Failsafe Triggered?


Just finished building a Flip FPV Pro G but have no gimbal yet, but have added some weight to compensate. The Flip could use a little more tuning but flies fine.

Flip FPV Pro G

Pixhawk running 3.15

MT2216 900Kv Tiger motors

Skywalker 25A Quatro 4 in 1 ESC

10 x 4.5 props

Twice today and the last flight yesterday, fail safe has triggered and I am not sure why.

The first flight today was about 2 1/2 minutes and the second flight was even shorter before fail safe triggered.

The Flip is set to RTL on fail safe so all was fine.  Both flights used a fully charged 3500 mAh battery.

Attached is the log from the second short flight today.

I would expect at least a few more minute out of this battery. 

Can someone look at my log and tell me why fail safe is triggering?

Thank you.


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  • Still seeing lousy flight times, probably due to weight.  Flip with no battery weighs 3.3 lbs compared to Iris which weighs 2.2 lbs.

    I do I have an extra small battery in front as a weight to compensate for lack of gimbal, which I plan on adding.

    Image on top is from Iris flight with same battery and a GoPro attached.  Got about 8 1/2 - 9 minutes flight time.

    Image on bottom is Flip with the same battery (3500 mAh ) charged to 12.49 volts.  Got about 2 1/2 minutes before battery was just under 60 percent at 10.9 volts.  I do have some 5000 mAh batteries to try , but expect flight time to be lousy, maybe I'll get 5 minutes.

    Other items on Flip are 915 Mhz antenna, speaker, external LED and 12C bus.

    I'm not sure what to do about the weight and I still need to balance the 10x4.5 props.

    Things to try are, remove extra battery and test flight time.  Balance props or try other props.

    Anyone have any other suggestions?



  • Voltage seems ok.  Had a look at at my ESC settings and they seem ok too.

    I did change the battery type from Lipo to Ni-xx as recommended by this page.

    I have another quad and will try the same battery in both of them this weekend to see if it is actually the battery or the Flip.

    • Voltage and current measuring not ok.

      Hooking the quad to apm and adding a 3.5 mAh battery at 12.45 v gets readings of .2 or .3v .

      If I try to adjust this under Battery Monitor/ Advanced Settings/ Measure Battery Voltage and put 12.45 I then get crazy voltage readings from 8.5 - 16 v, constantly fluctuating.

      Am Does this mean I have a bad power module? (using the one that came with the pixhawk.)

      Any ideas?

      • Fixed the voltage issue.  Replaced cable from 3DR Power module to power on Pixhawk.

        Ground wire had come loose.

  • Moderator


    Can you post a copy of your parameter file? Your log file does show an RTL event at line 5249, volts appears to have been around 10.4v and you were drawing around 15A at the time of RTL with 663 mAH having been consumed at that time. How old is your battery?


    Nathaniel ~KD2DEY

    • Thanks for looking Nathaniel.

      One battery is about 6 months old and one is about 3 months old.

      Attached are the parameters.


      • Moderator

        Hey Todd,

        Thanks for the parameter file! So, I'm by no means an expert here, but this is what I see. The Battery Failsafe (voltage) is set with the parameter FS_BATT_VOLTAGE, and currently it is set at 10.60000038 volts. We already can see that the voltage in your logfile dropped below this for over 22 seconds when the failsafe is triggered. Battery Failsafe is triggered if "your battery voltage becomes low for more than 10 seconds".


        Your battery voltage drops off quite sharply once you apply a load; it took less than 30 seconds for the voltage to go below 11 volts.

        I think your battery either isn't reaching a full charge state or perhaps is damaged somehow. Do you use a balance charger: one that monitors each individual cell? Also what brand of battery are you using? Do you have another battery you can try?

        Also have you calibrated your Voltage/Current monitor as shown in this video?


        Nathaniel ~KD2DEY

        • Thanks Nathaniel. 

          No, I hadn't seen that video.  I'll try calibrating the voltage/current with a freshly charged battery and see what happens. 

          I'm using a Turnigy Accucell 6 and balance charging the batteries.


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