Discussions

Battery Voltage display in Mission Planner.

Posted by Roger Hill on June 10, 2013 at 12:57am

I and a few others have noticed that the battery voltage displayed in Mission Planner is incorrect.

 

I am seeing about 0.4 - 0.6 volt difference from that measured at the battery input on the 3DR Power module.

 

The ability to calibrate this has been removed from the battery monitor setup page. The calibration used to consist of measuring the VCC on the board (at the fuse) and plugging that value into the first field on the battery monitor setup page. Refer to this wiki entry: http://copter.ardupilot.com/wiki/common-measuring-battery-voltage-and-current-consumption-with-apm/

 

I have found that I can roughly calibrate this by changing the VOLT_DIVIDER parameter in my case changing it from 10 to 10.3 brings it close. The value displayed in the HUD is very noisy and could do with a bit of filtering.

 

I did log a case in the Mission Planner Github. But this case was closed and I was told that the 3DR module was automatically calibrated.

 

Also as side issue, how do you read the VCC current value in MP when using the 3DR PM. hwvoltage used to show VCC but this is now mostly 0 with intermittent excursions to 30 - 40???.

 

Cheers, Roger...

 

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Replies

  • Francis Ignacio June 14, 2013 at 3:35am

    Hey Roger,

    Thanks for replying to the post I made to the 2.9.1b thread regarding this. Your reply what brought me to this thread.

    I'm assuming the VOLT_DIVIDER is in the Advance Parameter List.  I'll do the same with mine.

  • criro1999 June 11, 2013 at 7:54am

    You are right, me also I see difference on voltage displayed on HUD (or minimOSD) vs real voltage.

    My question is where is best location on Mission Planner to define the low voltage? Because there are many location. One is on Configuratio\Battery monitor. Also you can set the same on Configuration\Planner (last item), then Speech\Battery Warning.

    I am confused since speech says different value of battery voltage comparing to HUD (or Quick tab voltage).

    And last question is: for a quad with 3S 2200, which is the best low level to setup? 9.7v? 9.6v? I have a buzzer also, but when fly FPV at more than 200-300m, hard to hear.And even this buzzer start to make sound at 3.3v per cell (as per documentation), this is different comparing to what I see on HUD.

    For instance, I have the Low voltage set on MP at 9.7V, but looking on parameter list it says LOW_VOLT, 10.5

  • Marco Mueller June 10, 2013 at 11:03am

    Hi,

    I see the same difference. I am using an AttoPilot 180A to measure V and A. My Spektrum telemetry reports correct Volts (verified with multimeter), but telemetry data from the APM 2.5 for battery voltage is always around 0.5 V lower than it actually is. I also have no solution to the problem and it makes me worry about battery fail safe issues in situations where it should not be activated.

    It is not a problem of MP. DroidPlanner on Android reports the same voltage. I think this is because both get the same Mavlink data from the APM.

    BTW: I am running ArduCopter 3.0 RC5

  • Roger Hill June 10, 2013 at 1:27am

    Sorry, I should have given some version information in the message above.

    I am running Mission planner 1.2.53 and APM 2.5 with 2.9.1b

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