EZGO 36V issue with full throttle

[Shuey76]

Good Morning,

New member, first post, thank you for any and all help or suggestions as this one has me stumped. (Turned into a much longer post than intended!!)

I have a 1996 EZGO TXT golf cart. It is a 36 volt system that uses the DCS drive system.

My issue started last weekend. Went on a long ride in the morning, no issues. Came home, put it on my power wise charger and got the batteries charged back up. Went to go on another ride in the evening, gave it throttle, and it clicked, tried to move forward, and failed. Cycled between forward and reverse, no change, and no click this time either. Tried shutting the controller off for about a minute and turn it back on, no difference. Pushed it into the garage and called it a night. Left it with the controller on.

The next morning, went out and tried it, still nothing. Put a volt meter on it, and there is no change when pushing on the throttle. So I shut off the controller and let it sit. Came home from work, turned the controller back on, and it worked when lightly pressing the accelerator. Clicks and moves in forward and reverse. Push it to the floor, and it stops working, and no longer clicks. Shut the controller off again, and walked away.

That brings me to this morning. Controller has been off since Tuesday. All my battery voltages are as expected, 37.1 37.2 on all 6, and 37.8x on the whole system. Lightly push on the throttle, and I could see the voltage drop to 37.1 and it would move in forward and reverse. Measured the system voltage by putting probes where the charger plugs in, so I could see it while driving it. I pushed it to the floor expecting it to puke, and it didn't, which really has me baffled at this point. I did not run it far, just a half circle in the garage forward and backward, as I didn't want to have to push it back. : )

Thank you for taking the time to read this long post, and thank you again for any and all help anyone can provide in helping me figure out what is going on with this. Have a great day!!

Matt

[JohnnieB]

The batteries are not being fully charged. Should be a minimum of 38.2V about 12 hours after charger shuts of automatically.

What is make/model of batteries and how old are they?
What model Powerwise charger?

The DCS controller (Curtis 1206SX) was EZGO's first attempt at a sepex drive system and was only on the market for about 5 years due to the high failure rate of the controller. The biggest design shortcoming was the lack of under-voltage protection and you're running your batteries at less than a full charge, so under voltage conditions have probably been happening.

Also, when you say you turn the controller off, what are you doing, placing Run/Tow switch in Tow or turning the keyswitch to off?

[Shuey76]

Thank you for the reply

I am putting the controller in tow mode by the switch under the seat.
When doing this, I have the key in the off position as well.

I have the batteries on charge now. When taking my voltage readings this morning, they had been sitting since Sunday. I will get another reading on them after a good charge.

I will get the model of the charger and the batteries, but I do know all of the batteries are two years old, as I replaced all of them when I got possession of the cart.

[Shuey76]

Charger is a Power Wise 28115 G01
I have had to replace the voltage sensor in it, as it would cook batteries.

Batteries are US1800's, all three years old. Thought they were two, date says otherwise.

I did hop on it earlier, and it never cut out. Started pressing lightly and it went smoothly to full speed. Same in reverse. Did not drop it to the floor on take off to see what that did. Going to let it charge and then rest once done, then measure batteries tomorrow morning to see what the resting voltage is across all of them.

Wondering if switching out the controller Alltrax would be a good deal, but keep the stock motor. On the fence of putting money into it and keeping it around, or confirm everything is working correctly and try to sell it. (leaning to keeping it, as it's a fun toy)

[JohnnieB]

Us Battery brand batteries need a higher finish charge than Trojan brand batteries and a PW 11528 charger was designed for Trojan batteries and not all of them will fully charge US battery brand batteries.

The finish charge voltage for a 36V pack of US Battery brand batteries needs to be in the 45.0V to 46.8V range while the PW 11528 shuts off int the 44.0V to 45.0V range, so about half of them won't do the job.

Attached are a SoC chart and single stage charging instructions.

-----------
An Alltrax XCT48400-DCS is a good replacement controller. It'll up the speed to about 20MPH.

The stock DCS motor is a good one, but the one in a 1996 cart might need some TLC (cleaning out the carbon dust, new brushes and a new bearing).

[sthreatt]

Originally Posted by Shuey76

Charger is a Power Wise 28115 G01
I have had to replace the voltage sensor in it, as it would cook batteries.

Batteries are US1800's, all three years old. Thought they were two, date says otherwise.

I did hop on it earlier, and it never cut out. Started pressing lightly and it went smoothly to full speed. Same in reverse. Did not drop it to the floor on take off to see what that did. Going to let it charge and then rest once done, then measure batteries tomorrow morning to see what the resting voltage is across all of them.

Wondering if switching out the controller Alltrax would be a good deal, but keep the stock motor. On the fence of putting money into it and keeping it around, or confirm everything is working correctly and try to sell it. (leaning to keeping it, as it's a fun toy)

Voltage sensor ? Did you replace the control board ? Was it jumpered when you got it so that it ran all the time ? So that it came on when you plugged the charger to house current, instead of coming on when plugged to cart ? That would explain it "cooking " the batteries. Also could have already damaged the batteries.

[Shuey76]

Exactly on the charger.
Soon as it was plugged in, it cranked up, didn't matter if it was connected to the cart or not.

[sthreatt]

That means that the charger had been jumpered, straightwired to run wide open all the time, no control board. If left unattended that can way overcharge batteries and I have seen it boil them dry. That set of batteries never recovered and had to be replaced. Hopefully you have put a control board in it and UNJUMPERED it . It should come on when it senses the connection to your carts batteries.

[Shuey76]

Yes, when I replaced the control board in it, I removed the jumper.
The charger now acts as it should. Only comes on when connected to the cart, and as the batteries start to charge, it lowers the amps going to them. Shuts off once completed.

Before the meter would go all the way to 20 and never move. The original batteries had a wicked Sulphur smell to them as well. Checked, and most were dry, so all were replaced. This was done three years ago.

[sthreatt]

Originally Posted by Shuey76

Yes, when I replaced the control board in it, I removed the jumper.
The charger now acts as it should. Only comes on when connected to the cart, and as the batteries start to charge, it lowers the amps going to them. Shuts off once completed.

Before the meter would go all the way to 20 and never move. The original batteries had a wicked Sulphur smell to them as well. Checked, and most were dry, so all were replaced. This was done three years ago.

Sounds like you've got everything back in the groove now. Re-read your first post and my initial thought would be a high amperage connection breaking down under a load. Like a bad crimp or a corroded connection. But I guess you've looked at all that.