We're going to pick up where the LiPo Battery tutorial left off and look closer at the Adafruit Powerboost modules for charging your LiPos. We talked about the rules of using these batteries and how to make sure you don't set your project a light when working with them! Today, we will glean closer into the safe charging and usage of Lithium Polymer Batteries, in particular how to use them with Microcontroller platforms.
The best point to begin at would be from the battery itself. LiPo's are always partially charged with a storage voltage in each cell; then shipped out at that voltage. When receiving your LiPo, it can be a good idea to check the voltage across the battery to ensure it's above its minimum voltage (otherwise things can get a little dangerous). Next thing you will want to do is find a charger module for your LiPo that can safely charge your battery. Whatever you do, don't use the NiMH/NiCad chargers, they will cause a hot, explosive mess.
You're likely aware that 5V power is a common type of power source for most of our hobbyist projects, 3.3V would be the other. Adafruit made some modules that will output 5.2V from any 1.8V or higher battery source. The current rating will change per the voltage on the input of your module. However, we've observed 2000mA from a single 3.7V LiPo! The Powerboost Modules from Adafruit are a popular supply/charge option for single-cell LiPo batteries!
All of the Powerboost modules have similar features, but there are a couple of important differences. The modules each have an output current rating (a 500mA and 1000mA option available), varying depending on the voltage of your input cell. The Charger modules give you the option to charge your 3.7 LiPo battery in situ while powering a project. This can be a fantastic way to house your batteries and projects with access only needed to the charge micro-USB port on the board! Let's take a closer look at these boards!
The PowerBoost Basic
Input: Any 1.8VDC battery or higher
Output: 5.2V DC
The basic module is built on a TPS61090 Boost converter; this module features low battery detecting, 2A internal switching for loads and even supports charging your iOS devices via a LiPo battery. This is the basic version of the Powerboost modules and such it doesn't feature charge capabilities.
All you'll need to do is plug your LiPo into the JST connector on the board and connect your load circuit up to the board using the USB connector. It's as easy as that!
The PowerBoost Charger
Input: Any 3.7V LiPo Battery
Output: 5.2V DC
Built on a TPS61030 Boost converter, this module features low battery detecting, 4A internal switching for loads and you can even connect the enable pin to ground to turn off the output. Adafruit has provided you with a complete breakout solution too, allowing you access to the control pins, the battery in and power out. The load-sharing circuit will also switch your source from battery to USB when available. Be careful with the 1000 version of this board, though, when charging and supplying the power, you can be drawing up to 2A from your USB port so make sure you've got one that can provide it. Typically computers/Laptops are only offering 250mA-500mA over USB!
Just connect your LiPo up to the board using the JST connector, your load circuit to the USB connector and you can use any 2A micro-USB power supply to charge while you power your load.
The PowerBoost Modules are awesome for powering your project on the go and with a bit of creativity you could even set up an Uninterruptible Power Supply for a portable project!
