My old (adapted over the years) electric bike has a Bafang 36v 250w rear hub motor. With the old style twist throttle on full I pedaled up a long very steep hill. (Coming from flat Norfolk I was naively unused to Peak District Hills!). Nearing the top I heard a clunk from the rear hub motor and it instantly died. No smell of burning. If I now twist the throttle I can initially hear a very faint click within the hub motor as if something is attempting to engage. Any ideas on what went? What to do next? Is it repairable/replaceable? I have never removed a hub motor. Advice appreciated.
Hub Motor Clunked and died?
- Thread starter Chrisg149
- Start date
You've probably blown a mosfet in your controller, or your motor phase wires have melted where they come out of the controller. First, check the wires at the controller, then you can measure with a multimeter whether any mosfets have blown by measuring the resistance between the black battery wire and each of the three phase wires, then repeat for the red battery wire. List the 6 results here. Do those measurements on the controller after disconnecting it.
I once did exactly the same on my Bafang motored Quando, flogging it hard up a very steep hill, and the clunk was a huge bang.
But I was lucky, it was only a lost Hall connection and unplugging and replugging the five wire connector immedately got me going again and it never gave trouble again.
I hope you are as lucky.
.
But I was lucky, it was only a lost Hall connection and unplugging and replugging the five wire connector immedately got me going again and it never gave trouble again.
I hope you are as lucky.
.
Thank you vfr400 for your prompt and helpful reply. Turning throttle still initiated twitch from motor hub wheel. I then opened/inspected the cables near the controller and the larger ones had certainly melted (see photo).
I separated them and noted they still held a connection. I then opened up the controller for inspection but did something very stupid. I thought I'd turned off the battery, but hadn't, which caused a flash and bang when inserting a screw driver. This caused a mosfet leg to completely burn off and left the circuit board blackened near that leg (see photos).
I may have caused terminal damage? Anyhow I undertook some tests. Not being an electronics person I only did some basic testing as described below:With multimeter set to 20K resistance and attaching red probe to black earth all the phase cables read 3.30. Repeating this but with the red probe to red live wire the phase wires all read nothing. With the black probe on red live wire, readings climbed to 19 on all phase wires. Continuity testing from black earth to phase wires on circuit board all read nothing. Continuity testing from red power wire to mosfet tops I only got a buzz on 2,4 & 6.
I fear my electrical flash and bang may have caused damage? If so, I've noticed similar rated/spec controllers on ebay for around £25 (China) but instead of just stating 36v rated voltage, they state 36/48v - does this matter? These similar controllers have different connectors that I would need to change and I'm no expert solderer. Thanks again Chrisg149
There are two controllers that I'd recommend. One is the Brainpower 350w with LCD for about £40, which you can get from Aliexpress, Amazon, Ebay, etc. The other is the KT sine wave one from Topbikekit or PSWPower with LCD3 for about £70, which is much nicer. I'm assuming that you want to use PAS.
When will tinkerers ever learn ???
When playing with ebike electrics don't use anything metal to prod around with, use either plastic tools, wooden lolly sticks or bamboo skewers.
When playing with ebike electrics don't use anything metal to prod around with, use either plastic tools, wooden lolly sticks or bamboo skewers.