Harvesting laptop Li-ons- Mtbr.com
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  1. #1
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    Harvesting laptop Li-ons

    So my wife walked into my home office and noticed an old HP laptop sitting on the shelf and aks "Why do we still have that old laptop lying around?" and a light went on in my head 'bing'.

    So I pulled the battery pack out and it read 14.8v 4000mAH..hmmmmm. Dare I? So I did. I ignored the warning label and disassembled it and pulled the batteries out. The battery model was hp f4486a battery and SANYO pin 4UR18650f-2-QC-ET1 at the bottom.

    8 li-ons just waiting to be charged again.

    Now the advice I need- dangers known?
    1) Have been uncharged for over 3 years
    2) Treated well and stored in cool environment
    3) Used for two years before hard drive died cost to fix out weighed buying new
    4) 4000mAH? So what charger might work best?
    5) Anyone's best guess at protect or unprotected? < my gut says unprotected >

    DIY since the day I picked up my first soldering iron.

  2. #2
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    I've made several battery packs from new, cheap laptop batteries that I bought on ebay. Cells will be unprotected, but the pack will have a protection circuit. I'd guess your cells will be 2000mAh (count the cells and do the math). I always use protection boards that I buy from batteryspace and a charger form batteryspace or off of ebay.
    http://www.batteryspace.com/index.as...&Category=1376

  3. #3
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    If those batteries are actually 5 years old I would not bother with them. Li-ions do not age well. Laptop charging cycles tend to be done when hot and that is hard on them. You can try them if you would like, but I'd guess 50% or less capacity.

  4. #4
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    with laptop batts the pcb is in the battery casing. So they were protected till you pulled the pack apart.
    Measure the voltage for the cells, if it is less than about 2.6, most smart chargers will not chagre it. You can try and trick the charger by stating it is a different battery type like a nimh, and put in a few ma till the voltage goes over 3V, then switch it to li - ion charge.
    Record for each cell how many ma are taken to fully charge the cell then you will know if they are still good. they are probably less than 50% capacity now.

  5. #5
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    My 2 year old Dell battery lost already 32% of its capacity. So instead of 2400 mAh only 1600 mAh is remained. So I would suggest buying new cells.

  6. #6
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    Is there a way of seeing how much capacity is left without the obvious charging and then recording the discharge time??
    I have one of the fancy Turnegy chargers but havent tried it out yet.

  7. #7
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    Thanks guys for the info- I have some protected cells coming soon from DX so these would have been extras. I might just dispose of them properly then. Thanks again- it was fun trying.

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