What is the logic that causes "battery unhealthy" - before takeoff?

ArduCopter Copter 4.6
1

When connecting 52.2v battery, with these parameters, I get the error.
Voltage and current monitoring works fine - and it flies well, but I need to disable battery checks in arming bitmap.

BATT_AMP_OFFSET,0
BATT_AMP_PERVLT,126
BATT_ARM_MAH,0
BATT_ARM_VOLT,0
BATT_CAPACITY,39500
BATT_CRT_MAH,0
BATT_CRT_VOLT,40.5
BATT_CURR_PIN,3
BATT_FS_CRT_ACT,0
BATT_FS_LOW_ACT,0
BATT_FS_VOLTSRC,0
BATT_LOW_MAH,0
BATT_LOW_TIMER,10
BATT_LOW_VOLT,41.5
BATT_MONITOR,4
BATT_OPTIONS,0
BATT_SERIAL_NUM,-1
BATT_VLT_OFFSET,0
BATT_VOLT_MULT,16.236
BATT_VOLT_PIN,2

2

You probably should have these:

BATT_ARM_VOLT,44.30
BATT_CRT_VOLT,42.00
BATT_LOW_VOLT,43.20
BATT_FS_CRT_ACT,1
BATT_FS_LOW_ACT,2
MOT_BAT_VOLT_MAX,52.20
MOT_BAT_VOLT_MIN,39.60

What was the reported battery voltage?

3

As @xfacta said those values are incorrect. I f you had used ArduPilot Methodic Configurator they would have been corrected by the tool and you would not have had the problem in the first place.

Why solve problems you can avoid?

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4

@xfacta good catch mentioning the MOT_BAT_VOLT_* - the logical error is surely that my old MOT_BAT_VOLT_* are not in line with the new battery min/max voltages.

I am currently test flying a new 67Ah battery that is max 4.45v/cell and I flown it to 40.0v (at 65A) and it still climbs fine and does not show the accelerated voltage drop.

On 4x Tattu 22Ah ā€œ25Cā€ batteries (12s2p), I landed at 42v - which was where the voltage started to drop rapidly.

@amilcarlucas this UAV series had a long service life now, and recently got upgraded to current AC release + new battery bay/battery. I am aware of the Methodic Configurator, and look forward to put it to use. Given the size/weight/value of those machines, I am doing things carefully and step-by-step, where the first step was to establish new flight times (just flown 50 minutes) and learn the new minimum safe voltage - so that I can focus better on configuring/tuning later - and use more of the available power.

The weather is still so-so , but I expect progress in the next week/weeks.

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