Overview

How metrd detects and records charge session phases.

A charge session is split into phases when the charge rate changes significantly. This lets you distinguish bulk charging from absorption and float stages.

Phase detection

metrd uses a configurable gap threshold (BATTERY_CHARGE_GAP) to decide when a session has ended. Within a session, phases are separated when power drops by more than 20% for longer than 30 seconds.

Typical phases

1. Bulk — full rate charging from solar or grid
2. Absorption — charge rate tapers as battery approaches full
3. Float — minimal charge to maintain state of charge