The five phases

When a session ends, ChargeLog segments its power curve into phases — the same five, in the same order, painted in the same colors everywhere in the app. A charge is not one event; it is these five, and which ones dominate is most of what a curve has to say.

Ramp

The negotiation. Charger and phone agree on what power to deliver, and output climbs until it settles. Short — often seconds — and absent entirely when a session starts already settled.

Peak

The flat top of the curve: sustained fast charging near the session's highest settled power. This is the part spec sheets advertise.

Stepdown

Deliberate drops from peak, usually in visible steps, as heat or rising charge level makes the phone back off. Watching where stepdowns land is how throttling becomes legible.

CV taper

The battery is nearly full and holds a constant voltage while current falls away steadily. The long tail — this is where the last 20% spends its time.

Trickle

The final creep to full and the hold there. Low power, long minutes, and honest bookkeeping: a top-off held at 100% is excluded from efficiency numbers.

What the analyzer won't do

Phase detection runs on smoothed power, looking for the points where the curve's behavior actually changes. Samples that fit no phase's definition stay unclassified — the analyzer never stretches a label to cover data it doesn't explain, and a blip too short to be a real phase is not promoted into one.

Why segment at all

Because "this charge was slow" is not an observation — "peak lasted four minutes, then forty minutes of stepdown at high temperature" is. Phase makeup is comparable across sessions, chargers, and conditions in a way raw curves are not, and it is what turns one charge into evidence about the next one.