A Question re my conversion.

[Millymoo]

Hi all,
I have converted a mtb by putting a bafang 8 rear wheel on and the wiring controler and sundri bits are all from a sukura scooter type moped looking thing. I expect both about 10yrs old.
My problem when astride bike and moving along the motor creaks and wheezes when going up a slope ( gentle) and on the flat or downhill picks up ok.
My question is could the hall senors on bike be different to the controler as not sure which ones they both are either 60 degrees or 120 degrees.
Or the wires not set up properly and need crossing around a bit more. ( motor spins freely when back wheel off ground )
Or controler problem which I think is 200w whilst the back wheel is 250w
Wheel spins freely no wobbles etc.
I would like to get this sorted over xmas if anyone can help
many thanks
Millymoo

 

[Deleted member 4366]

Which Bafang motor is it? Can we see a photo if you don't know?

If there was something wrong with the hall sensors or phase angle, it wouldn't work.

Is there anything written on the controller that indicates the current?

What battery are you using?

 

[Millymoo]

hi d8veh,
I shall check the motor later and get back with the details if can be seen by torch light, I am using sla 12v 12ah x 3 to make 36v.
I shall check controler also catch up in 10mins or so
thank you

 

[Millymoo]

Right here are the pics, noticed the wheel was a 200w no other markings on wheel other than label in pic the multi plug wiring 2 shots was taken then the turned 180 degrees so you can see top and bottom if that makes any sense and the contoler details was the only thing on it no name or other details.
Hope that helps and thank you again

 

[Deleted member 4366]

Running sensorless, you can get bad response from the motor at low speed. Some motor/controller combinations work better than others. The old KU63 from BMSBattery used to be good, but they've changed it now, so I can't confirm that it still works so well.

Also, if you put a high current through those motors, they growl a bit. I think the Sakura had relatively high current because it wasn't really designed for pedalling.

 

[Millymoo]

Hi d8veh,
So maybe try one of my spare controlers see how that does.
What do you mean by running sensorless, sorry to sound dim but I assumed that was running with the thinner wires diconnected, like the new type that only have the thicker 3 wires.

 

[Deleted member 4366]

Most motors these days have hall sensors, in which case there will be 5 extra thin wires coming from the motor making 8 wires in total (adding the three thicker phase wires). The hall sensors tell the controller accurately the position of the motor so that the pulse timings can be accurate. Without them, the pulse timing can be off at low speed and startup.

Some motors won't start at all, so have to started by pedalling before using a throttle. Some motors, like the Q100, run sensorles, but not very well at any speed.

You could try a different controller. It has to be one that can run sensorless (assuming that you have no sensors). The other thing is that you shouldn't try a controller unless you know what current it allows. 20A is about as high as you go and 14A lowest.

 

[Millymoo]

Ah, mine has the 5 thin wires as well as the 3 thick and all the thin one are matching those for colour coding that comes off the controller. Sorry if I confused you. I have just been outside and checked. I also took a pic of the new controller I shall try a shame it does not have the amps on it. There is a growl coming from the motor like you said. I am now charging up the battery pack ready for a try with the new controller if I get chance tomorrow. Merry Xmas d8veh.

 

[Deleted member 4366]

That changes things then. You might have a false positive on the hall and phase connection sequence, which means that you have a sequence that works, but is not ideal. I see you crossed over two phase wires. How did you determine the present sequence? There's thirty six possible connection combinations, three of which wil give the correct forward motion, though one might work better than the otger two. In case you don't know, when you connect an unknown controller to a motor, you can't always go by the colours. You have to find the correctcsequence by trial and error. You must be very gentle on the throttle until you have the correct sequence otherwise you can damage the controller. Don't use more than a little bit of throttle.

 

[Millymoo]

Thank you I shall put on a centre stand on the bike in the morning and try before I change the controller.

 

[Millymoo]

Well I tried various sequences and ended back where I started which is the best one. Motor still roars when a load put on the wheel. No undue noises when spinning by hand so will try controller next just need to change a plug on the new one.
Ah just re read your post I have not checked the five hall wires by moving them around, they are all matched colour wise, did not know they could be played about with like the phase wires.
Thanks for your imput d8veh

 

[Deleted member 4366]

36 combinations to try.
Use a notebook to record the results otherwise you forget where you are and have to start again.

 

[Millymoo]

The phase wires are placed in the order they are as which gave the best results I did not realise you had to also move the position of the 5 thinner wires as well when trying to get the correct sequence and only did the 3 thicker ones.
I have my note book ready for tomorrow, bit late after getting back from daughters now.

 

[Millymoo]

Well a bit later than expected but tried all 36 combinations of conecting up the wires, back at square one motor spins progressivley from min to max with a whirring sound with wheel off the ground should I assume an internal fault and the wheel is dead or strip. Bearings appear ok spins freely by hand, dont know if clutch seizing up inside, I presumed they are nylon and would just break up if lack of lube or maybe electrical side packing up. Maybe time to look for another s/hand motor?