we've got -15 today and since the weather is very calm I tried to finally run autotune on my newly built quad.

I have the following failsafe settings for my 5000 mAh 3S battery:

* FS_BATT_MAH = 1000

I warmed up battery before flight.

The thing is that battery failsafe was triggered after about 6 minutes (voltage drop) while the battery was drained only for 30% according to the charger.

My question is if I should lover (or even turn off) FS_BATT_VOLTAGE and rely only on FS_BATT_MAH? What will happen in this case if voltage under load drops even lower while there still is enough capacity in battery?

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  • I believe 10.5 is a good number for a few reasons. Mainly you have voltage sag.Your main issue i believe is the temp. Even though you warmed your batt up,,-15 is COLD!!!!!!! In 30 degrees you get a 20 percent plus loss of flight time. -15,i would suspect a 40 percent loss at least. Sorry, but true. I can take my trex 700 on 12s that usually gets 7-8 mins, and when in 25-30degrees, i get about 4-5 min with not much punch through the entire flight. Hope this helps. On my Tarot x6, i had my batt fs set at 23v,went out in 30 degrees, and my failsafe went on in 4 min!!! And i have a 6s 20,000 mah bat!!!!!!  In 60 degrees, it took 12 min to do the same!  I have it set for 21v now,which is the same as yours--3.5v per cell. Dont chance anything lower or much anything else,especially in that kind of cold,or any temp for that matter. Frank.

  • I personally always use a Lipo alarm and set it to 3.7v Here that way I don't have to rely on multiple sources telling me to land :)

    @ 3.7 I normally have about a minute reserve before I get to the 20% left which is the minimum I ever let my lipos get.

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