How to fix an electric bike

14 05 2010

You might remember the earlier posts about my Wisper Sport’s ordeal such as I Hope This Ends Well and The Scary Insides of My Electric Motor and how when I was taking off the back wheel I twisted the wires going into the back wheel axle and stripped their insulation making the motor no longer work. To fix it I decided to cut the wires, put in a plug and socket and resolder the lot. Well I did that and the motor still wouldn’t turn. I thought I got all the wires correct, and it didn’t work. So I took out the plug and socket and resoldered the wires and it still didn’t work. Aaaagh!!! Of the 8 wires going into the back wheel, there were three thick ones carrying the power, and five thinner ones carrying signals from the Hall sensors. I figured one of the Hall sensor wires was still busted or shorting or something. So I called the friendly people at Electric Bikes NZ and Anthony there suggested I could put in a 3 wire controller instead of the 8 wire controller. Apparently there’s some dumb legislation in parts of Europe (that needs repealing) where the wheels must be turning from the riders pedalling before electric assistance kicks in. The Hall sensors work in conjunction with the purple wires coming out of the controllers. If you are one of the poor unfortunate Europeans with a crippled electric bike, unplug the purple wires of your controller (if your bike has one) and you can use the throttle (if your bike has one).

Here the wires are resoldered and heatshrunk:

Then I covered it all with insulation tape:

This is the compartment under the battery in which the controller goes:

This is a close up of the controller. I think they’re a commodity built in China and used by multiple electric bicycle manufacturers. I think they’re waterproofed and quite robust:

And this is where the controller sits and all of its connections:

Swapping out the 8 wire controller for the three:

The wheel’s back, and a cable protector is put over the cable and it is cable tied to the frame:


Next time I have to take off the back wheel I’ll be unplugging the cable back at the controller end, and cutting the cable ties and removing the wheel complete with it’s cable. And if I take it to a bike shop because I couldn’t be asked to do my own new tube, or broken spokes or whatever, I’ll unplug everything first too. There’ll be no twisting the wires going into the axle anymore. It’s not a recipe for success.

After all this my bike is working. Woo wee!!!! I’m going for a big ride this weekend. Weather permitting.

Now I have an insight into the maintainability of an electric bike maybe someone needs to reengineer an electric bike from the ground up – like GoCycle has. Cool hey? When this book called Build Your Own Electric Bicycle finally comes out (it’s been delayed til August 15th) I am going to have worked out a fair bit of it for myself already.

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