Help needed with Usprite UM44

[Astrobasil]

I bought this bike second hand about 8 months ago, no manual and no key to remove the battery, but so far it has performed very well. Then last week the pedal assist just suddenly stopped working. It's fully charged and so I suspect a loose connection, but I don't even know where to start looking!

Any help gratefully received...

 

[Deleted member 4366]

I think that's the same torque sensor as the Halfords Carrera Crossfire, but they seem to have trouble getting them too. Problems that I know about are that the wire can get pulled or damaged when the chain comes off, or the optical sensors inside get covered in dirt, so they can't see.

They're not difficult to take apart. You need a cranl-puller to pull off the chainwheel/crank, then it's straight-forward. Here are some pictures:

http://www.pedelecs.co.uk/forum/threads/carrera-crossfire-vulcan-torque-sensor.30490/

There are several other bikes that use that torque sensor, but I can't think what they are at the moment.

I can't understand what's on manufacturers minds when they choose that sensor over a normal PAS. It's a lot more expensive, has absolutely no tangible advantage and is very unreliable in dirty conditions.

 

[Astrobasil]

I think that's the same torque sensor as the Halfords Carrera Crossfire, but they seem to have trouble getting them too. Problems that I know about are that the wire can get pulled or damaged when the chain comes off, or the optical sensors inside get covered in dirt, so they can't see.

They're not difficult to take apart. You need a cranl-puller to pull off the chainwheel/crank, then it's straight-forward. Here are some pictures:

http://www.pedelecs.co.uk/forum/threads/carrera-crossfire-vulcan-torque-sensor.30490/

There are several other bikes that use that torque sensor, but I can't think what they are at the moment.

I can't understand what's on manufacturers minds when they choose that sensor over a normal PAS. It's a lot more expensive, has absolutely no tangible advantage and is very unreliable in dirty conditions.

That's really helpful, thank you

 

[Astrobasil]

Ok so I finally bit the bullet and bought a crank puller. When I opened up my bike it didn't look like the one in this advice - it looks like this.

Checked the wiring to the controller and it looks fine, but the pedal assist still doesn't work - any ideas or suggestions of where I can get help gratefully received!

 

[Astrobasil]

Anyone recommend someone who can fix my bike for me - local bike shop just scratched their heads!

 

[Nealh]

You are stuck with it as an OEM part it will only be available via a dealer who sells the UM44 model, then most likely it is only a warranty part and not available for retail onward selling.

 

[Nealh]

If you still want TS drive with the hub motor then you can get a complete new Kunteng (KT) TS kit from BMSBattery. It comprises a TS bottom bracket, TS SO6S controller with LCD3.
Alternately you scrap the whole TS thing and just settle for a normal cadence sensor drive for £70- £80 and a new bottom bracket.

 

[Astrobasil]

Thank you Nealh, but I don't understand any of that I'm afraid!

How do I know if the problem is with the controller or sensor?

 

[Nealh]

Controllers used have different programming them normal pas type controllers. Any bike with an OEM (Original equipment manufacturer) product is stuck with trying to get one thru warranty or via supplier which is most unlikely.

Does the bike have throttle ?
Controllers don't often go wrong unless a wire is shorted or voltage is wrongly applied or reversed.
Most likely the fault is with the torque sensor, pcb board which is more exposed to the elements.

 

[Nealh]

Looking at your pic again of the sensors pcb board, one of the screws is badly corroded so moisture has got in,likely hood is the back of the board with the solder traces etc may be compromised. If you were able to unscrew the board and gently move it to look behind, you may find that corrosion may have set in and tracked between one or more traces causing a short, this then compromises any command and may have damaged said board to render it useless.

Ultimately if spares can't be had or got hold of and yours is unrepairable you will have to replace the whole electronics kit with an after market one which includes
a new controller, bottom bracket torque sensor, and lcd display.
Or you ditch the torque sensor drive altogether and fit a normal pas magnet disc set up with new controller and lcd.
Both options will be approx. £80 - £150 to buy, the TS option being the slightly more expensive to buy.

 

[Nealh]

Taking it to an ebike shop is futile unless they deal with the model/brand then all they would do is replace parts if available. Very few are set up or have know how of how to repair electronics or look to try and find an issue ( exception being a company like Woosh bikes who are very good but they are in Southend). Shops/dealers are merely brand/ebikes sales agents who rely on the warranty to swap out major component parts.
These intimate repairs delving in to why and how, aren't cost effective to shops or the customer so they are treated as throw away items. You have to be proactive at diy self diagnosis or find an enthusiastic ebiker locally (within 15/20 miles) who will have a look for free or who will do it for a small remuneration of some beer or a small fee.

There are a few of us around but only of use to some one who lives not far away.