Battery preconditioning: what it is and when to use it
Warming the battery before a rapid charge can halve the stop. In winter it is the single most useful habit an EV driver can have.
A cold lithium-ion battery cannot accept much current. Arrive at a 150 kW charger on a winter morning with a cold pack and you may see 40 kW — not because anything is broken, but because the chemistry will not go faster when it is cold.
Preconditioning is the car warming the pack in advance so it can.
How it works
While you drive to a charger, the car uses energy to bring the battery into its optimal temperature window, typically around 20–30°C. By arrival it can accept full power immediately rather than spending the first fifteen minutes warming up on the charger's dime.
Why it matters so much in winter
The difference is not marginal. A cold-pack rapid charge that takes 50 minutes can take 25 with preconditioning. Over a long winter journey with two stops, that is most of an hour.
The trigger most people miss
Most cars only precondition when you navigate to a charger using the car's own navigation system.
Use a phone app to find the charger and the car has no idea a charge is coming, so it does not warm anything. This catches out an enormous number of drivers, and it is the single most common reason preconditioning "doesn't work".
Some cars offer a manual precondition button. If yours does, and you know a rapid stop is coming, use it about twenty minutes out.
When not to bother
In mild weather. If the pack is already in its window there is nothing to warm, and many cars will simply decline to run it.
On a short hop to an AC charger. AC charging is slow enough that battery temperature barely matters.
When you are nearly out of range. Preconditioning uses energy. If range is tight, arriving matters more than arriving warm.
The related habit
Precondition the cabin while still plugged in at home. Different thing, same principle — the energy comes from the wall rather than the battery, so it is effectively free range. Details in winter range.
Our charge time calculator shows what limits a given session; on a cold day, the answer is often the battery rather than the charger.
In pictures
Common questions
Does preconditioning waste energy?
It uses some, but it usually saves more than it costs by making the charge dramatically faster. In mild weather the benefit is small and it may not trigger at all.
Why did mine not activate?
Most cars only trigger it when you navigate to a rapid charger using the car's own system. Using a phone app means the car does not know a charge is coming.
About the author
ElectraMile EditorialEditorial desk
The ElectraMile editorial team covers charging, running costs and EV ownership for readers in the UK and US.
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