Got a Free Ebike. Need help fixing! (with pics)

unclejemima

100 W
Joined
Jun 10, 2012
Messages
272
Location
Western Canada
Got this bad boy today for the price of free. 250w 24v front drive. Bike worked just fine a year ago and then the throttle quit working. This odd job came from walmart, has no pedal assist oddly, only throttle what is nice! It tops out a 25km/h.

So, I got it in ok shape, cleaned it up and tried some simple stuff. The previous owner through the brake switches (the ones that cut power if brake lever is pulled) might be causing the problem. So he cut them off and the wires are loose.

I tested the battery, and it seems fine. I had a spare set of ebike brake levers with the brake switch, so I replaced that. I also put on a new throttle. I cut the wires to the old one and tried wiring a new throttle I had lying around. No go.

So, it could be a few things.

Throttle: The old throttle has the LED's to show power level. Its got 4 wires. Red, black, green and yellow. The new throttle I had only had 3 wires, it was missing yellow. I'd imagine the yellow wire is only for the LED lights?...or are the 4 and 3 wire throttles not compatible?

Brake Switch: Also, incase I have the brake switches wired wrong (my brakes have different colors so I had to guess) how would I wire the switches to the off position so I can at least eliminate that. I'd imagine simply letting all 3 wires (red, green and black) hang loose (so they don't touch each other) would be the same as the brakes being in their normal position. That would let the controller know that it can apply power. Or do I have to twist any of the wires together to turn the switch off. Not sure why a simple brake switch would have 3 wires anyhow. I thought it would only be 2 wire.

Controller: Where do I get a replacement for this and is it even worth it?

Any idea's would be appreciated.
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Little Bafang but a bad wheel lace job.

You should be able to leave the brake wires hang open. Use a meter to find which throttle wire carries the 24V from battery for the LED meter. Ignore that when adapting the new throttle. Check for 5V on throttle wires as well.

Free is good...
 
...fuse on the battery? It appears to be good visually...but its one of those ones that are not transparent...so its tough to tell.

I'm going to bring my voltage meter home from work tonight and test some more stuff. I'm thinking the controller went poopoo...but I'm not sure.
 
Check the voltage where the battery wires connect to the controller, which should be about 29v fully charged. If that's OK, check the 5V on the throttle between red and black. If that's OK, check the throttle operation while it's connected and switched on. Suff your probes up the back of the connector black and signal wires. It should change from about 1v to 4v when you operate the throttle.
 
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