleanest location to penetrate the trunk compartment that won't allow water to enter anywhere. Since this is a very limited street use vehicle, I also want the knob and lever to be aesthetically appealing.

 

[CPRsm]

CPRsm, The thinking here is from everything a car guy has ever seen . When the + 12v is disconnected the alt is running the car. If the alt. 12v is disconnected at the same time as the batt. then the car will die. The way you have it the alt. should keep the car running. IMO

I'm not sure if there is enough delay in the 12v source running back to the pcm to keep the alt turned on or what.

I am not going to spar with CPRsm and his method, although for the life of me I don't see it working as described, but that's neither here nor there. I'm not there so I can't confirm his setup will or won't work. Nonetheless I will be using GB10s setup as I clearly can see how it will work.

CPRsm no disrespect intended.

No worries. Figured it would throw people thru loops but seemed easier than your originally planning. Although at the time I didn't see the diagram for some reason. You should be able to easily test it out on yours if wanted to verify it yourself. I'd be curious myself.

 

[05stroker]

I'm not sure if there is enough delay in the 12v source running back to the pcm to keep the alt turned on or what.


No worries. Figured it would throw people thru loops but seemed easier than your originally planning. Although at the time I didn't see the diagram for some reason. You should be able to easily test it out on yours if wanted to verify it yourself. I'd be curious myself.

After mine is cranked I will test both ways. Inquiring minds must know the answer. LOL

It is a simple swap of 1 wire to test it. There could also be something arranged a little different on the cars in question that would make things work differently than another car . We should all post lots of pics of our configurations when they are done to see the different setups and how they work.

 

[MLC40]

Not a problem. My opening post clearly asked for ALL opinions, pro or con. Be careful what you ask for. But hey, that's how we all learn. Look at the way I was originally intending to move forward - fortunately someone chimed in with another method that is much simpler and cleaner to install.

I am not going to spar with CPRsm and his method, although for the life of me I don't see it working as described, but that's neither here nor there. I'm not there so I can't confirm his setup will or won't work. Nonetheless I will be using GB10s setup as I clearly can see how it will work.

CPRsm no disrespect intended.

PS: I have slightly altered my decision on where to mount the disconnect switch - you'll either like it or hate it. I have spent hours looking at the back of the vehicle trying to find the cleanest location to penetrate the trunk compartment that won't allow water to enter anywhere. Since this is a very limited street use vehicle, I also want the knob and lever to be aesthetically appealing.

Your posts and build have been helpful to so many of us, but I thought you weren't going to race your car. Did something change for the better?

 

[tmcolegr]

Your posts and build have been helpful to so many of us, but I thought you weren't going to race your car.

I'm not...

 

[tmcolegr]

So here's what the finished product will look like. Some things to keep in mind as you look at the schematic:

The alternator is powered directly off the (+) post of the 200 amp fuse for the starter/BEC. Total combined distance of all cable which is unprotected is about 3'

You'll notice I have a disconnect switch in the (-) battery cable in the trunk compartment. Since the alternator will be powered up all the time (just as when it was new), this secondary disconnect switch will allow me have a convenient method to disconnect the battery from the entire vehicle for routine maintenance/repairs without having to remove the negative battery cable from the battery.

Feel free to ask questions

 

[Norm Peterson]

Any particular reason for not running 1 ga all the way to the starter, or at least 4 ga? 6 for that last bit just sounds . . . a little light.

Is 200A enough for full starter draw under unusual circumstances?


Norm

 

[tmcolegr]

Any particular reason for not running 1 ga all the way to the starter, or at least 4 ga? 6 for that last bit just sounds . . . a little light.

Is 200A enough for full starter draw under unusual circumstances?


Norm

Both good questions.

The OEM starter and BEC cables are both 6 gage. These original 6 gage cables are now run to a common connection point (formerly the (+) battery terminal) with the 1 gage cable in the engine compartment. Both 6 gage cables are less than 30" long. After the battery relocation was performed, I ran a voltage drop test and an amp draw test. I cranked the engine for 20 seconds continuous with the crankshaft position sensor disconnected so the engine would not start. At 13.2 battery volts, voltage drop was less than .2 volt and amp draw was right at 110 amps. That proved the 6 gage cables were not an issue and a 200 amp fuse is more than sufficient even during the highest normal load. Keep in mind I'm also using a 1200 amp Odyssey battery which reduces voltage drop and amp draw.


***EDIT***

After further research, I have discovered the above highlighted information is incorrect. The OEM battery cables going to the starter and BEC are both 4 gage - not 6 gage as I stated. The only 6 gage cable used in the OEM battery starting circuit is the (-) ground strap which is routed from the (-) battery terminal to the passenger side strut tower. All other OEM cables are indeed 4 gage. This is probably why the voltage drop was only .2 volt while engine cranking.

Additional useless information: the OEM battery cable that runs from the (+) battery post to the alternator is also 4 gage. When upgrading to a 200 amp PA Performance alternator, the reason they require that battery cable to be changed is because the OEM cable contains an 8 gage fusible link which will not support the 200 amp alternator. Otherwise the OEM cable would be sufficient.

 

[tmcolegr]

Flaming River battery disconnect switch w/remote lever kit has been mounted.

Disconnect switch in the "On" or "Run" position - continuity light on (Starter & BEC circuits energized)

Disconnect switch knob pushed in or in the "Off" position - Starter/BEC circuits de-energized

Rear view

"Run"

"Off"

View from top of rear bumper cover w/knob in the "Run" position

Wiring to the battery disconnect switch will come this weekend. Once completed, everything inside the trunk compartment will be completely hidden from view.

More to follow...

 

[MLC40]

Nice work, as always.