Ezgo controller issue

[Oliviasmom]

We have a 96 electric ezgo. About two months ago, we were riding it and it just stopped in the middle of the road. No warning, just stopped dead. My husband changed the solenoid and still didn't work. Had one repair shop look at it and they said it was a bad motor, just need to get a new golf cart. Sent it to a second repair shop and after six weeks of troubleshooting he determined that it was a bad motor and controller. Replaced both and we got it back last week. We did replace the motor with a more powerful one in order to gain some speed but he assured us that the controller was compatible with that particular motor and it would not be an issue. We rode it for nine days and on Sunday it stopped dead in the road again. Guy picked it up yesterday and brought it back a few hours later. He said he replaced the controller again and that it had blown up due to "weak" batteries. He said that he will not honor the warranty on the controller again if we don't replace the batteries. We bought our batteries in May and when my husband load tested them they showed good. The person we bought the batteries from said that he had never heard of weak batteries blowing up a controller. We do have a warranty on the batteries but they will not replace them if they test good. We are between a rock and a hard place. Has anyone heard of weak batteries blowing up a controller? Is it possible that the motor is indeed too strong for the controller?

[Raystar57]

I don't buy it.

If controllers were damaged by weak or low batteries then a lot of folks
would be replacing controllers when they run the batteries down to far.

Usually it's the other way around.
High output capable controllers on a lower end motor can cause problems.
Lots of folks upgrade to high output controller and tune them down to run with a stock motor.

This guy should have updated the field map in the controller for the new motor.
If not then yes the motor could damage the controller.

I am not an expert but I think this is the case.

[Sir Nuke]

what your problem truly is.....IF your controller was bad....it should have been replaced with a new aftermarket controller....actually most are CHEEPER than a stick unit, and better as well. IF your batteries are good, it won't cause what they shop said.....and your new motor won't cause a controller to fail, as the motor can only draw to it the power that the controller allows it to. I would be willing to bet, you didn't get a NEW controller, the shop "fixed" yours or put in a "rebuilt/repaired" in it.....and its a proven fact that rebuilt/repaired controllers are just on their last leg and its just waiting to fail again.

[scottyb]

Pretty much yes to all of your questions.
Low voltage will drastically increase amperage draw. Weak or LOW battery charge can result in the motor drawing excess amperage when the battery pack voltage is sagging. Excessive ampunts of amperage cannot be converted into to power, some is converted to heat. This is a detrimental situation where yes, low batteries can kill off motors and controllers.
A bigger or higher performance motor does require more power (volts x amps) to work. So yes, a bigger motor can be adding to your problem.

The first thing I would do is determine if in fact the battery pack is adequate and healthy enough for the task at hand.

The best test equipment is a simple in dash LED digital battery meter and the cart.
Do tests for full charge voltage 12 hours after the charge has ended.
And under load tests such as when accelerating full throttle up hill.
Post these numbers here as well as a reading for each battery after the 12 hour rest after charging. One bad battery can be causing the trouble.

[kernal]

Can you post the serial no.? Should be stamped on a metal tag riveted inside the passenger side cubby.
Does this cart have a run/tow maintenance switch under the seat?

In 1996 this could be either a series or DCS cart. DCS carts had/have a flaw which is no low voltage protection in the controller as described in post #4. It is common under load with weak/undercharged batteries to be in this condition and take out the controller. This seems to be common to DCS carts. If the original controller is replaced with a repaired or even an original stock controller the root flaw remains and will happen again. The ultimate fix is an after market controller (Alltrax for example) which doesn't have this flaw, is significantly more reliable, will increase performance, is user programable and usually cheaper for everybody.

So, do as suggested in post #4. First thing is to verify the health of the battery pack. You said the batteries were purchased in May. New correct? Are they golf cart batteries specifically? Have they been routinely charged since then? Do you have some sort of energy gage on the cart to monitor the state of charge? The tests in post #4 can be done with a hand held digital volt meter. We need voltages to the tenth at least.

[Raystar57]

Originally Posted by scottyb

Weak or LOW battery charge can result in the motor drawing excess amperage when the battery pack voltage is sagging. Excessive amounts of amperage cannot be converted into to power, some is converted to heat. This is a detrimental situation where yes, low batteries can kill off motors and controllers.

Learned something new today!
Thanks scottyb!

[scottyb]

Volts x amps = watts. Watts being work, in this case rpms and torque. When voltage goes down the motor draws more amps to = watts. However the motor is not 100% efficient. Much of the excess amperage is converted to heat not movement or work. The result can be catastrophic.
This is why I have been urging people to keep their batteries charged and upgrade 36v systems to 48 volt operation. The result is better performance and longer useful life.