Battery fail safe triggered at wrong voltage?

Hey all,

Flew my DJI S1000+ with genace tattu 6S 22000mAh battery the other day. I have never pushed the battery to see what the longest safe flight time i could get was but am working my way to that point. I just loaded 3.4 rc1 and took it out. after about 13 minutes i heard the buzzer go off for failsafe and the GCS informed me the battery failsafe had triggered which I have set at 20.4 volts (3.4 volts/cell). It seemed a bit soon as I have gone a bit longer but I was doing an Autotune. When looking at the logs the lowest voltage recorded is 21.64 (3.606 volts/cell). I can not figure out why it triggered at the voltage it did. I am using a Mauch hall sensor for voltage and current that was supplied with a calibration report. So far the voltage and current readings have been ridiculously accurate. Even if the sensor was off, the logs dont match the specified failsafe voltage. Anyone have any ideas?

Post the log, that will help

Here is the log Bill,

Thanks in advance for looking at it. If you have a chance to take a look at some other logged parameters I would appreciate it. I have never had a chance for anyone to look at my logs.

https://drive.google.com/open?id=0B5vwo36WQS__V0RoVGwtUEVhV2s

Warning in advance, I log just about everything so the log is large… around 400mb.

It was only a warning http://ardupilot.org/copter/docs/failsafe-battery.html

You have FS_BATT_VOLTAGE set to 21.9

Even if the battery failsafe is not enabled (i.e. FS_BATT_ENABLE = 0) the “Low Battery” voltage threshold and “Reserved MAH” numbers are used to issue a battery warning

Thank you for your time and help in taking a look Bill. I feel a bit dumb now lol, i could have sworn it was set to 3.4v per cell or 20.4 volts total. Anyways thanks again for your support!

@nikker Can you post a link to your log again. It’s break one of our analyzers and we cannot figure out why, and we want to check it against it.

Was the log a pure data flash file or exported via a tool?

Sure, when get home I will post it again. It was straight from the pixhawk My logs are usually around 400mb and usually give me problems. I spoke to Mike Osborne? About this in the mission planner forum since I can not geotag images, I always get a log error but using ultra edit I see all looks as it should.

Bill, here is a link to the log.

Please let me know if you have issues downloading it.

https://drive.google.com/open?id=0B5vwo36WQS__V0RoVGwtUEVhV2s