Help with seized/shuddering front hub motor


1 µW
Apr 6, 2022
Help! I think I might have killed my ebike motor and/or controller. Don't know where to begin thinking about diagnosing this. It's a generic chinese front hub kit from carbonspeedcycle ( I have a 1000w front hub 20" wheel on my bullitt cargo bike.

I was riding to work this morning and hadn't made it half a mile from my house when the battery indicator on my (fully charged battery) ticked down to 3/4 - usually that doesn't happen until at least mile 3. Then I hit my first moderate uphill and I noticed that power/speed was only about 3/4 of what I used to. Then before the end of the hill the wheel began alternately stuttering and losing power, and the power indicator on the display started showing weird readings - 1999 watts (never shown more than about 1300 watts previously) while off the throttle, 0 watts while under power, etc. I tried limping home on power but it was too unnerving to be constantly shuddering, losing power and accelerating - I was sure I was going to make whatever's wrong worse. I was able to ride home analog without any noticeable extra drag.

I had left the bike outside in the light rain for a couple hours last night while I helped a friend rebuild his sailboat winches in my garage, so my best guess is the problem is caused by moisture in the system.

How can I triage this down to figuring out whether this is a problem with the hub motor or with the controller/something else in the system? I guess I'll open it up and try to dry it off and if that doesn't fix it, give it a few days to dry out? What else can I do to start?
It's almost definitely water either in a connector somewhere, or in the controller itself maybe.
I had that happen when I had to ride under an open fire hydrant spraying in the air, with just about the exact same symptoms.
Hope it works out 👍