If the battery has been over-discharged below the UV threshold, the bq40370 enters . Connecting a charger to the PACK+ pin with >9V typically "wakes" it up by activating the BATFET. If this fails, check the REG25 pin. If REG25 is 0V with >6V on BAT, the chip is physically dead.

: It is frequently paired with high-voltage Lithium Polymer ( LiHV ) cells (4.4V), which can drop voltage rapidly below 3.5V, sometimes causing the chip to struggle with State-of-Charge (SoC) calculations if not properly calibrated.

: A dedicated integrator tracks the energy flowing in and out of the cells to calculate the Full Charge Capacity (FCC).

: Communicates via SMBus , allowing the laptop’s BIOS and operating system to read health data, remaining capacity, and cycle counts.

configuration file for the bq40370. Users often try using the bq4050 profile as a workaround, though some parameters may display incorrectly. Hardware Connection Tips: For many Dell batteries, the must be connected to to enable the charge/discharge FETs. Activation: Sending a specific DELL_CHARGE

It controls the charging FETs (Field-Effect Transistors) based on internal parameters and communication with the laptop's motherboard. Why Do BQ40370 Batteries Fail?