Curious behaviour from my bike

[drsolly]

I took my bike out yesterday for a 10 hour caching marathon; 100-odd caches.

When I started out, the motor wouldn't run until I'd gotten up some speed, which was a bit annoying, Then, after about an hour, it refused to run at all. So I stopped, changed the cable from the batteries to the controller, in case the problem was my switch or the wattmeter. No joy.

So I took the duct tape off my mess of connectors, and had a look. Nothing looked loose, but I wiggled and pushed things anyway. Still no luck when I tried the throttle. So I decided to go back the the car, and go home, so I could investigate this properly.

A couple of dozen yards into my trip back to the car, I tried the throttle, and the bike responded. And I spent the rest of the day, about 9 hours, using a bike that ran perfectly.

I have no idea what was wrong, or how I fixed it, unless it really was a loose connection. If somoene described this to me, I'd say "Loose connection".

I've replaced the plastic box that I use to cover the mess of connectors, with part of an old inner tube, an idea that I got from this forum. Problem was, there are so many connectors, the inner tube wasn't big enough. So I used two inner tubes!

 

[dogman dan]

Yup, you jiggled something in the process.

 

[Ykick]

Back when I sat at a tech bench for 8hrs/day we used a code for this - B9 = intermittent. Often the most difficult fault to locate.

But if you have "a mess of wires" de-messing things will often help and at least make it easier to troubleshoot further while ruling some things out.

 

[alsmith]

I think a lot of us have suffered from an intermittent connection and they can be a real pain to track down.
Start by disconnecting all of the connectors one by one, you might spot one that is loose or has a loose wire. Spraying a little contact cleaner before reconnecting wouldn't do any harm. If your lucky that may sort it.

 

[drsolly]

When I said "mess of wires", I meant is didn't look pretty, and was exposed to wetness from rain or bike-washing. It's not a mess in terms of connections from this to that.

For the phase current connectors, I'm using what came with the controller and wheel; they're small and unsophisticated bullets. Do people tend to replace those with something better?

 

[Ghost (bike)rider]

My front light runs from the main battery (which gets a feed from the controller) and it helps to troubleshoot dodgy connections. I would suggest running something visible that does not have capacitors (don't rely on your controller LEDs for this reason) and I think you will need to wiggle the wires until you find the culprit.

If all is good, I would re-terminate the phase wires and check the hall sensors / connectors (if applicable).
Once you have found the problem, take the bike down a cobbled street at full speed to simulate a few years of road use

 

[cal3thousand]

When I said "mess of wires", I meant is didn't look pretty, and was exposed to wetness from rain or bike-washing. It's not a mess in terms of connections from this to that.

For the phase current connectors, I'm using what came with the controller and wheel; they're small and unsophisticated bullets. Do people tend to replace those with something better?

A multimeter goes a long way to solving these types of mysteries.

 

[drsolly]

I think the problem was the connector from the battery to the controller. That goes via a connector (which came with the kit) that to me looks completely inadequate for carrying 30 amps, it's the sort of connector with a spade and a female. And I think it was a bit loose.

I've replaced it with a 30 amp multiway terminal block, with the wires held in place by grub screws. The old inner tube has been replaced to make it water resistant and look decent, and the inner tube is held closed by re-usable cable ties, which makes it easier for me to reopen if necessary.