Will replacing an old controller make my hub motor run better?

TidyDinosaur

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I have recently bought a second hand electrified Gazelle cabby. I think it was electrified 10 years ago.
I am really underwhelmed with the front wheel (20") hub motor. It is a 36V 250W no-brand motor. The controller is a KT 14A controller. I have allready tried it with another battery but the results are the same. If I have to go up a bridge or even a mild slope the motor is no longer able to provide enough power to get to 25 km/h... I really have to hit the pedals hard to even get 20km/h
I also have a (rather heavy) bike with a Bafang BBS01 mid drive that i put together myself and that goes so much better, so I have something to compare it to...

Could it be that the old controller has it's best days behind it and would a new (maybe 17A) controller make things better? Or would I just be throwing my money away? I could not find anything with goole on maybe the old mosfets getting less powerfull with age?
 
No, they don’t get less powerful with age.

What you could do is to switch the controller for a more powerful one, let’s say a 20A controller with assist levels you can set. Since it’s hard to know what the motor can take (and how hard your driving loads it) it’s best to start out at low assist level and work your way up to full assist while watching the motor temperature.

check first if your battery also has what it takes to be able to output the increased current - otherwise you’ll just get cutouts from overloading it and it will also wear out faster.
 
TidyDinosaur said:
I have recently bought a second hand electrified Gazelle cabby. I think it was electrified 10 years ago.
I am really underwhelmed with the front wheel (20") hub motor. It is a 36V 250W no-brand motor. The controller is a KT 14A controller. I have allready tried it with another battery but the results are the same. If I have to go up a bridge or even a mild slope the motor is no longer able to provide enough power to get to 25 km/h... I really have to hit the pedals hard to even get 20km/h
I also have a (rather heavy) bike with a Bafang BBS01 mid drive that i put together myself and that goes so much better, so I have something to compare it to...

The reason the tiny low power hubmotor doesn't work as well as your BBS01 is that it doesnt' ahve the gearing available to it; it doesnt' ahve teh same torque, and you can't shift gears to give it better torque or speed.

You can use a bigger controller, but if it's a geared hubmotor (likely) then it probably won't handle much more than what it's already doing (500w on a 250w motor), and may overheat and fail (damaged hall sensors, motor windings, or plastic gears, or metal clutch).

If the times you need the extra power are short and infrequent, it may survive it just fine...but I suspect you will need more than another 100W of power (which is what you'd get at most using a 17A controller vs 14A).

Another issue is the battery--if the battery itself can't handle the extra current, it'll sag in voltage more, robbing you of some of the power you were trying to get (volts x amps = watts; increase the amps but make more voltage sag (drop in voltage under load) and watts doesn't go up as much (or at all if it's bad enough)).










Could it be that the old controller has it's best days behind it and would a new (maybe 17A) controller make things better? Or would I just be throwing my money away? I could not find anything with goole on maybe the old mosfets getting less powerfull with age?
It is much more likely that the motor, if it has been overheated at all, has gotten it's magnets weakened.

Capacitors age in the controller, but they don't cause a loss of power, they cause wierdness or system failure, as they become less able to filter out noise in the system.
 
Thank you for the elaborate responses! I guess I will just keep it as is. Not worth spending the money...

I got the bike for 350€ because the electric part was no longer working. I decided to make a gamble and bought it to see if I could fix it. After a little searching I found it was the disc with the magnets for the PAS sensor that had moved a little far from the sensor along the axle. I shifted it 1 cm toward the sensor and all was working again :)
 
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