An electric car has no petrol to go stale and no oil to change, so storing one looks simple. The difference is that it never fully switches off, and its battery has strong preferences about how full it is left.
A lithium-ion battery ages in two ways. It wears with use, and it ages while it sits. The second kind is the one storage controls, and two things drive it: how full the battery is, and how warm it is.
Battery University, a reference site sponsored by the battery test-equipment company Cadex, publishes estimates for lithium-ion cells stored for a year. The pattern is clear.
Those figures are for individual cells, and the source itself notes that not all lithium-ion chemistries behave the same. A car's pack is also managed by software that usually keeps some capacity in reserve. So the table shows the direction, and that is the useful part: full and warm is the worst combination.
The other end matters too. Tesla's owner's manual tells owners never to let the battery fully discharge, warns that reaching 0% "may result in damage to vehicle components", and says the resulting costs are not covered by the warranty.
So the edges are clear, and the manuals we checked agree on them. Don't leave the car full for months, and never let it reach empty.
Between those edges, the instructions differ. Recurrent, a US battery-data company, summarised the storage guidance in a range of owner's manuals in 2023. A few examples:
Some want the car plugged in so its battery management can keep running. Others want it unplugged. The numbers cluster around half, but the range runs from 20% to 80%. Each car's software, cooling and hidden reserve are different, and the instructions follow the car.
For a stored EV, the right answer is whatever that car's own manual says. General rules only cover the edges.
A parked EV keeps working. Tesla's manual says that when left idle and unplugged, the car periodically draws on the battery for system checks and to recharge its small low-voltage battery, and that the battery "can discharge at a rate of approximately 1% per day".
At that rate, a car left unplugged at 50% would be close to empty in about seven weeks, well inside an October to March lay-up. That is why Tesla says to leave the car plugged in if it will be idle for several weeks. Drain varies a lot between cars: Porsche's guidance for an unplugged Taycan is a check every three months, which implies a much slower rate.
Two things make the drain worse. Checking the car on a phone app wakes it up, and Porsche's guidance, as Recurrent reports it, is to avoid waking the car during storage. Features that keep the car alert, such as camera-based security modes, draw power too.
Every EV still has a small low-voltage battery, usually 12 volts, which runs the locks, screens and computers that wake the car up. In many EVs it is topped up from the big battery. Tesla's manual warns that if the car is left unplugged for an extended period, it may not be possible to charge or use it without jump-starting or replacing the low-voltage battery.
So the two batteries are linked. Let the big one run low and the small one can go flat, and then the car may need a jump start before it can be charged at all.
Electric cars do much of their slowing down with the motor, which turns movement back into charge. That is efficient, and it means the friction brakes do less work. Bare iron discs start to rust once a film of water forms on them, which happens above about 60% relative humidity on clean metal. On a car that rarely uses its brakes hard, there is less braking to scrub that surface rust off. A dry building helps, and so does a firm stop or two once the car is back on the road.
EVs are also heavy, which puts more load on each tyre. As our supercar storage guide explains, a flat spot can become permanent after around a month of standing. BMW, according to Recurrent's summary, advises raising tyre pressures for storage longer than three months. The car's own manual will give the figure.
A hybrid adds an engine, a fuel tank and a second battery, so it carries both sets of storage concerns.
A self-charging hybrid has no plug, so its batteries are charged by the car itself. Toyota's UK advice for owners not driving their hybrids is to put the car in Ready mode for about an hour, at least once a week. It says there is no need to go for a drive, that the petrol engine may start during that hour as a normal part of charging, that the car should never be left unattended in Ready mode, and that it must be done somewhere well ventilated.
That last point matters most in storage. An hour with an engine cutting in and out needs planning, with someone present and proper ventilation. Our winter storage guide adds one more caution: an engine run only briefly, without getting fully warm, collects moisture in its oil and exhaust. If weekly sessions aren't practical for a long lay-up, ask the maker or a dealer what they recommend for that car.
A plug-in hybrid needs its battery treated like an EV's, by its own manual's rules. It also has petrol, and that petrol can be old before the car is ever stored, because an owner who drives mostly on electric may not burn a tank for months. Our supercar guide notes that petrol loses its lighter, more volatile parts within about six to eight weeks. Fresh fuel before a long lay-up is worth it.
It depends on the car. Tesla, Porsche and Volvo say yes; Ford and Nissan say no. Follow your manual.
What the manual says, which for most makers is around half. Never full for months, never empty.
It can, because in many EVs it relies on the main battery staying charged.
Yes. A plug-in hybrid needs its battery treated like an EV's and fresh fuel; a self-charging hybrid needs the maker's weekly routine, done somewhere ventilated.
Henry's Car Barn has been storing cars since 1984, at sites in Warwickshire, London, Hampshire and West Sussex, with a fifth at Thruxton from November 2026. Storage sits alongside collection management, transport across the UK and Europe, and on-site work including detailing and Liquid PPF installation.
If you're thinking about storing an electric or hybrid car, the most useful first conversation is about the car itself: what it is, what its manual asks for, and how long it will be with us.
