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The open dataset

ChargeLog can ask to include your anonymized charging curves in a public, per-model picture of how devices really charge. This page is the receipt for that ask: what a contribution contains, what is published, and where the dataset stands today.

Nobody has a good public record of how phones, batteries and chargers actually behave. Manufacturers have the data and do not publish it; everyone else is guessing from one device. A contributed curve is one real measurement against that, and enough of them is what turns "your charger seems slow" into something the app can say with a number behind it — for you and for whoever asks next. It is off unless you turn it on, one tap turns it off again, and the app works exactly the same either way. If you do turn it on: thank you, genuinely.

Not live yet.

Nothing has been sent by anyone, because there is nothing to send it to yet — the service that would receive a contribution has not been deployed. Until it is, a choice made in the app is stored on that phone and each prepared charge waits there. The app asks for nothing to do its own job; the network is used for this and only this.

What a contribution contains

One charging session, reduced to this and nothing else:

  • whether it came from a phone or a watch; the device model, chip and memory to the nearest gigabyte — the kind of device, never which one; the Android version and the ChargeLog version it was recorded under; for a watch, the model of the phone it is paired with;
  • the battery's rated size, so a curve can be read against the cell it filled;
  • wired or wireless; the charger's advertised wattage and the voltage-and-current pair it settled at, rounded — enough to tell two chargers apart, never enough to name one; if you told ChargeLog what the brick claims on its label, that number too; whether the screen was on; whether the phone said it was pacing itself, running hot or running cold; a temperature band; on a folding phone, whether it was open or closed;
  • the starting charge level rounded to 5 %, and the week the charge happened — not the day, not the time;
  • the power curve, rounded to a quarter of a watt every ten seconds, with the level to 1 %, and when each charging phase began;
  • a pseudonym that changes every month, and — when the open dataset is live — the phone's own attestation certificate chain, the proof that an unmodified ChargeLog on real Android hardware sent it. That root of trust is strong, not absolute: it cannot see a manipulated battery driver, and a leaked device key has happened before.

The app shows you the contribution it would send — built from your own last charge, with a placeholder where the pseudonym will go — before anything is sent: Settings → Data management → Contribute.

What never leaves the phone

Your tags, notes and labels. Your location. Serial numbers, IMEI, Android ID, or any other identifier. Which screens you open, what you tap, how often you use the app. Usage telemetry is never sent, opted in or not — that is what "no tracking" means here — and a contribution is built so it cannot carry any of it: the list of fields is fixed in code, and a new one fails the build rather than shipping.

How it is published

As per-model averages, under the CC BY 4.0 licence (opens in a new tab). Individual sessions are not released. A point on a published curve exists only where the floor is met: 20 distinct monthly pseudonyms per state-of-charge point — below that a curve has a gap, never an interpolated line. Because the pseudonym changes every month, one device that contributes across a month boundary counts twice toward the floor; the floor is stated here as it is, not as something stronger.

Before any curve qualifies, this page will show how many sessions have been received, so a contributor can watch the number move; curves appear beside the count as models clear the floor.

Deleting what you contributed

Turning contributing off stops future sends at once, and discards anything prepared on this phone but not yet sent. Deleting will reach back: the app keeps the monthly pseudonyms it contributed under, and a deletion presents the ones it still holds so the contributions behind them can be removed — recorded in the daily manifest chain, so a removal is visible rather than silent. That will work while ChargeLog is installed on the phone that sent them, because those pseudonyms live nowhere else, on purpose. Uninstall first, or clear the app's data, and the months it no longer holds stay — best effort, not exhaustive, which is acceptable only because a contribution is anonymized: rounded, aggregated above a floor, and under a pseudonym that changes monthly.

To ask for a deletion, in ChargeLog on the phone that contributed:

  1. Open Settings, then Contribute charging curves.
  2. Tap Delete my contributions and confirm.

What is removed: every contributed charging curve this phone can still identify, from the dataset's storage, at once. What is kept: each day's manifest, which lists only a hash of every contribution accepted that day and is retained for at least a year, so the record of what was accepted and what was later withdrawn stays verifiable. No account, email or identifier is held, because none is sent. Turning contributing off without deleting keeps what was already sent and stops everything after.

Checking for yourself

Google Play lists the app's permissions on its own page, and the APK manifest is readable by anyone. When the open dataset is live, every day's accepted contributions are listed in a manifest that carries the hash of the day before, so nothing can be rewritten quietly. Questions go to hello@chargelog.org.