Bad solenoid? Best solenoid?

[chadlogan112]

So right now I have an old cushman wired with the solenoid to a 12volt switch until I figure out my accelerator micro switch situation. The solenoid I bought off eBay for $12 and said it could be used for golf carts and worked perfect for about a month. But now when I turn on the switch, the solenoid opens, but will only close after the cart is returned to neutral and the whole power load is inert. Does this mean the solenoid is going bad and can't handle the load anymore it's being given? Anyone have a suggestion if so for the best budget solenoid? Also sometimes when the batteries get a little low or I'm going up a hill, I believe the solenoid shutters as well.

[scottyb]

"Also sometimes when the batteries get a little low or I'm going up a hill, I believe the solenoid shutters as well."
This will burn the contacts of any solenoid. Inexpensive ones have lower quality contacts and degrade faster under such 'abuse'. The shuttering you feel is the solenoid contact dropping out (under low voltage) and pulling in (voltage recovers) over and over very quickly. This pits the contacts and compromises the connection.
Address the battery problem. Once the pack is healthy you should be able to run any solenoid. Of course you get what you pay for, a $12 solenoids will never last like a good quality unit.
I hope this helps

[DonBenigno]

I would rate them in the order from best to worst:

Curtis Albright
Gigavac
Ametek
White Rogers
China knock off crap

At $12 you are using pot metal for most of the stuff. The higher quality contactors have silver tin alloy tips, the springs are more rebust, and are also tested for the specific application. Keep in mind some controllers PWM the coil to reduce the power to the coil while maintaining the pull in on the contactor. The other design considerations are break, with the proper spring.

When a properly designed contactor pulls it, if you take a look at the contactor switch profile, all contactors "bounce". The cheaper ones bounce too much providing a larger arch eroding the contactor tips, while the properly designed ones use the arch profile to actually wet and clean the tips.

[chadlogan112]

Thanks for all your help guys! What you both have said makes sense. Today I charged the cart, battery pack read 38.5v, drove it around neighborhood streets, ran fine and solenoid functioned properly. Took it in the woods and dropped into a ditch, with about a 120 degree incline, and the solenoid shuttered for a few seconds then creeped up the hill. After that, the solenoid would not open back up and was very hot to the touch. The batt pack at that time then read 36.5v. The solenoid is a 12v I must add, and I have it wired properly to 12v. Is a 36v solenoid required on the cart, or does it not matter? Any recommendations on where to buy a decent solenoid?

[DonBenigno]

What is the contactor rated for ?

A proper contactor will have a power dissipation curve along with what the pull in voltage, drop out, and power requirements of the coil.

Now keep in mind, the contactor tips and bus bars is the portion taking the larger current, not the coil.

If it is truely a 12V conactor, you have some issue with heat, both on the contactor tips as well as the coil. It will not last long.

[chadlogan112]

http://www.ebay.com/itm/251257396423...84.m1497.l2649

There's the direct link to the solenoid I purchased. You're starting to loose me with all the specifics! :/

[pachanga90]

I've been using the Trombetta 12v. Snow-Plow solenoids for years with very good results. Another Member said the new Yamahas use them as well.

[DonBenigno]

When you are using a contactor rated at a lower voltage, in this case 12V vs 36V or 48V you have to consider two things. One the duty cycle of the contactor (that 150A) at 36V is going to evetually melt or pit the tips and the contactor is going to get very hot. The second is the coil voltage, its going to get hot and eventually delaminate if hot enough, and its a waste of energy.
Take the vehicle up a long incline and keep doing it, see how hot the contactor gets. Keep in mind the external temperature is lower than the internal and at the contacts. Do this repeatidly and see how long it will last.

If you are designing a "proper" system, use one that is appropriately rated for its application. Its like taking a 350A welder and using 10 gauge wire to power it. Yes, it may work for certain loads, but why risk failure