93 Ezgo controller issues

[kidroc2133]

I have a 1993 ezgo electric that I am working on for my father in law. I hooked up a new Alltrax controller, and getting a new solenoid for it as well. First question, does the solenoid have to work in order for the controller to turn on? I get pack voltage on the two large terminals when accelerator is not pressed. If i test the small terminals I have a low voltage but when I press accelerator voltage drops to zero. Second question is if the key is on should I be reading pack voltage on the key switch? Last question (for now) the alltrax controller does it require 12volts to power on or the 36volts from the cart and how does it get a negative or ground (from solenoid)??
Thanks

[JohnnieB]

Originally Posted by kidroc2133

I have a 1993 ezgo electric that I am working on for my father in law. I hooked up a new Alltrax controller, and getting a new solenoid for it as well.

1. First question, does the solenoid have to work in order for the controller to turn on?

2. I get pack voltage on the two large terminals when accelerator is not pressed.

3. If i test the small terminals I have a low voltage but when I press accelerator voltage drops to zero.

4. Second question is if the key is on should I be reading pack voltage on the key switch?

5. Last question (for now) the alltrax controller does it require 12volts to power on or the 36volts from the cart

6. and how does it get a negative or ground (from solenoid)??
Thanks

A 1993 would most likely be a Marathon body style with a series drive, electronic speed controller and pot-box throttle.

Attached is a schematic for the above described cart with the solenoid activation circuit highlighted.

For voltage measurements, connect black test lead to B- (Either most negative battery terminal or B- terminal on controller) so all voltage readings will be positive.

1. No. The controller's internal electronics are powered up when 36V is placed on Pin-3 (Blue wire.) That happens when keyswitch is on and a direction is selected, closing the contacts of MS-2 (Run switch)

2. If there is a precharge resistor connected between the two large terminals, the large terminal that is connected to the battery pack will have full battery pack voltage (38.2V when fully charged) and the large terminal connect to the controller will have slightly less. (The resistor keeps the filter capacitors inside the controller charged and reduces arcing when solenoid contacts bounce to a close.)

3. The terminal with the black wire on should be 0V since it is connected to the controller's B- terminal. The other small terminal (red wire) should have battery pack voltage on it when key is on, a direction is selected and pedal is pushed. Schematic with solenoid activation voltage path highlighted is attached.

4. One side of keyswitch is connected directly to the most positive terminal on the battery pack (B+), so it should have B+ on it at all times. The key-switch's other terminal should have 36V on it when key is ON.

5. Unless the cart has lights or other 12V accessories, there is nothing in it that runs on 12V. Controller, solenoid and drive control switches all operate on 36V.

6. For safety reasons, there is no "ground in an electric golf cart. Every thing uses two wires, B- & B+ . B+ is directly connected to the motor via the solenoid contacts and B- is supplied by the controller via the M- terminal. Schematic with high amp (motor) circuit highlighted is also attached.

[kidroc2133]

I had to rewire a few things with the key switch, it was not wired correctly. I now have it correctly wired. I had to bring the controller in and check the program for the throttle. It was set at ITS when this cart is 0-5k throttle so I change it to 0-5k 2 wire and clicked the set button and it said throttle was set. I hooked it all back up and the solenoid would click but cart would not move. At first when I pressed the throttle it would blink 1 green and 6 red for pre-charge failure after that while pressing the throttle the controller would blink 2 green and 4 red for high throttle like it went back to ITS setting some how. The solenoid has pack voltage on battery side and about 30 volts on the other side without pressing the throttle. Is this normal? Or do I still need a new solenoid? The small terminal with orange wire shows pack voltage when throttle is pressed also as it should.
Thanks for the help so far.

[JohnnieB]

Precharge failure means the voltage at the controller's B+ terminal varies more than 5V from the voltage at the KSI terminal. With your voltmeter's black test connected to the controllers B- terminal, check the voltage at the B+ and KSI terminals.

High Throttle Under Range. Disconnect the black and white wire from the pot box and connect an Ohmmeter between the two loose wires. Should read under 300Ω with pedal up and about 5,000Ω with pedal down.

You can also try clearing the throttle auto cal.

[kidroc2133]

I figured out what was going on and got the controller working. I can now drive the cart around. Now the problem I do have is that when I barely press the throttle the cart jumps like its trying to go full speed. I need to know how I can fix this so it goes like a normal cart would and not all jumpy at the beginning.
I have cleared auto calibration too but it still does it.
Thanks for the help so far.

[JohnnieB]

Cart:

Might need to adjust the pot so it is closer to 0Ω when the solenoid clicks. May need some tweaking on the pedal switch to get it to close the contacts closer to the fully up pedal position. Attachment-2 gives you and idea of how the pedal should be adjusted mechanically.

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Controller:

Reduce the Throttle Rate %. Set to about 10% and tweak from there.

Also, reshape the Throttle Linearization. Attachement-1 is what I adjusted mine to. I had a problem starting from a standstill without spinning the tires.

[kidroc2133]

Ok so the pre charge failure issue is fixed but now I get a slow cart like batteries are dead. I have a new controller, all new batteries and a new solenoid just put in today and still can't get this thing to move normal. I have 36 volts from batteries and when I press the accelerator voltage drops to about 20 to 21 volts. What can cause this issue? All your help have been great.

[JohnnieB]

The batteries are dead! Or at least far from being fully charged.

A 36V pack whose voltage is only 36.0V is only about 43% charged.

Charge batteries over night and check the voltage about 12 hours later. You should get 38.2V or there is something wrong with either the batteries or the charger.

[kidroc2133]

The battery charger won't kick on to charge the cart as if the charger isn't recognizing the less than 36 volts to charge. When I plug it in it clicks on for a moment then off.

[kidroc2133]

Ended up hooking up an automotive battery charger to two of the batteries to charge them up and switch to other two batteries until I got the charger to kick on. Didn't realize the charger wouldn't work unless there was a certain voltage in the batteries. Learn something new everyday. I'll let it charge over night and see what happens tomorrow.