Joe's 4 Post Switch Wiring

[cv2065]

This is instruction sheet for a Joe's Racing 4 post cutoff switch. Anyone know why it has two power runs from the battery to different poles? Also, when wiring for the starter, this diagram goes from switch to bus bar, then to the starter. Any reason why one couldn't go straight to the starter with another pole going to bus bar?

191381

[edwardb]

Theoretically the alternator could keep the engine running even when switching off the battery with the disconnect. So a 4-terminal switch isolates the alternator and keeps that from happening. Also provides a measure of protection of the alternator. These setup is required per many competition rules. Maybe not as important for a street driven car. But doesn't hurt anything.

I don't see any reason why the starter couldn't be wired direct as you describe.

[cv2065]

Theoretically the alternator could keep the engine running even when switching off the battery with the disconnect. So a 4-terminal switch isolates the alternator and keeps that from happening. Also provides a measure of protection of the alternator. These setup is required per many competition rules. Maybe not as important for a street driven car. But doesn't hurt anything.

I don't see any reason why the starter couldn't be wired direct as you describe.

Thanks Paul. The way I'm reading this is that there are two power inputs from the battery, and two power outputs on the switch, one to the bus bar and one to the alternator. The switched input goes to the alternator. Does that mean that the other power input to the bus bar would remain hot or would the switch turn that output off as well? With only two outputs, it would seem that I'd have to route to the bus bar and then to the Starter as shown? I originally had it like the diagram below for the 2 pole switch.

I didn't have a cutoff switch in the last build, so not 100% sure. Thanks for the input.

191385

[edwardb]

Thanks Paul. The way I'm reading this is that there are two power inputs from the battery, and two power outputs on the switch, one to the bus bar and one to the alternator. The switched input goes to the alternator. Does that mean that the other power input to the bus bar would remain hot or would the switch turn that output off as well? With only two outputs, it would seem that I'd have to route to the bus bar and then to the Starter as shown? I originally had it like the diagram below for the 2 pole switch.

I didn't have a cutoff switch in the last build, so not 100% sure. Thanks for the input.

191385

On the original diagram, both of the outputs are switched on/off.

[cv2065]

On the original diagram, both of the outputs are switched on/off.

Ok great. Thanks!

[Rdone585]

Instead of running 2 separate wires from the battery, you could install a jumper between the 2 switch inputs and run only 1 wire from the battery. Just make sure your jumper is the same gage wire as the battery wire. This might be helpful if the run from the battery is long.

[cv2065]

Instead of running 2 separate wires from the battery, you could install a jumper between the 2 switch inputs and run only 1 wire from the battery. Just make sure your jumper is the same gage wire as the battery wire. This might be helpful if the run from the battery is long.

Good idea. Not sure how much room I have behind the switch for a 2 GA wire from post to post, but I'll give it a go. Run is short as the battery will be in front.

[edwardb]

Good idea. Not sure how much room I have behind the switch for a 2 GA wire from post to post, but I'll give it a go. Run is short as the battery will be in front.

At that point, you've disabled the alternator switching off function. Negates the reason for the 4 post switch. If that's important to you.

[Rdone585]

At that point, you've disabled the alternator switching off function. Negates the reason for the 4 post switch. If that's important to you.

I agree, that if the outputs were jumpered, it would defeat the purpose of the 4 post switch.

How would a jumper between the inputs cause the alternator to still power the system with the switch off. If the switch is off, it will still disconnect the battery from the alternator, the starter and the rest of the 12V system. The alternator being connected to a separate output would not be tied to the 12V that drives all other parts of the system. This is the way my 4 post kill switch was advertised to be installed by the instructions that came with the switch.

Adding this link showing the installation: https://www.joesracing.com/46216-46221-4-terminal-battery-disconnect-instructions/

[cv2065]

Part #46221 is the only one that is available on Joe's, which is the instruction set you posted Rdone. The one I posted is for part #46220, which no longer exists, so yours is the most current.

[F500guy]

I Purchased a 6 post cut off that has the main cutoff for battery, a cut off for ignition and a ckt to ground the alternator thru a resistor, but with 1 wire alternators that is sometimes still a problem. I read some racing forum and the way to save a (1 wire alternator) is to mount both alternator output and battery input on same post, so if the switch is cut while running, the alternator will not spike due to having battery source to discharge any left over power. Ignition is cut so engine dies.

[cv2065]

Resurrecting this post from last year. Attached is the 4 post Joe's diagram that I didn't have before, as well as my own diagram. I've changed up my electrical routing. I'm no electrician, so if you see something that is troubling, please let me know. A couple of questions:

1. I've got all 3 power leads running through the distribution block, similar to the last build. I've got the alternator feed from the harness running through the distribution block powered through the cutoff switch then to the alternator. Does this look correct?

2. I've got 2GA wire running from the battery to the starter as I had better startups last build versus 4GA wiring. Should I keep the 2GA wiring going to the cutoff switch and then to the distribution box or can I pull it down to 4GA?

3. Is the 150amp Mega Fuse situated in the right sequence between the alternator?

Thanks for the look.


https://hosting.photobucket.com/images/c310/cv2065/Screenshot_2024-06-30_181837.png?width=960&height=720&fit=bounds (https://hosting.photobucket.com/images/c310/cv2065/Screenshot_2024-06-30_181837.png?width=960&height=720&fit=bounds)



https://hosting.photobucket.com/images/c310/cv2065/Screenshot_2024-06-30_190702.png?width=960&height=720&fit=bounds (https://hosting.photobucket.com/images/c310/cv2065/Screenshot_2024-06-30_190702.png?width=960&height=720&fit=bounds)

[CraigS]

1-Yes looks good to me. I can tell you 100% that disconnecting the battery only will not shut off an engine. As a dealer tech I did that a lot, leaving the engine running when swapping in a new battery so I didn't have to re-program all the windows, radio stations etc that were lost by swapping a battery w/ the engine off. So w/ the view that this switch is a safety item, wiring it like this is a good idea.
2- I would drop to 4ga. A starter may draw 200-300amps so it needs the thick wire. The rest of your load should be under 100 amps.
3- Others will need to chime in on this as I have never used one. I see them in a lot of standard cars but have never looked into how they are wired

[cv2065]

Thanks for the feedback Craig. Greatly appreciated.To clarify, From question 2, I’d run 2GA from battery to starter, then switch to 4GA from starter to switch and beyond? Except for the alternator run, as I think the harness alternator wire is 10GA or 8GA (not sure). I’d keep that as is?