Test an Alltrax Controller

[somfas]

Is there a way to test a 450 amp Alltrax AXE7245? It seems like it must be bad, based on some diagnostics of other items on the cart. I have a message into Scotty for a new one. But in the meantime, is there a way to just test it and confirm it is bad? Thanks

[somfas]

Also, is there a way to see if the reversing contactor is bad? Thx

[JohnnieB]

Attached are Tech Notes 7 and 13. Plus a JPG of the diode test drawing in TN-7 and a JPG of how to bench power an AXE. (Might take more than 18V to power up a 72V version)

Verify that the LED flashes green FOUR time when AXE powers up. Otherwise it is programmed for something other than an ITS throttle.

[JohnnieB]

Originally Posted by somfas

Also, is there a way to see if the reversing contactor is bad? Thx

Measuring between B- and M- checks that. Or at least it verifies there is continuity through the contacts. It doesn't verify if the contacts are capable of passing high current.

You can eliminate the reversing contactor by connecting a 100W 120VAC incandescent light bulb between the M- and B+ terminals (Remove the M- cable to take the motor out of the circuit also) . The voltage between M- and B+ terminals should start at zero when solenoid clicks and climb to full battery pack voltage when pedal is on floor.

[somfas]

Thanks. Now I see. Since Pin 1 had power that most likely meant the controller wasn't working and since I had full power from B- to M- that most likely meant the reversing contactor was working. I don't know anything about how to hook up the controller to a computer or what I would even do with it if I did hook it to a computer. Thanks for the attachments. The problem was intermittent; is that reasonable that the controller would have intermittent faults?

[JohnnieB]

DVM test leads connected to the controller's B- and M- terminals are only looking at the voltage drop across the MOSFETs inside the controller. They are in series with the motor and the F/R device, so when the controller isn't passing any amps to the motor, they drop all the battery pack's voltage. As the controller starts passing amps to the motor, the voltage drop across the MOSFETs decreases until the controller is wide open and the no voltage is dropped across them.

Technically, the MOSFETs are switched fully on or fully off at about 18kHz and it is the duty cycle that is is modulated - So you have PWM (Pulse Width Modulation) output - but the DVM reads it as an analog output.

Here is a block diagram of a Curtis 1204 controller, but the new stuff works the same.

Also attached is a series drive reduced to about as simple as it can get.

Controllers, like any other electronic device, can be intermittent, but are usually hard failures.

[BobBoyce]

The Alltrax AXE 7245 was obsoleted many years ago. I used to keep a stock of AXE Alltrax controllers in inventory back in my DC EV days. I boxed up the DC controllers and put them in storage after I switched over to designing and building AC drive EVs. I still have a pair of NOS (New Old Stock) AXE 7245 controllers that had never been installed, if you have trouble finding one.

[somfas]

Just an update, it seems it was the controller that went bad. I replaced it with a new controller and it works now.

[BobBoyce]

Originally Posted by somfas

Just an update, it seems it was the controller that went bad. I replaced it with a new controller and it works now.