I was hoping someone more skilled in reviewing logs might be able to assist me with a mishap that happened today. I was flying a small simple grid, and things went wonky on the final leg… After 91.5% of the attached log you will see the plane hit WP 13. As it hits WP 14 it veers offtrack for a bit and then seems to correct itself and starts heading down towards WP 15 with what seems to be power off (because of the low draw) and descending!!! Unfortunately, I had looked to the computer and lost site of the bird as it descended into a tree on this final leg…
Could a battery ‘losing’ a cell possibly cause this?
I noticed the battery was a little puffy when I pulled it… just checked it on the charger and it has a dead cell. At least the charger is reporting it on see’s 3 cells on the 4 cell battery?
I checked out your tlog with Mission planner using the log-playback and the tuning-check box.
The indicated starting voltage of the battery was 14.6 volts and it steadily drops down to about 12.35 volts.
Just after mission time point of 14:48:35 the Amps drop off , the power consumption is about 7 Watts at this point, and the RC3-Out [ Throttle ] output from APM is still high.
The battery was not charged. 14.5 - 14.6 volts should be the lowest operating voltage for 4-cell Lipo.
I’d guess that the auto-voltage-cutoff on the ESC was triggered.
I don’t think the ESC will re-arm until the throttle is returned to zero.
If the ESC has a “hard cuttoff” it will dis-arm the throttle suddenly , a soft-cutoff IMO is much more desirable .
Also, 12.35 volts for a 4-cell Lipo is 3.075 volts per cell. If the battery voltage is not evenly distributed across the cells, then very likely one or more cells dropped below the “death voltage” of 3.0 volts and puffed-up.
It seems easier to use the tuning window on playback (I didn’t know you could do that) than trying to cipher through the dataflash logs. And yes, the battery wasn’t fully charged, and I thought I could get another short flight in with it… chalk it up operator error… learning the hard way.