Bad Motor?

[jdoll42]

I own a EZ-GO TXT (Manuf. Code M202, Serial 1558231). From what I've gathered it's a 2002 model with a series motor. It's 100% stock. So here's my problem:

With a full 100% battery charge, it runs like a champ. After about 5 minutes you can hear the motor change from the normal driving noise to more of a whirring noise and the cart more or less comes to a halt. You can visibly see the motor VERY slightly shaking while it does this. I can't drive it up even the smallest incline or soft ground. I literally have to tow it back to the house.

I ran through all the electrical troubleshooting and have come to the conclusion that the electronics are fine. (via the sticky at the top of this forum.) I also get continuity between both S terminals and both A terminals, but not between S and A in any configuration.

I also took the rear tires off and examined the hubs and there are no issues there. I cracked open the rear end and all looks good there. I just took the motor off expecting to see a stripped spline or something, but all looks good there. I can't find a smoking gun anywhere!

I'm really pulling my hair out on this one. Any ideas would be appreciated.

Thanks!

[gornoman]

Welcome to BGW!

Check those hubs again. Sounds like one or both are stripped.

[Sir Nuke]

Originally Posted by gornoman

Welcome to BGW!

Check those hubs again. Sounds like one or both are stripped.

you took the wheel and checked....what you might want to do is actually take the drivers side hub off.....

[rib33024]

when the motor stops and starts shaking, see what the battery pack volts are?, How old are the batteries. Sounds like a bad battery or old under volts batteries

[JohnnieB]

Originally Posted by jdoll42

I own a EZ-GO TXT (Manuf. Code M202, Serial 1558231). From what I've gathered it's a 2002 model with a series motor. It's 100% stock. So here's my problem:

With a full 100% battery charge, it runs like a champ. After about 5 minutes you can hear the motor change from the normal driving noise to more of a whirring noise and the cart more or less comes to a halt. You can visibly see the motor VERY slightly shaking while it does this. I can't drive it up even the smallest incline or soft ground. I literally have to tow it back to the house.

I ran through all the electrical troubleshooting and have come to the conclusion that the electronics are fine. (via the sticky at the top of this forum.) I also get continuity between both S terminals and both A terminals, but not between S and A in any configuration.

I also took the rear tires off and examined the hubs and there are no issues there. I cracked open the rear end and all looks good there. I just took the motor off expecting to see a stripped spline or something, but all looks good there. I can't find a smoking gun anywhere!

I'm really pulling my hair out on this one. Any ideas would be appreciated.

Thanks!

To check the hubs for stripped splines, remove any hubcaps so the castle nuts on the axles can be seen.
When the cart is misbehaving, have someone watch the castle nuts as the cart tries to move.

If the castle nut on either side is turning, but the hub isn't, the splines are stripped. (It only take stripped splines on one side to keep cart from moving.)

Could also be a battery issue as Rib mentioned.

[jdoll42]

Thank you all very much for your help. I took the back hubs off and the splines look great. There is no signs of wear or stripping. All is tight and snug. I can't find ANY physical signs of anything wrong anywhere.

I did some more testing with my meter while the motor is under load and doing its funky thing. Since it tends to do this more as the batteries drain, I've let my batteries discharge until my battery charge indicator is currently showing just over half charged on it's gauge. Here's what I found:

Battery pack voltage before running motor: 35.60v
Battery pack while running motor under load: 31.34v

Motor voltage (across A1-S2) no load: 0.00v
Motor voltage (across A1-S2) full load: 4.895 dropping rapidly to 4.378 after 10 seconds.

The way I put the motor under load was to hold one foot on the brake and the other foot on the "gas".

Soo.... bad battery? Bad controller? Help!

Thanks!

[jdoll42]

Originally Posted by rib33024

How old are the batteries.

I forgot to mention that the batteries are about 5 years old and are Trojan T-105's. Is there a date code somewhere on them to verify the manufacture date?

[cgtech]

Yes, battery date is stamped on the lead terminal, A9 = Jan '09. I think the motor controller may be shot, it is only supplying about 5 volts to the motor at full throttle. Since it works at first, i think the throttle sensor is fine. I had a controller do the same thing to me, took about 3 blocks to get up to speed, wouldnt climb over a pebble. In my case, i caused it by using 48v on a 36v controller (i knew it was wrong, but i didnt care as i had a new controller to go in), it actually lasted a month or so before it started acting up.

[jdoll42]

Originally Posted by cgtech

Yes, battery date is stamped on the lead terminal, A9 = Jan '09.

All 6 of mine are stamped G9, so July 2009?

Originally Posted by cgtech

I think the motor controller may be shot, it is only supplying about 5 volts to the motor at full throttle. Since it works at first, i think the throttle sensor is fine.

What's the best way to test the controller? I'd hate to have to shell out a few hundred $$ for a new one to find out it's not the controller. I ran through the diags listed in the sticky at the top of this forum and everything showed OK there.

[cgtech]

You have basically already done it. Clip your wire probes to the controller B+ & M- terminals and repeat test (i expect it will still be 4.x volts).