Broken ebike


New member
Local time
3:34 PM
Jun 21, 2018
On the way to the pub last night my bike started playing up. It was very 'jerky' for the first 100yards or so then the power failed. I had to PEDAL!

This morning I checked the battery - OK. Checked the motor - OK. Joined the battery directly to the motor - OK.

Stuck now! Can anyone out there tell me how to test the controller and throttle please?
It'll depend on the model you have (which you haven't told us). What makes you think it's the controller or throttle? In my experience, things like battery terminal connections and any/all other connections are more likely to cause problems, especially if it involves intermittent or jerky operation and the bike is a production model or is designed and assembled to spec (eg no over voltage situation).

Have a look at all your connections, unplugging, inspecting and cleaning with contact cleaner then reconnecting them.
I'm still using my home-built bike which has a secondhand 180w brushed hub motor, three new motorbike batteries and a 36v 500w controller with Hall-effect twist grip throttle bought on Ebay from someone called e-crazyman in Hong Kong. The set-up has impressed people who have ridden it, although it would not win any prizes for looks. A bonus in some ways because that deters the many local bike thieves. The batteries are charged after every use and are still in good nick.

On the day, the bike began to judder and the power dropped off dramatically, hence the long pedal home. I first suspected the motor brushes but these look ok. I connected the motor directly to the battery (off the bike) and it whizzed round. So fast, in fact, that it nearly tore itself from the jig.

I emailed e-crazyman (not expecting much because the gear was purchased over a year ago) and, in fairness, received an immediate response. He told me to test between the red and black wires of the throttle connector. I did, and obtained a reading of 5.7v. I informed him of this but have yet to receive a reply, so I don't know if this is normal or not. I am not familiar with the electronics side of things although I have some electrical knowledge. I have no diagrams for this unit so I don't know how to test the components correctly. I don't even know how the throttle works - or the controller, if I'm honest! Oh, and I also get a reading of 37v on the indicator connector when the battery is fully charged. I suspect that many controllers of this type work in a similar way as most of the ones advertised seem to have the same connections - battery, throttle, isolator, indicator, brake, etc. - so I need to know what readings to expect.

One thing that has always puzzled me is that I get a spark when connecting the battery after charging even though I have installed an on/off switch on the controller. This tells me that there is a closed circuit somewhere in the set-up. I, therefore, disconnect the battery when I park for any time to save power.

Once I find the faulty component I can order a replacement and rest my weary legs again.

Hope this is helpful to you in helping me,
I had a similar Experience.

Replaced everything eventually. Originally the dealer said that two wires were bare and touching where all the wires connect near the governor.

I was losing distance on a per charge basis. After four months of trouble shooting the motor wheel locked up.

The magnet in the motor had cracked off and jammed the works.
Just because the motor spins up very quickly while not under load, doesn't mean that when it's under load, it'll work fine and that the brushes are definitely good but if you've stretched the spring slightly and even though the brushes look OK, it still plays up, then I'd assume the brushes are not to blame. Running a brushed motor without load is never a good idea because it can easily over speed and damage itself due to centrifugal/centripetal forces (one way magnets can get cracked).

If you can get into the throttle and controller without damaging them (they may well be sealed unit's though in my experience), then have a look for anything out of the ordinary. Did you inspect all the connections on the bike as well as checking for the other idea put forward that there may be bared wires where there shouldn't be?