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New battery auto-discharging feature?

Discussion in 'General Discussion' started by cahutch, Oct 28, 2014.

  1. cahutch

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    From the firmware notes...
    "New auto-discharging feature to address the issue of fully charged battery swelled when it was stored for an extended period."

    I'm all updated, including new battery firmware on two batteries and I can't see any control for auto discharging.
    Nothing in the Phantom Assistant software (3.2 or 3.4)
    Nothing that I can find in the Vision app.
    Nothing mentioned in the updated manual (Vision+ V1.6)

    Anyone have a clue?

    I assumed it would give us a way to charge to 50% or discharge down to 50% when we plan to store the battery.
    Maybe it's completely automatic if the battery is left fully charged for too long?
     
  2. GerdS

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    I also can only guess:

    LiPo batteries are very sensitive to temperature. They can take more charge with higher temperature than with low temperature. If they get fully charged e.g. at 25°C and then get stored while temperature is varying it might happen that their cell voltages increase above the maximum alloved voltage of 4.2V per cell if the temperature goes e.g. below 20°C. This leads to cell damage.

    So I guess DJI has implemented a voltage governor even while the battery is not actually connected to the charger for automatically re-balancing the cells as soon as a cell voltage will increase beyond 4.2V.

    Regards, Gerd
     
  3. 4wd

    4wd

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    I suspect this (continual?) self balancing should see a major reduction in failed batteries, assuming that's the main reason for them failing as suspected.
    Hard to see how it could discharge itself to 50% if stored more than 7 days, where would the power go?

    It's a typical DJI muddle yet again - trumpeting an apparently good new feature but not explaining properly how it is used in practice. Perhaps the DJI forums will reveal all first.
     
  4. GerdS

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    The power will go just into heat. It's not that much power as you are expecting because the battery cells will be only discharged while overvoltage until they are in the safe region below 4.2V again. So maybe the battery may warm up itself for 1-2° while discharging cells, no more.

    Regards, Gerd
     
  5. npalen

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    So is this auto discharge feature available only in new batteries or in existing batteries with updated firmware?
     
  6. GerdS

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    No word from DJI about a limitation to a specific hardware revision, so I guess it works on all P2 batteries.
    The hardware was already there from the beginning but just used for cell balancing during charging.

    Regrads, Gerd
     
  7. VoicOfReason

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    When I upgrade my firmware, there was no update for my battery. Am I missing something? Should there be?
     
  8. cahutch

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    Yeah. The new 3.4 version doesn't show the battery upgrade option. You have to use version 3.2 to update the batteries.
     
  9. Stile2112

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    Yep, use 3.2 to upgrade the batteries, 3.4 for everything else.
     
  10. ianwood

    ianwood Taco Wrangler
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    Wow. DJI have really outdone themselves in the "WTF?" department.
     
  11. knuckles

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    I was going to post the same question. Man that sure seems stupid to not include the battery upgrade with the latest software version :roll:
     
  12. BlackTracer

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    I think we will see the release of 3.41 or the like very soon. This was not intentional. They blocked it in 3.4 somehow and will be fixing it I assume.
     
  13. VoicOfReason

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    So, what exactly does this new battery firmware do? Does it drain the battery down to 50% automatically just sitting on the table (among other things)?
     
  14. Meta4

    Meta4 Moderator
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    Probably not .. it wouldn't be very smart to have your batteries start discharging as soon as you take them off the charger.
     
  15. VoicOfReason

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    Hmmmm... So,what DOES it do?
     
  16. cahutch

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    Maybe.... If you power on the battery with it removed from the Phantom, it will stay on, discharging down to 40-60% and automatically power off. ??
    I'll give that a try when I'm at home tonight. It should take a very long time to discharge that much power or it will get very hot.

    Update: Nope. It shuts itself off in a few minutes with no noticeable temperature change while it's on.
     
  17. gunslinger

    gunslinger Moderator
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    Umm... yeah... that's just a bit sketchy.... :shock: :shock: :shock:

    -slinger
     
  18. cahutch

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    I think I figured this out. My batteries were fully charged a couple of weeks ago. Today I checked them getting ready to fly and they were down to ~75%
    It looks like they self discharge when not in use. Hopefully only down to 50% but I'll need to leave a battery unused for a while longer to find out.
     
  19. 4wd

    4wd

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    I deliberately left my original battery (smaller round pins) fully charged since 4th November and it has lost one LED so 75% this morning - auto discharge seems to be working.
    It's surprising (or maybe not!) DJI started obfuscating on their own forum about how the new features only worked with the very latest batteries which might not even be available yet :roll:
     
  20. N017RW

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    It begins after 10 days of no useage and takes about two days (from full charge).

    Simply turning it on-off resets the timer.
    (not sure if just a level check resets timer or not but I would guess yes)