LiPo Battery Breakout Add-on for USB and WiFi Nuggets

We've been testing our LiPo battery breakouts for the past year, and now, we have finally released our Nugget portable LiPo power Add-on!

This board supports LiPo batteries with Adafruit-style JST-PH two-pin connectors. In case you use a battery with the wrong polarity connector, the board includes reverse polarity protection with a warning light indicator. You can also change polarity of the battery by moving two resistors on the board.

This add-on will power your Nugget from a LiPo battery, while still keeping you able to power it from your laptop - and even charging the battery! Among other features, this board includes a voltage divider on the A0 (GPIO3 on the USB Nugget) pin for measuring battery voltage, as well as a switch for turning your device on and off. There's also a charging LED which shines purple as long as the charging process is happening, so that you can see when your battery is fully charged.

The add-on works with both the WiFi Nugget and USB Nugget. Furthermore, it's also thin and narrow enough to work with any add-ons our team might develop in the future, fitting between any add-on board and the Nugget! For instance, it should work well with the breadboard add-on. 

There's two ways you can attach this board. You can solder a 8-pin header and plug the board into the Nugget. You can also insert an 8 pin header into the holes on the add-on, they are staggered to make press-fit contact. This aspect also allows you to insert the battery add-on between the Nugget and an add-on board.

The battery add-on does not include a LiPo battery, but you can buy one from Adafruit or other places! Just make sure that the connector is two-pin, and if it isn't, it's not hard to rewire such a battery. See: https://hackaday.com/2022/10/03/lithium-ion-batteries-are-easy-to-find/

- It's only possible to power the Nugget off using the switch while USB power isn't applied - once you apply USB power, the Nugget will boot up either way.

*This add-on does not support LiFePO4 batteries. You should not use a LiFePO4 battery with this add-on!!

This add-on only supports single-cell batteries with voltages marked as 3.6V/3.7V/3.8V or 4.1V/4.2V/4.3V. You should not use a LiIon pack with two cells in series or higher (voltage 7.2V or above).

If you decide to use AA or AAA batteries instead (three in series), you should cut the jumper marked "LiIon" on the PCB, and check with a multimeter that it's properly cut. The purple (charging) LED should not light up during USB plug-in if the jumper has been successfully cut.

Any battery experimentation is solely at your own risk.