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Thread: re: battery polarity reversed

  1. #1

    Default re: battery polarity reversed

    I have a polarity question.

    I have a remote control with 4 NIMH cells,
    i guess there is no polarity protection on this remote, as one of the cells reversed polarity to -.01v.

    I was wondering if it is possible to fix the cell? let it drain to 0v?
    or is it garbage?

    side question.
    Of the three remaining cells, 2 cells are now at 1.2v, the third is at 0.1v.
    I wanted to know if I can charge that third cell separately (on it's own) to get it to the same voltage, or can i charge the remaining 3 cells together?
    I have a first gen GP powerbank rapid charger
    -G
    Last edited by gramps416; 04-22-2009 at 04:16 PM.

  2. #2
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    Default Re: battery polarity reversed

    happens all the time, the cell that is showing a reverse voltage, has been damaged, depending on how many times that happens, how hard it hit, and how long it stays/stayed that way, will depend on if it is usable.
    being an alert and aware person, you already know what is going on, because you got the voltage on it.
    charge it back up (if you can SLOWLY at first) and check it if you can.

    you did not provide enough information about the charger, because there are more than one GP powerbanks, 15 min one, and 1 hour one, and who knows what else.

    the data we would need to know is:
    does it charge as single channel? meaning can you charge just One item, or does it require a team?
    if its single then each battery will recieve the charge needed for it, if its series charger then it prefers matched battereis.
    and if you ask me matching up the .1V with the -.1v should work fine , if your stuffing it in a series charger as a team.

    most likly all the batteries are 90+% discharged, and the most damage of reverse has already been done.
    some chargers will not Charge a battery that severly depleated, but if you knew how to read the voltage, then you probably know how to kick the voltage back up so the battery will start charging again. you would not drain it back to +0 from -.1 , you would just slowly recharge it.
    you know that the .1v battery is drained a bit too far ALSO, as the preferred low for them is to stop around .9-.4v , but mostly its to make sure it doesnt fully deplete and get reverse charged.

    there just isnt a lot you can do. If you can, bring it up slowly, then send it on its normal routine. it helps to have some way to check each of the cells because of this, so you can toss out the ones that will just cause you greif.
    Last edited by VidPro; 04-23-2009 at 07:45 AM.

  3. #3

    Default Re: battery polarity reversed

    Quote Originally Posted by VidPro View Post
    you probably know how to kick the voltage back up so the battery will start charging again. you would not drain it back to +0 from -.1 , you would just slowly recharge it.
    i understand everything up until this part. How do I "kick the voltage back up so the battery will start charging again?"

    and what do you mean be you would not drain it back to +0 from -0.1, you would slowly recharge it?

    my charger will allow a single cell to be charged. Which is the better charger to use

    i own 2 charges actually. One is a rapid charge 3-4 hour (ish) gp powerbank.

    the second is a energizer value charge slow charge 16 hour
    -g

  4. #4
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    Default Re: battery polarity reversed

    you kick the voltage back up with the charger if you can, if it will not charge (on the charger) then you just hit it with some power from a powersupply, or parellel it with another battery for a short time.

    yes trying to redrain it back to 0 from -.1 wouldnt do much to help, you would just charge it, to get it going in the correct direction again.

    use the 16 hour charger so the intitial charge out of reverse gets done with less torture, at least till it is back up a bit. also the slow charger is more likly to be dumb charging, and charge the reversed cell, wheras a smarter charger might have a fit about the voltage.
    Either way you will still have to check it , to insure that it is charging. it might just SIT there not charging and heating up till the voltage shows going positive, you do want it to start moving back in positive voltage even if you have to whoop it to do so. sitting there not charging will not help.
    Last edited by VidPro; 04-23-2009 at 08:58 PM.

  5. #5
    Flashaholic* TakeTheActive's Avatar
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    Lightbulb Re: battery polarity reversed

    Quote Originally Posted by gramps416 View Post
    i understand everything up until this part. How do I "kick the voltage back up so the battery will start charging again?"

    and what do you mean be you would not drain it back to +0 from -0.1, you would slowly recharge it?
    Picture a plucked rubber band in slow-motion [or a 'lopsided' (in the case of a NiMH cell) SINE WAVE] - it always wants to cross ZERO.

    Thus, your cell, during DISCHARGE, will always go from ~1.2VDC (plus OR minus) downwards (towards ZERO). If it's at -0.1VDC, DISCHARGE will only bring it back to 0VDC. *BUT*, CHARGE will bring it back, THROUGH 0VDC, to ~1.2VDC+!

    Quote Originally Posted by gramps416 View Post
    ...my charger will allow a single cell to be charged. Which is the better charger to use

    i own 2 charges actually. One is a rapid charge 3-4 hour (ish) gp powerbank.

    the second is a energizer value charge slow charge 16 hour...
    I'd use the "energizer value charge slow charge 16 hour" because I'd like to SIMULATE a "BREAK-IN" cycle on those poor TORTURED cells:
    1. CHARGE @ 0.1C for 16 hours (i.e. use your Energizer Slow Charger)
    2. DISCHARGE @ 0.2C (What do you have available? What's the mAh CAPACITY of your cells?)
    3. CHARGE @ 0.1C for 16 hours
    4. DISCHARGE @ 0.2C - compare the results. Did they improve?

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