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Asus battery tear down A41-X550A

I got a free laptop that has a stuffed battery so I thought I would tear it down.

Asus A41-X550A laptop battery
Back cover almost in one piece
BMS
eeprom?

The BQ9000 is a custom gas gauge ic with no public datasheet. It may have signature validation of the eeprom to stop 3rd parties making compatible batteries.

https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/415037/looking-for-data-on-communicating-with-bq9000

https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1071541/bq40z50-srec-programming-for-bq9000-bq9002-and-bq9004-generation

The shunt resistor is small, so the losses must be low meaning the resistance must also be low.

The thermal fuse over the MOSFETs

Back to back MOSFETs

By David Dobson

I try not to let my age dictate how old I act