I’m trying to find out what exactly influences the efficiency of my EV charger. For example some days I charge the car for 8kWh which should be 11% added charge for my car but it only added 8%, other days it will have added 9% or 10%.
I currently use the total charged amount and the percentage added to calculate the kWh/%, currently it is at 1.02kWh/%. This will probably change over time, maybe with the way I charge (pure solar or grid), ambient temperature or length of charging session.
To figure out exactly what impacts the efficiency of my charger I want to keep track of these values for a specific charging session. What is best way to do this? I would love to look back at all the charging sessions throughout 2026 and get some sort of formula to calculate the charging efficiency up front before charging.
This is the data I want to keep per charging session:
Length of charging
Amount charged in kWh
Amount charged in %
kWh/% rate
Average ambient temperature throughout session
Solar, Grid or mixed charging
Start and end datetime of charging session
How can I keep track of this data and look back at it throughout 2026? What I understand from attributes is that only the attributes for the current value are stored, not attributes of old values, but I might be wrong.