My Nokia phone charger (type ACP-7X) has now been plugged in and switched on but with no phone connected to it for more than 24 hours and it has apparently used precisely zero electricity.

However, it also registers zero with a partially-discharged phone plugged in and charging, so I suspect the tracker's just not sensitive enough to register very small currents.

Interesting - certainly I'm less bothered about leaving the phone charger plugged in than I was.
--
Simon