After approx 700 miles my DIY project:

http://www.pedelecs.co.uk/forum/electric-bicycles/6859-my-diy-electric-brompton-project.html?

has developed a fault.

 

The symptoms are that the motor judders a little but then goes silent when pressing the throttle button.

 

Actually it did the same thing about 300 miles ago but came back to life without me doing anything and has been fine since.

 

I have got a spare motor and spare controller etc so could try swapping them but it's quite inconvenient given I'd need to sort out connectors etc.

 

The motor is a brushless/sensorless tongxin. Would I get the symptoms described above if, say, one of the 3 motor wires had come undone or broken somewhere?

 

I wondered if it was a broken controller but thinking about it, since the fault occured before but then recovered it feels more like a dodgy connection.

 

My suspicion is the mini sureseal connector I used to connect the motor is not making a reliable connection. Everything got very wet last night when I cycled home in the rain/sleet/snow so this may have something to do with it.

 

Failing that, is it possible/common that a wire could get broken within the motor itself?

My guess would be a loose/broken connection. After about 300 miles one of the wires broke off my switch where it was too short and the controller bouncing in the rear pocket, eventually led to the connecting wire to the switch breaking off. I lost all power and thought the worse, oh no the motor has failed or the controller has packed up!

 

As with most these things, it was more obvious and in the end was a simple fix.

 

If you can't find a loose connection then its going to be a case of trying the spare controller :o

 

 

Regards

 

Jerry

Edited December 17, 201015 yr by jerrysimon

Looking at your picture here

 

http://www.pedelecs.co.uk/forum/electric-bicycles/6859-my-diy-electric-brompton-project-2.html#post87025

 

If the controller is jumping around in the back pocket one of the three motor wires could have come loose in that connection block

 

Regards

 

Jerry

I've still got some power becuase the computer light comes on when I switch on the bike and the motor does judder a bit when the throttle is pressed.

 

No obvioius loose connections so I'm now looking for a non-obvious loose connection.

If you spin the wheel then apply power does it work ?

 

Regards

 

Jerry

If you spin the wheel then apply power does it work ?

 

Regards

 

Jerry

 

Nope. I was continually spinning the wheel when trying to apply power this morning as I pedaled to work - but whenever I pressed the button I just got the juddery noise from the motor then nothing.

If you are sure it is not a loose connection then the next stage is to try the spare controller I think. Even then, without doubting your checking I would want to be certain all the connectors are working properly ?

 

It goes without saying that the battery is fully charged/ok ?

 

As I am sure you are aware when the problem is not obvious, unfortortunalety its a process of elimination

 

If it does end up being the motor, at least we now have my thread/post on how to take it apart. I will also be more than happy to lend you the tool I had made to help get the motor apart.

 

Regards

 

Jerry

Edited December 17, 201015 yr by jerrysimon

O.K. with a bit of wiggling and pushing the mini-sureseal connectors firmly together it seems to be working again. That looks to be the source of the problem.

 

I think I'll see if I can pick up some switchcraft connectors to replace them.

Yep the sypmtons really did sound like a connector problem.

 

As I said its usually something simple but the Tongxin's being so hard to source, means we panic because we know how hard they will be to replace :o

 

I use the Switchcraft connectors. Neat but really fidly to fit.

 

I did try bullet connectors for a while which are robust and make it all very easy to dismantle, but are more difficult to waterproof.

 

Regards

 

Jerry

Motor judder

 

Hi

 

From our experience of the motors and sound of your problem - it is most likely to be a bad connection of one of the 3 wires to the motor.

 

Sorry a few days late - sounds like you have already fixed the problem.

 

Martin

The Electric Wheel Company

I use the Switchcraft connectors. Neat but really fidly to fit.

 

Is that fiddly with respect to some fine soldering required?

 

The mini sure seals are also fiddly. Easy to solder but then require a special (and ridiculously expensive) tool to push the pins into the rubber housing. Without the tool it's a case of pusing them through with a pair of pliers - which is the tricky bit as it seems impossible to get them all the way in without scrunching up and damaging the wire. Heating up the rubber housing helps a bit but it's still tricky.

 

Where's the best place to get the switchcraft connectors? RS seem to have them, but will they sell to non-trade customers?

Hi

 

From our experience of the motors and sound of your problem - it is most likely to be a bad connection of one of the 3 wires to the motor.

 

Sorry a few days late - sounds like you have already fixed the problem.

 

Martin

The Electric Wheel Company

 

Thanks for the reply Martin. It's good to hear that your diagnosis matches mine. I have fixed the problem for now but want to make it a little more robust which probably means changing the connectors.

Is that fiddly with respect to some fine soldering required?

 

The Switchcraft connectors I got from RS. I ordered mine as a private buyer and even got free delivery. The pins are already fitted so just some fine soldering skills, plus I made sure I insulated the pins well after I soldered onto them. Mix of heat shrink and insulating tape

 

You have to keep the stripped wire and individual wire insulation really short to make sure the grip part of the connector clamps onto the outer wire sheath correctly. There is a sheet you can download that gives you the correct dimensions of the stripped wire(s).

 

Regards

 

Jerry

Edited December 20, 201015 yr by jerrysimon

Properly broken it this time!

 

It had been running again for a few weeks but now I think I've well and trully broken it.

 

The symptoms this time are that the motor sounds like it's spinning internally, but it's not turning the wheel. I do have a spare motor which I think I'm going to have to get laced up. Is there any hope the broken motor can be recovered though?

 

With this kind of breakage is it safe to still use the motor? i.e. it's not likely to totally collapse or anything? I'll need to continue to use the bike without motor power until I can fix up the replacement wheel.

 

The motor managed a little over 750 miles. I'd read the Tongxin motors have reliability issues but now I've experienced it for myself.

Pedalo,

 

Yes as you may know mine developed a really bad noise after about 4-500 miles. Metal grating on metal.

 

 

Although the Tongxins have been known to have reliability issues, in the Brompton application they are suppose to be pretty reliable.

 

After learning how to take it apart here I found out it was one of the clutch springs. Either it had moved or a tiny chard of metal had got in it. Anyway I cleaned out the clutch mechanism, regreased it and it has been fine ever since. It also enabled me to shorten the shaft and cut off the roller brake fitting having purchased the wrong motor in the first place :o

 

Your fault sounds a lot like another reported, where the clutch plate cracks and is not engaging properly. Its hard to tell unless you take it apart. I would be happy to send you the special tool I had made to take it apart, or you could send the motor for me to have a look. Alternatively it's not hard to make if you have the applitude.

 

In the meantime my guess is that running it freewheel should not cause any problems.

 

Regards

 

Jerry

Edited January 12, 201115 yr by jerrysimon

Pedalo,

 

Yes as you may know mine developed a really bad noise after about 4-500 miles. Metal grating on metal.

 

 

Although the Tongxins have been known to have reliability issues, in the Brompton application they are suppose to be pretty reliable.

 

After learning how to take it apart here I found out it was one of the clutch springs. Either it had moved or a tiny chard of metal had got in it. Anyway I cleaned out the clutch mechanism, regreased it and it has been fine ever since. It also enabled me to shorten the shaft and cut off the roller brake fitting having purchased the wrong motor in the first place :o

 

Your fault sounds a lot like another reported, where the clutch plate cracks and is not engaging properly. Its hard to tell unless you take it apart. I would be happy to send you the special tool I had made to take it apart, or you could send the motor for me to have a look. Alternatively it's not hard to make if you have the applitude.

 

In the meantime my guess is that running it freewheel should not cause any problems.

 

Regards

 

Jerry

 

Thanks for the info Jerry and the offer of the loan of your Tongxin deconstruction tool. I'll probably take you up on this in a couple of weeks but for now I'll focus on getting another wheel rim (Brompton instead of Sun this time ) and get my spare motor in there. Once I'm up and running I'll see if anything can be done to recover it.

 

For the next couple of weeks though it's back to full on pedaling

I'm Back up and running again! I fitted my spare motor to a fresh rim and attached it to the bike last night. All was working fine this morning. I've done about 100 miles in the last couple of weeks using pedal power alone and I'm worn out! I will use the new motor more carefully though. With the old one I'd started using it to help accelerate at full power from junctions and I think that might have helped in the motors demise. Now I'm only using it on my middle power setting and only when I need it up hills.

 

Sadly, the undrilled Brompton rims are no longer available so I had to buy another Sun CR18 rim - which are always a struggle with the tyre. I've got blisters on my thumbs to prove it...

 

I guess next step is to pull the old motor apart to see if there's anything that can be done to repair it.

Good to hear you are up and running again.

 

It is ashame about the undrilled Brompton rims

 

Let me know if you want to burrow the DIY tool to undo your motor.

 

PS I should have thought about it, but I also have a spare Sun CR18 rim

 

Regards

 

Jerru

 

Let me know if you want to burrow the DIY tool to undo your motor.

 

PS I should have thought about it, but I also have a spare Sun CR18 rim

 

Regards

 

Jerru

 

Ooh, yes I may well want to borrow that. Thanks for the offer. I did find a lump of aluminium which I might be able to turn into a similar tool but I don't think it's wide enough to cover 4 screws. Do you think it would work if I only managed to hold it using 2 screws on one side? Or does it need quite a force to get it turning?

 

PS I would have taken that rim off your hands if I'd known. Ah well never mind!

Ooh, yes I may well want to borrow that. Thanks for the offer. I did find a lump of aluminium which I might be able to turn into a similar tool but I don't think it's wide enough to cover 4 screws. Do you think it would work if I only managed to hold it using 2 screws on one side? Or does it need quite a force to get it turning?

 

PS I would have taken that rim off your hands if I'd known. Ah well never mind!

 

Two screws might be ok, though would probably need to be opposite each other not adjacent. I guess you could try just don't use too much force.

 

It really depends on the motor use but some motors are more stiff to open than others, as use tends to tighten them up.

 

Unused are quite loose. One of mine could almost be opened by putting a couple of screws in adjacent holes, and using your hands to undo them levering on the longer screws.

 

Yer shame about the rim. It is laced with one of my motors but had done less than 500 miles or so. I still need to delace it and put the motor in one of the Brompton rims I have, as its always good to have a spare wheel laced and ready to go.

 

Regards

 

Jerry

Edited January 21, 201115 yr by jerrysimon

Hello Jerry,

I am not sure if you are still active on this forum.

I was wondering if you could help me with the "tool" for dismantling the planetary gearing on a tonxin motor. Could you send me a photo (with a ruler on it) so I can see how it looks. I assume thee trick is to pull the sun gear ring and the planetary gear rings off from the center shaft. I would like to replace the whole friction gear system with a proper toothed planetary gear system. This might be slightly noisier but it should be a bit more efficient. The other aspect I would like to change is the freewheel / uni directional clutch. I am using the motor on a Brompton and I would like to change the direction of rotation such that the cable enters the motor on the right side which makes folding easier. I had twice damage to the cable at the point where it enters into the hollow axle because of the folding action. Hope you are still around and can help. Thanks

Robert

It would be a lot cheaper and easier to chuck that motor and treat yourself to a nice Q85 motor, which is the same size, but a lot more powerful and reliable.

Thanks d8veh for your comment.

>>a nice Q85 motor,

 

Possibly yes, but then the cable would still probably be on the same side.

I am unfamiliar with the Q85 motor. Why should it be better than the Tongxin of Bafang motor? Could you send me a link for more information and where to get this motor and how much is it.

 

Robert

 

PS: I am in the UK

Edited April 17, 201511 yr by Robert M

You get them from BMSBattery.

 

They're better than Tongxins because they don't break, you can get more torque out of them and they're cheaper.

See here for how to take the Tongxin apart.

 

 

Ignore the intial ones where I remove the roller brake bossing. The only tool I have is the one to take the case cover off.

 

 

 

I have never stripped down the internals more than whats shown in the intial pics where I removed the bossing and stripped down the clutch as shown.

 

The other pictures were sent to me by someone else who stripped one down to remove all the roller bearings and ring that was prone to cracking on the early units. There is a post on here somewhere that details it.

 

Beyhond that you will need this other tool which I dont have.

 

 

In my experience the larger Tongxin (not the Keyde motor) has proved very reliable in smaller wheel setups.

 

It is also virtually silent when running

 

Regards

 

Jerry

Edited April 19, 201511 yr by jerrysimon