no power

mgan

Finding my (electric) wheels
Jun 29, 2022
14
1
Hi, I have bought an used cheap china bike, named Epoque Lynx. The retailer have gone out of business so there is no luck getting help there.

The motor is only rotationg the wheel really slowly and in short 'steps'. No assistance at all. I have checked the MOSFETS and they seem ok, according to https://ebikes.ca/documents/BlownMosfets.pdf

There is only one Hall sensor in the motor, probably for checking the speed? It is giving the correct signals when I dismantle the motor and test he sensor on the bench with a magnet.

The battery is in good condition after changing a couple of cells that where dead.

Any Ideas where to look for the issue?

IMG_1155.jpgIMG_1156.jpgIMG_1173.jpg
 

Woosh

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May 19, 2012
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the visible Hall sensor in the middle of the board is the speed sensor. There are 3 Hall sensors below the circuit board.
You should see their legs on the soldering pads at the edge of the board.
You can check the Hall signal by rotating the motor slowly.
I usually clamp the motor axle onto a bench vice. That allows me to turn the wheel which turns the motor in a controlled manner.
 

mgan

Finding my (electric) wheels
Jun 29, 2022
14
1
No, the board is probably a generic board. That is why you see the three slots for rotational hall sensors.

There are only three connected slots out of 6 on the board.
The motor is wired with three thicker cables and then the speed sensor is wired by three thin cables. When there is three rotational hall sensors there is normally at least 5 signal wires.

I guess a motor can run without rotational sensors? It becomes a standard three-phase motor rotating in the direction it is wired, that is the way my large 3-phase motors works for my water pump in y house.
 

Nealh

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Aug 7, 2014
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How many pins does the motor cable connector show 6 or 9 ?
 

Nealh

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Aug 7, 2014
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I don't know if the motor is older then the contoller , the motor pcb board has a poss date on it of 2013 June 20. Though I could be totally wrong.
The controller Lishui is 2019.
Is the controller sensored ?
Is the display a paired item compatible with said controller ?
 

mgan

Finding my (electric) wheels
Jun 29, 2022
14
1
You are wrong ,;) the manufacturing date of the PCB is week 49 2018.

There is no display, just a push button with some leds on. Looking at a similar bike, it has got the same 'display', so I guess/hope it is compatible.

Is the controller sensored? That I don't know, how do I check it?
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
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If you say the pcb date is 2018 then it fits in with the controller date and both are likely original parts. I was wondering if the controller was different then the one supplied.
 

Woosh

Trade Member
May 19, 2012
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6: Three for power and three for the speed hall sensor.
I agree, 6 pin connector: the motor has no Hall, just phase wires and speed sensor.
In that case, if the motor does not have much power then you will have to check your controller.
Is the controller sensored? That I don't know, how do I check it?
Most Lishui controllers will work with and without Hall.
 

mgan

Finding my (electric) wheels
Jun 29, 2022
14
1
Just buy a new controller and test if it works? Or do you have any troubleshooting tips except the MOSFET test that I already tested?
Does the speed sensor matter? If it is unplugged, it will just make the bike go faster?
 

Woosh

Trade Member
May 19, 2012
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Southend on Sea
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Just buy a new controller and test if it works? Or do you have any troubleshooting tips except the MOSFET test that I already tested?
you can check the MOSFETs first before buying anything.
The symptoms are not clearcut to come to any conclusion.

Does the speed sensor matter? If it is unplugged, it will just make the bike go faster?
Not in common Lishui controllers. The manufacturer can request specific features to be programmed in though, like reduced power if the motor stalls or if someone disconnects the speed sensor while trying to derestrict the bike.
Stock controllers you buy on aliexpress don't have these features.
 

mgan

Finding my (electric) wheels
Jun 29, 2022
14
1
How do I check the MOSFETs other than doing the measurement I already performed?
 

Woosh

Trade Member
May 19, 2012
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Southend on Sea
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How do I check the MOSFETs other than doing the measurement I already performed?
If the LCD reports error 21 then I would check the motor cable. When one of the FETs goes, you should see a short between one of the phase wires and BAT+ or BAT- (you have to remove the battery before testing). If the FETs are working but apparently not functioning properly, you'll need an oscilloscope for that.
I usually don't check for the MOSFETs. I will just swap out the controller.
in your case, the symptoms are not clearcut for any quick diagnosis. I would put the bike back to where it was and check carefully for battery voltage sag under load.
 

mgan

Finding my (electric) wheels
Jun 29, 2022
14
1
The LCD is non existant, see pic.

The controller is flashing with a red led inside. I guess you can see the red light shining throgh where the red/yellow/black cables are entering the controller. The flashing is about one second on and one second off.

The battery is most likely healthy and keeps the voltage during the (probably limited) load when I activate walk assist, and get a slowly rotating wheel.IMG_1176.jpg

47856
 

Woosh

Trade Member
May 19, 2012
17,196
15,026
Southend on Sea
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you have a 790 analog LED panel. You can see the battery level (4 LEDs).
Is the bike still rideable? if it is not, then the controller is suspect. If it is, then check that the battery level does not lose more than 1 LED when going uphill.
It's difficult for us to help you because your kit is rarely sold nowadays.
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
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I suspect the issue is abnormal current fault so a controller /mosfet fault.
Have the mosfet tests on the three phase wires been done on both the high and low side measured via both the neg and pos controller wiring ?
 

mgan

Finding my (electric) wheels
Jun 29, 2022
14
1
I have measured the resistance between the three power wires and power, both positive and negative. The result were if I remember correctly, roughly 5 kohm on one side (negative) and infinate on the positive side.

I dont know if this is a test on both the high and low side?

I know troubleshooting in a forum can be difficult, especially when there is a noob in one end of the conversation. I am happy and grateful for all the help I can get.
 

Woosh

Trade Member
May 19, 2012
17,196
15,026
Southend on Sea
wooshbikes.co.uk
I have measured the resistance between the three power wires and power, both positive and negative. The result were if I remember correctly, roughly 5 kohm on one side (negative) and infinate on the positive side.

I dont know if this is a test on both the high and low side?

I know troubleshooting in a forum can be difficult, especially when there is a noob in one end of the conversation. I am happy and grateful for all the help I can get.
Your FETs seem OK.

don't worry about being a newbie, everyone has to start somewhere. The problem is the fault is not clearcut. Your motor still spins up.
You may spend a lot of time testing various components without coming to any concrete diagnosis. Show us a pictures of the connectors at the controller.


Does the pedal assist work?
 

Nealh

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Aug 7, 2014
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Yes if you have carried out the test on pos & neg then one has doen the high & low side.
In my experince I have only seen the reading of approx. 9 -10k on the high side, 5k seems to be low even if they all read so. Infinity is ok .
 

mgan

Finding my (electric) wheels
Jun 29, 2022
14
1
I wouldn't call it that the motor spins up, it is only revving really slow. Probably about 2-3 rpm. And not in a smooth way, more moving/jumping a couple of degrees and then waits for some time before jumping to the next angle. Maybe around three "jumps" per second.

Yes the PAS works, that is the motor spins at the same speed as when I am using the walk assist function.

Photos of the connectors will be uploaded tomorrow.