I am using Copter 4.0.2 with the Mauch PL Sensor (200A) and I have set up the power info in Mission Planner and it seems to work fine on fully charged batteries. I am getting amp draw, mAh consumption and voltage numbers and the battery percentage will start to go down from 100% as I am flying.
The problem I am having is after flying for say 10 minutes and my batteries are about 50%, I land and unplug the batteries, but when I plug the same batteries back in the battery percentage goes back to 100% on the screen, even though the batteries are now at roughly 50% left and the voltage it is showing in Mission Planner is correct.
Any idea on why this is doing that and how I can fix it? It seems to be only going by mAh consumed and as soon as you turn it off and plug back in the mAh goes from 8000 mAh to 0 and will say 100%, which is completely wrong.
The percentage shown in Mission Planner is based on mAh consumed related to whatever the battery capacity parameter is during the power cycle of the drone, therefore unplugging the batteries resets the percentage.
You would need some type of smart battery for mission planner to keep track of the percentage after unplugging and plugging back in.
Yes a smart battery would be a specific type of battery, they usually have some sort of microchip installed internally that monitors battery parameters and provides them to their charger or a flight controller. I don’t believe there is any way to do this with base PX4 or Ardupilot and standard LiPo batteries
The bottom line is you’ve got to know your own batteries and flight times. So if you’ve flown 5 minutes and then restart you drone, you’ve got to understand that you’ve only got (example) 4 minutes safe flight time left.
Make sure the battery failsafes are set and tested.
These are the paramaters I’d check:
BATT_ARM_VOLT (set so that you’re not arming with a low battery)
BATT_CRT_VOLT 3.5 x no. of LiPo cells
BATT_LOW_VOLT 3.6 x no. of LiPo cells
BATT_LOW_TIMER (test, depends how your batteries recover and how safe you want to be)
MOT_BAT_CURR_MAX (depends what your batteries and/or distribution system will supply)
MOT_BAT_VOLT_MAX 4.2 x no. of LiPo cells
MOT_BAT_VOLT_MIN 3.3 x no. of LiPo cells
The problem is that you cant reliably do that, or even come reasonably close - hence the requirement for smart batteries which will monitor their own usage.
There’s numerous discussions on all this already.