Discussions

Lipo Drain: Is it possible to shutdown the ardupilot when lipo voltage drops too low

Posted by AVS on May 11, 2010 at 4:30am

Hi,

 

I managed to destroy a lipo when testing an ardupilot. I didn't notice the ESC had powered down because the LIPO voltage had dropped too low, The ardupilot susequently drained the lipo.

 

I was surprised that the ESC could power down but still provide power to the ardupilot via the throttle cable.

 

Is is possible to add some form of power conservation when the battery voltage drops too low. For example the xbee pro telemetry which uses 250ma to transmit could stop transmitting?

 

The gps could go into sleep mode?

 

I realise that disabling these items might not be considered viable for a UAV but based on the fact that an airbourne UAV must always remain in sight these things are not mission critical and not worth the cost of a lipo?

 

I know that the telemetry provides lipo voltage along with an alarm. Maybe I just need to be more careful and also to hook up the ardustation voltage alarm but this does seem like something that can happen quite easily. What if we forget to switch off the power after a flight, easily done, the ESC will power down but not the ardupilot?

 

Any thoughts?

 

Tim

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Replies

  • John C. May 11, 2010 at 7:51am
    I just saved a lipo that this happened to (left a balancer hooked up to it). Had to borrow a friends charger, but it's was able to switch into NiCd mode....

    I was at ~3V on a 3S 2200 mAh battery...

    Charge it in NiCd mode until it hits about 10V, and then switch to lipo mode.

    Worked for me! Battery has been in good shape for about a month so far.
  • 3D Robotics
    Chris Anderson May 11, 2010 at 7:31am
    Sure, since you have access to the voltage data, you could write code that would turn off some functions (such as sending out telemetry data) when the battery got too low. I'm not quite sure how to power down a GPS but maybe that's possible, too. But you'd only be reducing the power consumption, not turning off the board. To turn off the board, you'd have to wire up a power relay to a spare digital pin and write code to trigger it.

    BTW, even you ESC just by itself with eventually drain a LiPo. It, too, has a microprocessor running, along with other circuitry. If you leave it connected to a battery, it will kill it in a day or two.
  • hopslink May 11, 2010 at 5:35am
    Sounds a bit dodgy - shutting down critical systems to avoid long term battery drain.

    Make yourself a poka-yoke. Splice a different batt. connector onto your aircraft and connect the batt. via a short custom cable. Now epoxy the custom cable to your car key (adapt as necessary) and you will never leave the field without disconnecting your batt. again. Simples :P
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