2001 Ezgo series solenoid

[chief- willie]

I have a recent purchase that I am putting together and notice that the resistor across the solenoid shown on the wiring diagrams I see on the site is not there. Is it required for a Curtis controller? The cart is a 2001 series without the run/tow switch.
thanks

[camaroluvz28]

They are recommended but not required...I hardly ever use them at my dealership, which I'm sure some are going to disagree with but has never led to a problem in my 15 years...hope that helps.

[Sir Nuke]

Originally Posted by chief- willie

I have a recent purchase that I am putting together and notice that the resistor across the solenoid shown on the wiring diagrams I see on the site is not there. Is it required for a Curtis controller? The cart is a 2001 series without the run/tow switch.
thanks

as camaroluvz28 mentioned.....its not "required" and the cart will run, and it "won't hurt" it if its not there......but think about it....it is there for a reason, and EZGO designed the drive system with it......AND the fact that is a part that will cost you only about $5 or less.....get one and install it.

[JohnnieB]

The purpose for the pre-charge resistor is to keep the two dozen or so filter capacitors inside the controller charged.

If the controller sits for a few minutes without B+ applied to its B+ terminal, the filter capacitors will discharge completely and when solenoid contacts close, the capacitors will try to draw an infinite number of amps. The is impossible because there is a few Milli-ohms of resistance in the high current cables and within the batteries, but for the first TC, the caps will draw all the amps the battery pack can produce and the cables will deliver.

Electromechanical contacts typically bounce a few times before they stay closed, so arcing occurs and if occurs often enough and intense enough, the contact will weld themselves together. Also, arcing causes pitting and pitting cause excessive resistance, so the contacts will eventually overheat and fail.

I don't believe the solenoid damage seen in the attached picture was caused by not using a pre-charge resistor, but the damage that will eventually happen will very likely be similar.

I have no idea how long a solenoid will function properly without a pre-charge resistor installed, but I'm pretty sure it will last longer with it than without it.

NOTE: Some of the latest generations of controllers (IE: Alltrax XCT and Curtis 1264) get the voltage to keep there filter capacitors charge somewhere other than their B+ terminal and do not use a pre-charge resistor.

[camaroluvz28]

Thats good info JohnnieB...

[JohnnieB]

Just so the diode doesn't feel left out.

When de-energizing the solenoid coil, the collapsing magnetic field generates a high voltage spike whose polarity is the opposite of the voltage that was energizing the coil. The mechanical contacts of an electric switch open in milliseconds, but the high voltage spike arrives in microseconds and if its voltage is high enough to ionize the small, but growing, air gap between the contacts as they are first opening, an arc occurs.

Opening the pedal switch contacts is what most often de-energizes the solenoid coil, but it could be the key switch or MS-2 on the F/R assembly, or even the reed switch, they are all in series. (Except in SepEx and AC drives)

Essentially, the diode across the solenoid coil lengthens the life of the pedal switch.

[chief- willie]

Great information. I will add the resistor 250ohm 5w but what is the value of the diode? The present problem is reverse is forward and forward is reverse? What did I wire wrong.
thanks

[JohnnieB]

A 1N4004 will work, but I prefer a 3A (IE: 1N5404 from Radio Shack)

Direction issue: A couple of cables need to be transposed on either the F/R switch or the motor.

Connect the high current cables as shown on attached schematic and if it goes backwards when the lever is in Forward, transpose the cable on the F/R switches B and D terminals.

[chief- willie]

Thanks for the help johnnieB. I will get the parts and install ASAP.
I have changed the handle location to agree with the operation until I can change the other.

[chief- willie]

JohnnieB I started checking the wiring per the diagram but I guess I don't have the 1206 controller. There is no A2 on the controller only three post. Will the wiring be the same without A2 to FNR "C"?