Battery Junction
Results 1 to 9 of 9

Thread: Self discharge rate for Li-ion cells?

  1. #1
    Flashaholic*
    Join Date
    Apr 2001
    Location
    Massachusetts
    Posts
    4,857

    Default Self discharge rate for Li-ion cells?

    How does that compare to nimh's? I want to take my spare digital camera which takes a proprietary Li-ion cell and basically leave it in the car's glove box and am wondering how long the cell will hold a charge.
    I live in a van down by the river

  2. #2
    Silver Moderator
    SilverFox's Avatar
    Join Date
    Jan 2003
    Location
    Bellingham WA
    Posts
    11,652

    Default Re: Self discharge rate for Li-ion cells?

    Hello Geepondy,

    Bare cells have little self discharge, however the protection circuit can draw some power and who knows what else is drawing power in the camera.

    I would start out with charging after 3 months and keep track of the time it takes to charge. From there I would go to 6 months, then 12 months.

    You will find that your batteries will last longer if you store them at a lower voltage than full charge. 3.8-4.0 volts would be a good range to try for. When Li-Ion cells are stored at full charge, they loose capacity and it can not be recovered. When they are stored at a lower state of charge, they still loose some capacity, but it is not as drastic. I believe the numbers suggest that 1 year of room temperature storage with a fully charge cell will see around a 20% loss in capacity, where as the same storage conditions and time at a 40% (around 3.8 volts) state of charge will only see around a 4% loss in capacity.

    You also need to keep temperature in mind. If you store at high temperatures the self discharge rate goes up as does the damaged to the cell when stored at full charge.

    Tom
    Behind every Great man there's always a woman rolling her eyes...

    Most batteries don't die - they are tortured to near death, then murdered...

  3. #3
    Flashaholic* jar3ds's Avatar
    Join Date
    Sep 2005
    Location
    USA
    Posts
    1,988

    Default Re: Self discharge rate for Li-ion cells?

    so when you say 'loss in capacity' are you saying the cells life in general? or only the loss of energy during the storage condition...

    in other words... storing @ high charge rates will damage the battery permantely?

    Thanks

  4. #4

    Default Re: Self discharge rate for Li-ion cells?

    Quote Originally Posted by jar3ds
    so when you say 'loss in capacity' are you saying the cells life in general? or only the loss of energy during the storage condition...

    in other words... storing @ high charge rates will damage the battery permantely?

    Thanks
    Basically

  5. #5
    Flashaholic* jar3ds's Avatar
    Join Date
    Sep 2005
    Location
    USA
    Posts
    1,988

    Default Re: Self discharge rate for Li-ion cells?

    Handlobraesing,

    according to your post # count (above)... you better go see that movie that comes on on tuesday
    Last edited by jar3ds; 06-02-2006 at 10:12 AM.

  6. #6
    Silver Moderator
    SilverFox's Avatar
    Join Date
    Jan 2003
    Location
    Bellingham WA
    Posts
    11,652

    Default Re: Self discharge rate for Li-ion cells?

    Hello Jar3ds,

    If you have a Li-Ion cell that has 750 mAh of capacity and you store it at room temperature for one year, you can expect it to only have 600 mAh. The loss in capacity is permanent and not recoverable. It is caused by oxidation within the cell. Li-Ion cells tend to be unstable at full charge and full discharge, but work quite nicely inbetween... This information is a few years old and I believe newer cells are doing a bit better, but I don't have any data on them.

    Tom
    Behind every Great man there's always a woman rolling her eyes...

    Most batteries don't die - they are tortured to near death, then murdered...

  7. #7
    *Flashaholic* wquiles's Avatar
    Join Date
    Jan 2005
    Location
    Texas, USA, Earth
    Posts
    8,422

    Default Re: Self discharge rate for Li-ion cells?

    So Tom, basically, what you are saying is that cell is aging, and that as part of the normal aging process the battery will loose capacity, right?

    The other point that I got from this is that if I store (or not use the cell) at a lower voltage than full charge (4.20 v) that this aging process/capacity loss is not as bad?

    Will
    Please no PM/Visitor Msg's. Email for questions/Paypal: wquiles [at] gmail {dot} com. Please visit my new website.

  8. #8
    Flashaholic*
    Join Date
    Apr 2005
    Location
    San Jose, CA
    Posts
    3,964

    Default Re: Self discharge rate for Li-ion cells?

    Check the operating temperature range for that camera. The ambient temperature inside of a car during summer (and in your area, during winter) may be outside of the operational temperature range for the camera. Same caveat goes for MP3 players and other similar digital devices.

    Quote Originally Posted by geepondy
    How does that compare to nimh's? I want to take my spare digital camera which takes a proprietary Li-ion cell and basically leave it in the car's glove box and am wondering how long the cell will hold a charge.

  9. #9
    Silver Moderator
    SilverFox's Avatar
    Join Date
    Jan 2003
    Location
    Bellingham WA
    Posts
    11,652

    Default Re: Self discharge rate for Li-ion cells?

    Hello Will,

    I think we are on the same page, but let me make sure...

    Let's first define that the useful life of a Li-Ion cell ends when the cell drops to 80% of its initial capacity. In normal use you may get somewhere around 300 cycles of normal use before you reach this end point, or you can fully charge your cell up and leave it on the shelf at room temperature for 1 year.

    Tom
    Behind every Great man there's always a woman rolling her eyes...

    Most batteries don't die - they are tortured to near death, then murdered...

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •