iPhone 4S corroded battery terminal

Discussion in 'iPhone Tips, Help and Troubleshooting' started by Divinearoma, Aug 26, 2012.

  1. Divinearoma macrumors newbie

    Jul 6, 2011
    Hi guys,

    The stock battery that came with my iPhone 4S (purchased 11/2011) was showing low capacity reports and poor performance out of the gate. After iOS 5.1.1 update failed to improve this, I replaced the battery with an OEM I purchased through iFixit in May of 2012.

    The performance and capacity reports were much better up until a week ago. I popped the battery out today to check and noticed there was corrosion built up on the battery terminal. I know that it's not from water damage, so I'm wondering if anyone has any ideas to the source of this corrosion. Secondly, my battery from iFixit should still be under warranty, so I'm wondering if people consider this user damage or a faulty battery.

    I have a metal backplate that I've replaced the stock backplate with, and I'm suspicious that it's causing too much heat build-up and degrading the battery. Could this cause the corrosion to occur somehow?

    Attached Files:

  2. miles01110 macrumors Core


    Jul 24, 2006
    The Ivory Tower (I'm not coming down)
  3. Divinearoma thread starter macrumors newbie

    Jul 6, 2011

    Somewhat humid. If that were the cause, wouldn't corrosion have occurred with the original battery as well? Or are you suggestion that during my initial battery swap, humidity was able to access the terminal for the first time?

    Does anyone have any suggestions for proper cleanup of corrosion in this case?

  4. Florida iDoctor macrumors newbie

    Sep 7, 2012
    Likely Causes of Corrosion

    Thanks for the photo. From my experience with repairing Apple products for some time now, I would say that the original OEM battery that came with the unit is the likely culprit. I am sure that the replacement battery is not the cause simply due to the fact that you experienced operational degradation with the first battery. What I suspect is that the first battery had some internal issues related to heat which caused the chemicals within the li-ion battery to change. This, in turn, causes corrosion to build within the battery cells themselves which results in an inhibited electron flow (loss of power). Some of this liquid likely drained into your battery terminal area. You then replaced the battery with a new one but, over time, that terminal continued to oxidize since it was not cleaned initially. Now you probably have oxidation on the new battery connector as well as the connector on the motherboard. Best bet is to use an electrical contact cleaner such as


    You can use a tiny brush and get into the battery connector crevices and slots with the cleaner as well as cleaning the connector on the motherboard. Hope this helps. We see a fair number of these issues and this solution should work.

    Florida iDoctor

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