I'm going to post a Sensor Watch battery update later today, and this post is to connect it to the old battery test thread. If you're new to this: in late 2021, I put a fresh coin cell into Sensor Watch, my board swap for the Casio F-91W wristwatch. This month that watch hit one year on that same battery, and in this thread I'm tracking how long the battery will last. You can click the “Replying to @josecastillo” link repeatedly to get back to the beginning of the test. https://twitter.joeycastillo.com/josecastillo/status/1590059216798388224/

@josecastillo Battery test, day 380: 2.59 volts. To reiterate the parameters of the test: this watch (red line on the graph) is running an old firmware from 2021 that lacks some low power optimizations I did early this year. I also started a new watch (green line) in February of this year that I've been wearing daily since; it's still sitting pretty at 3.08 volts here on day 275.

@josecastillo Forgot to post this yesterday! Battery test, day 390: 2.51 volts. I think we're finally near the end with the old firmware; I expect it'll die within a week or two. There's an app note that once the LCD voltage is more than 700 mV above the system voltage, current consumption increases, and I think I can see that on the red line: it's dropping faster now that we've crossed the threshold. New, more efficient firmware though: still going strong! 3.07 volts at day 285.

@josecastillo Battery test, day 400: 2.4 volts. It’s low enough now that the extra power of beeping the buzzer on mode change causes a voltage drop to ~2.3, but it recovers to 2.4 over about ten seconds. New firmware is back up to 3.08 volts here on day 295! Both lines are red this time, but it’s the one on top.

@josecastillo Battery test, day 410: 2.195 volts. (Mostly 2.19, but it did hit 2.20 once). No more big voltage drop when I press the mode button, which signals to me that its steady state current consumption is higher now. That and the steepening of the red line 😬. This microcontroller operates down to 1.62 volts, which gives me optimism that this watch with the old firmware will still be with me in 2023, if only for a few days. (New firmware, green line: 3.07 volts at day 305.)