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[DPRG] Lithium Ion Batteries from BGMicro

Subject: [DPRG] Lithium Ion Batteries from BGMicro
From: Quinones, Jose jquinones at ti.com
Date: Mon Mar 29 06:45:10 CDT 2010

Hi Ed,

Not certain about this battery pack in particular, but what I have often seen on lithium-ion battery packs is what the industry refers to as a gas gauge. Although, not filled with gasoline, the energy on the battery module is monitored in the same fashion your car gas tank is monitored.

Except it is pretty easy to know how much gas there is on your tank. With a battery, however, how much charge is left is not that a trivial effort. So these devices are made aware of how much charge the battery can take, and then are at all times monitoring whatever comes in and whatever comes out.

This allows the chip to know when the battery is reaching its full potential (either up or down), which is when you should not charge/use the battery anymore. Also, if the battery is above certain charge level (90% or 95% I think), the chip determines there is no need for charging, which is kind of dangerous.

Hence, the protection chip is much more than just controlling the current flowing into (or out of) the battery.

I think you could just allow a small current into the battery and monitor the temperature. If the pack starts to warm up, disconnect the charging current. I am not certain how super duper safe this open loop method would be, but I don't see why it would be unsafe. Run the experiment by your local firehouse, just in case ;-)

Best regards,

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