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how to drain a battery without the drone

Discussion in 'Pro/Adv Discussion' started by Corey Tucker, May 15, 2016.

  1. Corey Tucker

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    i sent one of my drones back for a replacement but i have a second battery that i kept. i heard your supposed to drain batteries if you want use it in 10 days. but how do i drain the battery that i kept without the drone - since its at the shop??
     
  2. msinger

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    You can buy a battery discharger, but it would easiest to let them auto discharge. Just don't press the battery button. That'll add another 10 days (or whatever was set in DJI GO) to the time before they start auto discharging.
     
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  3. Corey Tucker

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    ok cool. i'll just let it run out i guess. didn't know if that was really a big deal or not. thanks
     
  4. msinger

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    It'll be fine. No worries.
     
  5. robinb

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    I use a car main headlight bulb plugged into the terminals of battery. (main beam bulb 60w)

    You must keep it away from anything as it gets VERY hot.
    You must keep an eye on voltage level as it discharges.
     
  6. FantomFlier

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    I see this question frequently, but I don't understand why it is ever required to manually discharge the Phantom 3's batteries?
    This is 2016, these are 'intelligent' batteries, with parameter-driven auto-discharge. Set the required discharge period in the app and forget about it, until the day before you want to use it again.

    Nothing will get VERY hot, and there is absolutely no need to keep an eye on anything.

    No?
     
  7. robinb

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    Well sometimes I need to discharge them down to do a full charge on them as per manual.

    I could wait 10 days or do it in 40 mins.
     
  8. FantomFlier

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    You got me there, although I have never found that it suddenly out of the blue becomes time for a full recharge as per the manual, unless I have been flying, in which case I just override the critical limit and fly it down to 8%.

    As usual, YMMV.

    PS. The original poster was specifically asking about storage for 10 days.
     
  9. Corey Tucker

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    so does it alert you when you need to do a full discharge? i thought you just kinda had to guess
     
  10. Zzyzx

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    It all depends how meticulous you want to be about battery storage and maintenance. Allegedly a battery's life can be extended by being meticulous (saw a test study somewhere that I think reported about 15%, can't locate it right now), but whether it's worth the time and attention is up to you.

    The recommendation (from DJI and battery manufacturers and the experience of folks) is that if you're going to store the battery for longer than 24-48 hours, it should be stored at about 50% charge level.

    Yes, the DJI batteries are smart enough to discharge themselves for storage automatically. Through the DJI config (through DJI Go), you can set how long they wait until they do that. I think the default setting is 3 days. But the auto-discharge takes a couple of days, so with the default wait it could take 4-5 days until it gets to storage level. Pushing the battery power button seems to reset the wait cycle. Again depends how meticulous you want to be, but it might be better to take it down to 50% sooner than that.

    The recommendation is also to deep-cycle the batteries every 20 charge cycles. Deep-cycle is taking it down to 8% (be careful not to excessively discharge, it could damage the battery). The deep-cycle refreshes the battery's ability to hold a full charge. The battery doesn't deep-cycle automatically, and there is no reminder in the app for it (that I know of), you have to keep track of it. The common way to do it with just the Phantom and accessories is by flying the battery down and/or running the motors on the ground.

    There are dischargers out there that can help. One was linked above. I like this one: Phantom Angel The better ones can do both storage and deep discharges, and the really good ones aren't fire hazards (the sketchy ones have a bare unprotected bulb hanging from wires that gets super hot).

    No it's not necessary to use a discharger. If you're happy with the pace of the smart discharge, and with flying/spinning it down for the deep discharge, you're good. The discharger can do it when you want, can discharge faster, and can discharge without putting more time on the motors.
     
  11. msinger

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    In DJI's battery safety guidelines, they recommend not storing the battery fully charged for more than 7 days.

    The dangling bulb dischargers can also do a deep discharge. They are pretty safe to use if you clip the bulb to something stable. And, just like when using any other type of charger/discharger, it's best to be in the room during the charging/discharging process.
     
  12. With The Birds

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    The performance characteristics of lipo (more specifically li ion) battery chemistry are well documented. More than an allegation. Charge a pack to 100% and keep it there for 12 months and you will loose up to 40% of the usable capacity.

    Bettery maintainance was a tedious undertaking. I kike the smart batteries, set auto discharhe to 1 day and charge as close to when i fly as spossible. I might keep partially charged to 60% if im travellinh to reduce wait times. My batteries have 40+ cycles on them and still reading 100%.

    I have seen lipo packs dilligently kept topped off at full charge ready for flight rendered almost useless with 10 cycles.
     
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  13. John Decker

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    I've been leaving them on the 10 day setting on the assumption that DJI wouldn't have a setting that would be anything other than good for the battery, but now I wonder, especially when the manual says

    "The battery automatically discharges to below 65% when it is idle for more than 10 days to prevent it from swelling."

    So, it seems I'll be changing my settings.

    One question: the same manual says to discharge the batteries to 30-50%. Does the auto discharge do this, because 'below 65%' seems a little vague?
     
    #13 John Decker, May 15, 2016
    Last edited: May 15, 2016
  14. msinger

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    The auto discharge feature will discharge the battery to 65%.