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How to fully drain battery??

Discussion in 'General Discussion' started by drew4392, Feb 25, 2014.

  1. drew4392

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    I remember seeing on one of the DJI videos that they recommend fully discharging your batteries every ~10-15 (somewhere around there) charges.

    I tried leaving the phantom on after a 15 minute flight, and this battery is tough to get below 8% (I think that is what DJI calls for).

    Any tips on how to discharge these batteries? A way other than letting it sit there for hours would be great.


    Thanks!
     
  2. DanCH

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    Got a link for that video? Sounds like a stunningly bad idea to let lipo batteries full drain, unless you intended to dispose them.

    General consensus seems to never let each cell go below 20%. Lower than that can cause unrecoverable damage (drastically reduced capacity).
     
  3. OI Photography

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    I think DJI just means to fully drain them to 20% every so often as opposed to only using/recharging a portion of the working capacity all the time.
     
  4. ElGuano

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    I wouldn't bother doing this, unless you have a smart battery like the p2 that counts mah to determine battery health. For a standard lipo, there is no need to ever deep discharge it from a regular maintenance perspective.

    If you really needed to get it below your flight threshold, you can use a smart charger that has a discharge feature--those will bring the cells down to 3.0v (danger).
     
  5. Pull_Up

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    That advice is certainly valid for the Phantom 2 Vision, which uses the new DJI smart battery. Every 20 charging cycles the manual recommends discharging to 8% - this is to help keep the battery meter calibrated, apparently.

    If you do have one of these batteries and a Vision with telemetry then the easiest way to discharge it is to keep flying beyond the autoland threshold. You can override the autoland by giving more throttle. You can then just hover it in front of you using throttle to override autoland until you get to 8% on the readout on the app.
     
  6. Wind_Shear

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    I left my P2 on with the gimbal active and GoPro recording while sitting on the deck of the boat to get the battery drained to 7%.

    It stayed at 8% for at least 20 minutes after relatively quickly draining from 20% to 8% in about the same amount of time.

    Wish I'd measured the flying time before and after, but I didn't, so can't verify any benefit from this, though.


    Sent from my iPad using Tapatalk
     
  7. pault

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    Have not yet got to the 20 discharge level yet but when I do I plan to just run the P2V on the table indoors with the props off and motors running. I know most internal combustion engines do not like running without load but cannot see this applies to electric motors. Just a bit concerned that the motors might get a bit hot without airflow so will monitor them with a digital thermometer.
     
  8. Pull_Up

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    I did that once pault, and the good news is the motors and ESCs ran cool and smooth, no issues. The bad news is that it still took me over an hour to get it down to the level I needed it to be! :lol:
     
  9. ElGuano

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    IIRC the static drain on the gimbal is about 100ma, so it should take about half an hour to go down 1%, give or take. The %ages at the poles are a bit wonky for everything; my laptop and phone batteries sit at 1-5% for hours it seems, just as my software installation progress bars stick at "less than a minute remaining" for hours. So there's some calibration optimization that can be done...