TSDZ2 36v: screen shows low battery

[washichi]

I just bought a secondhand TSDZ2 36V (250w) stock.
My battery is 41.7 V when fully charged.
My battery is 35.8 V when fully discharged by riding my bike.

My tsdz2 display shows that my battery is emptying quickly, and it gives me less support when It thinks the battery is low/empty.
But I don't think 35.8V is that low, I've read (not confirmed) that the cut off voltage is around 32V.

Why does my bike not discharge my battery further?
Or why does it show my battery is empty while it's not?
I don't think my battery is so bad (charging up to 41.7V).

I didn't flash OSF yet, (Waiting for parts).
opened the battery but couldn't see the cells because it's wrapped and covered, so I ask here first before I do that.
Hope you guys have an idea what could be the problem.

Edit: when I take a break during a trip and turn off my e-bike for a bit, after turn on the displays shows more battery (than when I started my break) and thus gives me more support. (Untill it think my battery is low again) .

 

[Elinx]

....
Edit: when I take a break during a trip and turn off my e-bike for a bit, after turn on the displays shows more battery (than when I started my break) and thus gives me more support. (Untill it think my battery is low again) .

The Voltage will go down under load and you can measure the Voltage only without load. That is why the measured Voltage will always be higher.
You see a higher Voltage after a break, because the Voltage recover a bit after rest with no load.



Shut down of the battery is done by the BMS inside the battery.
You can see only the Voltage of the complete battery
The BMS measures all 10 serial part Voltages separated.
If one of these serial Voltages goes under 3.2V, there will be a cutoff.
This is why I think one cell or more in a serial part is bad.

For example:
Full charge 41.7V can mean 9x 4.2V and 1x 3.9V
Empty 35.8V can mean 9x 3.6V and 1x 3.2V

There is a very small chance you can try to recover this by charging the battery a very long time, so the BMS can try to equalize all serial parts to the same Voltage level.