What this charger does for your battery stack
The BQ24125RHLT is a Li-Ion/Polymer battery charger from the bqSWITCHER™ series, handling 1 to 3 series cells with a programmable constant-current charge up to 2A max. It accepts a supply up to 16V, which covers most USB-C PD adapters and 12V wall warts without an extra pre-regulator. The charge current and a safety timer are programmable, and the IC includes over-temperature fault protection.
2A charge current and thermal reality
At 2A charge current, the power dissipated in the internal MOSFETs and sense resistor heats the die. For a 2-cell (8.4V) pack, the charger regulates the final battery voltage at 8.4V. The constant-current phase delivers up to 2A until the cell voltage reaches the regulation threshold, then the charger switches to constant-voltage until the current tapers.