Coper LEDS low voltage does this feature work?

Hi all,

I finally have some time to work with my tricopter project.  I've been slowly getting things working.  I just added the UBlox GPS to my APM 2.0.  Nice upgrade - the tricopter no longer has the jitters in Loiter mode and the lock is super fast.  Need to do more tweaking.

I have implemented the copter leds feature on my tricopter and I presently have motor arm status and GPS lock status working.   Works great - the arming status is a good safety feature. 

The only thing that doesn't seem to work is the low voltage alarm.  I set the bit on and off and nothing happens.  I assume the motor leds are supposed to oscillate at low voltage which appears to be set at 9.6V.  I moved the voltage up higher - no change.

I have the AttoPilot sensor and its working properly - voltage and current displayed in Mission Planner.   When voltage is below the set limit (verified in Mission Planner) nothing happens.

What am I missing?

You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –


  • I assume the LEDs you guys are talking about are the tiny ones on the APM board?

    What I was hoping to do is have larger red/green/white nav lights on my quad (for orientation) which are solid when >75% charge, and have them blink when they hit 75%. Is there a straightforward way of getting something like that hooked up? I assume I could just power the LEDs from any available 5V output on the APM for the first part of the functionality, but how would I hook into the low voltage alarm blinking?

    If this was easy to get set up, I think it would be a really handy feature to help everyone keep their batteries in good shape, and help normalize the flight times people are quoting, if they count from takeoff to when the lights start blinking.

  • Hi Lloyd,

    Thank you for the response.  I haven't tried modifying and compiling the base code.  I'm sure the BATTERY_EVENT set to DISABLED is my problem.  I don't see a way to set this in Mission Planner.

    My BATTERY MONITOR flag is set already to 4 for voltage and current so I don't think that parameters turns on BATTERY_EVENT.

    Well I'll have to learn how to download and compile the code for testing.  I'm sure that will be a good learning experience.

    Thank you again,



  • Brian,

    I wasted a lot of hours on this one.  I even wrote my own low voltage detect logic and added it to the LED code.  Then one day, just couldn't stand it and found the answer staring me in the face.


    In config.h,   BATTERY_EVENT  is DISABLED.      BATTERY_EVENT enables the low voltage check logic. 

    To enable it, I added the following two lines to APM_Config.h:

    #define  BATTERY_EVENT        ENABLED

    #define  LOW_VOLTAGE          10.2

    I only add the LOW_VOLTAGE define since I'm in there and it saves setting it in the parameters config screen of Mission Planner. 

    You could also ENABLE BATTERY_EVENT in config.h, but I tend to avoid modifng things in that file. 

    Also, I couldn't find a way to enable BATTERY EVENT in Mssion Planner.  I'd love to know if there is a way.

    One other thing.  I set LED_MODE to 1 for my quad.

    Hope this works for you!

This reply was deleted.


Laurie J. Troy liked Jasper Kueppers's profile
Apr 1
Timothy Miller liked Joseph Udofia's profile
Mar 18
Joseph Udofia liked Joseph Udofia's profile
Mar 3