how to tell if controller or hub motor is dead ?

[DTBAKER61]

I have inherited an old 48v eBike that has seen better days.... and is not currently running.

1. battery was replaced not long ago, voltage test fine, so that's probably fine.
2. original display-throttle was crashed on several times and was highly suspect, so I've tossed that and bought an inexpensive twist grip throttle
3. I don't need PAS, fancy display or brake interlocks.... just twist-grip 4-wire throttle
4. I've wired up the new throttle, but bike is still not working.

Q: how can I tell what *should* be measured coming from the controller output (with *some* throttle) to make sure the controller is ok ?
I am attaching picture of controller/motor connector; 3-phase wires and 6 contacts around the outside

Q: I do have a variable voltage/current power supply.... can I jumper to hub motor connector to make sure hub motor is ok?

Q: if the hub motor is bad, can I keep the existing wheel, and buy 'just the guts' of the hub motor to keep repair cost down?

 

[E-HP]

2. original display-throttle was crashed on several times and was highly suspect, so I've tossed that and bought an inexpensive twist grip throttle
3. I don't need PAS, fancy display or brake interlocks.... just twist-grip 4-wire throttle
4. I've wired up the new throttle, but bike is still not working.

Do you have a link to the throttle? Hall based throttles use 3 wires, +5v, gnd, signal. How are you wiring the 4th conductor?
KT controllers that normally use a display, require a couple of jumpers added to the display connector to turn the controller on. Can you provide a pic of the display connector as well as how the new throttle is connected?

 

[DTBAKER61]

Do you have a link to the throttle? Hall based throttles use 3 wires, +5v, gnd, signal. How are you wiring the 4th conductor?
KT controllers that normally use a display, require a couple of jumpers added to the display connector to turn the controller on. Can you provide a pic of the display connector as well as how the new throttle is connected?

I pulled a 6-wire throttle from parts box.... and spliced to a simple old 4-wire controller. no display, no PAS input. using the button switch on throttle for on/off of 5+v .

throttle battery status lights up, and 3 ouput pins show a voltage change when I twist throttle, but I don't know enough about eBike controllers to know what those three outputs are supposed to be showing if throttle is correct, so I don't know for sure if controller is good.

what should the 3 controller pins to motor be showing ? should I ground voltmeter - lead to battery -, and measure those output pins all as V+ ?

then, if I want to test hub motor WITHOUT a controller/throttle, can I use a power supply and directly power the hub motor ?

 

[amberwolf]

2. original display-throttle was crashed on several times and was highly suspect, so I've tossed that and bought an inexpensive twist grip throttle

It's a KT / KunTeng controller, so they're normally paired with a display. Without one, there's no access to the assist levels or settings, no power button to turn it on, etc. That's true of any controller that normally has a display.

The last you can fix by wiring the keyswitch/ignition/doorlock/etc wire (whichever they called it on yours) that came from the display to battery positive directly, so the controller is always on if power is connected. If you aren't sure which wire that is, there's plenty of wiring diagrams out there for KT controllers, some of them model-specific you can find with the info on your label. Usually it's another red or orange wire that comes out of the controller in the same grommet as the main battery positive wire, but ifyou have waterproof connectors it's going to be in the 5 pin one that normally goes to the display, and those pinouts are also available for KT displays and controllers.

The rest you can't fix without a KT display, so it will only run in the default assist level at power on, whatever that was setup to in the menus of it's display. If it is one that has the option to require pedalling before the throttle works, and that's setup as the default power on mode, then you'll have to have the PAS sensor connected and be pedalling to make the motor run (or you can use an oscilloscope to see what the waveform is that it outputs and make a small circuit (555, etc) to emulate that to have the PAS run either all the time or anytime you are engaging the throttle).

Q: how can I tell what *should* be measured coming from the controller output (with *some* throttle) to make sure the controller is ok ?

Nothing testable will come from the controller's phase wires unless it also detects the correct hall signals *or* the correct feedback from the phases as it starts the motor spinning. (an ebike tester box has stuff in it to emulate that to feedback to the controller and signal you wiht LEDs if it's doing the basic stuff).

Without that you just get something between zero and battery voltage at the phases, relative to battery negative or each other.

Q: I do have a variable voltage/current power supply.... can I jumper to hub motor connector to make sure hub motor is ok?

No, because it's a brushless motor that requires three commutated phase signals to make it spin. Connecting a power supply across any two will not make it spin (though a low current should make it "jump" to the next magnet pole closest to the stator teeth that are enegized by that phase pair). Allowing too high a current could damage the motor windings, since it isn't spinning it is just turning all the current into heat. I don't know what too high is for your motor, but I'd start as low as you can and go no higher than an amp or less.

But it is probably not your motor, it's probably that you have no display anymore.

Q: if the hub motor is bad, can I keep the existing wheel, and buy 'just the guts' of the hub motor to keep repair cost down?

Some of them you might find--you have to talk to the motor manufacturer for stuff like that most of the time--individual sellers rarely carry anything but whole kits or main subsystems (motor, controller, display, etc).

 

[amberwolf]

and 3 ouput pins show a voltage change when I twist throttle,

There should only be one pin that has a voltage change, and that is your throttle signal output. If several pins change, something may be miswired, and you'd have to verify the wiring to the hall sensor inside, which will be like this

The output range for a typical hall throttle is around 1v or less when "off", and around 3-4v or so at max rotation.