Hi Everyone

I am designing a mobile device and currently working on the power system. The device will be powered by two 18650 Li-Ion cells in series. The batteries will be charged by a small solar panel. I have designed the solar charger part and it works well. Now I would like to add circuitry to continually balance the two cells and report an accurate state of charge to my microcontroller (over I2C or SPI). Also reporting current and voltage is a bonus.

I was wondering if anyone who has done something similar can recommend any simple IC's that can provide this functionality for me? Preferably something that is simple to implement in terms of the hardware and code. Any recommendations or advice will be most welcome

 

I'd use an off-the-shelf PCM (protection circuit module) which provides balancing, and protects from over-charge and over-discharge. State of charge could be determined by the microcontroller's ADC (or a separate serial ADC) looking at cell voltage; the PCM may have a shunt resistor that could be used for measuring current, if the ADC has enough resolution. But there are plenty of real smart BMS chips out there, like the BQbunchofnumbers from TI.