Bafang BBS02 at 36 V problem with video

Hi!
Just bought a BBS02 togheter with the 850c display and a 36 V, 12 Ah battery.
I've set the battery voltage to 36 V and the battery is full. The cables are pretty thick, 4-6 mm2.
As soon as I put some load on the bike the controller cuts out and indicates that the battery is empty. But it never goes under 41 V?
On the clip I use the thumb throttle and gently lower the rear wheel to the floor. It's pretty much the same on the road.
Any thoughts?
https://youtu.be/fOVoJ252TEo

Had a thought. I've only changed to 36 V battery on the display. Maybe that doesn't adjust the LVC?

How did you determine the battery is full? Green light on the charger can mean full, or the plug is not connected. Ive taken off with an empty battery a few times, taking the green light to mean full.

The battery was at 42 V
But I've read that the LVC is 41 V regardless of the setting on the display.
I'll lower the LVC as much as possible (38 V?) when I get my programing cable.
Then I'll have to get a 48 V battery I guess.