First test on DIY ebike running slow and hot

[wobble]

So the throttle sohuld vary voltage and not current?

The throttle itself always varies it's voltage.

What it causes the controller to vary at the motor, for a brushed system, is the width of the voltage pulse to the motor. The voltage pulse is always battery voltage. How long it applies that voltage determines the current draw of the motor. The current is also in pulses, becuase the voltage is in pulses, and also changes. So the controller varies the average current by varying the average voltage by varying the width of full-battery-voltage pulses. Because of the motor inductance and resistance, it may not look like "squarewave" pulses, but that's how brushed controllers work.

Unless you use an oscilloscope you can't see this occuring, and the only "valid" multimeter / ampmeter / voltmeter measurement you can make of what the motor is doing is at the battery input to the controller, not at the motor output from the controller.

But what is the actual throttle signal voltage, at the controller's signal input?

If that dosent' vary, then neither will the controller output.

The throttle was about 4.4V and it is able to vary the speed of the motor. The seller of the controller had paired it with the throttle and sold the two together in a package deal.

If it's always 4.4v, then it cannot vary the speed of the motor.

The throttle voltage must vary with throttle rotation.

If it is able to vary the speed of the motor, then the voltage at the motor, and the current draw from the battery, will also vary.

What is the actual throttle signal voltage, at the controller's signal input, when at zero rotation?

What is the actual throttle signal voltage, at the controller's signal input, when at maximum rotation?

What is the motor's current draw when directly connected to the battery?

I've tried my best to answer your questions:
I measured the throttle voltage between two of the wires which go from the throttle to the controller

1. The throttle voltage at zero rotation is 4.4V
2. The throttle voltage at max rotation is 4.4V
3. The motor draws more current that i can read so >19A when connected directly to the battery

I'm so confused because i thought the controller would be regulating the voltage and current, and also that the motor would draw less current from the battery when directly connected.

 

[TommyCat]

Hi Wobble,
It sounds to me like your throttle is ether incorrectly wired, or your trying to see the output voltage at the wrong location.
From the controller pictures it looks like the wire colors at the throttle connector would be RED= 5vdc+, BLACK= Ground, with the BLUE wire the throttle voltage output.
So back probing the throttle connector with your meter's black probe on the BLACK or ground wire, and the meter's red lead on the BLUE or throttle signal (output) wire (set VDC < 20 volts) you should be seeing ~1vdc (home) to ~4vdc (WOT) varying according to throttle position.

The labeling of the throttle wiring in the link seems very odd. I am skeptical of how they have them labeled. :?
Is it truly a 5 wire throttle with key switch and LED power lights?
This is more as what I would be expecting...

How do you have it wired?

To be sure you may have to open it up and verify the wiring connections.
Use this link for information on how to do so...
https://electricbike.com/forum/foru...r-throttle-operation-testing-and-modification



As far as the amperage draw of your motor connected directly to your battery, >19 amps would not be a surprise as the motor is rated @ 26.7 amps at 36 vdc...

EDIT: Thinking... read at battery power connection with motor loaded. Sorry for the confusion. My mistake.


Regards,
T.C.

 

[HrKlev]

Motor should not draw more than a few amps if connected directly to the battery and unloaded. Was it unloaded when you did the measurements? If it was, it sounds like theres a short in the motor.

 

[amberwolf]

I measured the throttle voltage between two of the wires which go from the throttle to the controller

Which two wires? The ground and the signal? Or the ground and the 5v supply? Or the 5v supply and the signal?

1. The throttle voltage at zero rotation is 4.4V
2. The throttle voltage at max rotation is 4.4V

Either you're measuring between 5v supply and ground, instead of signal, or something is wrong with the wiring, or the throttle is defective, etc.

If you disconnect the throttle signal output from the controller, but leave the 5v and ground wires connected, then what do you read with the voltmeter set to 20vdc, and it's red lead on the signal wire, and it's black lead on the ground wire, when rotating the throttle?

3. The motor draws more current that i can read so >19A when connected directly to the battery

Almost certainly there is an issue inside the motor itself. No load current, meaning motor just spinning without anything connected to the output shaft, should be pretty low, usually an amp or two, for a small motor like this.

It should only read high currents when driving a load, meaning when something is connected to the output shaft.

I'm so confused because i thought the controller would be regulating the voltage and current,

It can't, if the throttle isn't commanding it to.

As I said before:

If it's always 4.4v, then it cannot vary the speed of the motor.

The throttle voltage must vary with throttle rotation.

If it is able to vary the speed of the motor, then the voltage at the motor, and the current draw from the battery, will also vary.

If that dosent' vary, then neither will the controller output.

and also that the motor would draw less current from the battery when directly connected.

It should. If it doesn't, something is almost certainly wrong with the motor. You can start by checking some of the things I listed before, but you have to take the motor apart to do it, and they aren't as easy to put together as they are to get apart. Some people never get them back together, so keep that in mind.

If it's under warranty, or within return/exchange period, I'd just do that, and get another one.

 

[wobble]

I measured the throttle voltage between two of the wires which go from the throttle to the controller

Which two wires? The ground and the signal? Or the ground and the 5v supply? Or the 5v supply and the signal?

1. The throttle voltage at zero rotation is 4.4V
2. The throttle voltage at max rotation is 4.4V

Either you're measuring between 5v supply and ground, instead of signal, or something is wrong with the wiring, or the throttle is defective, etc.

If you disconnect the throttle signal output from the controller, but leave the 5v and ground wires connected, then what do you read with the voltmeter set to 20vdc, and it's red lead on the signal wire, and it's black lead on the ground wire, when rotating the throttle?

3. The motor draws more current that i can read so >19A when connected directly to the battery

Almost certainly there is an issue inside the motor itself. No load current, meaning motor just spinning without anything connected to the output shaft, should be pretty low, usually an amp or two, for a small motor like this.

It should only read high currents when driving a load, meaning when something is connected to the output shaft.

I'm so confused because i thought the controller would be regulating the voltage and current,

It can't, if the throttle isn't commanding it to.

As I said before:

If it's always 4.4v, then it cannot vary the speed of the motor.

The throttle voltage must vary with throttle rotation.

If it is able to vary the speed of the motor, then the voltage at the motor, and the current draw from the battery, will also vary.

If that dosent' vary, then neither will the controller output.

and also that the motor would draw less current from the battery when directly connected.

It should. If it doesn't, something is almost certainly wrong with the motor. You can start by checking some of the things I listed before, but you have to take the motor apart to do it, and they aren't as easy to put together as they are to get apart. Some people never get them back together, so keep that in mind.

If it's under warranty, or within return/exchange period, I'd just do that, and get another one.

I really appreciate all the help you guys are giving me, i dont know what i'd do without it!

https://imgur.com/a/Fv4MjX5
thats a picture of my throttle connections (left) going into the controller (right)

The voltage between the green and black varies from 0.8V (zero throttle rotation) to 3.6V (max rotation)
The voltage between black and red is always 4.4V

The throttle and controller are able to vary the motor speed, however the voltage measured at the motor output of the controller is constant for all rotations of the throttle above zero (it jumps from 0V to 35V with the slightest turn of the throttle)
making me believe that the current is being varied (at a value i cant read >19A) since the current also jumps above 19A with the slightest turn of the throttle.

 

[wobble]

Hi Wobble,
It sounds to me like your throttle is ether incorrectly wired, or your trying to see the output voltage at the wrong location.
From the controller pictures it looks like the wire colors at the throttle connector would be RED= 5vdc+, BLACK= Ground, with the BLUE wire the throttle voltage output.
So back probing the throttle connector with your meter's black probe on the BLACK or ground wire, and the meter's red lead on the BLUE or throttle signal (output) wire (set VDC < 20 volts) you should be seeing ~1vdc (home) to ~4vdc (WOT) varying according to throttle position.

The labeling of the throttle wiring in the link seems very odd. I am skeptical of how they have them labeled. :?
Is it truly a 5 wire throttle with key switch and LED power lights?
This is more as what I would be expecting...

How do you have it wired?

To be sure you may have to open it up and verify the wiring connections.
Use this link for information on how to do so...
https://electricbike.com/forum/foru...r-throttle-operation-testing-and-modification



As far as the amperage draw of your motor connected directly to your battery, >19 amps would not be a surprise as the motor is rated @ 26.7 amps at 36 vdc...


Regards,
T.C.

Thanks for the help, i think i have it wired correctly now!
I wish i could measure the actual current of the motor but i couldnt find any multi-meters which can read above 10/20A

Everyone seems to think that this no-load current over 19A is suggesting a faulty motor as no-load current is usually around 3A

 

[amberwolf]

https://imgur.com/a/Fv4MjX5
thats a picture of my throttle connections (left) going into the controller (right)

Can't see the pic. If you attach the pic directly to the post using the attachments tab, then anyone that can see your post can see the pic.

But it doesn't matter--if the controller is able to vary the motor speed with throttle rotation, then throttle wiring must be correct.

The voltage between the green and black varies from 0.8V (zero throttle rotation) to 3.6V (max rotation)
The voltage between black and red is always 4.4V

There you, go, then the throttle voltage is NOT stuck at 4.4v. That's just the power supply to it.

The throttle voltage varies just like it's supposed to.

The throttle and controller are able to vary the motor speed, however the voltage measured at the motor output of the controller is constant for all rotations of the throttle above zero (it jumps from 0V to 35V with the slightest turn of the throttle)

I already explained you can't "accurately" measure the voltage at the motor without an oscilloscope, because of the way it works.

You can't accurately measure the motor current without an oscilloscope, either.

You can only measure the *battery* voltage and current.

If the motor speed is varying, then the controller is doing it's job.

You have a MOTOR problem.

 

[amberwolf]

I wish i could measure the actual current of the motor but i couldnt find any multi-meters which can read above 10/20A

Most wattmeters would be able to do that. Just do a forum search for wattmeter in topic/thread titles, and you'll find at least dozens of informative threads about them.

Everyone seems to think that this no-load current over 19A is suggesting a faulty motor as no-load current is usually around 3A

If no load is normally 3A, then getting over 19A, even when no other component *except* the motor is in the circuit, should indicate to you that a problem exists with the motor.

 

[wobble]

https://imgur.com/a/Fv4MjX5
thats a picture of my throttle connections (left) going into the controller (right)

Can't see the pic. If you attach the pic directly to the post using the attachments tab, then anyone that can see your post can see the pic.

But it doesn't matter--if the controller is able to vary the motor speed with throttle rotation, then throttle wiring must be correct.

The voltage between the green and black varies from 0.8V (zero throttle rotation) to 3.6V (max rotation)
The voltage between black and red is always 4.4V

There you, go, then the throttle voltage is NOT stuck at 4.4v. That's just the power supply to it.

The throttle voltage varies just like it's supposed to.

The throttle and controller are able to vary the motor speed, however the voltage measured at the motor output of the controller is constant for all rotations of the throttle above zero (it jumps from 0V to 35V with the slightest turn of the throttle)

I already explained you can't "accurately" measure the voltage at the motor without an oscilloscope, because of the way it works.

You can't accurately measure the motor current without an oscilloscope, either.

You can only measure the *battery* voltage and current.

If the motor speed is varying, then the controller is doing it's job.

You have a MOTOR problem.

Okay. I was reluctant to believe this at first because I bought two of the same motors and they are both displaying the same behaviour. I guess the manufacturer is at fault. Would connecting the 26.7A rated motor to the battery capable of supplying 40A cause problems for the motor? Even if just for a few seconds

 

[HrKlev]

The motors I have installed gets 40A bursts all the time, no problem.

Just to summarize - you have 2 indentical motors that you connect directly to the battery and there are no load on the shaft of the motor And both draws 19A? Are you 100% sure the current measurements are correct?

 

[TommyCat]

I wish i could measure the actual current of the motor but i couldnt find any multi-meters which can read above 10/20A

This is always very helpful to troubleshoot motor operation. I used this one to keep an eye on things. Nice to keep track of your battery's voltage and amperage output.

This is a Bayite DC 6.5-100V 0-100A LCD Display.

Bit of the install...
https://electricbike.com/forum/foru...t-52v-11-5ah-huffy-parkside?p=56004#post56004

With the shunt shown further down...

Everyone seems to think that this no-load current over 19A is suggesting a faulty motor as no-load current is usually around 3A

Sorry for the confusion as I was thinking under a loaded condition, and as measured at the battery power supply. My mistake.


Is the amperage draw still greater than 19 amps, with the motor unloaded, having your meter leads in series in one leg of power from the battery?

 

[wobble]

I wish i could measure the actual current of the motor but i couldnt find any multi-meters which can read above 10/20A

This is always very helpful to troubleshoot motor operation. I used this one to keep an eye on things. Nice to keep track of your battery's voltage and amperage output.

This is a Bayite DC 6.5-100V 0-100A LCD Display.

Bit of the install...
https://electricbike.com/forum/foru...t-52v-11-5ah-huffy-parkside?p=56004#post56004

With the shunt shown further down...

Everyone seems to think that this no-load current over 19A is suggesting a faulty motor as no-load current is usually around 3A

Sorry for the confusion as I was thinking under a loaded condition, and as measured at the battery power supply. My mistake.


Is the amperage draw still greater than 19 amps, with the motor unloaded, having your meter leads in series in one leg of power from the battery?

Thanks I think ill get the Bayite display because it will be more appropriate.

Im not totally sure my current readings are correct to be honest

Connecting the multimeter in series with the motor and battery wouldnt start the motor at all

 

[TommyCat]

Connecting the multimeter in series with the motor and battery wouldnt start the motor at all

Are you using the meter's amperage lead jacks?

 

[wobble]

Connecting the multimeter in series with the motor and battery wouldnt start the motor at all

Are you using the meter's amperage lead jacks?

I think i've done it right, heres an image of the setting i used

 

[wobble]

This is a Bayite DC 6.5-100V 0-100A LCD Display.

I've ordered a wattmeter like this which will be delivered tomorrow, so hopefully i'll have some decent results to share

 

[amberwolf]

Okay. I was reluctant to believe this at first because I bought two of the same motors and they are both displaying the same behaviour.

There's a piece of information I don't recall seeing before. FWIW, giving the whole story with every single piece of information available at the beginning often helps with resolving a problem.

Did you also get two controllers? If so, does the second one also display the same symptoms?


It is possible that multiple motors could be built wrong, with the same brushholder/brush position/rotation problems described before. But it's less likely than just one.

Would connecting the 26.7A rated motor to the battery capable of supplying 40A cause problems for the motor? Even if just for a few seconds

No. A motor will only draw the current that it's load creates. That's why it's unusual for a small motor like you have to draw so much current for so little load.

I probably should have asked this way back at the beginning, but exactly how are you measuring the current? What are your meter settings, and what are the specific wire connections you're using from it, and to which points on the battery and controller / motor are you connecting it and how?

That way we can see if it's a measurement method issue giving you the high current result.

Connecting the multimeter in series with the motor and battery wouldnt start the motor at all

This implies you were not measuring current before, becuase that's how it must be done. Additionally, if the motor won't start with the meter in series, there's something else wrong with either your connections, or your meter settings, or your meter itself (blown fuse, etc). So please describe what you're doing to test current. Just list the exact steps you perform to do so, one at a time.


I still can't see your images, so I'll say again: if you upload your image directly to the forum, using the attachments tab, it will show up for anyone that can see your post. Using external sites to host images means that anyone taht can't access that site can't see your images, and so they can't get information necessary to help you.




We do know that if the current was more than 40A, your battery should shut off it's output, if it is working properly, so the current is less than that, unless the BMS doesn't actually have a current checker, and is just rated for 40A before it blows up the FETs. (which usually fail shorted, so it leaves the BMS stuck on, so it can't do it's job and protect the cells against overdischarge.



Just to stick them all out there, other issues that can make a system slow, when it "should" be faster:
--wrong gearing, either:
-just too low so it literally can't spin the wheel any faster, for the battery voltage,
or
-such high gearing that it puts such a load on the motor that it draws so much current that the battery voltage then sags so much that the motor can't spin fast enough to spin the wheel any faster.

--wrong battery voltage, vs motor winding (kV), so it can't spin the motor fast enough.

--battery unable to supply the current needed, due to cells sagging in voltage under load so much that it is effectively the same as the wrong battery voltage. (BMS often shuts off output in those cases, at lower states of charge, unless it's incapable of it or broken).

--Something else I was thinking of but can't remember now. Will edit it into the post if I remember.

 

[wobble]

Thank you for the help everybody. I now know that i have a torque issue. My 2500rpm motor wont be efficiently using current with my current gear ratio of 2:1. I must figure out a way of increasing the ratio to 10:1 to have a usable bike

 

[amberwolf]

The gear ratio doesn't even matter right now, because you don't have the motor connected to a chain, right?

Cuz if you do, then you aren't doing the tests you need to do, which is to test the motor *without connecting it to anything on it''s output shaft*, and thus all the test results so far are useless.

If you don't have it connected, then you still have to resolve the problem with the motor itself before worrying about chains and sprockets and gear ratios.

If you are dealing with the motor problem by replacing them, then I would recommend replacing them with somethign that has a much lower RPM at the voltage you are running the bike on, so you don't need a high gear reduction.