Assemble the battery pack, insert it into the laptop, and perform a full charge/discharge cycle. This allows the newly programmed microchip to synchronize perfectly with the physical chemistry of the new cells. Modern Alternatives

Over time, the original lithium-ion cells wear out. When you replace them with new ones, a problem arises: the EEPROM chip still holds the old, degraded data. It still thinks it is an old battery with a low capacity and a high cycle count. This leads to:

In a smart battery, the EEPROM sits right next to the gas gauge IC (e.g., Texas Instruments BQ20Z75, BQ3060, or BQ40Z50). It stores: