Possible 2010 Tomberlin Curtis 1268 SepEx DC Motor Controller issue

[TomberlinNewbie]

Hello All,
I'm new to golf carts... I bought one not working thinking i can fix it but nope... and i need help... i've been reading a lot on this forum but i still cant get it running.
I too bought a 2010 Tomberlin 48V Emerge 500 LE from the neighborhood. It doesnt run but i got it for cheap. I am hoping to fix it and use it before Halloween to ride around with my kids.
Original Symptom:
Fully charged to 52V, started running rough with a little jerking but finally ran for 3min at 15mph then suddenly stopped. Batteries at 49V. Let it cool down for an hour and then it ran for 1min with no issues then stopped. Now, it will only run for a few seconds with rear wheels off the ground.

Current Symptom Sequence
Fully charged. Turn on keys, Curtis 1268 has error code 12 at start.
I press on the throttle, Main contactor receives 48V signal and contactor shorts/clicks. Curtis 1268 powers the motor and wheels turn freely for a few seconds, then main contactor 48V signal goes away and main contactor goes open. Curtis 1268 has new error code 55 and then it tries to close the main contactor again. Main contactor receives 48v signal, and contactor shorts/clicks, the motor runs for less than 1 sec then 48V contactor signal voltage goes away. Main contactor goes open. Curtis 1268 stops sending signal to contactor, and nothing happens afterwards. I let go of the throttle.
I can repeat the whole sequence again when I press the throttle.

Troubleshoot:
Batteries are a little old but fully charged to 52volt and stays at 48 to 49V for a long time. All fuses are good. I ohm out F/R switch, Brake switch, main contactor, motor and run/tow switch by following the service manual guidance.
I changed out axel gear oil. Motor, axel and wheels all turn freely.
I removed the motor wires from the Curtis 1268 and hooked up an Oscope to Motor(-) and B(-). I can see PWM signal when i press the throttle. But it repeats the same symptom sequence i wrote above and then the PWM signal goes away. I can repeat it when I press the throttle again. So, i dont think its a load or motor issue. Instead of error code 55, now its 34. But im sure it will go back to 55 if i hook up the motor.
I have not test overheat sensor and speed sensor.

What to do next?
I think I have a bad Curtis 1268 because it turns on/off the main contactor, turns main contactor back on/off again and then finally stops. I assume the Curtis 1268 is trying to protect itself? What other test i can do on the 1268? or is it the main contactor? or something else to test?
Any help and recommendation is appreciated.
Error code 12 "The sliding signal of accelerator is outside the scope"
Error code 34 "Excitation Damage"
Error code 55 "Main contactor is open"

[ojo]

I'd recommend to start with new batteries! When your voltage drops from 52 to 49v after 3min, the batteries are bad... a battery pack with 48-49v is pretty dead
Enclosed a SOC chart for Trojan brand batteries >

[TomberlinNewbie]

Thanks OJO for replying and posting the State of Change vs Voltage graph. Your recommendation makes lots of sense, and basically my battery went from 100% to 50% in 3min.

This makes sense as why the golf cart didnt run after 4min mark... So, any recommendations on batteries? Samsclub has Duracell golf car battery for $106. Duracell is a good brand but $106 seems pretty pricey.

Also, a few websites claimed replacing the battery acid with epsom salt solution (1 part epsom salt with 3 parts distilled water) can revive the battery for a little while or back to "full" glory. I dont know anything about car batteries, i am not a chemist but this solution sounds shady. Or at least its not painting the full picture. So, I would like to ask if anyone tried it and whats the truth behind those claims? Is there a battery forum on this site that goes down this rabbit hole?

[ojo]

My recommendation for deep cycle batteries is always Trojan, next would be US Batteries... have read positives about Crown also. Maybe look at the "Stickys" in the Ezgo section, you'll find a lot of information about golf cart batteries!

[Tech Support]

I have used the Duracell from Batteries Plus when Trojan or US weren’t geographically close enough and had really good luck with them. They are from East Penn which is same as Deka and some other brands.

Overall I prefer US Battery but sometimes you have to go with what you can find AND afford.

[TomberlinNewbie]

Thanks all for the battery recommendations. So, i finally repaired the Tomberlin and here is what all i had to do. Hopefully it can help others if they stumble into this post.

1. Old batteries charged to 52v, but drained to 49v in 4min. I drained and filled the acid with epsom salt solutions and it didnt make any difference. (p.s. I do not recommend draining battery acid, it was dangerous and took 8lbs of baking soda to neutralize the acid)
If i floor the throttle, it will dip from 52v down to 46v and shuts off. I had to slowly press the throttle to make sure it doesnt dip down below 48v for it to run for 4min. I had a DMM hooked up to the +/- battery terminals and monitored it while the rear wheels were jacked up on jack stands.

2. New info! While the cart was on jack stands, I realized my rear wheels would vibrate and jerk a little before the wheels would get going. Something is odd...

3. I replaced new batteries and i resurfaced the Curtis 1268 heat sink compound since i took it out to examine. Put everything back and did a test drive.
The test drive started out with a little vibration and jerked a little. I had to floor it for it to get going. I smelled burning rubber after 1min driving down the road. I quickly turned it off and pushed it back home. My heart sunk thinking i blew the Curtis 1268 some how...

4. After inspection, i found out the smell came from the motor. I took the motor out and found out all 4 motor brush were seize. The motor rotated freely with little to no friction from the brushes. I rebuilt the brushes, put everything back and its now running so smooth. I now have great motor control from slow to fast. Also, no more vibration and jerking. Its just so smooth and quiet.

So, I tried to rejuvenate old batters, end up replacing new batteries, drain and fill axel oil, new thermal compound for the Curtis 1268 and rebuild electric motor brushes. 20hrs and $700 later... I'm just happy the Curtis 1268 wasn't the problem.

Next think i should do is to bleed the brakes and fix the hand brake too. The hand brake cable snapped. Any recommendations on what site to buy the hand brake cable?

[ojo]

Nice to hear that it's back to life... reg Tomberlin parts you could check seller Forest Cart on eBay

[JoeToneRusso]

I'm glad to hear you got it working! It seems that the brushes are a common issue in these motors because my motor also had the brushes stuck at one point. I buy everything from cartpros.com I do not work for them or anything but they seem to have everything for our carts. I also have a 2010 E-Merge 500 LE and I have downloaded the Illistrated Parts List for our cart which has the Tomberlin Part Number on it. Then I copy and paste that part number in their site and it pops right up (most of the time without a picture) but when it shows up it's the correct part. Cheers.

[Tech Support]

For anyone else who picks up a car that has been sitting for any period of time (brand doesn't matter), first two things to look at:
1. Batteries, which is rather obvious I think to everyone...
2. Motor brushes. (This of for a DC cart, not AC). Any periods of time a motor sits the brushes are static and over time the just stop moving. The brushes are the connection between the "power" and the motor armature, and pressed by springs against the armature's commutator. If the brushes can't slide freely inside their "brush boxes", then the power is being delivered to the armature and the motor isn't spinning.

Brushes are indeed a wear item over time, but the biggest issue is the time spend not being used causes them to seize, or even move sluggishly diminishing the power transmission. Most if not all service manuals note that brushes are something to be checked for a periodic maintenance item.