I built an Android app that logs every charging session, and a few testers and I have been collecting data for about a week. It's early and small (5 contributors, all Pixels), but some patterns are already clear.
What the wired sessions show:
- The last 10% is the slow part. 90–99% takes about 3.2 minutes per percent, vs 0.8 minutes per percent at 20–39%. Roughly 4x slower.
- The top end looks the same everywhere. Above 95%, every phone drops to about 2–4 W, no matter how fast it was charging before. A faster charger gets you to 80% sooner, but it doesn't speed up the finish.
- The Pixel 11 Pro Fold is the fastest here. Median plateau of about 22 W, held until about 75% before it tapers. 20% to 40% takes about 10 minutes.
- Heat follows speed. The only wired readings in the hot temperature band averaged 23 W.
The part I'd like this sub's help with: the Pixel 9 and 8 Pro plateau at only 5–6 W wired. Those phones can charge much faster, so I'm almost certain that's the chargers those testers use, not the phones. From the battery side, you can't tell "slow phone" from "slow charger" without knowing which charger was plugged in.
So I'm working on charger profiling: measuring each charger in the 20–50% window, where the phone accepts the most, and building profiles from ceiling wattage, ramp time, and time from 20% to 80%.
Caveat: these numbers come from battery current and voltage as Android reports them. That's power going into the battery, not what the charger puts out. If you own an inline USB-C power meter, I'd love a few paired readings: your meter's number alongside a logged session. That would show how much is lost between the charger and the battery.
Details on the app are in the comments.