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QuickTip: how to "kick start" deep discharged NiMHA batteries

Discussion in 'Flashlights & Other Illumination Devices' started by FiaOlleDog, Jan 4, 2019.

  1. FiaOlleDog

    FiaOlleDog Loaded Pockets

    Oct 27, 2017
    Likes Received:
    (Please excuse the typo in the thread title - it should say "NiMH" and not "NiMHA".)

    Disclaimer: I'm not responsible for any damage or negative impact that may occur for this tip - if you are unsure: simply DON'T DO IT.

    Situation: Christmas tree cable-free illumination "s*cked" my IKEA Ladda NiMH batteries empty, to a level below 0.9V so my chargers did not accept them any longer and did not start charging them.

    Solution (can't remember where I've read about this): using my Olight UC USB charger, put a full NiMH between the charging poles together with a "fan out" on each side (used a 5 Cent copper coin between each charging pole and battery end) and put one of the "dead" NiMH for 1-2 seconds in parallel to the full battery (made sure the + poles of both batteries are on one side, so are the - poles). After this short time i removed the full battery immediately without interrupting the charging connection of the empty battery, so charging continued.

    Result: after a few minutes of inital charging I could remove the still mostly discharged battery from the Olight USB charger and put them it into my other charger, where it continued to get charged. Problem solved by "kick starting" the NiMH battery charging process.

    Hope this helps - at least it did for me in the "YOU are a tech guy and can't charge empty batteries - so the Christmas tree will remain dark ... really?!" situation:hot:

    P.S.: I'm sure I will get a lot of replies like "use a good charger that handles those deeply discharged batteries too, so you won't need to 'grill the Electricians mind and gut' with such a tip". Yup, you are right - a new charger is on it's way to my home ... missed to put it on the wish list, will arrive next week (hopefully) - when the Christmas tree will long be gone. Nevertheless your recommendations for NiMH (or NiMH/LiIon) chargers are appreciated :)
    Last edited by FiaOlleDog, Jan 4, 2019
    #1 FiaOlleDog, Jan 4, 2019
    Last edited: Jan 4, 2019
  2. turbo6

    turbo6 Loaded Pockets

    Feb 23, 2015
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    Even some good chargers can fail to detect dead batteries. The Eneloop branded charger is notorious for this. Good, basic smart charger but if they are over discharged, forget it.

    Another option is if you have an old "dumb charger" that just blindly feeds it juice via a timer system, it should bring back dead cells after several minutes so the "smart charger" detects it is a good cell and begins charging.

    I have a few old Rayovac chargers from maybe 2009 or so and I use these in the event my other chargers won't detect a Nimh cell.