Diode question

[Dallas-S]

What is the purpose of the diode on my ezgo if it will run without it? I Have already put a new one on it but just curious.

[Volt_Ampere]

You should NOT run without it. It is called a "Flyback Diode" and the purpose is to keep a very large voltage from building up when the solenoid is turned off. It protects the switches and controller from over voltage arcing. It is important that it is installed in the proper direction. It will be a dead short when the solenoid tries to turn on if it's in backwards - taking out something in it's path. Usually the microswitch but can also be the controller.

[Dallas-S]

Thanks for the info. Just like to know how things work. I know mechanic's but not up on diodes and resistors and such.

[scottyb]

Diode, save your arse one way and burn your arse the other. Tricky little devils

[orangeman6]

Originally Posted by Volt_Ampere

You should NOT run without it. It is called a "Flyback Diode" and the purpose is to keep a very large voltage from building up when the solenoid is turned off. It protects the switches and controller from over voltage arcing. It is important that it is installed in the proper direction. It will be a dead short when the solenoid tries to turn on if it's in backwards - taking out something in it's path. Usually the microswitch but can also be the controller.

Volt, I get it about the diode at the solenoid but is it good practice to have a diode other places in the cart. It seems that I've come across it on here a couple of times but was always trying to figure something else out when I saw it, so never looked into it.

[cgtech]

When the power is removed from the solenoid (letting gas pedal to at-rest), the magnetic field that moved the ferrous slug, and the solenoid contact, collapses. When the field collapses, a huge spike of energy is created, sometimes over 1000v, (same effect fires the spark plug in most gas engines). This spike could be lethal to any electronics your cart may have, like motor controller. The spike will also cause cumulative damage to the relatively small contacts in your gas pedal switch, reducing its lifespan. The diode "traps" that energy at the solenoid coils, forcing it into a "endless loop" around the coils and diode, until it is dissipated by the resistance in the coil and small drop each time it passes through the diode. This all happens in less than a second, but does have a small-but-measurable effect on the reaction time of the solenoid. I totally understand the "I just needed to know why" thing .

[Volt_Ampere]

All relays and solenoids need a diode across the coil if they are driven by a solid state device.

[orangeman6]

Originally Posted by Volt_Ampere

All relays and solenoids need a diode across the coil if they are driven by a solid state device.

Thanks Volt. I'm assuming everything in our carts is solid state? I installed a dc converter in my rebuild and did put a fuse inline. I also used a relay to wire a switch to control the reducer. In addition, I installed relays for all of my 12v accessories (head/tail/brake lights, stereo, dome light) to protect some relatively expensive switches I used. Do I need to put diodes with each of those relays? And, how exactly are they wired in? What to what? I've got a lot of time and $ into the cart and don't mind redoing that part if I need to. I'd just rather have it correct.

[cgtech]

Sounds like a good idea, because all solenoids exhibit this behavior, unless specifically designed not to. Terminals 85 & 86 on standard relays are the "energize" terminals. The diode would be installed on those terminals. The stripe would point towards the positive wire on those terminals, the unmarked side goes to the negative wire.

[orangeman6]

Thanks a lot for the info. Ill get some diodes and get them in before I wreck something.
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