Testing with dc power supply

[Slenner]

Hello, I work in a shop and we've started accepting ebikes in for diagnostics. One problem I'm trying to solve is when a bike comes in with no battery or the battery doesn't power the bike on.

I have methods to test everything on the bike without power, but aside from checking the controller mosfets with a multimeter, it could still have a different internal fault.

My thought process is if I could use a benchtop dc power supply connected to the controller I could test the system, unloaded with the wheel off the ground.

I'm not an electronics engineer, so is this doable or even a safe thing to do? The motors would be geared without regen braking so there should be no current trying to feed back to the power supply? What about the capacitors in the controller, I assume I need to discharge them before connecting the supply?

I'm considering this 60v 20a power supply and the motors we see are 500-1000w and 36-48v, would this handle the initial startup current of these motors?

Will this burn down our shop?

Appreciate any advice!

 

[E-HP]

Hello, I work in a shop and we've started accepting ebikes in for diagnostics. One problem I'm trying to solve is when a bike comes in with no battery or the battery doesn't power the bike on.

I have methods to test everything on the bike without power, but aside from checking the controller mosfets with a multimeter, it could still have a different internal fault.

My thought process is if I could use a benchtop dc power supply connected to the controller I could test the system, unloaded with the wheel off the ground.

I'm not an electronics engineer, so is this doable or even a safe thing to do? The motors would be geared without regen braking so there should be no current trying to feed back to the power supply? What about the capacitors in the controller, I assume I need to discharge them before connecting the supply?

I'm considering this 60v 20a power supply and the motors we see are 500-1000w and 36-48v, would this handle the initial startup current of these motors?

Will this burn down our shop?

Appreciate any advice!

It could work, but if by “we've started accepting ebikes” you are referring to prebuilt factory e-bikes, then a lot of time not. Many ebike manufacturers are developed with a closed system, with communication between the battery pack and controller, rather than a simple bat(+) and bat(-). In those cases, simply connecting the power supply will likely not work. A lot of early e-bikes, like the first Rad bikes still used the simple two conductor interface.

 

[Slenner]

It could work, but if by “we've started accepting ebikes” you are referring to prebuilt factory e-bikes, then a lot of time not. Many ebike manufacturers are developed with a closed system, with communication between the battery pack and controller, rather than a simple bat(+) and bat(-). In those cases, simply connecting the power supply will likely not work. A lot of early e-bikes, like the first Rad bikes still used the simple two conductor interface.

Yeah, we mostly see cheaper factory made bikes with a simple pos/neg Anderson or xt60 battery connection to the controllers. Those are the bikes that seem to break and need repair anyway.

 

[fill]

Ive used my 2a 36v (42v) battery charger to provide 'battery voltage' to test the controller/display and sensor inputs are all ok.
I also chanced a quick motor test at the time too with no issue but it was via a walk assist limited trigger control

 

[E-HP]

Yeah, we mostly see cheaper factory made bikes with a simple pos/neg Anderson or xt60 battery connection to the controllers. Those are the bikes that seem to break and need repair anyway.

That’s good.
It should work. If nothing trips when you first hit the throttle, with no load/wheel off the ground, usually takes less than 100w. If it requires more, then there may either something mechanical (bad bearings, dragging brakes) or a mismatch of the phase and hall wiring.

 

[Slenner]

That’s good.
It should work. If nothing trips when you first hit the throttle, with no load/wheel off the ground, usually takes less than 100w. If it requires more, then there may either something mechanical (bad bearings, dragging brakes) or a mismatch of the phase and hall wiring.

Sounds like I need to convince my boss to shell out the dough for the power supply then, thanks!

 

[mrmojorising]

If you're not needing full power tests, you can get similar 300-400w units for $100 cad or less. I have one like this which has served me well for all sorts of electronics testing and battery charging.

https://a.aliexpress.com/_mLLA5tt

 

[afzal]

The motors would be geared without regen braking so there should be no current trying to feed back to the power supply?

With no regen, no current would be fed back to PSU & is safe (once with a direct drive motor, my controller went kaputt)

What about the capacitors in the controller, I assume I need to discharge them before connecting the supply?

I have always connected without discharging the capacitors & never faced an issue (controllers were low power)

I'm considering this 60v 20a power supply and the motors we see are 500-1000w and 36-48v, would this handle the initial startup current of these motors?

I have seen a little < 1A w/ wheel in air. While starting, for a split second, it will take slightly more. For more safety, current limit can be reduced such that it is just enough to get the motor running.