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To: Publius6961
I was hoping someone more knowledgable would supply a correction but, if memory serves me right, that would be current limiting circuit....

You're probably correct about the nomenclature (voltage vs. current).

That being said, I do have a fair amount of experience using lithium batteries in an extreme environment (electric R/C model airplanes. See: http://www.rcgroups.com/forums/showthread.php?t=209187).

If you charge a LI battery over 4.2v per cell, they'll puff & explode.

If you discharge a LI battery below 3.0v per cell, they'll puff & explode.

If you charge them at a rate higher than 1C (capacity of the cell(s)), they'll puff and explode.

If you puncture them or damage them, they'll puff and/or explode.

In short, lithium batteries are a lot more volatile than either nicad or nimh batteries and need to be treated with a certain measure of respect.

Most consumer-level LI batteries are sold with a protective circuit that prevents over/under voltage situations from occurring. Most third-party LI batteries are sold without this circuit, which is why the OEM pack costs $50 and the third party pack costs $30.

Where most people have problems with consumer-level LI batteries is when buying the cheap replacement batteries. These cheap replacement batteries do not have the protective circuitry which prevents over/undervoltage problems. Hence, the news stories of cell phones exploding while in use, being dropped, etc.

Below is a photo taken during just such an event where a hobby-level Lithium polymer (really Lithium Ion Polymer) battery was deliberately charged at a higher voltage.


59 posted on 07/10/2006 11:33:16 AM PDT by Ol' Dan Tucker (Karen Ryan reporting...)
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To: Ol' Dan Tucker; Publius6961
Below is a photo taken during just such an event where a hobby-level Lithium polymer (really Lithium Ion Polymer) battery was deliberately charged at a higher voltage.

Correction:

This photo shows a battery deliberately charged at a voltage higher than 4.2v.

In short, LI batteries are sensative to both voltage and current. Unlike a nicad, which will simply *pop*, a LI battery ignites. Several hobbyists have had their cars/trucks burned to the ground when charging their batteries inside their vehicle. While no one has lost their house, several have come close.

If you go down the thread to which I linked in the previous post, you can see videos of the process. The dense white smoke generated prior to the fire is both toxic and corrosive.

60 posted on 07/10/2006 11:39:37 AM PDT by Ol' Dan Tucker (Karen Ryan reporting...)
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