Minimum battery level in APM for 3S pack


#1

I am now starting to refine my settings for my APM and am looking at setting up the battery failsafe. What level would people suggest as a save level. I know that LiPo’s aren’t meant to go below 3V per cell, so I was thinking something around 3.5V per cell? So about 10.5V overall?

Would anyone go lower?


#2

3V per cell is the bare minimum and I would try stay away from that as much as possible as some ESC can shut down at 3V and cause a crash :boom:! I think that 3.5V is ok, it will give you about 60 seconds or so land which should be fine :battery: but some people push it to 3.4, or 3.3v! I guess it really depends how far you plan to fly. I think it would be cool to calculate this low voltage fail-safe based on the distance from home, maybe ina future arducopter release :-).

One thing that I would highly suggest is that you make sure that the APM power module is calibrated properly.

Calibrate APM power module

First check if it needs calibration

  • Check the voltage of your lipo battery with a hand-held volt meter or a power analyzer
  • Connect your APM/PX4 to your computer and plug in the lipo battery
  • Check the voltage through the mission planner’s INITIAL SETUP > Optional Hardware > Battery Monitor screen or on the Flight Data screen’s HUD or Status tab.

If it needs to be calibrated then do the following.

  • Go to the battery monitor screen (under initial setup>optional hardware)
  • Enter the voltage according to the hand-held volt meter in the “Measured Battery Voltage” field
  • Press tab or click out of the field and the “Voltage Divider (Calced)” value will update and the “Battery voltage (Calced)” should now equal the measured voltage