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P3 battery - 41 cycles - voltage dies at 46%

Discussion in 'Pro/Adv Discussion' started by Reflex Films, Sep 7, 2016.

  1. Reflex Films

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    Hi Guys,


    Has Anyone had any success bringing a battery "back from the dead" ?

    I have 2 batteries - each with 41 cycles on them.

    Battery #1 just started dropping voltage fast at about 46% capacity. I watch the cells in the go app (battery window open) mid flight and the cells suddenly drop from yellow to small red bars.

    Auto landing low voltage warning comes on - and the P3 auto lands.

    On landing at rest the batteries show healthy green bars - i take off and they drop immediately to small red bars.

    I only fly my batteries to 25% before landing - so they shouldn't be that stressed.

    i have auto discharge set to 4 days to avoid stressing them.

    I would have thought the intelligent circuitry would have managed the battery better than this given my considered and conservative flying approach.
     
  2. RedHotPoker

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    I Suggest doing a deep cycle procedure..
    Drain them batteries down to 8% then charge back to 100%.

    RedHotPoker
     
  3. Reflex Films

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    Thanks for the tip

    I am doing that now - will recharge battery and go flying....and see what happens. I nearly got caught out as I took off with 50 % battery expecting to be good for a 5 minute sortie - luckily the P3 wasnt over water or trees when the sudden voltage drop happened.

    everything has been rock solid on the Advanced for over 14 months of flying so this was my first wake up call.

    Might deep cycle my second battery as well just to be sure.
     
  4. Mark The Droner

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    Did you know DJI advises to always launch with a fully charged battery?
     
  5. msinger

    Approved Vendor

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    Reflex Films, when you put a lot of stress on the battery (e.g. taking off), the voltage will temporarily dip. That could bring a partially charged battery down to the low or critically low level.

    Do you have any trouble with your batteries if you take off when they are 100% charged?
     
  6. Reflex Films

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    Batteries are all good at higher charge levels - behaving as expected.

    I have regularly flown partially charged batteries as i often have jobs that require multiple location 5 minute shoots - this is the first time I have been caught out.
     
  7. Reflex Films

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    Ok I got a final result

    Just as final conclusion and heads up to anyone that has a similar issue

    I deep cycled the battery to 5 %, put it in the fridge to cool it down for 5 minutes and then recharged to 100% (actually it only went to 97% - so some understandable wear and tear on the battery has occurred - no worries!)

    I flew the battery and the issue has gone - i particularly paid attention to when it got between 51% and 40 % - monitoring the individual cells through the go app on the ipad (it really is quite brilliant the amount of telemetry that comes through) -

    I hovered in close giving it a few full throttle climb bursts to reveal any excessive voltage drop - all good now - although cell 1 does drop into red before the others . But all all very functional.

    So in summary -for anyone experiencing a similar issue- the deep cycle trick worked!
     
    monkeychops likes this.
  8. John Locke

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    When you do multiple sorties like you explained, if you turn off the craft at 40% battery you may see 55 or 60% when you turn it on 30 min late with no load. It can be misleading.

    Pay attention to the voltage and percentage before shutting down the craft as you land (not after you land) and compare that to when you fly it again without recharging. I don't trust the battery display percentage algorithm, I only watch the voltage level and land by 3.5V.
     
  9. arierep60

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    when you land with 3.5V how much percentage you have left?
     
  10. Reflex Films

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    I never fly to less than 20 % - which is rare - I have my first warning at 30% - and If i ever hear it i land the Phantom.