Voltage question

Looking for some assistance in diagnosing a voltage issue. New 4S 5200mAh battery. Sudden drop in voltage after a few minutes. I am confident that it is not a battery problem because the battery works as expected on the bench. I wonder if anyone could help me diagnose the problem Link to bin file attached. Thanks

Apart from the battery voltage going catastrophically low the Vcc also goes low and that could cause a flight controller brown-out or reset.

The odd thing is there is no increase in current or motor output when that voltage drops, so I’m wondering if it’s a measurement/heat issue with your voltage sensor.
The flip side to that is: it could still be the battery, since you were generally descending, so the motor output and current draw could be reasonable, and the fact that Vcc drops too indicates the battery voltage measurement may be real.

You are going to have to test your voltage sensor more, on the bench, probably using MissionPlanner motor test.
I would say the battery is dead. You could try a couple of charge/discharge cycles on your charger to measure the capacity. That will tell you about the battery health.

Thanks for taking the time to look at this. I will have a good look at sensor and battery,