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-   -   ezgo controller testing (https://www.buggiesgonewild.com/showthread.php?t=64483)

kingcobra 05-19-2012 02:53 PM

ezgo controller testing
 
I was wondering if anyone knows how to test the controller on a electric golf cart I have a 1994 ezgo medalist 36v set up I am using a multimeter to check as much as i can i have 37 volts on both sides of my solenoid 37 volts at first 2 posts on controller but am not getting any voltage on the runs that lead back to motor ie no go am pretty sure that is the problem just wanted to double check also does anyone know of a good place to get either a stock controller new or used or aftermarket thanks

JohnnieB 05-20-2012 08:08 AM

Re: ezgo controller testing
 
First - Charge your batteries.
Their State of Charge is only 65% and the plates are sulfating as we speak.

It is best to start troubleshooting (or a drive) with a fully charged battery pack. (38.2V) :mrgreen:

A 94 Medalist could have either a Series drive or a DCS drive, which do you have?
(If there is a Run/Tow switch on controller cover, it is a DCS)

The phrase: "at first 2 posts on controller" is relative to the the position a person is viewing from. The posts are labeled B+, B- and M- and depending on type controller, there could be one labeled A2 as well as a pair of smaller posts labeled F1 & F2.

If the solenoid does not click when throttle pedal is pushed, troubleshoot the solenoid activation circuit.
If the solenoid clicks when pedal is pushed, you should have full battery pack voltage on both main terminals of solenoid.
If you do, attach DVM test leads to B- and M- posts on controller.
When pedal is pushed just far enough for solenoid to click, you should read full pack voltage.
If you don't, you have a open somewhere in the high current circuit.
If you do, slowly press pedal to floor. (Be sure to have rear wheels off ground while doing this, or cart might run over someone or something.)
As pedal is pressed to floor, the voltage should decrease to near zero.
If not, either controller or ITS circuit is bad.

Good luck.

kingcobra 05-20-2012 10:04 AM

Re: ezgo controller testing
 
thanks for your help the cart is a series model no switch the solenoid clicks when the pedal is pushed i get a 37.8 volt reading on both sides of solenoid on the a2 and bplus posts i also get 37.8 volt reading when i check the b- it only reads .05 but when i press the pedal it does drop to 0 the m1 post reads 0 at all times pedal pushed or not i had to rewire cart with the help of this forum and am pretty confident that it is done correctly anyways if this info gives you any more ideas please let me know thanks

JohnnieB 05-20-2012 11:43 AM

Re: ezgo controller testing
 
Quote:

Originally Posted by kingcobra (Post 728273)
1. when i check the b- it only reads .05 but when i press the pedal it does drop to 0
2. the m1 post reads 0 at all times pedal pushed or not

1. Where is this voltage reading referenced to? (Where exactly are the red and black test leads attached?)
2. M1? Perhaps that is a typo and you mean M-?

Here is what I am trying to do:
There are a bunch of MOSFETs inside the controller that control the amount of current going to the motor and by attaching your DVM test leads directly to the B- and M- terminals, you are measuring the voltage drop across the MOSFETs.

When the solenoid first clicks, the motor circuit is complete (closed loop), but the MOSFETS haven't been turned on by the throttle input yet, so the entire battery voltage is dropped across the MOSFETs. (AND ONLY THE MOSFETs)

If you do not measure full battery pack voltage, there is an open or high resistance in the motor drive circuit somewhere. High current cables & connections, F/R switch and/or Motor need to be tested to find whatever is dropping voltage and shouldn't be.

If you do get full Pack voltage, it should drop to near zero as throttle is pressed. (FWIW: The MOSFETs will drop someplace between 0.1V and 0.5V per 100 Amps of current flow through them depending on the type used.)

If the voltage doesn't drop to nearly zero, either the controller is not being told to turn on the MOSFETs by the throttle circuit, or the controller is being told to turn them on, but isn't.

Bottom line: Measuring between B- and M- terminals on controller, won't tell you what is wrong specifically, but it will tell you where to look next.

kingcobra 05-20-2012 12:48 PM

Re: ezgo controller testing
 
johnnie thanks for the info your right on the m- post my bad I am placing the black probe from my tester on the far left controller post and the red on each corresponding post to get my readings Im no electrical expert by any means I am assuming the black probe from my meter is for grounding? and the red for current? I did notice the two leads m- and b- from my controller run back to the motor so obvious no go with no voltage I am wondering if I am using my meter correctly for each reading any thing you can glean from this info?

kingcobra 05-20-2012 12:55 PM

Re: ezgo controller testing
 
johnny I also tested the forward and reverse switch posts I am getting 37 volts only on the bottom post and there are obviously 4 connection points seems 2 of the 4 should be getting juice dont know if that helps at all

scottyb 05-20-2012 03:40 PM

Re: ezgo controller testing
 
1 Attachment(s)
A lack of continuity through the F&R will stop the cart from running too.
Try this little test...

kingcobra 05-20-2012 04:07 PM

Re: ezgo controller testing
 
johnny i gave it a shot what i came up with is this the only way i can get the 4 ohm reading is by placing the probes from my meter on the left and right side of the forward reverse switch it gives me this reading in forward and reverse if i try to get a reading from the bottom like is shown in your diagram i get a big fat 0 ohm reading not sure if this gives you any clues thanks for all your help

JohnnieB 05-21-2012 07:21 AM

Re: ezgo controller testing
 
1 Attachment(s)
Quote:

Originally Posted by kingcobra (Post 728342)
johnnie thanks for the info your right on the m- post my bad I am placing the black probe from my tester on the far left controller post and the red on each corresponding post to get my readings Im no electrical expert by any means I am assuming the black probe from my meter is for grounding? and the red for current? I did notice the two leads m- and b- from my controller run back to the motor so obvious no go with no voltage I am wondering if I am using my meter correctly for each reading any thing you can glean from this info?

What is the "far left" terminal on your controller labeled??????????????????
The word "Left" doesn't tell me a darn thing because it could mean driver's side or passenger's side of cart depending on which way one is facing.

The black test lead should be connected to B-, either as shown in the attached drawing or the controller terminal labeled B-.

If the cables attached to M- and B- both run to the motor, your cart is wired wrong!!!!!!!!!!!
M- attaches to A1 terminal on motor, but B- should attach to negative terminal on right-rear battery as shown on drawing.

eejay001 09-29-2013 08:34 PM

Re: ezgo controller testing
 
Quote:

Originally Posted by JohnnieB (Post 728227)
First - Charge your batteries.
Their State of Charge is only 65% and the plates are sulfating as we speak.

It is best to start troubleshooting (or a drive) with a fully charged battery pack. (38.2V) :mrgreen:

A 94 Medalist could have either a Series drive or a DCS drive, which do you have?
(If there is a Run/Tow switch on controller cover, it is a DCS)

The phrase: "at first 2 posts on controller" is relative to the the position a person is viewing from. The posts are labeled B+, B- and M- and depending on type controller, there could be one labeled A2 as well as a pair of smaller posts labeled F1 & F2.

If the solenoid does not click when throttle pedal is pushed, troubleshoot the solenoid activation circuit.
If the solenoid clicks when pedal is pushed, you should have full battery pack voltage on both main terminals of solenoid.
If you do, attach DVM test leads to B- and M- posts on controller.
When pedal is pushed just far enough for solenoid to click, you should read full pack voltage.
If you don't, you have a open somewhere in the high current circuit.
If you do, slowly press pedal to floor. (Be sure to have rear wheels off ground while doing this, or cart might run over someone or something.)
As pedal is pressed to floor, the voltage should decrease to near zero.
If not, either controller or ITS circuit is bad.

Good luck.

the terminals in my controller has a1, b-, b+, f1, & f2 respectively. where is the m- terminal that i should attach the dvm? tnx


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