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1216Re: 11.7 Volts from Lithium Ion Cells?

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  • radio_kx0r
    Jun 3 8:56 PM
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      Rick,

      I doubt that the lithium polymer cells would replace lithium ion in
      an older pack, because they have different shapes, often flat and
      rectangular instead of cylindrical cells. You might be able to
      substitute a complete pack if you find something that will fit or
      plug in with a cable. The voltages must match closely, but you might
      be able to do that.

      If the computer is designed to run on a voltage range that includes
      12 volts, you might be able to run on a 12 volt battery. You should
      be OK if you match the voltage the AC adapter puts out. All the
      lithium packs function over a moderately wide range, usually about
      4.2V down to 3.0V per cell. This means a 3-cell pack would deliver
      about 12.6V fully charged, dropping to about 9.0V at the end of safe
      discharge. These voltages differ among various cell chemistries, so
      you have to read the data sheets for the batteries you have.

      I think rebuilding a pack is dangerous. It's very easy to create a
      short with your pliers and other tools. A careless short circuit
      might weld instantly....then you have to run, because things will get
      too hot and something bad will happen real fast! The problem is that
      the cells are always on, and you can't safely discharge them to work
      on them. If you discharge the cells well below 3V, they may be
      permanently damaged. You might be smart to work outdoors and wear
      safety glasses if you choose to work on any lithium packs.

      The people who build packs do it according to procedures that
      minimize errors and risks. They know their game.

      It might be smart to use the services of someone who knows how to
      service lithium packs, instead of taking such large risks.

      KX0R


      > Well, I was wanting the cells to rebuild an existing pack - an old
      laptop
      > battery pack to be exact. Would the lithium polymer cells be
      compatible
      > in this application ? The laptop is an old one and on its way in
      > shipment. It will be used for amateur radio applications only and I
      > don't want to spend a bunch on it. The battery pack isn't all that
      > important as long as it will run on the AC adapter, but having
      battery
      > capability would be nice if I can do it without spending a
      fortune. I
      > have noticed that some of the AC adapters for laptops are rated at
      12
      > volts. Has anyone ever tried running a laptop on a 12 volt battery
      > plugged direct into the power jack ? Sounds logical or am I missing
      > soemthing here ?
      >
      > Rick McKee, KC8AON, Ohio - www.angelfire.com/electronic2/qrp
      > Monthly QRP Field Day Group - http://groups.yahoo.com/group/MQFD/
      > With God all things are possible <><
      >
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