Battery Charger and Fuel Gauge Integration

Overview

Use this skill to bring up a Li-ion/LiPo charger IC (TI BQ24xxx/BQ25xxx) and a fuel gauge (TI BQ27xxx Impedance Track, or Maxim/Analog MAX1704x ModelGauge, e.g. MAX17048) over I2C. The hard parts are keeping the charger in host mode past its watchdog, and getting an accurate SOC before the gauge has a matching battery profile.

When To Use

Use this skill when:

• Charging never starts or restarts in a loop: check input current limit (IINLIM, REG00[2:0]), EN_HIZ, the CE pin, and the I2C watchdog resetting registers to default.
• The charger reports faults: REG09 latched faults, NTC_FAULT (REG09[2:0], with a real thermistor such as 103AT on the TS pin), safety timer expiration, or JEITA temperature de-rating.
• SOC from BQ27441/MAX17048 is wrong or jumps at power-up: profile not loaded, no learning cycle, or bad OCV calibration.
• I2C reads to the charger/gauge fail or the wrong 7-bit address is used.

Do not use this skill when the I2C bus itself is dead (no ACK on any address) or the board rails are wrong; debug the bus and power tree first with hardware-interface-debug.

First Questions