Looking at doing some rewiring and I was thinking about using a 500 amp continuous duty solenoid. Utilizing it would allow me to shorten the main battery cable by 5-6 feet because I would be able to put it in a better location. I would just the current cutoff switch to turn on and off the solenoid. I looked at the rule book and couldn't find anything that said I can't do it this way.

Any reasons why I wouldn't want to do it this way?

Banjo, good to see you here.... cool tag

quote:

Originally posted by J178RED:
Banjo, good to see you here.... cool tag

This, Welcome back.

My Nelson racecraft uses a continues duty solenoid for the master switch.

Hooks to a on/off 250 amp push pull switch in the ****pit then loops to a switch on the rear of the car so they can work in a series.

Maybe that big solenoid will work. I tried a solenoid years ago, down to 4 cars and flipped the switch and the solenoid wouldn't engage. We tried everything and had to forfeit the round.

Now I just use a big master cutoff switch and on race day I never turn it off. Once bitten, twice shy.

Thanks all, lots of life changing stuff, but things are finally settling out and the plan is to hit the racetrack a lot more this year.

I was considering something like this. https://www.amazon.com/gp/prod...1&smid=ATVPDKIKX0DER

Handles 500 continuous and 700 peak. In my car, I measured the peak it will see is about 250-300 amps when I hit the starter. More than over kill on capacity.

I bet my main power cable is probably 18-20 feet by the time. Relocating would knock 5-6 feet off of that. I like the idea of shortening it.

Bill, is the length difference going to come from not going backwards to the switch from the battery doubled?

My cutoff switch is in the center of the rear of the car where the license plate was. Battery is on the right corner of the car. So the cable runs from the battery, through the trunk floor, then runs left to the switch. Then from the switch follows the same path over to the frame rail and then runs forward to the starter. I estimate this is probably 5-6 feet of cable with all the twist and turns. I could mount the solenoid just a head of the battery and run straight forward.

I thought that might be the case. I'm not a big fan of making another possible failure point, but don't see why it wouldn't work.

Good to see you back Bill.

banjo only one thing bad that i know of,the solenoid draws power anytime it is on versus the reg master that doesnt.not an issue unless you are like me(forgetfull),mine draws nothing other than sol

quote:

Originally posted by rusty:
banjo only one thing bad that i know of,the solenoid draws power anytime it is on versus the reg master that doesnt.not an issue unless you are like me(forgetfull),mine draws nothing other than sol

Good point. I have seen solenoids that require power to stay energized, and of course they are pulling power all the time, and if there is a dip in voltage, it could drop the solenoid out, cutting power to the car.

The other kind I have seen requires power to move it from one state to the other. Those require no power while in a state, but obviously these would be a safety problem if a crash cut a small activation wire or if the voltage was so low that it couldn't move to the off state.

I'm not a fan of either one personally. Although I see the draw.

quote:

Originally posted by banjo:
Looking at doing some rewiring and I was thinking about using a 500 amp continuous duty solenoid. Utilizing it would allow me to shorten the main battery cable by 5-6 feet because I would be able to put it in a better location. I would just the current cutoff switch to turn on and off the solenoid. I looked at the rule book and couldn't find anything that said I can't do it this way.

Any reasons why I wouldn't want to do it this way?

I have wired several cars this way. First one I did was in 1981. I have not looked at this years rulebook but it has always been accepted by NHRA.

What I do is use two switches wired in series to apply + voltage to the coil through a fuse. I put one switch on the rear of the car and another inside the car. Whatever type of switch you use at the back of the car, make sure it is weatherproof, or plan on changing it every couple years. Both have to be on for the solenoid to engage. Let's the driver have the ability to kill the car from inside.

Have not had seen any failures. The first car I did in 81, we changed the solenoid out in 2000 as part of routine service. I only use Cole Hersee continuous duty solenoids. Make sure you get the one with two small terminals for the coil.

I avoid grounding the coil with the switch due to the possibility that if the switch wire were damaged or shorted to the chassis in a accident the solenoid would remain on, regardless of the kill switch/s position.

quote:

Originally posted by rusty:
banjo only one thing bad that i know of,the solenoid draws power anytime it is on versus the reg master that doesnt.not an issue unless you are like me(forgetfull),mine draws nothing other than sol


Good point. I have seen solenoids that require power to stay energized, and of course they are pulling power all the time, and if there is a dip in voltage, it could drop the solenoid out, cutting power to the car.

The other kind I have seen requires power to move it from one state to the other. Those require no power while in a state, but obviously these would be a safety problem if a crash cut a small activation wire or if the voltage was so low that it couldn't move to the off state.

I'm not a fan of either one personally. Although I see the draw.

Does your party represent personal responsibility?

i will add,on mine i installed a small off delay timer that kills the solenoid after a preset time.works well

I d think if you did it wiring them in series would be a good idea because you could turn off power from inside the car or in back.
For me my main power is in the back and I leave he power on all day at the races.

I have changed my mind on this and have just wired up the stuff to do it electrically. It will have E-Stop buttons front and rear and a 200amp continuous, 400amp peak inrush solenoid. I should have it powered up this weekend.

What brand is that solenoid?

quote:

Originally posted by SP 124X:
What brand is that solenoid?

Trombetta

im going this route myself

I've used the Cole hersee solenoids on the past few cars Ive wired. I use two of them. One to kill the starter/alternator power and the other kills the rest of the power. In all honesty I'd prefer a solid state battery disconnect but the cost is a killer.