Preconditioning heats the cabin and sometimes the battery while the car is still plugged in, so the energy comes from the wall rather than the pack. You set it in the car, often as a departure time. The charger has to be willing to supply power at that moment. If the charger schedule has already closed, or a supplier is holding the session, the car may try to precondition from the battery instead. Align the charger's available hours with the departure time, then test it once on a cold morning.
Check preconditioning from a home wallbox before you accept a price
Battery preconditioning for a rapid top-up later is a car feature aimed at public DC. It is not something a basic wallbox 'supports' as a special mode.
The price effect of preconditioning from a home wallbox
Done well, you leave with a clear screen and more of the pack. Done badly, you leave late and blame the tariff.
A miss that shows up later: preconditioning from a home wallbox
The mistake is a charger off-peak window that ends at 5am and a departure precondition set for 7:30 with no power available.
Write preconditioning from a home wallbox into the quote
Note the departure time in the handover and set one schedule that still allows a morning precondition.
Preconditioning from a home wallbox
A five-minute test in the driveway tells you more than the manual. Put a hand on the vent, look at the app, see whether the session is live.
- The car requests the heat
- The charger must be allowed to deliver then
- Test one real morning
- This is not a special charger brand feature in most cases
Frequently asked questions
Does every EV do this?
Most modern ones can heat the cabin on a timer. Battery preconditioning varies. Read the car manual.
Will it cost a lot?
It is a short burst of kWh. It is usually cheaper than losing range on the road, and it should sit inside a cheap window if you can arrange that.
Can the charger do it without the car timer?
Not really. The car decides to heat. The charger decides whether power is available.
What if I unplug at the last second?
Then the car finishes the heat from the battery. Plug in until you are ready to leave.
Core buying guides
Start with these high-intent guides, then dig into the rest of the library.
Related guides
Sources and further reading
How this guide was prepared
This guide was written by the Local EV Installers Editorial Team. We compare official guidance, legislation and established consumer information, separate general information from project-specific advice, and show publication dates and sources. We do not accept installer accreditation claims at face value.