Li Ion Battery charger safety

[Nautica Rick]

I am building a small DC powered air pump for aerating a tank of fish. I have a Acer netbook that was kinetically disassembled, but still has a good battery pack and charger. I am going to salvage this battery pack for the power supply. I know that Li Ion batteries have tight tolerences for the cutoff voltages and can be dangerous if not properly regulated. Does anyone know if the regulation of the charging cycle is built into the charger or the computer?

 

[dcselec]

I would think that as the battery can be charged with the laptop
shut down the charging cycle is built in the charger

 

[ronv]

I could be wrong, but I think in most laptops the "charger" is really just a bulk power supply and the charging circuits are internal to the PC. Are you in a hurry to charge it or would a real simple charger work?

 

[bubun stupid]

same as ronv said, you need to build good regulated supply with some current protection beside over voltage. I had bad experience with fast charging for Li Ion, especially if it is almost empty. may be looking to datasheet/specification will be make safer for longer lifetime.

 

[Nautica Rick]

Thanks for all input. I've done some more digging on this subject including looking the equipment over. Without a doubt, the regulation for the charging cycle is built into the computer. The charger's output is a whopping 19VDC compared to the 11.1V of the battery pack. The battery pack has 3 3.7 volt cells and the charging voltage is typically 4.2V per cell. This would make the charging voltage about 12.6V. Salvaging the cells is still cost effective as I have found chargers in the $12-$25 price range; well worth avoiding a flameout. I found a very educational website for all things battery related. The following link is to the Li-Ion page.
**broken link removed**