Motor weak power

[seba240698]

Hi all.
I'm new member.
Pardon me if I post in a wrong section, I was contemplating to post in "General Discussion" section or this section.

I bought an used e-bike about 4 months back and it was working fine about 1 month, then came plenty of problems, plenty of downtime and disappointment.
Problems like rear tyre punctured, drive side crankarm stuck in frame, rear freewheel hub worn, chain worn, bottom bracket came loose, rear derailleur hanger broke, motor power cut off intermittently , battery connectors came loose etc, all of which I managed to resolve and repair them satisfactorily, at least based on my standard. I consulted You-tube and relevant bike forums to get the solutions.

To cut the long story short, I have new problems which I am lost for a solution for almost 2 weeks with my e bike, I hope to get some expert advice from here.

I replaced my controller and LCD display recently after the old LCD display showed no sign of power after a heavy rain. I waited for the parts for 2 weeks from China and installed in my e-bike. Alas, the LCD display lights up BUT the motor now runs at less than 10% of power (based on my experience when my e bike was working fine). My LCD display and controller photos are shown. The sticker on the rear hub motor reads 36V and manufacturer from China.

My diagnosis so far :
1) I suspected the Hall sensor, but when I disconnected the Hall sensors, I started the motor running by pedal assist (throttle is not allowed in my country), there was no difference in performance, motor still ran at less than 10% of power,
2) I checked the battery voltage with a multimeter, it showed 40V for a 36V rated battery, when the motor was not running,
Both controller and LCD display are brand new, bought online.
3) I measured the voltage between the 2 phase wires of the motor, it varied from 10 V to 29 V ac (I switched my multimeter to measure Vac) and the current in the phase wire to motor was from 3A to 13A ac, my motor is rated at 250 W but controller is rated 250 W to 350W.
4) my next step is to measure battery's voltage when motor is running and to measure the hall sensors voltage when motor is running,

My question is, what is damaged? LCD display (unlikely as it is new), Hall sensors (which is redundant as not connecting them doesn't seem to make a difference) or motor (my worst fear as it will cost me about $300 and 3 weeks waiting).

 

[docw009]

1) Does the other side of the controller say Brainpower? What is the Amp rating?

2) Did you follow the intelligent identify process?
a) connect wires and power up controller. WHeel spins briefly.
b) disconnect wires and power off controller
c) leave wires alone and run bike.

I didn't think the Brainpower controller would run without the Hall sensors connected. I have a small one I only used for a week. Very compact, inexpensive, but only 13A. Not enough power for me.

 

[seba240698]

Hi docw009,

Thank you for your prompt response.

1) Yes, the motor controller is Brainpower, it is rated at 13A.

2) Yes, I connected the intelligent wires, but I'm not exactly sure now if I followed your procedure. To describe to you what happened, when I first connected the controller to the LCD display, to the motor and to the battery, before I used the intelligent wires, I ran the motor, it was noisy but it still turned slowly. After I connected and disconnected the intelligent wires, the motor turned less noisily (based on my standard) and with less than 10% power. Nonetheless, I'll redo the intelligent wires connection and update the forum the results.

Not to dispute your statement but I read online that if one starts the bike by pedal assist, since the controller will know the positions of the 3 phases, it dosen't require the signal from the hall sensors?

It may sound academic, but isn't P = I.V? With 29V and 13A, the power is 377W, above my 250W rated motor. Technically, 250W is the legal restriction on e-bikes in my country, nothing is written on the label of my motor except 36V and the Chinese manufacturer's name.

I have an old controller which was replaced by this new controller now in my e-bike. The old controller has 19A rated current and 350W rated power. Maybe I try to revive it (if that is possible and not damage more component) and see if the motor can turn with more power.

Do you suspect the controller is undersized that causes this low power?

 

[Chalo]

Is the bike making a different sound than before? Does the controller get warm quickly when you use it? If so, you may have the wires connected incorrectly. Color codes for wires usually don't match between different manufacturers.

There is often an incorrect wire assignment that will run, but weakly and inefficiently-- sometimes too fast but with weak torque. Unusual noise and waste heat are the signs that you have this kind of incorrect wire connection.

 

[docw009]

Brainpower is self learning.Yep, I got the exact controller from Phoebe Liu on aliexpress a few years ago. Maybe I can run it on the bench w/o Hall sensors.

But I wonder if the answer isn't comparing a 19A controller to a 13A model.

 

[Pinesal]

Is the bike making a different sound than before? Does the controller get warm quickly when you use it? If so, you may have the wires connected incorrectly. Color codes for wires usually don't match between different manufacturers.

There is often an incorrect wire assignment that will run, but weakly and inefficiently-- sometimes too fast but with weak torque. Unusual noise and waste heat are the signs that you have this kind of incorrect wire connection.

Too fast but weak torque, you say?

I didn't know that was possible. I may be suffering from that but I don't have a history with my motor so I'm not sure.

Is there a way to know the correct setting without ride the bike each time?

 

[seba240698]

Is the bike making a different sound than before? Does the controller get warm quickly when you use it? If so, you may have the wires connected incorrectly. Color codes for wires usually don't match between different manufacturers.

There is often an incorrect wire assignment that will run, but weakly and inefficiently-- sometimes too fast but with weak torque. Unusual noise and waste heat are the signs that you have this kind of incorrect wire connection.

Hi Chalo, thank you for pointing out another possibility. I have to try to rectify whatever possible causes that comes along. Bringing it to a e-bike repair shop will be my last resort, here e-bike repair shops are not as common as conventional bicycle shops (they used to be more common but things changed after the regulation came into play), usually don't accept bikes that are not sold by them or they will charge you prices that make you will feel waiting and replacing component online is more worthwhile.

After reading your message, I somehow feel that the motor was indeed slightly noisier and the controller warmer than the old one. Maybe this is psychology at work but nonetheless I will swap the phase power cables and see how it goes and update the forum.

 

[seba240698]

Brainpower is self learning.Yep, I got the exact controller from Phoebe Liu on aliexpress a few years ago. Maybe I can run it on the bench w/o Hall sensors.

But I wonder if the answer isn't comparing a 19A controller to a 13A model.

Thank you. I bought it from Ruby Xie of Aliexpress.

I was thinking about 19A and 13A too, but the power loss doesn't feel like the difference between 19A and 13A. I've test-ridden a 250W e-bike from a showroom before, it was not that low power.

I will, of course, replace the controller with a higher rated current if I can't resolve the issues with the advices from the forum. A controller is much cheaper than a motor.

You don't suspect the LCD display?

 

[amberwolf]

When the components are matched correctly, the LCD displays generally only display what the controller tells it to, and can only change the settings teh controlelr has available. So if the settings you want aren't available in the controller, the LCD can't change them.

If they're not matched, it's psosible that the LCD might not correctly (or at all) show the stuff the controller sends it, and maybe the controller wouldn't understand button presses from the LCD, but other than that it shouldn't matter. The LCD may correctly display some things, and may even have settings available that the controller doesn't understand...most likely the LCD will simply always display the same value for those, even after you've changed them and power cycled the system.

If you have a wattmeter, you can verify the actual battery current being drawn, to see if perhaps it is just a setting in the controller (which might or might not be accessible via the LCD).

There have been controllers that will not output the amount of power they are rated for, for whatever reason (not common for anyone to continue troubleshooting them, usually they just replace them, or get their money back, etc).

It's also possible that the difference really is between the "rated" 19A, and the "rated" 13A. That's just battery current. Phase current is different, and is what the motor actually sees. It does take more battery current to get more phase current, but the curves aren't identical, depending on the controller design/settings (if it has any).

Sometimes a system may "wake up" at a somewhat higher current than it's being fed, making it feel "powerless" or weak when the controller won't give it waht it needs for the conditions.

Some controllers also have a soft-start, ramping up much slower in response to throttle input than others.



As an aside, I can't imagine why a business would call itself "Annoy Bike" in english, that kind of name would keep me away from them by itself. (sure it could be someone's name...or a word in another language that means something completely different...but if advertising in english, one might want to consider the meanings of names chosen.... )

 

[seba240698]

Thank you all for your valuable suggestions.

This morning, I went to rectify my e-bike again.

Firstly, I adopted docw009's suggestion and do the intelligent wires connection. I connected the wires and power up the controller, wheel span faster but LCD display still showed only 1 bar of motor power. I then disconnected wires and switched off the controller.

Thinking that the problem still exists, I did what Chalo suggested, that is swapped the motor phase cables.

This is what I did;

I swapped the blue cable with the yellow cable, ran it, then I swapped yellow with green, ran it, then green with blue, ran it, finally yellow and blue, and ran it. These are the results:

Case 1 :
blue motor cable to yellow wire to controller
yellow motor cable to blue wire to controller
green motor cable to green wire to controller
Result : motor ran with a slight jerk initially, otherwise smoothly.

Case 2 :
blue motor cable to yellow wire to controller
green motor cable to blue wire to controller
yellow motor cable to green wire to controller
Result : motor did not run.

Case 3 :
green motor cable to yellow wire to controller
yellow motor cable to blue wire to controller
blue motor cable to green wire to controller
Result : motor did not run.

Case 4 :
green motor cable to yellow wire to controller
blue motor cable to blue wire to controller
yellow motor cable to green wire to controller
Result : motor ran with a slight jerk initially, otherwise smoothly.

Verdict : motor runs as long as one colour is connected correctly.

I then measured the voltage of the battery when the motor was running, it read between 38V to 40V DC. My battery is rated at 36V.

Without wanting to give up, I tried my luck to ride it.

Voila, the power came back! It was as good as before the replacement of the controller and LCD display!

As I didn't ride the bike immediately after each action, I am not sure which action caused the motor power to come back, could it be the intelligent wires connection or the swapping of motor phase wires? I tend to think it is the intelligent wires connection since my motor phase cables connection is now matching all the 3 colours.

I, however, noticed that there was slight change of the motor behaviour :
1) the motor was noiser than before when the it was under very high load, eg, when I used the highest gear (48 teeth chaining with 11t cog, 26" rim, about 10 deg slope), pressed assist level 5 and moved up slope, it did deliver the power though. It was not noisy when I used a lower gear or used assist level 4 and below,
2) the motor took a longer time to cut in and cut out
The lag is about 1 sec, previously I estimated it to be about 0.25 sec.

But these 2 are not major problems to me, at least now I can ride it without replacing any more components.

Thank you all for your help!

 

[seba240698]

When the components are matched correctly, the LCD displays generally only display what the controller tells it to, and can only change the settings teh controlelr has available. So if the settings you want aren't available in the controller, the LCD can't change them.

That is very true. My LCD has a speed display but it is displaying crab info. I know my Hall sensors have only 5 wires so it doesn't have the speed signal wire (the 6th wire), but still there is a speed display in my LCD. I highly suspect it is a number converted from the rpm of my crank (cadence), because when I stop pedaling, the display shows zero speed.

 

[seba240698]

It's also possible that the difference really is between the "rated" 19A, and the "rated" 13A. That's just battery current. Phase current is different, and is what the motor actually sees. It does take more battery current to get more phase current, but the curves aren't identical, depending on the controller design/settings (if it has any).

But I've ridden a 250W e-bike from a showroom before and it had much more power than this.

I didn't know that the phase current and battery current curves are different, I thought they are the same except for a time lag, thanks for pointing it out.

 

[seba240698]

Sometimes a system may "wake up" at a somewhat higher current than it's being fed, making it feel "powerless" or weak when the controller won't give it waht it needs for the conditions.

Some controllers also have a soft-start, ramping up much slower in response to throttle input than others.

I think my motor is like that. It was subjected to a higher current, when it was connected to a lower current rated new controller, it couldn't deliver the required power.

I think my new controller has a slow start and stop, it cuts in and cuts out the motor power with a longer time lag than the old controller.

 

[docw009]

When the components are matched correctly, the LCD displays generally only display what the controller tells it to, and can only change the settings teh controlelr has available. So if the settings you want aren't available in the controller, the LCD can't change them.

That is very true. My LCD has a speed display but it is displaying crab info. I know my Hall sensors have only 5 wires so it doesn't have the speed signal wire (the 6th wire), but still there is a speed display in my LCD. I highly suspect it is a number converted from the rpm of my crank (cadence), because when I stopped pedaling, the display shows zero speed.

It's common for controllers to get their speed from the hall sensors in the motor when running. On a direct drive motor, which is always turning, the signals always flash. On a geared motor, the signals stop when the motor is off because the gears/clutch allow the motor to stop. You can add a speed sensor, just another hall device and a spoke magnet to that white wire.

If you think the speed is wrong, you can check your P1 settings, which is wheel diameter. Also look at P2 which is the number of magnets x gear ratio. If you do not know the latter, adjust P2 til you got the right speed from a calibrated source.

Here's the P setting copied off Phoebe's web site. She never had any documentation. Told me to look at the pix on her site when I asked.

Basic data setting
Press simultaneously button up and down will go in to setting interface

P0: set battery low voltage protection point , used to adjust battery level indication precision, setting for common lithium battery:
24 battery—low voltage protection point 20v
36 battery—low voltage protection point 31v
48 battery—low voltage protection point 42 v
Other battery should adjust up or down according to materials and string

P1: SET rim diameter , unit inches
Such as if bike rim is 26inches, then make it 26
Scooter motor 8inches , make it 8

P2: INTERFACE SET magnetic poles ratio , should be set according to motor magnetic poles and reduction gear ratio
Common 26inches geared motor should be 45
8inches gearless motor should be 15
Adjust up or down according to motor rated top speed indication, if slow then down the data, if faster then add data

P3: set speed testing standard
Ordinary motor hall sampling set is 1, if take external speed test hall then set is 0

P4 interface setting speed display unit
Common is 0 kilometer , aboard is 1 miles

 

[docw009]

One more comment. There is an external potentiometer attached to the wires in the picture. It is also on my unit and is used to adjust the top speed. Did you try it?

 

[amberwolf]

My LCD has a speed display but it is displaying crab info. I know my Hall sensors have only 5 wires so it doesn't have the speed signal wire (the 6th wire), but still there is a speed display in my LCD. I highly suspect it is a number converted from the rpm of my crank (cadence), because when I stopped pedaling, the display shows zero speed.

It doesn't require a separate speed sensor from the motor to determine speed, as long as there is a place in the settings to change number of poles (to match the magnet count / 2 in the motor).

But the controller may not be wired up or setup inside (software) to count hall sensor pulses, and may only understand a separate sensor input. If you don't mind taking the risk of damage to the ocntroller, you can try to open up the controller, and check what wire has the pulses on it that correspond to the timng/amount of speed shown. Then connect it to one of the hall sensor signal wires instead of the signal it's on now, with a little jumper wire inside the controller. Then see if the speed is right (asusming there's a place ot set the number of poles n the settings, which is probabl 23; i's a cmmon number).

Keep in mind that if it's a geared hub, rather than DD, then using a hall sensor for speed means it only detects the *motor* pseed, meaning when the motor isn't runing the speed is wrong or zero. (If your system only runs the motor during pedalling, then that would also explain why speed is wrong f not pedalling).

YOu may also be able to use a separate reed switch sensor like a bike computer uses, with a magnet on the wheel. You can probably just take it off an old bike compuer if you have one, but you can order these sensors from places like http://ebikes.ca etc.

 

[amberwolf]

But I've ridden a 250W e-bike from a showroom before and it had much more power than this.

There've been various "250w" labelled systems that are actually capable of quite a lot more than that, for short periods (some of them, no limit to that time). I don't recall which ones ATM.

Without a wattmeter in the system you can't really see how much power is really being used from teh battery, and without a dynamometer (dyno) test you can't know how much power is actually being output--which is always less than is used from the battery).


Systems that use 250w thru teh gears, if shifting correclty, can also feel quite a lot mroe powerful than a 250w hubmotor.

 

[seba240698]

Here's the P setting copied off Phoebe's web site. She never had any documentation. Told me to look at the pix on her site when I asked.

P2: INTERFACE SET magnetic poles ratio , should be set according to motor magnetic poles and reduction gear ratio
Common 26inches geared motor should be 45
8inches gearless motor should be 15
Adjust up or down according to motor rated top speed indication, if slow then down the data, if faster then add data

Thank you so much. I also found online the setting instruction, just can't understand the P2 setting.

Now I understand it. But just curious, why is common 26" geared motor set at 45? What exactly is this number? Is it the ratio of the number of poles with something? Since we already input the wheel diameter, what other dimension will affect the computation of the bike speed?
I'll use an independent speedometer to calibrate it and get back to you the results, but it will take about 3 weeks to arrive as I ordered it online yesterday.

 

[seba240698]

It doesn't require a separate speed sensor from the motor to determine speed, as long as there is a place in the settings to change number of poles (to match the magnet count / 2 in the motor).

Keep in mind that if it's a geared hub, rather than DD, then using a hall sensor for speed means it only detects the *motor* pseed, meaning when the motor isn't runing the speed is wrong or zero. (If your system only runs the motor during pedalling, then that would also explain why speed is wrong f not pedaling)

Thank you for your detailed explanation.

Am I right to say that the speed in the LCD is from the hall sensor? That explains why the speed shown is zero even when I was on open road downhill, because I didn't pedal downhill (mine is the pedal assist system only).

However, I just need to know that why although my e-bike has a motor cut off speed, I have never experienced it either on the road or when I hand pedalled it with the bike supported with the side stand with rear wheel lifted off the ground.

I would expect these to happen if I have a motor cut-off speed ; when the speed limit is reached, I should :
1) hear and feel the motor cut off, and
2) see ZERO speed display in my LCD, since motor is already cut off.

However, I didn't notice any of the above happening. On the LCD, I only saw a constant speed shown (35 km/h) when I hand-pedaled it very fast, real fast, I think it is over 35 km/h, but the display is always 35 km/h. Is this the motor cut off speed?

 

[seba240698]

One more comment. There is an external potentiometer attached to the wires in the picture. It is also on my unit and is used to adjust the top speed. Did you try it?

I tried it but I have no means to verify its effect until I get hold of a speedometer. What I know is turn the knob counter-clockwise to reduce speed limit and clockwise to increase speed limit. I noticed that after I turned too much, the knob seemed to be not moving in nor out, I think there is a limit to the speed limit setting.

 

[dogman dan]

I have a suspicion that your problem is quite simple. Your new controller is defective.

But before you complain to the vendor, do what you can to see if you can change any settings on the display. You might be just stuck in power level one or something, because they sent you a display that reverts to level one each time it powers up.

 

[docw009]

Am I right to say that the speed in the LCD is from the hall sensor? That explains why the speed shown is zero even when I was on open road downhill, because I didn't pedal downhill (mine is the pedal assist system only).

Yes, it is from the Hall sensor in the motor. And on a geared motor, the motor is stopped when coasting, so there is no signal to tell the controller the motor rpm, because it is zero. If you fit an external sensor, the P3 setting is changed to 0 to tell it to only use the external sensor.

However, I just need to know that why although my e-bike has a motor cut off speed, I have never experienced it either on the road or when I hand pedalled it with the bike supported with the side stand with rear wheel lifted off the ground.

If you had a throttle, you would see the motor reach a maximum speed with the wheel off the ground. The Brainpower controller did not choose to implement a user programmable cutoff. It's such a small controller, this is not needed anyway.

 

[docw009]

I see that you went back and swapped the motor cables, and now it runs better. You did not mention whether you tried the intelligent setup before each test. If you did not, then it suggests to me that the original intelligent setup picked a false positive combination, and by swapping wires, you now have the correct relationship. Congratulations!

By the way, I tried my 250W Brainpower controller out on a 500W motor. To my surprise this 13A controller seemed to pull harder than the 18A 500W controller already on that bike.I got a higher top speed of 21 mph (on an accurate bike computer) than the 19 mph with the bigger model, but I could have run my 36V battery down as I only had the throttle hooked up. The bike doesn't need to go fast and it currently only has a 3 speed PAS, so maybe I'll use it.

 

[seba240698]

If you had a throttle, you would see the motor reach a maximum speed with the wheel off the ground. The Brainpower controller did not choose to implement a user programmable cutoff. It's such a small controller, this is not needed anyway.

Do you mean there is no max speed cut-off for the controller we are using? But then why the potentiometer? Isn't it for the adjustment of the max speed?

Incidentally, there was a throttle in the e-bike when I bought it pre-owned but I disconnected and discarded it as throttle is not allowed here. (I do not know how the ex-owner got by with the half-throttle fitted in the bike).

 

[seba240698]

I see that you went back and swapped the motor cables, and now it runs better. You did not mention whether you tried the intelligent setup before each test. If you did not, then it suggests to me that the original intelligent setup picked a false positive combination, and by swapping wires, you now have the correct relationship. Congratulations!

Thank you.

Yes I did try the intelligent wires set-up following your instructions but I didn't test ridden it immediately after the set-up.

Then I swapped the motor phase cables. But I swapped them back to the correct colours before I test rode it, then the full power came back.

So I do not know which one rectified the problem, the intelligent wires setup or the phase cables swap, but I suspect it was the intelligent wires set-up that solved the problem because my motor is now running fine with the phase cables connected to the matching colours.

By the way, I tried my 250W Brainpower controller out on a 500W motor. To my surprise this 13A controller seemed to pull harder than the 18A 500W controller already on that bike.I got a higher top speed of 21 mph (on an accurate bike computer) than the 19 mph with the bigger model, but I could have run my 36V battery down as I only had the throttle hooked up. The bike doesn't need to go fast and it currently only has a 3 speed PAS, so maybe I'll use it.

P1120125.jpg

In that case you may just use the 250W controller. Sometimes numbers are just psychological.

I see that you have exactly the same LCD as I have. I had the speedometer shown in your photo ordered online too. Is the speedometer good? Does it come with backlight?