EZGO RXV Electric Cart will only go 1mph in forward or reverse

motoman442000

2008 Electric EZGO 48V Golf cart w/AC motor
Motor: Iskra AMT 7109 3 phase AC motor 30v 3.3kW 4.4HP
Batteries: Trojan T-1260
Controller: 230-amp AC EZGO 604125 (probably rebrand so I am not sure of actual mfg)
Solenoid: EZGO 606971

Was just riding along in my cart when it suddenly stopped and now it only moves at a slow crawl. It will go in both forward or reverse and up an incline but not more than about 1mph

Here is what I looked at so far:
-Took off motor brake to eliminate that as an issue. No change
• Checked battery voltage – 50.40v at both battery and solenoid terminal
• Checked solenoid – 50.30v (controller side) when key activated, also jumpered around solenoid (no change)
• Checked controller with negative probe to “W” and positive probe to B+. With key on and accelerator pushed it went from 3.6v to 24.94v. “W” to B- read 46.25v when key turned on.
Does this indicate a motor issue? Is there a way to check whether it is a motor issue for sure? Did I measure the controller output correctly?
Also, can this cart be put in diagnostic mode somehow? I have a dash mounted key switch with fwd-nuetral-rev integrated into the key switch
Thanks

BGW

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cgtech

No, not really the correct way to diagnose a Danaher controller. Only way to get diagnostic codes is with handheld programmer. I think you could have a failed motor temp sensor, (two small wires @ motor, not motor brake). I dont remember the ohm values right now for the sensor, but remove the rear access cover to get at the plug for testing. When the temp sensor fails max low or max high, the controller goes into cutback to attempt to control temp. I did the math, when the temp sensor fails "high", the motor indicates it is hotter than the surface of the sun, its pretty funny. These carts are quite difficult to work on without a handheld programmer, a lot of guessing will be going on. Even the official troubleshooting guide doesn't go by symptoms, but starts with the error codes in the controller.

Jerj7907

I was thinking temp sensor as well. Question for you. How fast were you driving when it suddenly stopped? And for how long?

motoman442000

Thanks.I will take a look at the Temp sensor. I was only driving for about 20 minutes in the woods riding between 3-5 mph and about 10mph for 5 min to get to the woods from my house

cgtech

I was just thinking as i posted in another thread "2five in RXV - cost update". The speedo also serves as a code scanner for currently happening (or last shutdown, if you turn cart off while moving) error codes. Not too bad of a price. Only works on Danaher controller RXVs & 2fives, like yours.

motoman442000

can you replace just the temp sensor in the RXV motor (Iskra AMT 7109)? .... or bypass it somehow to make the controller think it is ok

cgtech

It is inside the motor windings, i have no idea how you would replace it without a new motor. Sure, you could fake it out with a resistor (i'll get you a resistor value that would work tomorrow). You may be able to get a thermal diode (temp sensor) and install it at the motor. It wouldnt be inside the motor like the original one, but that would be better than a total BS resistor that is a totally fake lie as far as motor temp.

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yurtle

I doubt if this exists in commodity priced motors, but at work, most 3 phase motors come with multiple RTDs per phase. We would sometimes pick the "hottest" one and monitor it. If it failed, there was always a backup. Is it possible that the motor has extra temp sensors? Are they RTDs or thermistors?

yurtle

I'm not sure how "deeply" the sensor is located within the windings, but if the option is buy a new motor, it may be worth seeing if a motor rebuild shop could install a new sensor (or two)?

motoman442000

Thanks CGTECH. I was afraid the temp sensor was buried in the windings. A resistor value would be great in that I could try that to make sure that is indeed the issue. A thermal couple at the motor would probably be a good compromise given I would have to buy a new motor anyway (unless I could get it rebuilt). Haven't had a chance to measure the value of the temp sensor yet but it sounds like that may be the problem