Understand a number
Charging efficiency and battery health
mi/kWh comes from the odometer: the distance between two readings and every kWh charged in between, losses included. With the battery % before and after a charge, Stats → Charging estimates its health (Plus).
Efficiency
mi/kWh is the miles between odometer readings over the kWh charged in between. Every kWh the charger delivered counts, losses included, as at a fuel pump.
Battery health
How an electric car’s or plug-in’s battery holds up, estimated from your charging.
Log the battery % before and after a charge and Stats → Charging (one vehicle at a time) estimates the kWh a full charge takes: the kWh added ÷ the points added × 100. Only charges that added 30 points or more count, since the car rounds its %; a home total has no %.
An estimate
It’s an estimate, not your battery’s size. The kWh counted include charging losses (more on a wall outlet than on Level 2, fewer on DC fast), so it reads high. Each place and charger (home Level 2, public DC fast…) is kept apart, never mixed with another; a switch shows each.
An entry far from the rest is taken for a typo and left out. Watch the line over the years rather than the number: it’s each month’s median.
Once 3 months have charges a year apart there’s a change per year too, each month against the same month a year before, so winter (cold weather adds losses, so it reads higher) isn’t taken for a change.
With the car’s own mi/kWh (an electric car’s from the odometer, a plug-in hybrid’s from its gas and electric split) it also shows how far a full charge goes.
For the steadiest line
For the steadiest line, take the kWh from the same place each time (the charger’s app, or the car’s), and log charges that add a lot.