The SparkFun Battery Babysitter is an all-in-one single-cell Lithium Polymer (LiPo) battery manager. It's half battery charger, half battery monitor, and all you'll ever need to keep your battery-powered project running safely and extensively.
The Battery Babysitter features a pair of Texas Instruments LiPo-management ICs: a BQ24075 battery charger and a BQ27441-G1A fuel gauge. The charger supports adjustable charge rates of up to 1.5A, as well as USB-compliant 100mA and 500mA options. It also features power-path management, guaranteeing power to your project even if the battery has died. The self-calibrating, I2C-based BQ27441-G1A measures your battery's voltage to estimate its charge percentage and remaining capacity. It's also hooked up to a current-sensing resistor, which allows it to measure current and power! It's a handy IC to have, if you ever need to keep an extra eye on your project's power draw.