Any Solenoid Savants Here?

[RNajarian]

Recently my 48v H3 Low Speed Vehicle (souped up street legal golf cart) putzed out.

Normally when I turn the key you hear the solenoid “click,” which then powers the vehicles controller.

Yesterday I was going to go out for a drive, turned the key, got a click but heard other weird sounds and the dash volt meter was fluctuated wildly. No burning smell noted.

I turned off the key and the dash voltmeter normalized and registered a consistent voltage.

I turned the key on again this time no “click,” but the dash voltmeter began fluctuating wildly again.

I disconnected everything (battery and voltmeter.) with a Fluke I checked each individual battery (all normal), and the total voltage of the 6 eight volt batteries (normal.)

I first suspect the solenoid. People on my Golf Cart forum suggested bench testing it, but as Clint Eastwood once said “A mans got to know his limitations.” I wasn’t interested to play around with that much voltage and amperage.

I did open the suspect solenoid and saw this. . . those areas of “soldered” metal obviously are the result of 15 years of use.

What do you guys think? Based on the photos would you say the solenoid failed?

[dad911]

If you want to test it, measure the voltage past the relay. I would just clean up the pits with a nail file or fine sandpaper, and put it back together. Order a spare.

[island911]

/\ yep. Looks serviceable.

[RNajarian]

I did measure it past the relay, “0” volts (obviously with the key on).

Before the solenoid (after the fuse) full voltage.

This solenoid may be under rated for my controller. It is rated at 200a max, I have a 500a controller. The literature recommends a 400a max solenoid for a 500a controller.

[Scott Douglas]

That looks like damage the old Chevy solenoids we used to play with as kids would exhibit. On those we'd take them apart and flip the copper washer around so 'new' material would interface with the contacts. Good as new then.
If that were mine, I'd file the surfaces in the first photo flat and flip the copper part around (second photo) after filing those surfaces flat, and put it back together while waiting for the new 400a solenoid to arrive.

[wdfifteen]

Looks lik there has been a lot of arcing between the contacts. If you keep your foot off the go pedal when you turn the switch on there should be very little current through the solenoid when it closes. There shouldn’t be a lot of arcing. Considering the arcing and the fact that you know it is underrated for the load, I would replace it

[dad911]

Originally Posted by RNajarian

I did measure it past the relay, “0” volts (obviously with the key on).

Before the solenoid (after the fuse) full voltage.

This solenoid may be under rated for my controller. It is rated at 200a max, I have a 500a controller. The literature recommends a 400a max solenoid for a 500a controller.

In that case file it and try it.

As the first one made it 15 years, I'd probably replace with equal or higher rated.

May be worth an upgrade to a newer controller and a solid-state relay (SSR)?

[dad911]

Also check the resister across the contacts. It may be there to equalize or bleed voltage(Drain a capacitor) to prevent arcing.

[1990C4S]

Clean the contacts up, and make sure they are parallel. And make sure the coil isn't open circuit.