This is a solar lithium-ion single cell battery charger unit using the Texas Instruments IC BQ24210. It is designed to run small electronics projects (such as data-loggers and environmental monitoring units) in places where there is no supply of electricity.

This is a 800mA single-input, single cell Lithium Ion battery charger IC. The datasheet is available here: http://www.ti.com/lit/ds/slusa76b/slusa76b.pdf

This IC takes care of charging the battery with the solar energy available.

This IC is pre-soldered, as it is a very small surface-mounted package, along with all the other main components.

You only need to solder the battery holder and screw terminals.

You need to add a small solar panel with an output voltage of (ideally) between 3.5 and 7V DC. I use modules with 5.5V output and 200mA

We do NOT supply the 18650 size lithium ion cell. This is due to shipping restrictions. These cells are usually available locally. We suggest getting a good-quality cell with a decent capacity (in the region of 1800 - 2400mAh).

I designed it originally to run a small weather station which monitored and wirelessly sent back data to a base station.

There are other lithium battery chargers, but I could not find a nice battery charger for very small solar panels for small energy users. The BQ24210 fulfils all I wanted and I could not find other boards which use this IC.

I have needed this small charger circuit for many prototypes and environmental monitoring projects, so I decided to make a batch of PCBs. Hopefully this might be useful to others!

Full details and KiCAD PCB files are available here:

https://github.com/curiouselectric/solar_charger_2020

This is a simple kit, with just a few items to solder. We have already done the surface mount components! Instructions for this kit are available here.