Airport car parks are one of the more overlooked parts of any holiday, but for EV drivers, leaving the car behind for a week or two raises a question that never troubled petrol and diesel owners: will the battery still have enough charge left to get you home?
Harpreet Sandhu recently emailed me to ask: “I travel quite a lot and sometimes leave my car at an airport for two or three weeks. With a petrol car I’ve never really thought about it, but what happens with an EV? Will the battery gradually run down while it's parked, and could I come back to find I haven't got enough charge to get home?”
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It's one of those things that sounds like an EV problem but, in normal circumstances, really isn't. An electric car doesn't suddenly start haemorrhaging miles simply because you've left it in an airport car park. The main high-voltage battery loses relatively little charge while the car is sitting unused, so leaving it with a sensible amount of charge should see you through two or three weeks without any trouble.
There can be some energy use while the car is parked, though, and this is where it gets interesting. Modern EVs are very connected cars, and some features carry on working when you're nowhere near them. Security systems, remote access, battery management and other electronics can all draw small amounts of power.
Tesla's Sentry Mode is a good example. It uses the car's cameras to keep watch while it's parked, which is clever, but keeping that technology awake also uses energy. If you're leaving the car for several weeks and don't need features like that, switching them off can reduce the amount of battery you lose.
It's also worth resisting the temptation to keep opening the car's app from a sun lounger to check how it's doing. Depending on the car, repeatedly checking in can wake up systems that had been happily asleep. Your EV doesn't need checking on every couple of hours.
There's another battery in an EV that people sometimes forget about: the conventional 12-volt battery. It powers many of the car's everyday electrical systems and allows the high-voltage battery to be brought into operation. EVs have systems to keep it topped up, but a weak 12-volt battery can cause trouble just as it can in a petrol or diesel car – something worth bearing in mind if your car is getting on a bit and you're leaving it for a long stretch.
As for how much charge to leave it with, avoid either extreme if you can. There's no need to arrive with 100 per cent and leave it sitting full for three weeks, and parking up with two per cent and hoping for the best isn't wise either. Follow the manufacturer's advice, but somewhere comfortably in the middle gives you breathing space and enough range to get home when you land.
Temperature can make a difference, too. Come back to the car after a freezing couple of weeks and the range on display may look lower than you remember, simply because cold batteries are less efficient. That doesn't mean all that energy has vanished while you've been away – as the battery warms up, things should improve.
If the airport has chargers, it's not necessarily worth leaving the car plugged in for the whole holiday either. Long-stay charging spaces are increasingly common, but check how the particular service works – you don't want to block a public charger for a fortnight or come home to an unexpectedly large overstay bill.
And here's one of the nicer EV tricks for the journey home: once your flight lands, use the app to warm or cool the cabin before you reach the car. After a long flight, getting into a car that's already at the right temperature feels wonderfully decadent.
So charge sensibly before you leave, turn off any energy-hungry features you don't need, and then forget about the car. Leave a healthy EV with a decent amount of charge, and the chances are it'll be considerably less exhausted after two weeks at the airport than you are.
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