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How to increase lithium-ion battery pack life?

Discussion in 'Electronic Basics' started by John Doe, Nov 14, 2011.

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  1. John Doe

    John Doe Guest

    Does a high-quality commercial tool do enough to prolong the life
    of its lithium-ion battery pack?

    Should they be recharged whenever convenient instead of waiting
    until the tool requires recharging?

    I just had a lithium-ion battery pack die before it's time. I'm
    wondering if better handling would have prolonged its life. Seems
    that one of the 3 cells switched off. One cell is 3.75 V, one is
    about 4 V, and one is 0 v.

    There is no way to turn the cell back on? Assuming that's what

  2. As Tim pointed out keep the cell in the 25% - 75% range of charge.
    The original LI-ion formula has nasty ageing outside that range.
    Newer cells seem to be better. Out of the LI-ion battery packs I've had,
    the one I rebuilt with individual cells has lasted the longest.
    If you can freeze them, you'd slow the ageing process. I have a little
    Hayer TV, for emergencies, that the pack is in the freezer all year.

  3. mike

    mike Guest

    Lithium cells are not yet ready for prime time use in tools.
    They have two advantages.
    1) lightweight
    2) When you pick up an infrequently used tool, it's more likely
    that it will work.
    I have one lithium screwdriver. Guess what, one of the cells is open.
    And there is NO replacement battery available for it. Even if there were,
    it would fail again if I used it.
    NiCd batteries are best when used in power tools. Problem is that
    Cadmium fears killed 'em.
    I don't have any power tools new enough to use NiMH.

    Each cell has a "snap disk" that opens the circuit when the internal
    pressure exceeds some design value. I've read reports that suggest
    you can flip it back on by poking an object through the hole in
    the positive terminal. I played with the concept and was never
    successful. Also risky if you puncture something.
    I've thought about applying external air pressure, but never had any
    way to exert enough pressure. I thought about hooking up a 2000PSI
    argon tank to a pressure cooker...briefly...I didn't want to die
    when it exploded.

    The primary failure mode of lithium cells is increased series
    resistance. The electrons are in there, but you can't get them out
    because the external circuitry won't let you. A side effect of
    increased internal resistance is increased heat. Heat raises pressure
    and the disk snaps. Can happen on charge or in use.

    Power tools ABUSE batteries. Lithiums ain't up to the task...yet.

    Ridgid addressed the issue with a lifetime warranty that includes
    the battery. Sounds good on the surface, but I worry about who's
    lifetime. More likely, the battery won't be available 20 years from
    now when I try to claim the warranty. And I'd be inconvenienced by
    the 10 weeks it takes them to send me a replacement.

    Chemical reactions happen more slowly at lower temperatures.
    Conventional wisdom suggests that you should NOT freeze a battery.
    Depends on your definition.
    If the temperature in your freezer is below the freezing point of water
    but above the freezing point of the electrolyte inside the cell, you're
    probably ok. I don't know that number.

    The suggested storage state of charge number for laptop batteries seems
    to be 40%
    It's a balance between the chemical reaction and the pack discharging
    itself through chemical reaction and drain from the battery supervisor.
    If any of the cells gets below the threshold, the controller shuts it off
    and you can't use the pack, even though all the cells would work.

    Vendors don't care how much money we spend replacing battery packs.
    They care a LOT about getting sued if they do anything "better"
    than the competition. This causes everybody to be conservative.
    They also like to make new stuff incompatible with the old stuff
    so buying a new tools is an attractive alternative to fixing the old one.
  4. John Doe

    John Doe Guest

    They are in the best tools.
    That makes a world of difference in most hand-held power tools.

    The battery pack that failed here came with a Dremel rotary tool.
    The charger is obviously cheap. You plug the battery in, the light
    turns on, the battery takes hours to charge, and then the light
    goes out. I have other hand-held power tools. Bosch 12V MAX pocket
    driver and pivoting angle drill that use lithium-ion batteries and
    a real charger. Lithium ion battery performance is stellar in most
    modern handheld power tools. That's why lithium-ion batteries are
    used almost exclusively in the best new handheld power tools.
    Lithium-ion batteries are what make cordless cutoff tools a
    reality, an extremely useful tool for a do-it-yourselfer.

    I have a Bosch 36 V lithium-ion drill that has not been used so I
    can't say much about it, except that it's charger is fan cooled
    and beeps when the charge is complete.
    That's why they include a heat sensing thermistor that can shut
    the tool down. Even my cheap rotary tool includes one. Going by
    the other replies, the cheap charger is probably what killed my
    lithium-ion battery pack. I don't like cheap chargers for my NiMH
    batteries either, that's why I got a Maha/EnerMax 9000.
    Another reason is because it is nontransferable, you are a virtual

    Professionals who use their tools HARD and long love modern lithium battery powered tools. Festool is high class. Their expensive
    cordless drills are lithium. The same for the best Bosch cordless
    drills. The same for DeWalt. Ect.
  5. mike

    mike Guest

    Yep, and LCD displays were in the best laptops before they were ready.
    You gotta start somewhere.
    It'll likely last longer 'cause it draws 1/3 the current of a 12V drill.

    except that it's charger is fan cooled
    Lithium chargers are the simplest chargers around. All you have to do
    is limit the charge current and let it run till it reaches 4.2V/cell
    (some variation for variants of the lithium concoction) and shut it
    down if something goes awry.
    Yes, there's all manner of protection around it, but the charge algorithm
    is much simpler than NiCd or NiMH.
    For professionals where time is money, I can't argue against expensive
    For the rest of us, lithiums ain't worth the cost...YET.

    Oh, there's another advantage to lithium. Because of the risk of fire,
    lithium tools just stop working when the battery is low. One of the main
    reasons for NiCd battery failure is people who drill just two more holes
    after the battery gives out and reverse the weakest cells. Doesn't take
    much of that before your battery is toast.

    And you say:
    "I just had a lithium-ion battery pack die before it's time."

    Sample size is small (1), but I've experienced 100% failure rate with
    lithium batteries in power tools.
    And the failure mode is characteristic of over-stressing the cell.
    The reason I don't have more lithium powered tools is that they're not yet
    ready for prime there an echo in here??
  6. Guest

    Really? Laptops were better with CRT displays?
    I have 6 LiIon cordless drills, four 10.2V/12V Bosch and two 18V Bosch. The
    only problem I've had is one of the 12V batteries had an early-life failure.
    Somewhat disappointing but as a little compensation my local Home Despot was
    closing them out and I bought five for $15 each. Love the drills/drivers. By
    contrast, my NiCd drivers are heavy and clunky.
    You *obviously* know nothing about the subject. Cheap chargers are nothing
    but a T/R and resistor.
    Not at all. The "all manner of protection" *is* a necessary part of the
    algorithm. Neither are terribly difficult, anymore, since there are chips
    designed to handle both, well. It costs an extra buck, though.
    They are for me. Though for things like saws, I'll likely stick with NiCd.
    Yes. By the time you know it's dead, it really is.
    Of twelve packs, I had one die after maybe three uses. Yes, it happens.
    I have a half-dozen dead NiCd packs. Two of them were just rebuilt and hadn't
    been used in a year or so. Dead. No battery technology is perfect. If you
    dead batteries worry you so, used corded tools.
    Yes, you're talking to yourself, again.
  7. John Doe

    John Doe Guest

    That's why they include a heat sensing thermistor that can shut
    I just noticed that's not the case here. The tool has only two
    inputs, for the battery.

    But my 10.8 V Dremel rotary tool has been converted to use Bosch
    10.8 V batteries. The lousy charger problem should be solved.
  8. mike

    mike Guest

    You're *obviously* smarter than me. Here's another chance to
    demonstrate your superiority.
    Please edumacate me on lithium ion chargers. I wanna git smarter.
    What's your definition of T/R? Then go on from there.
    Again, please explain how the protection does anything until it detects
    a fault???? And how that affects the charge algorithm...other than
    preventing you from charging or discharging a "faulty" battery pack.

    Neither are terribly difficult, anymore, since there are chips
    Methinks you're looking at the wrong end of my assertion.
    The point is that you are UNABLE to drill that one more hole that would harm
    the pack. Cell reversal often happens with NiCd tools without this
    shutdown feature.

    What few samples I have suggests that the fully discharged shutdown
    function is in the tool. A removable pack will probably have additional
    shutdown features that may not be recoverable by simple external means.
    Overvoltage, undervoltage, cell imbalance.

    Overheat, undertemperature, etc. should recover without intervention.

    Each cell has additional protection often based on internal pressure
    being too high.

    Normal use does not activate ANY of the shutdown features of a battery
    pack. They're there as the last line of defense for a system fault
    or a battery fault.

    There were a zillion tools, flashlights, radios that charged the crap
    out of batteries and terminated the charge when the battery got HOT.
    Works surprisingly well for NiCd packs IFF you fully discharge the tool,
    but don't over-discharge it, before recharging. For devices that aren't
    in continuous use with properly scheduled recharges, the batteries get
    cooked in short order.

    But we're talking about LITHIUM batteries here. All the NiCd stuff is
    a preemptive strike that will hopefully suppress ranting off topic
    with issues irrelevant to lithium chargers...yeah, right!
    The important thing is that I listen to myself. ;-)
  9. Guest

    Well, you said it.
    Transformer/Rectifier. You're not an engineer, right?

    Now, go back and read what you wrote.
    It keeps you firm setting fire to your pants.
    Me thinks you're right. I *am* smarter than you.
    Please read what's written, not what you think has been written.
    What *are* you yammering on about?
    You were talking about batteries, in general. It's understandable that you
    can't read what others write but most illiterates can read what they wrote,
    Good thing no one else does.
  10. ehsjr

    ehsjr Guest

    Which makes them very definitely ready for prime time use
    in tools. Maybe it's a case of "some people like vanilla
    while others like chocolate". Is there a definitive
    comparison of battery types in tool usage?


  11. Guest

    Since every manufacturer is moving swiftly to Li-Ion, there will be little
    choice. The benefits of Li-Ion over NiCd are significant for most tools. I'm
    not sure I'd want a Li-Ion circular saw, though.
    Is there a "definitive comparison" between vanilla and chocolate? OTOH, the
    direction that manufacturers are taking is pretty definitive.
  12. mike

    mike Guest

    Thanks for the education. Sounds like tool battery packs have caught up
    available technology.
    My Skill 2-cell lithium screwdriver has a two-terminal connection.
    They don't even bother to sense the middle voltage.
  13. mike

    mike Guest

    If you read what I said, there is no, zero, none, not any wire connected
    to the junction between the two cells. The cells are not removable without
    disassembling the screwdriver.
  14. Guest

    Read what WW wrote. "It's in there."
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