checking controller output

[ncseadad]

Hey Guys....I am checking the controller output on my series model 36 volt ezgo. The response I got from another post I made a couple years ago tells how to check but does not tell what if it don't on one part. Will try to explain below.

I put (-) probe from my Volt meter on B- on controller
I put (+) probe from Volt meter onn B+ on controller

The reading indicates 0 volts...as it should
Slowly depress accelerator pedal until it clicks I get pack voltage as I should
However, as I press the pedal nothing happens, It does not go to 0 as it should

Now, my instructions tells what is wrong if you press the pedal and it goes to 0 and the motor does not run

It does not tell what is wrong if I press the pedal and it does nothing. It does not go to 0..So, if it don't, my golf cart friends...What is wrong...

Thanks...Ole Bill here

[JohnnieB]

Sounds like you've got your test points and expected results mixed up.

If you have a precharge resistor installed between the solenoid's two large terminals, the voltage between the controller's B- and B+ terminals should be about 3V to 5V less than the battery pack voltage at the time. When the pedal is pushed far enough to make solenoid click, the voltage between the B- and B+ should be equal to the battery pack voltage and will stay equal to the battery pack voltage (at the time) as the pedal is pressed to the floor.

However, if you connect your DVM between the controller's B- and M- terminals, you'll get a little less than pack voltage before solenoid clicks, exactly the same as the battery pack voltage when pedal is pushed just far enough to make solenoid click and will decrease to zero as pedal is pushed to floor.

On the other hand, if you measure between the controllers M- and B+ terminals, the voltage starts at zero and climbs to battery pack voltage as pedal is pushed to floor.

Since the solenoid is clicking, you want to measure between B- and M-.
The MOSFETs that controls the amount of power sent to the motor are located between those two terminals should be an open electrically before the pedal is pushed far enough for a throttle position signal is sent to the controller telling them to pass amps to the motor. They are the only electrical open in the motor/controller/solenoid/battery/F&R switch circuit, so the full battery voltage will be dropped across them. As the pedal is pushed further and they start passing amps to the motor, the pack voltage is divided proportionately across the MOSFETs and the motor and when at 100% throttle none of the pack voltage is dropped across them and all the pack voltage is being dropped across the motor.


If you don't get full battery pack voltage when solenoid clicks, Leave the negative test lead on the controller's B- terminal and go searching for the missing voltage with the positive test lead. Attached is a schematic with the high current circuit highlighted.

Typically, the F/R switch is the most likely suspect.

[ncseadad]

Hey JohnnieB..ok..The output test that I copied I guess is a little different that what you sent...The one I had said with the probes on B- and B+ says the voltage should be PV (36)when solenoid first clicks then to 0 as the pedal is pushed
Those results were PV (36) when it clicks and PV when pushed to floor. Nothing changed


So, I did the test according to your message. I have no resisters or anything on the solenoid. When I connect DVM between B- and M- I get 1.3 volts. When I push the pedal to make the solenoid click my voltage is 00.5. and as I push pedal to floor it goes to 0.

on the other hand, if I measure between M- and B+ my voltage is 35.3 and climbs to PV (36)

Either way I don't get the proper voltage.

Thanks

I know 36 volts a only half battery but should be ok to test.

[JohnnieB]

If you trace the attached cables, you'll find the other end of the cable on the B- terminal is directly connected to the battery pack's main negative terminal (B-) and the cable on the B+ terminal is connected to the battery pack's main positive terminal (B+) via the solenoid's contacts, so what your are doing is measuring the battery pack voltage with a longer set of test leads and the voltage won't vary from the pack voltage no matter how much the controller is conduction to the motor.

Voltage between B- and M- should start at pack voltage and drop to zero as controller conducts more, while the voltage between M- and B+ should do the opposite, start at zero and climb to pack voltage.

Based on the voltages you are getting between B- and M- as well as the voltage between M- and B+, I suspect most of the MOSFETs in your controller are blown with only one or two of the dozen or so in parallel working enough to pass enough current to get a voltage reading, but not passing enough amps to get any motor movement.

Let's try this:
Lift the cart's rear tires off ground and put on jackstands.

If the cables are long enough, move the cable on the battery pack's main positive cable two batteries to the left and the cable on the main negative terminal one or two batteries to the left. In other words, create a 18V of 12V battery pack.

Then move the cable on the controllers B- terminal to the M- terminal, so there will now be two cables on M- terminal. This bypasses controller and when pedal is pushed, the 12V or 18V battery pack is connected to the motor.

If the motor runs, the controller is bad.

If it doesn't, return the cables back to their original positions and start looking for the bad cable, connection or contact.

[BeauB]

Having similar issue when you say search for missing voltage can you dumbify that lol I have full voltage between b- and m- and maybe drops a couple of volts and that’s it and when I check the F/R I have full voltage on whichever one is selected

[JohnnieB]

Originally Posted by BeauB

Having similar issue when you say search for missing voltage can you dumbify that lol I have full voltage between b- and m- and maybe drops a couple of volts and that’s it and when I check the F/R I have full voltage on whichever one is selected

If you get full battery pack voltage between B- and M- when pedal is pushed just far enough to make solenoid click, the high amp circuit is intact and you don't have to go searching for missing voltage. If that voltage does not go all the way down to zero volts when pedal is pushed to the floor, then either the controller is bad or the throttle input to the controller is bad.

Check the ITS (throttle) voltages and if they are good, the controller is bad.

[BeauB]

Originally Posted by JohnnieB

If you get full battery pack voltage between B- and M- when pedal is pushed just far enough to make solenoid click, the high amp circuit is intact and you don't have to go searching for missing voltage. If that voltage does not go all the way down to zero volts when pedal is pushed to the floor, then either the controller is bad or the throttle input to the controller is bad.

Check the ITS (throttle) voltages and if they are good, the controller is bad.

Ok where do I check the ITS at? Sorry for asking stupid questions but I’m just ignorant on it haha and is “good” full voltage? When pedal is pressed?

[JohnnieB]

Originally Posted by BeauB

Ok where do I check the ITS at? Sorry for asking stupid questions but I’m just ignorant on it haha and is “good” full voltage? When pedal is pressed?

In order to tell you how to check the ITS voltages, I have to know which drive system your cart has. More specifically, which controller.

Your earlier statement "when I check the F/R I have full voltage on whichever one is selected" leads me to suspect you have a PDS drive, so I'm attaching PDS info. If you don't have a PDS tell me what it is and I'll post the info for it.

[BeauB]

Originally Posted by JohnnieB

In order to tell you how to check the ITS voltages, I have to know which drive system your cart has. More specifically, which controller.

Your earlier statement "when I check the F/R I have full voltage on whichever one is selected" leads me to suspect you have a PDS drive, so I'm attaching PDS info. If you don't have a PDS tell me what it is and I'll post the info for it.

No it’s not the PDS it has the selector by the seat a lever you slide back and forth it’s a late 90’s I think txt 36v just meant when that plate rolls from one
Side to the other that switch with the roller wheel thing on it set in a groove i dont know a lot about golf carts or electrical just enough to get me in trouble. I originally thought batteries were shot but they all show good voltage it just won’t move the solenoid clicks and all just won’t move

[JohnnieB]

Originally Posted by BeauB

No it’s not the PDS it has the selector by the seat a lever you slide back and forth it’s a late 90’s I think txt 36v just meant when that plate rolls from one
Side to the other that switch with the roller wheel thing on it set in a groove i dont know a lot about golf carts or electrical just enough to get me in trouble. I originally thought batteries were shot but they all show good voltage it just won’t move the solenoid clicks and all just won’t move

How about some pictures of the cart, controller and F/R switch.