Nothing wrong with this disconnect switch you presently have imo. If it were me wiring to my sbc with analog ignition I’d do it this way.

This message has been edited. Last edited by: markemark,

quote:

Originally posted by DragRaceResults:
The problem you get NOT using a 4 post disconnect is if the voltage regulator / diode in the alternator sticks it can drain your battery. I had this happen more than once before I switched to them.

Yes you can use whatever, but I wouldn't use anything other myself anymore.

SL...

Can’t say that is a concern of mine, as it has never happened once in over 3 decades and apparently not a concern of my car builders Undercover and MPR either.

Engine won't stop by shutting off the switch, wired that way, or you have a constant live wire to the alternator, on or off.
That's kinda the whole point. Track personnel must be able to shut you off.

quote:

Originally posted by Goob:
Engine won't stop by shutting off the switch, wired that way, or you have a constant live wire to the alternator, on or off.

Your post is incorrect.

quote:

Originally posted by rs72z:
What brand of battery disconnect is most using with good luck?

Moroso has been on my car for over 20 years, so I guess that's good luck or a good part. It is most likely a Cole-Hersee. It is the simple one and the alt. is wired direct to the battery. The car will shut off with no problem as it cuts all power to ign when the switch is off.
Now the down side is there is always a large hot wire even with the switch off Also I have had my alternator have the problem of draining the battery down. I have purchased a new Cole-Hersee with the 4 3/8" terminals that I will install.

quote:

Originally posted by Goob:
Engine won't stop by shutting off the switch, wired that way, or you have a constant live wire to the alternator, on or off.
That's kinda the whole point. Track personnel must be able to shut you off.

Markemark I think this post was directed at Ed.

With the 2 pole switch like Ed has, there’s either a wire that is hot all the time from the battery to the alternator, or if the alternator wire is on the ignition box side of the switch then it won’t shut the car off when the switch is pushed. The 4 post disconnect fixes this.

Both my cars shut off when the master disconnect is pushed off

Why would you not wire the alternator thru the disconnect switch ? Having a master disconnect switch is to isolate the battery from all components is it not ? Otherwise it is halfazzed done.

quote:

Originally posted by DragRaceResults:
The problem you get NOT using a 4 post disconnect is if the voltage regulator / diode in the alternator sticks it can drain your battery. I had this happen more than once before I switched to them.

Yes you can use whatever, but I wouldn't use anything other myself anymore.

SL...

I have never heard of that before.

quote:

Originally posted by 67TSCHEVY2:
Why would you not wire the alternator thru the disconnect switch ? Having a master disconnect switch is to isolate the battery from all components is it not ? Otherwise it is halfazzed done.

Improperly wired cars CAN keep running off alternator. Many have power relay to prevent this.

This message has been edited. Last edited by: BG7X77,

quote:

Originally posted by 1320racer:
Both my cars shut off when the master disconnect is pushed off

Yeah because you have a hot wire running directly from the battery to the alternator.

It is preferable to not have a 10+ plus long wire that’s hot all the time.

quote:

Originally posted by 67TSCHEVY2:
Having a master disconnect switch is to isolate the battery from all components is it not?

The Master Cut-Off is to stop all electrical functions. You are Not required to remove all power from the battery in the car.

I use the same CH 75912 and wire it same as what I drew minus the relay board. This CH 75912 disconnect is Not controlled by the ON/OFF push - pull arm in my car. It stays on all the time and is only turned off when I want power removed from those items.

For the Push-Pull master Cut-Off switch I use a CH SPST switch that feeds +12v to the relay board. Turning off the relay board stops all functions in my car.

quote:

Originally posted by 183N:

quote:

Originally posted by 1320racer:
Both my cars shut off when the master disconnect is pushed off

Yeah because you have a hot wire running directly from the battery to the alternator.

It is preferable to not have a 10+ plus long wire that’s hot all the time.

says you. not a concern for me, the professionals that wired my car nor the NHRA.

quote:

Originally posted by 183N:

quote:

Originally posted by Goob:
Engine won't stop by shutting off the switch, wired that way, or you have a constant live wire to the alternator, on or off.
That's kinda the whole point. Track personnel must be able to shut you off.

Markemark I think this post was directed at Ed.

With the 2 pole switch like Ed has, there’s either a wire that is hot all the time from the battery to the alternator, or if the alternator wire is on the ignition box side of the switch then it won’t shut the car off when the switch is pushed. The 4 post disconnect fixes this.

My post to Goob was for Eds wiring.

Just for my own info I have contacted IHRA and NHRA and asked them about having a car wired where the alternator wire stays hot all of the time. They had no clue or problem with it as long as the car shut off as in all functions stopped.
Talked to people that wire race cars for a living, they do it the same way where the alt. stays hot and said the sanctioning bodies don't have a problem with it.

of course they don't, 10s of thousands of cars are wired this way, new cars are being built right now wired this way.

My Firebird was wired by Wires and Pliers who was the best before his death.

My Undercover was wired by Bill Frederick who has wired every Undercover out of that shop for decades and Bill wired my good friend's new Elite Chassis and it too is wired exactly the same.

Also have a good friend that used to wire race cars and he too wired everyone of them exactly the same.

That said, if a 4 post master disconnect makes you sleep better at night, well it's your time, your money, your car. Me along with thousands of racers and the professionals that wire these cars say its a non issue.

This message has been edited. Last edited by: 1320racer,

I use a constant duty 200-amp RV solenoid. All it takes to shut everything down is a flip of a toggle switch or push-pull switch. I have one on my dash and one on the rear of the S10, marked "Push-Off". Takes only some 18 gauge wire to send a ground signal to the Solenoid and all Power is OFF. Alternator wire is on the battery side of the Solenoid. Flip one of the master switches, No Power. Easy and no big cables, rods or mechanical switches.

If I am in a emergency situation or hauling the car even then I want to be able to isolate current to only from the batteries to the switch and no power anywhere else past the disconnect and that seems to be pretty logical to me.

SL
I have had the diode in the alternator "stick" two different times on 2 different cars. One professionally wired one was not. One east Coast the other Powermaster. One 12v the other 16v. It happens. I guess some folks are just luckier than others!

More like some folks are just unlucky.