Alpenglow Industry's Carrie Sundra Designs a USB Replacement for Coin-Cell Batteries

Alpenglow Industry's Carrie Sundra has created a clever adapter board that turns coin-cell battery footprints into USB power inputs — designed to work around new battery safety regulations which require batteries be retained by a screw.

"Hey soldering kit makers," Sundra writes by way of introduction to the board. "Struggling with new coin cell regulations and have a pile of PCBs with coin cell battery holder patterns on them? I made a thing for ours that converts them to USB power, maybe it's handy for you. Ship this instead of a CR2032 holder and boom, your kit no longer contains or uses a coin cell, no compliance needed. It's designed for side-slide style holders (SMT or through-hole) and easy to solder."

The idea for the board came about following the introduction of or more rigid enforcement of battery safety laws around the world. Where it was previous acceptable to have a friction-fit battery holder for coin cells, it's now required that the cells be retained by a screw — to prevent a curious child pulling the battery out and swallowing it.

The board is designed to be soldered onto the footprint of a push-fit coin-cell holder, with no changes to the underlying PCB design required. A 10Ω resistor on the output mimics the resistance of a typical coin cell while on-board hardware limits current to 250mA and provides other protections.

"If this is useful for you, let me know," Sundra writes. "I'm about to get a pile of them made and can do bulk pricing if you want 100 or more. Still need to finalize cost, but can prob do somewhere in the 35-75 cent range depending on qty. I'm also getting some 5V output ones made for our kits that use 2× 2016s stacked in a holder. This passes USB out with a 10-ohm inline resistor and PTC fuse with a 250mA current limit."

More information is available in Sundra's Mastodon thread.