Need help with my e bike

[Sami fouad]

Does the motor work when you pedal or when you stop pedalling?

The motor stops when i stop turning the pedal bcs i turned the bike with the seats on the floor and wheels up.

 

[Deleted member 25121]

The motor stops when i stop turning the pedal bcs i turned the bike with the seats on the floor and wheels up.

When you are using the bike on the road does the motor stop when you stop turning the pedals?

 

[Sami fouad]

Yes, that certainly looks like your batteries are past their best and starting to go high resistance.

But what do you make of Sami's report that "The thing that i can't understand is while im pedaling the battery loss power. And when i stop pedaling the power assist comes full energy again " ?

Here i mean that when im riding the bike it works normally and suddenly the display indicator of the battery gets lower and lower untill it collapses.. And i have to turn the key other time so as to put power again

 

[Sami fouad]

When you are using the bike on the road does the motor stop when you stop turning the pedals?

Yes it stops, i can't here it

 

[Sami fouad]

Yes it stops, i can't here it

At that point where i can see that the display start to gain power

 

[gw8izr]

Here i mean that when im riding the bike it works normally and suddenly the display indicator of the battery gets lower and lower untill it collapses.. And i have to turn the key other time so as to put power again

When you turn the key off and back on is the bike normal again for a while without charging and will it work in pedal assist Three

 

[Sami fouad]

When you turn the key off and back on is the bike normal again for a while without charging and will it work in pedal assist Three

Yes it works but shortly collapses few meters

 

[Deleted member 25121]

At that point where i can see that the display start to gain power

Do you mean that the voltage goes up or the motor speeds up?

 

[Sami fouad]

Do you mean that the voltage goes up or the motor speeds up?

Voltage goes up

 

[gw8izr]

Yes it works but shortly collapses few meters

the Only thing left to check then is volts drop right at the battery terminals as described earlier, just to confirm the wiring connectors and your key switch.

If the voltage drops sharply right at the battery then it sadly looks like it needs a new battery ( as suggested much earlier) if the battery voltage remains stable but the voltage after the key switch drops you have a problem with the switch. Same goes for any in line power connectors.

From your description and test results thats about as far as it can go I think.

 

[Sami fouad]

the Only thing left to check then is volts drop right at the battery terminals as described earlier, just to confirm the wiring connectors and your key switch.

If the voltage drops sharply right at the battery then it sadly looks like it needs a new battery ( as suggested much earlier) if the battery voltage remains stable but the voltage after the key switch drops you have a problem with the switch. Same goes for any in line power connectors.

From your description and test results thats about as far as it can go I think.

Sorry i didn't get your point

 

[Sami fouad]

Sorry i didn't get your point

actually i have problem with the switch but i dont think it would be the problem

 

[gw8izr]

actually i have problem with the switch but i dont think it would be the problem

What do you mean you have a problem with the switch?

 

[Sami fouad]

What do you mean you have a problem with the switch?

The place where we introduce the key, sometimes when i turned the key so as to start or to take out battery, sometimes it gets out from its place.. And i have to replace it again

 

[Sami fouad]

This one

 

[Deleted member 25121]

Voltage goes up

At this point I'm going to join Nealh and give up, this is crazy.

 

[Sami fouad]

At this point I'm going to join Nealh and give up, this is crazy.

I want to say the signal become higher and regain its power where the pedal assit is located...

 

[gw8izr]

The place where we introduce the key, sometimes when i turned the key so as to start or to take out battery, sometimes it gets out from its place.. And i have to replace it again

Okay, So far all we really know for sure is that the voltage that you are measuring changes as you start to pedal (or use the throttle)

A few things can be causing this problem and it’s frustrating when only some of the symptoms are given but I know remote testing is hard sometimes.

I’m going to give a bit of background which might help explain, I hope it doesn’t make it more confusing for you. The mathematics behind this isn’t complicated but if it isn’t your knowledge then it’s confusing so no maths I promise ;-)

Because of the way electrical circuits work pedal assist one only needs a small amount of current whereas pedal assist three needs a lot more current, also when you go uphill or ride faster you need more current.

When you draw current from the battery the voltage will drop, this is because the battery and all of the wiring and switches have a property called resistance.

If the resistance of any of the wires, switches or the cells inside the battery is higher than it should be then too much voltage will be lost. Your tests so far tell us that you are losing voltage when pedalling or using the throttle so the only conclusion is that somewhere you have a high resistance.


At the moment you don’t know where and whilst it’s probable that the battery is faulty I don’t want you to buy a battery and still have a fault.

The voltage will reduce as you have described if the battery is bad or there is a resistance in the wiring between the battery and where you make the measurement.

If the key switch is not working properly there is a risk that rather than being an on off switch it is failing and when the switch is in certain positions it is introducing a resistance in series with the battery. We don’t know that because the testing that you have done so far is after this switch .

What I suggest you do is as follows:

First prove that you can reproduce the fault when testing. Stand the bike so that you can spin the wheel with the throttle and apply the brake to that wheel and guarantee that you can make the fault occur every time.

Measure the voltage at idle, ie motor not running and write down the voltage.

Next measure the voltage right at the battery terminals when the motor is running and the brake applied, measure the voltage as you gradually apply the brake and watch it slowly drop. Remember the voltage just at the point that the motor cuts out, not after it cuts out but just before it cuts out and write that voltage down.

Next measure the voltage after the key switch when the motor is running and the brake applied, measure the voltage as you gradually apply the brake and watch it slowly drop. Remember the voltage just at the point that the motor cuts out, not after it cuts out but just before it cuts out and write that voltage down.

Repeat the measurements a few times to be sure that the test results are consistent.


If the voltage measurement right at the battery drops suddenly then the problem is almost certainly inside the battery,

If the voltage at the battery remains relatively constant the problem is in the wiring or the switch, I hope those tests above should pinpoint where you need to spend your money.

 

[Nealh]

Because of the way electrical circuits work pedal assist one only needs a small amount of current whereas pedal assist three needs a lot more current, also when you go uphill or ride faster you need more current.

It depends on the controller type in use, is it a current or speed controller ?

Current controllers like KT or Lishui use varying current in each PAS level.

Speed controllers use constant current in each PAS level.

If ops bike has the later type then it will collapse in any level or with throttle use.

 

[gw8izr]

It depends on the controller type in use, is it a current or speed controller ?

Current controllers like KT or Lishui use varying current in each PAS level.

Speed controllers use constant current in each PAS level.

If ops bike has the later type then it will collapse in any level or with throttle use.

I am trying to ensure that Sami understands that more current is drawn as the motor works harder. Regardless of the type of controller, as far as I know neither Ohms nor Kirchoffs principles have been rescinded but if your saying that the motor will draw maximum current when completely unloaded I’m learning something new. I do find it surprising that the peak of current at start up when the motor is completely unloaded is sufficient to make the battery fail yet by Sami’s description the cycle is often able to progress along the road normally under low demand. I would have presumed that if the battery was so far gone it would be on able to move the weight of the bike and cyclist at all? The only way I can see that being the case is if there was a significant resistance in series with the battery thereby dropping a significant voltage at start-up.

Taking all that aside, Sami needs to load the motor and it’s battery's compared to simply freewheeling it upside down in the air. In the context of this fault finding exercise I don’t believe my explanation nor suggested testing is incorrect.

I did consider earlier on whether I needed to mention that there may be brake cut-off switches, so my testing method may fail if that is not disabled but at this stage I’m beginning to wonder whether we will ever get to the bottom of this