Battery failsafe did not trigger in AUTO mode

ArduCopter Copter 4.4
1

Hello everyone, I was flying the quad in auto mode to find out flight time from full charge to battery failsafe which is at 13.2V as low value and 12.8 as critical. The failsafe at low value didnot occur and I manually put RTL.
Log1

I previously did a test in which quad did not go to failsafe even after crossing the critical value so I forcefully put RTL.
Log2

Can someone please help me understand why it did not go to battery failsafe?

Thank you!

2

In those logs you were only just hitting your low voltage level for a couple of seconds.
Your battery settings are mostly OK, I think you have 4 cell Li Ion right?

The critical and low settings were a bit high, but that’s not too bad. The battery wasnt showing any sign of sagging, which is good.

I would use these:

BATT_ARM_VOLT,12.70
BATT_CRT_VOLT,12.00
BATT_LOW_VOLT,12.40
MOT_BAT_VOLT_MAX,16.40
MOT_BAT_VOLT_MIN,11.20

EDIT: you might want to leave you existin CRT and LOW values as they are now

and to make it “conservative” do not change the voltage values, but change the timeout:
BATT_LOW_TIMER,5
and then if you expect a long RTL distance maybe slightly lift the CRT and LOW voltages.

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3

Thank you @xfacta for your comments.
Yes it is Li-ion battery.
Is there any parameter that logs how much seconds the timer has recorded from the time of voltage below BATT_LOW_VOLT to trigger failsafe action? Because in the second log I can see that battery failsafe triggered at 18:34:01.241, the voltage was always below 13.2V since 18:32:37.441

4

I think the battery voltage was not staying below 13.2 for long enough in one stretch to trigger the failsafe.
The voltage was still very much up and down around that 13.2 region which will keep resetting the timer.
So retest with
BATT_LOW_TIMER,5
which is what I use, and you may be able to go a bit lower like 3 seconds, but the battery didnt appear to be in any trouble at that stage.

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