Stumped on Contactor Operation & Corresponding Voltage

[Denntt]

Hello, I powered up my cart and controller for the first time this evening. In commissioning the functionality, I cannot get the wheels to rotate. When i depress the accelerator pedal I can hear the contactor engage/disengage. When I return the pedal to 0% throttle I can also hear the contactor engage/disengage. When the pedal is at rest I can confirm 49.5V across the smaller terminals. When the pedal is depressed I read 0.005V across the main contactor lugs. As you can see from the picture, I believe the controller is reading everything as it should but I am getting no significant voltage across the contactor, regardless of pedal %. I am rather stumped as to why the contactor would be reading such a low voltage when I can feel/hear the contactor moving as a result of the pedal movement.

I have confirmed 49.6V across the battery pack.

Is there something I am missing? I feel it may be stupid-simple but I am stumped.

48V system, Alltrax XCT48500 Controller, MZJ-400 Contactor

Any help in troubleshooting would be appreciated!





Thanks!

[Denntt]

I am having difficulty figuring out how to embed the pictures in the post, so I am posting links directly to each photo in the essence of time:

https://drive.google.com/file/d/1-6z...ew?usp=sharing

https://drive.google.com/file/d/1-J2...ew?usp=sharing

https://drive.google.com/file/d/1-9I...ew?usp=sharing

[ThreeCW]

Originally Posted by Denntt

When the pedal is depressed I read 0.005V across the main contactor lugs. As you can see from the picture, I believe the controller is reading everything as it should but I am getting no significant voltage across the contactor, regardless of pedal %. I am rather stumped as to why the contactor would be reading such a low voltage when I can feel/hear the contactor moving as a result of the pedal movement.

The large posts on your solenoid (main contactor) are both "48 volt POSITIVE" posts (so you can remove the "-NEG" sticker). I am not sure from you photos where you were checking voltages from, but it kind of looks like you were checking across the large posts which is not correct. The solenoid is really just an electrically operated power supply switch. It is controlled by a positive and negative on the small posts which activates a coil in the solenoid and connects the two large posts together (both positive). When you de-activate the coil (disconnecting power to the small posts), the two large posts are disconnected from each other.

You can test your solenoid as follows:

1st measure voltage between the battery pack 48V “Negative Post” and the Battery “+” side of the Solenoid. Should be battery pack voltage

2nd measure voltage between the battery pack 48V “Negative Post” and the Controller side of the Solenoid with the Key Switch off. Should be 0 volts (or a residual Controller voltage depending on how much voltage has bled off)

3rd measure – repeat 2nd measure with the Key Switch and foot switch on. Should be battery pack voltage.

As per the Alltrax XCT wiring diagram, you are correct to NOT have a pre-charge resistor between the two large posts of the solenoid ... many controllers require a pre-charge resistor, so your looks a little naked without it.

See attached diagram for more information. Note that your cart may not be wired as per this generic XCT wiring diagram.

9:45 pm - Note - just made some corrections to my first posting

[Denntt]

Originally Posted by ThreeCW

You can test your solenoid as follows:

1st measure voltage between the battery pack 48V “Negative Post” and the Battery “+” side of the Solenoid. Should be battery pack voltage

2nd measure voltage between the battery pack 48V “Negative Post” and the Controller side of the Solenoid with the Key Switch off. Should be 0 volts (or a residual Controller voltage depending on how much voltage has bled off)

3rd measure – repeat 2nd measure with the Key Switch and foot switch on. Should be battery pack voltage.

Thank you for the quick response. I was able to sneak out from my desk and to the garage this morning. Below are my test results:
1) 50.2V
2) 0V
3) 49.6V - Interestingly enough, I am getting the 49.6V without depressing the accelerator pedal

Further, I witnessed the controller power up and get the following:
Green - (0-5K throttle? this matches my setup w/ Curtis PB6 as the throttle)
pause
GREEN blink, RED blink, RED blink
pause
Solid GREEN

In review of the manual this Blink Code corresponds to Battery Under Voltage. This seems odd as the battery pack voltage is approx 49.7V... It is my understanding that 49.7V is within tolerance. Is there a reason the controller would be throwing this blink code with the battery pack voltage as measured?

[Denntt]

Thanks to those who looked at this thread and a special thanks to @ThreeCW for responding with the testing suggestion. After contacting Alltrax today I was able to diagnose the issue and traced it back to the Foot Pedal Switch. The wire was connected to the wrong terminal on the PB-6 foot-switch... NO or NC, I cannot recall.

Now with the wheels actually turning I can continue with testing/commissioning.

Thanks Again!

[ThreeCW]

Glad to hear that you are making progress