High voltage contactor

[jssneptune]

the control voltage says up to 36v but i,m going to use my main pack voltage of 48v. As far as schmatics its pretty simple. just 2 main 5/16 conections for the high voltage/amps and the two control wires witch energize the solenoid.
hope this helps and good luck on the 72 volts. I have fun at 72volts but settled on 48 plus 12 for ease of charging and placement of the batteries.
with the 2 speed motor its plenty fast
jeff

[roady89]

Exactly....Depending on what controller all you have to do is tap 36 or 48 volts for the control wiring.

[buckmanmike]

Let me know if I have this figured correctly. I am assuming there are 4 poles on contactor, 2 small, 2 large. The control voltage would wire to the small terminals actuating the contactor. If I had a 6x12v pack I could wire to the first 3 batteries. This 36 volts would then actuate the contactor. Then I could wire the full pack into the large poles sending full voltage to my motor.
if this is correct, why couldn't I just use a HD 48 volt solenoid. They seem to be much cheaper in price over the contactor you recommended.
Thanks, Mike

[Nate]

I don't see the contactor recommended but the reason you don't want to run a 36/48V solenoid in place of a 72V contactor is safety. The 48V solenoid does not have a large enough air gap to extinguish the arc in the event you had to shut down your 72V pack under load.

Example:
Something goes wrong on a 72V system, first reaction is to lift the accelerator and the 48V solenoid opens. There is too much power so the solenoid contact surface is damaged but you shut down. As human nature goes you say to your self "That was strange” and you re-engage your solenoid. It closes under full load with damaged contacts and they weld closed. Now you can't shut down by lifting your foot. If you don't panic and remember your F/R switch your might be safe but it will take a huge hit as it opens under load.

We are not going to discuss how I know this.

[roady89]

I may be misunderstanding something here....

Nate...the Czonka's have different coil voltages depending on what model. One model will handle 36-95 volts on the coil but will handle 12-900 volts on the contacts. And I believe they all come with "coil economizers"...I guess those would be caps.

[jssneptune]

buckmanmike,
besides what nate said when you use a 48v solenoid they weld and arc shut. so you always want to go with higher ratings. I,m new to this forum but I know Nate knows his stuff from other sites. he helped with my 72v setup and explained alot about the safety issues.
jeff

[roady89]

buckmanmike...If your gonna play around with high voltage don't mess around with a 48 volt "HD" solenoid. It may work for a little while but not very long before melting/welding the contact's. I did the same thing you are wanting to do but with 108 volts and it didn't last a week before it melted the solenoid. This was using a brand new H/D white-rodgers solenoid....$60 dollars down the drain.

[buckmanmike]

I sure do appreciate ya'lls advice. I definitely want to keep it safe, especially with wife occasionally driving cart. Those contacts welding together would be bad news if you stopped for a second to check out how bad the down hill trail was and then decided to creep down slowly and whooooosh. There you go, holding on for dear life.
So, I'll get the high voltage contactor. Roady I looked at the sight you had posted and on the second page on that sight it listed a 72 volt contactor for I think $60-$70. But it was a non stocked item with no description of it. Is that the part I need or search for a 72 solenoid elsewhere.
I agree that Nate knows his stuff. I have read a lot of his post on BU. So, Nate, if you have some advice on my solenoid, contactor, I'm listening.
I will be going to deer camp today/tonight. I am waiting for my controller to get here. It was suppossibly to be here no later than today. My cart is at deer camp and I wanted to install controller and potbox this weekend, try it out at 48 volts, and jump to 72 volts in two weekends when I get a chance to go back to camp. Thanks again for your advice, Mike

[Nate]

Thanks for the confidence in me. The Czonka is a sealed unit and has a special gas inside the can that extinguishes the arc very fast. This is how they get such high voltage ratings and it keeps dirt out of the contacts as well.

Your controller shuts the power off even if the solenoid were to stay closed but I set the solenoid/contactor to open when the accelerator goes to home position just in case a controller would fail in the "ON" state or something shorted across the controller or if a throttle pot failed and gave the controller a full ON signal. These cases are all rare but not impossible and it would only take one case to seriously hurt people.

[caddymankc]

the contacts on my stock cart welded shut and i almost took out the garage door i think because my resistors are bad and they were arking