Hit a bump and motor no longer spins...

[pjpeter]

Hi all,

Basically my bike today, was working great at first - went in to work in the morning with no problem at all. Heading out from the office I came along, hit a couple of bumps as I went over the streetcar tracks and all of a sudden, no power. My lights and horn still worked, but the throttle did nothing. I went off the side, propped up the back wheel and throttled it - nothing. Took out the battery, put it back in, twisted the throttle - working. So I put back on the helmet and all, go back on the road, hit the throttle - nothing. Go back off to the side, disconnect the battery, make sure the breaks aren't at all stuck, turn it back on - and works. Back on the road and it died again. So I pedalled as fast as I could (got up to around 17km/h or so - bike usually cruises at 25km/h powered) - I managed to get it to work one more time while at the shop, but when I got back on the road, again it was dead.

I took it to a bike repair shop - I asked if they could disconnect the brake sensor thinking that might be it - the owner suggested it was the motor that had died, that because it was a 20" bike and I am putting so much weight on it, thats why it died. Before I got the bike, I checked the specs - it said a capacity of 100kg - I'm about 180, add on my backpack and so on takes it up to maybe 210 max. So I wasn't going past spec - and I told him so - but he said its what happens and I should get a 26" bike and toss this one...

Does anyone have any suggestions? I had the motor changed a few months ago (you can see my long thread from then) - I've probably only gone about 20 trips there an back total with it since then (so around 1,000km) - so it should last longer than that I should hope. This was my first week riding it every day this year after a cold and wet spring and I was really starting to get back into it.

Do you guys think it could be something else? I'm thinking to go at it with an ammeter tomorrow, but I'm not an expert on what to look for - someone suggested trying to hook it up direct battery to motor without the controller, but I'm not sure about that - he said to have a fire extinguisher ready if I did it . Its a 36V Battery (confirmed the battery is fine, tested with a new one even) - other things are getting power - the motor is a 250W Bafang. I tried disconnecting cables one by one (reconnecting the previous each time) from the controller until I'd disconnected all the wires to the front end of the bike, but that had no effect. I haven't gotten it to work again since that time in the store. It all started from that hard jolt over the streetcar tracks about 5 hours ago. It seemed like the other wires were seated/connected in there, but I haven't looked too closely.

My guess is it could be the brake sensor (though they said they doubt it), the throttle (the pedal assist broke back in November so if the throttle isn't turning, that could also cause this), the motor, or the wires between. Those are just my uninformed/noob guesses tho.

Any suggestions are welcome,

Thanks,
Peter

 

[auraslip]

Could be intermittent wiring connections..... A PITA to test for, but it shouldn't take that long to test for continuity with a multimeter.

Could be the throttle. See how to test and repair here.

Controller? Not sure where to start with testing that.

It probably isn't the ebrake - disconnect it and the motor should run.

It probably isn't the motor. Please don't hook your battery to it directly, or at least film it for our entertainment if you do.

 

[amberwolf]

Probalby just a loose connection; one of the most common is a pin that's backed out of it's housing just a bit, so sometimes it touches and sometimes it doesn't.

Could be in the throttle or brakes or hall connector, or even a motor phase wire.

Also possible it's in the battery connections, even though your lights are working. Do the lights work fine even when trying to throttle up, or do they dim when you do that?

 

[pjpeter]

Thanks for your replies - I brought it in from the garage now that the thunderstorm has finally ceased and I can say that there is no effect on the lights when turning the throttle - not sure about the rest though at this point.

I've got my video enabled DSLR ready and waiting for the battery test - - thanks for the warning . Bringing out the multimeter now

 

[pjpeter]

Update:

We tested all the connections, they all looked secure. One wire seemed a little loose, but it was making fine contact when connected. I decided it might be the throttle, so we took apart the handle bar grip, took off the gearshift and brake and the basket so we could get the cables around it and I took off the throttle entirely. Took off the side plastic and found the connectors looked ok.

I hooked things up to change the different voltages when turning the throttle to see if it was the hall sensor/magnet. We tested the continuity on the wires and it looked good. When we were hooking it up to try to see the alternate voltages on turning the throttle, we found another ground (since the ground up top was taped up and unconnectable for us). I turned the throttle and the bike moved. So we congratulated ourselves, made sure it did so without us completing the circuit - it did so we started to put it all back together, testing it after each stage.

Finally, I shoved everything back into the controller compartment, controller and wires all, and I put on the screws and had it all sealed up - then I tested it again, and nothing. It had just responded right before I put everything back inside the compartment - but now - nothing.

So back to square one - we're looking for any loose wires again and any sort of bent connectors.... but nothing. Bit bummed now - was all set to do a road test and back to just where I started 4 hours ago. Does this help to narrow down the possibilities at all you think?

Thanks,
Peter

 

[neptronix]

Well dude.. i have had loose throttle connectors on 3 pre-built electric bicycle kits i've worked on so far. Always has been the culprit! Been meaning to change out those connectors for something much sturdier for a while.

I would hold the throttle down and shake the connector, see what happens. Most likely, you have a jiggly pin.
Hall sensors are the other big gotcha.. try the same test while jiggling the hall sensor connector around.

 

[amberwolf]

Given the failure and success and failure info, I'd say it's gotta be a bad connection. That could be a wire that still has it's insulation crimped into the connector pin, but the conductor inside is broken. Same thing could happen anywhere a wire could get pinched in a cable run somewhere.

I'd do a continuity beeper test on the whole wire runs, with as little disassembly of things as possible. Use a safety pin on the meter leads to insert into small connnector housings, and set the meter to continuity (tone) check, if it has a setting for that. Otherwise use Ohms on the lowest range; any wire ought to read less than 1ohm for the lengths on a bike, or close.

Bad connections and broken wires are what is wrong with nearly everything I have to fix, electrically, when it isn't bad capacitors.

 

[pjpeter]

Hi all,

Thanks again for your suggestions - unfortunately the saga continues... We thought we had it licked, we found that:

- The 4.69V was not getting through the red wire from the controller all the time to the throttle
- The red wire had a ton of resistance (around 11 - not sure the scale but it was much, much more than the 0 or 1 we were expecting)
- We used alligator clips to pass through the 4.69V direct from the controller and the bike worked
- So we switched the red with a yellow wire that was used for a continuity button to activate pedal assist - the pedal assist has been broken on the bike since last year so it was no real loss if it could fix the rest
- After switching, everything looked perfect. I tested it multiple times all the way along the way while re-assembling, even got up in the middle of the night to make sure it was still working lol.
- I road the thing about 10 feet with my full weight on it and it was working no problems.
- Got it out to go to work this morning, was all hooked up and ready to go - when I hit the throttle the wheel turned a little bit, then nothing.
- It would sometimes give a little bit of a turn of the wheel, but then shut off again, I spent a couple of minutes with it, then gave up

We took it apart again and re-soldered the yellow at the throttle end, it worked great for a few minutes, but then when we put the throttle back on the bike, it died again.

So basically, I'm not sure what is going on. It's really tough to fit everything into the box because when they replaced the throttle the first time the guy left a lot of extra wire all over the place (he soldered the pins into the wires instead of removing the old pins and putting them through into the connector). So its definitely quite tight at the controller side, and it could also be pinched somewhere along the length of the bike as well. Both wires we tried were from the same overall cable.

I was thinking we could test and if continuous, take out one of the cables from the right brake sensor (which also no longer works) and try to use that instead - but if its more than just the one wire giving problems with the throttle... It could be the ground or white (throttle cable) that are giving problem as well maybe - I just don't know.

We really thought switching the wire would do it - now back to square one again. Does this narrow down things at all? Does it sound like it's both the wire and throttles that are messed? I have not yet risked taking apart the entire throttle beyond the wiring (I didn't take out the spring or check the hall sensor) - is it likely in there?

Thanks,
Peter

 

[JayF]

I ran into the exact same problem a couple weeks ago. My bike sometimes wouldn't even turn on, and sometimes would turn off mid-ride, especially after bumps. Just like yours, my fan, lights, etc kept working regardless.

The culprit turned out to be a loose connection to the ON/OFF switch for the controller. Luckily, that was the first connection I checked
When I un-taped the wiring behind the switch, I found that the only thing holding the connection together was a piece of shrink wrap... They didn't even solder the connection at the factory! My accessories worked all along because they operated on a separate circuit, and didn't run through the controller.

The key switch is the first place I would check, if I were you. Your problem definitely sounds like a loose wiring connection, so if the culprit isn't the key switch, then check all of the connections off of the controller.

Good luck!

 

[pjpeter]

Hmm, That's really interesting - thanks for signing up to post your reply JayF .

The one thing about that is, I don't think I have an On/Off switch for the controller on my bike - I have a key on the battery, but out of the battery only comes two cords, + and -, and I'm pretty sure they both go straight into the controller. Now I suppose it could be the controller not giving out the voltage all the time - but that wouldn't explain why the crossover cable allowed things to work (we went from one of the welds in the controller box straight to the red wire on the throttle and it worked fine for that first test.

I mean it could be I suppose - but it's all within the battery in that case - I had noticed one of the screws in the back of the battery was loose when I first had this problem, but I tightened that all up since. Is the way things work on mine the same sort of way it works on yours?

I'm not sure what was going on with the resistance - if that could mean a short somewhere along where the wires may be touching inside? - but it does seem like it's something with that wire or the throttle somewhere...

All replies welcome,
Thanks,
Peter

 

[amberwolf]

Anytime something works until moved or remounted, almost always there is a problem in the wiring from that something. My guess is there is at least one wire that is broken inside the throttle cable itself.

It might not actually be "broken", but instead could be a factory splice. I found one of these when installing my Fusin kit, where when making the multi-wire cable at the wire factory, they ran out of one of the wire colors, and then just lap-spliced (without solder) the end of that to the end of a new spool of that color, and continued making the spool of multi-wire cable. Apparently it's very common, because I have found this a second time in a totally unrelated manufacturer of ebike stuff that probably gets their wire from a different place (because tehre are probably many of them, and it's unlikely I would personally end up with two from the same original wire factory, in a very short space of time, with the very little manufacttured ebike stuff I have).

http://www.endless-sphere.com/forums/viewtopic.php?p=232837#p232837

 

[jateureka]

I had a similar fault, turned out that the throttle wire was pinched by the controller lid and had cut the wire internally although the insulation was still ok. Every time we took the controller out it worked but when we put it back in it bent the throttle wire so it no longer had continuity...

 

[pjpeter]

Hi all,

Thanks for all your replies .

I think I've found the problem - if I move the throttle wire, I can start the bike . I found this when coming home when after trying to fix the gearshift (can't go to last gear) it wouldn't start - I grabbed the cord about 5 cm down from the throttle and moved it around the side, and boom - worked. I did this 2 other times on the way home and it worked each time and stayed for a good 20+ mins between.

The idea came in part from that first throttle info link - the guy mentioned the wire had no reinforcement - guess this is what happens in those cases. I've now solidified the position of the cable with some non conductive clay and electrical tape - when it next goes out I'll open it back up and take a closer look and see where the break is. I have a suspicion it may be caused by the wires having been stretched when I folded the bike - when the folding front basket was first installed it gave me problems, and when the new throttle was put on that cord and others were put around it the wrong way - I've now fixed that and hopefully none of the other cords will also fail.

Thank you all again for your replies - very happy to have my eBike working again ,
Peter