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Thread: How to recognize a protected cell ??

  1. #1
    harro's Avatar
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    Default How to recognize a protected cell ??

    This may sound like a dopey question to you, but are you able to tell if an 18650 cell has pcb protection just by looking at it, ie; does it have some distinguishing physical feature over a non-protected cell ? A good quality cell will have a brand name, MAh rating and protection status ( eg; AW18650 [ this is a random pick only ! ] ). I recently disassembled an established manafacturer's cordless drill Li-Ion battery, with a faulty cell. Inside was 10 x 18650's all spot welded together with fine metal strips. The cells were shrinkwrapped in waterclear green wrap with absolutely no marks on either the wrap, or the metal body of the cell to indicate anything. + and - were easy enough, and a DMM found the faulty cell, but other than that, what would show the cell to be protected, if at all ??
    Best Regards;
    Mike.

  2. #2
    Administrator Norm's Avatar
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    Default Re: How to recognize a protected cell ??

    The individual cells will not be protected as far as I'm aware the pack as a whole will be protected.

    Norm

  3. #3
    HKJ's Avatar
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    Default Re: How to recognize a protected cell ??

    Quote Originally Posted by harro View Post
    This may sound like a dopey question to you, but are you able to tell if an 18650 cell has pcb protection just by looking at it, ie; does it have some distinguishing physical feature over a non-protected cell ? A good quality cell will have a brand name, MAh rating and protection status ( eg; AW18650 [ this is a random pick only ! ] ). I recently disassembled an established manafacturer's cordless drill Li-Ion battery, with a faulty cell. Inside was 10 x 18650's all spot welded together with fine metal strips. The cells were shrinkwrapped in waterclear green wrap with absolutely no marks on either the wrap, or the metal body of the cell to indicate anything. + and - were easy enough, and a DMM found the faulty cell, but other than that, what would show the cell to be protected, if at all ??
    Best Regards;
    Mike.
    Battery packs does always have a common protection for all cells, not individual protected cells.

    It is easy enough to see if a battery is protected, it has a wire down the side (under the wrap) and a PCB mounted on the bottom. You can see my "Anatomy of a protected battery" for some photos.
    My website with flashlight, battery and charger information: lygte-info.
    More than 200 battery reviews and 80 charger reviews.
    Compare 18650 LiIon batteries or smaller (RCR123, 16340, 14500, 10450) LiIon batteries.

  4. #4
    harro's Avatar
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    Default Re: How to recognize a protected cell ??

    Thankyou HKJ and Norm, i understand what you are saying, and its obvious that these cells arent protected after looking at your ' Anatomy of a protected cell '.
    Cheers;
    Mike.

  5. #5

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    Quote Originally Posted by HKJ View Post
    You can see my "Anatomy of a protected battery" for some photos.
    Wow, excellent documentation HKJ! Always wondered how the protection looked/worked. Thanks

  6. #6
    harro's Avatar
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    Default Re: How to recognize a protected cell ??

    Quote Originally Posted by reppans View Post
    Wow, excellent documentation HKJ! Always wondered how the protection looked/worked. Thanks
    Hear,Hear reppans. HKJ's link was everything i needed to know and nothing i didnt. Its so obvious by just two methods,how to pick a protected cell ( for me, the narrowing at the - end and the slightly raised conductor down the side ). We learn every day.

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