Display query

[cyclenut1952]

Hi, while out riding recently I was looking at the battery level indicator, there was two segments left, I just squeezed the brake lever not actually braking.
on doing this the battery indicator increased 1 segment when lever released the level went back down. Anyone have any idea what is happening? Many thanks. Brian

 

[matthewslack]

I'm guessing you have brake cutoffs, and whatever was turned off when the sensor operated reduced the load on the battery enough for the voltage to creep up enough to register as just into two bars instead of not quite.

The bars are a primitive voltmeter, so the display will fluctuate as load and so voltage changes.

It will probably not happen most of the time, as the battery voltage is not always close to a bar change threshold.

 

[saneagle]

Hi, while out riding recently I was looking at the battery level indicator, there was two segments left, I just squeezed the brake lever not actually braking.
on doing this the battery indicator increased 1 segment when lever released the level went back down. Anyone have any idea what is happening? Many thanks. Brian

It's the opposite way round. when you use the motor the battery goes down. It's called voltage sag. the more current you take from the motor, the lower the voltage goes down. As soon as you stop taking power, it bounces back up again. All Ebikes do that. Some LCDs have a damping factor in the LCD, which stops the display bouncing up and down, though it doesn't actually stop the battery from doing it.

If you're old enough, you can remember the old car fuel guages that went up or down when you went round a corner, uphill or downhill. Modern ones have the damping factot in the ekectronics, so that doesn't happen anymore, even though the fuel is still moving around in the tank.

 

[cyclenut1952]

Thanks for replies, bike does have brake cut offs, not being electrical minded I was curious as to what was happening.

 

[cyclenut1952]

Also I was free wheeling so I thought the battery wasn’t under load and it didn’t go up, but when lever pulled level it went up.
anyway thanks again I can see this is well above my pay grade.

 

[saneagle]

Also I was free wheeling so I thought the battery wasn’t under load and it didn’t go up, but when lever pulled level it went up.
anyway thanks again I can see this is well above my pay grade.

There is a slight time delay in recovery.

 

[cyclenut1952]

There is a slight time delay in recovery.

 

[Nealh]

Having no brake sensors and seeing the display bars change under braking is coincidental, as d8veh has said you are simpy seeing the voltage sag delay when the loading isn't there.

 

[cyclenut1952]

Thanks, always learning with e-bikes

 

[Sturmey]

Hi, while out riding recently I was looking at the battery level indicator, there was two segments left, I just squeezed the brake lever not actually braking.
on doing this the battery indicator increased 1 segment when lever released the level went back down. Anyone have any idea what is happening? Many thanks. Brian

I have a mid-drive (as well as a hub drive)(TSDZ)that I use mainly because it conveniently fits in the back of car with wheels quickly removed. Anyhow, the same happens when I quickly take my thumb off the throttle. In my case its worst as it jumps up several bars to give a full reading.
I did look into this once. There is two significant factors that seem to cause this in my case.
The first can be considered fairly normal for a motor in that when its on full power and then the power is suddenly switched down/off, the momentum/inertia in the motor (which now acts as a generator) creates a short voltage spike/surge which is usually absorbed by the controller's capacitor and the battery.
The second factor in my case is that I use parallel batteries with diodes and this can make matters much worse as it prevents current from flowing back into the battery.

 

[cyclenut1952]

I have a mid-drive (as well as a hub drive)(TSDZ)that I use mainly because it conveniently fits in the back of car with wheels quickly removed. Anyhow, the same happens when I quickly take my thumb off the throttle. In my case its worst as it jumps up several bars to give a full reading.
I did look into this once. There is two significant factors that seem to cause this in my case.
The first can be considered fairly normal for a motor in that when its on full power and then the power is suddenly switched down/off, the momentum/inertia in the motor (which now acts as a generator) creates a short voltage spike/surge which is usually absorbed by the controller's capacitor and the battery.
The second factor in my case is that I use parallel batteries with diodes and this can make matters much worse as it prevents current from flowing back into the battery.