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Recovering low voltage lipos

Discussion in 'Scratchbuild Talk' started by bhawken, Dec 19, 2009.

  1. bhawken

    bhawken Cadet

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    Apologies if this is a repeat question. I did a (admittedly quick) search, but nothing came up.

    I have two batteries that my thunder power charger will no longer charge (with or without the balancer plugged in). It errors out on 'Voltage error or wrong polarity'; won't even give me the option to do the recovery on countdown. Is there a way to salvage these batteries?

    Thanks!
    Brian.
  2. Cabledawg1

    Cabledawg1 Cadet

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    I had a plane stuck in a tree and had that problem...heres the post

    I got the Hawk Sky out of the hypothetical tree. After 4 days up there and 1 night of freezing cold heavy rain and wind, I found it on the ground. One of the aileron rods and hinge came off and the aileron hinges where the foam hinges is cracked. Should I buy hinge tape or will strapping tape work ok?
    As far as the LIPO goes, it was dead. It wouldnt charge on the balance charger, so I put it in my nicad cgarger at 1/2 an amp until it got to 9V. Then I put it back on the balance charger, and its perfect now.
    The electronics in the plane are working fine. Id say I was pretty lucky.
    [​IMG]
  3. Dredogol

    Dredogol M0DERATOR - (aka "Dred")

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    THAT is not a good idea...
    The way NiCad's and LiPo's charge are slighly different...
    Yes, you were lucky for that LiPo.

    This is why Dave (and everyone else) says to NEVER discharge your LiPo below 30%.

    Example:
    For an 11.1v (3-cell) LiPo, the max charge is roughly 12.6v. You do not want to discharge below 8.0v (or roughly 2.6v EA cell).
    Any lower than that, you risk your LiPo dying.
  4. bhawken

    bhawken Cadet

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    Well, I left one of them plugged into one of the cheapies that trickles through the balancer, and it seems to have jump started it enough that the TP charger recognizes it again. Phew!

    Thanks for the advice. :D

    Cheers,
    Brian.

    P.S. I just realized I'm a senior member now. woohoo!
  5. MoTheG

    MoTheG Airman

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    You connect the battery to a power-source of >4V <3W for a short time and then you connect it immediately to the charger.
    thread
  6. JettaManDan

    JettaManDan Administrator

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    for lipo's that weren't completely at zero volts i've done 2 different things...used one of the slow balance chargers to bring it back up..or the NiMh method talked about above (think i pioneered it lol!) i do .5 amps for 30 seconds and watch the battery voltage..as soon as it gets above 9 volts i stop the charge and then put it back on the balance charger...has saved 3 packs that were not puffed...
  7. Jbirky

    Jbirky Airman

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    I do a charge for Pb (Lead Acid/Car) charge for a 6V lead cell... (I would do 12V, but it tops out at 14v, which would be bad if I don't watch)


    Anyway, eventually, it reaches 7V and won't put any more in. (It won't recognize it as a 3S cell)

    Now, I select LiPo 2S and charge it again... this brings the 3S to 8.4 V, balanced

    I now hit it with like 5000 mAh NiCd while watching it until it breaks 9v; I use this fast rate because I get annoyed fast and don't want to watch a pot boil.

    As soon as it breaks 9V, I stop the charge & Select 3S...

    Then I come back like an hour later & it is fully charged.
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