Hello,
I installed an Attopilot 90amps sensor for current and voltage on my Octo.
I then did the mission planner configuration in battery monitor, first trying with the preprogrammed Attopilot 90 option in the sensors drop down list. The calced voltage and current is totally way off.
So I went for the "other sensor" choice in the drop down list, following the calibration instructions here : http://copter.ardupilot.com/wiki/common-measuring-battery-voltage-and-current-consumption-with-apm/#Calibrating_the_voltage_reading
I stopped at the voltage calibration step because it does not work for me as I would expect: when I enter the measured voltage (via a power analyzer) in the corresponding field: "1. Measured battery voltage", then the voltage divider (calced) is updated and for a few seconds the voltage displayed on the HUD is correct. But after a few seconds, the voltage measured by APM drifts way off by a couple volts (while the voltage on the power analyzer does not budge). I did try many times to re-enter the measured voltage to "resync" the calced displayed voltage, but it remains unstable and drifts a lot.
I did not go further in the calibration procedure (on to current calibration) because I'd like first to solve this voltage measurement instability.
(PS : I did the voltage calibration on the ground, disarmed, motors not turning)
Is there a trick I did not get in the calibration procedure?
Replies
Funnily enough, I have lots of problems with voltage sensing, both with Atta and the 3DR PM. Inaccurate reading, or just frankly ridiculous figures (anything from 34,000 as a voltage divider to 0.01V detected).
One thing that fixed it each time? Re-upload the firmware, and do factory reset. Bit drastic I know, but it did work for me.
The only important values to write down/take a screenshot of all the basic PIDs, and your RTL settings (if used). I tried wiping the voltage settings in "all parameters" but that didn't really work.
It now reads ok, but is usually about 0.1V-0.3V less than actual (on 6S). This is not actually too much of a problem because it means you're landing with more volts than you think.