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Thread: Protection circuit question

  1. #1

    Default Protection circuit question

    I seem to have tripped the protection circuit by leaving this Trustfire RCR123a on the WF-139 charger for too long. Will it eventually reset, or is it done?

    I know they are cheap batteries, but I didn't want to go with pricier ones yet for my first foray into Li-Ion.

    Hoping this one isn't killed.

  2. #2
    *Flashaholic* mdocod's Avatar
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    Default Re: Protection circuit question

    the protection in cheap cells often just trips and dies within the first few times it is tripped and will not recover.

    Ordinarily, when the voltage gets high enough to trip the charge limit protection, the cell is overcharged enough that it will have some voltage "settling" after the charge, this should theoretically be sufficient within a few minutes off the charger to trip the protection back off, if not, dunno.
    Last edited by mdocod; 07-05-2008 at 07:05 AM.

  3. #3
    Flashaholic* rizky_p's Avatar
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    Default Re: Protection circuit question

    One of my ultrafire RCR123 refuse to charge after its over-discharge protection kicked-in.
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  4. #4

    Default Re: Protection circuit question

    Well it's weird, the circuit never seemed to reset, until I decided to put it back in the charger, then it started charging the cell again, I took it off immediately, and it seems to be working just fine again.

    Seems like it needed an external power source to reset the circuit in this case. Either than or between the time I took it out of the light, and put it onto the charger it reset, but it had been doing nothing for an hour or more, but I tested right before it went back to the charger...

  5. #5

    Default Re: Protection circuit question

    Quote Originally Posted by wildstar87 View Post
    Well it's weird, the circuit never seemed to reset, until I decided to put it back in the charger, then it started charging the cell again, I took it off immediately, and it seems to be working just fine again.

    Seems like it needed an external power source to reset the circuit in this case. Either than or between the time I took it out of the light, and put it onto the charger it reset, but it had been doing nothing for an hour or more, but I tested right before it went back to the charger...
    Here is a link to a file that describes the internal workings of the typical protection chip.
    and a typical application (with only one back to back mosfet switch).
    http://pdf1.alldatasheet.com/datashe...C/SC451XX.html

    Reset can be accomplished in two ways. You found one

    Protection boards with twice the current trip have 2 dual mosfets, and those with 3 mosfets have ?

    Yup, about 3 times the current trip.

  6. #6
    Moderator Kestrel's Avatar
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    Default Re: Protection circuit question

    I'm hoping for the OP's sake that he's retired those particular RCR123's by now?
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