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Percent of Battery for Semi Long Term Storage

Discussion in 'Pro/Adv Discussion' started by DeeX, Jul 3, 2016.

  1. DeeX

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    What is the best percentage (or number of lights) to store batteries for a long while. (3 - 6 months or longer)?

    Thanks!
     
  2. Mark The Droner

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    IMO, it would be best to "exercise" them periodically even if you can't fly, by charging them fully and then discharging them back down to 50% or so every three weeks or so.

    If that's impossible, I'd say you probably want to have the charge at around 65% or so for storage - with the assumption that the battery will naturally discharge slowly over the next six months or more.

    I'd be afraid of storing them at 50% for such a long time because the cells may naturally drop down to levels that are not recoverable.

    MHO
     
  3. DCDrone

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    I'd flown other quads with standard lips for a while, before moving to DJI a few months ago.

    With standard lipo batteries, which are "dumb," a decent charger tells you the voltage and you can set it to charge/discharge to whatever voltage you specify.

    What's the accepted practice for DJI lipos? Seems we have smart batteries, but "dumb" chargers. Is there a way to know the % of charge (without putting it in the craft and reading it on the app)? Do people just use the LED's as a gage?
     
  4. msinger

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    Fully charge them and let them auto discharge or charge them until the 3rd battery light starts blinking. At that point, they are safe to store as-is for about 2 months. If you're storing them for longer than that, you should check them and charge them up again if the second light is no longer blinking/illuminated.
     
  5. DeeX

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    Ok, sounds good.
    It was about 3 months and all were stores with the 3rd light blinking and now have the 2nd light blinking.

    Also curious what about one that is new. I have a spare p3p still in the box. I assume I should pull the batt out of that and do the same. Or is the factory charge good for awhile.
    This leads me to wonder what stores do when they have a stock sitting for a while.



    Sent from my SM-N910T using Tapatalk
     
  6. msinger

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    Yes. You should keep an eye on all of your batteries. If only the first light is blinking/solid, the charge is too low.
     
  7. Vertigo

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    They dont. Or if they do, its because they where no good, and its better find that out in storage then in flight. I have lipo's that I stored (read: lost and/or forgot) for several years, and they still have their charge. I dont think it matters much what the exact charge is, anywhere between 30 and 70% should be ok. Its just fully charged and fully discharged that is no good.

    And if you really want to show your batteries some love, store them cold, like in a fridge.
     
  8. BayouBill

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    The accepted method of storing LIPO batteries long term is to discharge or charge them to 65% and then refrigerate them. But that is for standard (non smart) batteries. Don't know if the smart electronics in the DJI P3 batteries could take refrigeration.
     
  9. msinger

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    Per DJI's Battery Safety Guidelines, they recommend storing batteries between 22°C-28°C.
     
  10. DCDrone

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    It seems there isn't currently a very quick and accurate way to determine your state of charge.
    In the non-DJI world, these are great, and I carry a couple around in my flight bag:
    RMRC Battery Voltage Tester 1-6s [RMRC-VOLT-TESTER] - $2.49 : Ready Made RC LLC, The Leader in All Things FPV, RC, and Beyond
    You can get a quick and detailed read on a battery in an instant. I think the common references for full, storage and minimum charge are based on the voltage (e.g., 11.4v for storage) rather than a %, or some number of flashing green lights.
    I love the DJI products, but I find not knowing the exact state of the batteries a little unsettling. I realize I can hook them up and get the % reading off the tablet, but that's a PITA.
    I'm guessing some clever folks come up with a monitor similar to the above for the DJI - if they haven't already.
     
  11. Vertigo

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    You can read the individual cell voltages in the DJI app. Of course, thats under (very low) load, and a huge hassle, but if you want to know, you can. Sorta. Its also basically the only thing I watch in flight, well, not cell voltages, as that screen blocks almost the entire screen, but overall voltage. Ive seen enough examples of DJI's % estimate going way wrong, and voltages dont lie. Unless the built in voltage sensor lies that is.
     
  12. Vertigo

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    Noted. I have to wonder why they recommend that though. Its well known lipo cells are best stored at cooler temps. Im guessing they dont want condensation issues, considering the electronics in their "smart" battery? So what you could do, is put the battery is a ziplock bag in your fridge. And allow it to warm up long enough before turning it on.

    BTW, I also noticed they tell you to discharge the battery before taking it on a commercial flights. Common sense, but it was questioned here a while ago.
     
  13. DeeX

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    What does one do about the RC. I assume the RC also has a LiPo and typically speak it drains much slower so its more often then not at 80 - 100%.
    Any suggestions for the RC?
     
  14. msinger

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    DJI's offer no advice for maintaining the remote controller battery. I fully charge mine once only one LED is illuminated. I've been doing this for a few years with many remote controllers and never had any trouble with the batteries.
     
  15. DeeX

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    Pardon. Forgive me but "I fully charge mine once only one LED is illuminated" confuses me. I interpret "fully charge" as a battery being at 100% but then you said only one LED. So needless to say Im confused. Were you saying you store at one LED?
     
  16. msinger

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    No. I always store the remote controller as-is. While in storage or actively using it, I recharge the remote controller fully when the battery level drops down to one LED.
     
  17. Brian Nazium

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    Hi,
    Do you NOT recommend using the RC when its lithium batt level drops below several (2) led readouts?
    I am curious about the recommendation to discharge this batt on occasion for longevity...
    thx!
     
  18. Vertigo

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    Its a lipo battery, so there is no benefit in cycling it. If anything, its harmful. Cycling batteries is needed for NiCd and NiMH, not for lipo of Lifepo4.

    For longevity, the same rules apply as for any other lipo: dont store it fully charged, dont store it nearly empty. ~50% is ideal.

    Its recommended to occasionally cycle the flight batteries, but understand that this is not for the battery itself, but rather for the added logic that does capacity estimates.

    BTW, I dont understand why DJI doesnt use lifepo4 in the transmitter.
     
  19. iflyhelis

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    I would rather we went back to NiCad batteries, they were trusted. I have a set that is in my Heath Kit Digital alarm clock I built in 1974 & they are still A-OK. 42 years! Amazing!

    Sorry to say Cad is a heavy metal that has now been banned.

    Kurt
     
  20. Vertigo

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    LifePo4 shares many of the same qualities. Its not quite as energy dense as lipo but much better than nicad and its a far more stable chemistry than lipo. No risk of fires, they dont care how you store them and can stand a lot more abuse. Its perfect for low current applications like receiver or transmitter packs.