I made a thing, part 57: My dream battery charger for a Teensy-powered wearable

TL;DR: Tiny soldering leads to a Teeny that can tell when its battery is being charged

I’ve been using and loving Onehorse’s STBC08 High-Current LiPo Battery Charger. It sits on the back of a Teensy, you plug in a lithium battery, it charges off USB and has a host of LEDs to let you know what it’s doing – red for charging, yellow for external power. However, I’m working on something where all the electronic gubbins are going to be buried and I’d like to have the Teensy do the reporting of battery charging rather than the LEDs.

The STBC08 chip in the charger has signal lines to tell when charging power is connected and when the battery is fully charged – those are what lights those LEDs. Sadly, they are not broken out to the spare holes in the charger board. So no worries, I’ll just solder to those LEDs and break the signals out. Like this:


Yeah. Those LEDs are a single millimeter long. So that’s a job to do with no caffeine in my system. Managed it though.



And then I smothered the wires with epoxy, coz they are tiny, fragile, uninsulated, and right next to the battery connection.


Now the Teensy can read pins 1 & 2 to find out whether external power is present and whether the battery is charging or charged. And then it can tell me.


1 thought on “I made a thing, part 57: My dream battery charger for a Teensy-powered wearable”

  1. You could have connected Vbat and Vusb to analog ins on your Teensy, if it had spare ones?

    That looks a nice chip though – no inductors, or are they on the obverse?

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