Test your CR2032 coin cells using this breakout. Below 2.64v, the LED ceases to light, indicating that the coin cell is nearing the end of its useful life.
This builds 1 board. You'll get at least 3 from OSHPark.
| Quantity | Description | Digikey/Mouser Part Number | Board Placement |
|---|---|---|---|
| 1 | TPS3809L30DBVR | 296-10917-1-ND / 595-TPS3809L30DBVR | Q1 |
| 1 | 20mm coin cell holder (through-hole) | 3003K-ND / 534-3003 | Rear |
| 1 | 0603 imperial series resistor for LED | Generic value** | R1 |
| 1 | 0805 imperial LED | Generic/Any type*** | D1 |
I used the following parts for these, but you should really source to your desired quantity:
** 1k 0603 resistor (from the spare parts bin, if you really want one though.. RMCF0603JT1K00CT-ND. Try another part and order a bunch for a better discount / price.)
*** Mouser 645-598-8130-107F (Orange Dialight LED, Vf=1.7V, If=20mA)
Creative Commons CC0 1.0 Universal
This board is actually a mashup of Chris Gammell's and Dave Jones' projects. The coin cell holder and layout comes from the free Getting to Blinky KiCAD tutorial. The TI part and usage is derived from Dave Jones' µCurrent.
The - battery contact area was inspired by Adafruit's Ultimate GPS Breakout (leaving the purple soldermask causes the copper ENIG contact area to be in-set, preventing an inserted battery from making proper contact).
With a 1k series resistor and 0805 LED, this board uses approximately 1mA if the battery is left inserted with the LED on. Below the IC's threshold, everything takes up 9µA without the LED lit.