How a battery is ageing.

Every battery slowly loses capacity. The model tracks how fast, for each bus, from the way it is charged and driven.

Two identical buses can age very differently. Fast charging, deep discharges and hard routes all leave a mark. Charging sessions record the first two. Vehicle location records the third.

Knowing what each battery has left tells schedulers which bus can still cover a long day, and tells the agency when a replacement is due.