How to Store an Electric Car Over Winter

Storing an electric car over winter, or leaving it unused for several weeks, takes a little planning but nothing complicated. The main concern is the battery: leaving it fully charged or completely flat for an extended period can cause gradual degradation, so the widely recommended approach is to park with the state of charge sitting somewhere in the middle range before you walk away. For straightforward guidance on keeping your charging equipment in good shape while the car is off the road, see our EV charging cable guide.

What state of charge should you leave the battery at?

Aim to leave the traction battery sitting somewhere between half and roughly three-quarters full before you park up for a long period. A full charge creates slightly more stress on the cells when they sit at that level for weeks at a time, and an empty battery is worse still: if the charge drops below a certain threshold the car's battery management system cannot protect the cells effectively. Most manufacturers publish a recommended storage range in the owner's manual, so check there first. If you are leaving the car connected to a charger, use any available "charge limit" setting to cap it below maximum.

Does the storage location make a difference?

Yes, and a garage is noticeably better than the street. Cold temperatures reduce the capacity a lithium-ion pack can deliver, so a car left outside in freezing conditions will show a lower state of charge than it actually has. More practically, condensation and freeze-thaw cycles are harder on connectors, seals, and especially the small 12V auxiliary battery that most EVs still carry. A sheltered carport is better than nothing. If outdoor storage is your only option, try to keep the car away from standing water and check on it more often during cold snaps.

Why do tyre pressures matter during storage?

Cold air is denser, which means tyre pressures drop as temperatures fall. A tyre that was correctly inflated in autumn can be noticeably underinflated by mid-winter, even if the car has not moved. Beyond the handling implications when you bring it back into use, a heavily underinflated tyre sitting in one position for weeks can develop a temporary flat spot that takes a few miles of gentle driving to work out. Check pressures before storing the car and again before you drive it back onto the road. Your car's recommended pressures are usually on a sticker inside the driver's door frame.

Should you disconnect the 12V auxiliary battery?

This is worth doing if the car will be unused for more than a month. Most EVs still carry a small 12V lead-acid battery that powers lights, locks, infotainment, and safety systems. Unlike the main traction pack, this battery is not designed to hold a charge over long idle periods, and a completely flat 12V battery can prevent the car from starting even when the traction pack is fully charged. Your options are to disconnect the 12V negative terminal (check the owner's manual for the correct procedure), connect a low-amperage trickle charger designed for lead-acid batteries, or simply start the car every couple of weeks and let it run for a short time.

Which systems drain the battery during storage?

Modern EVs are not truly dormant when parked. Several background processes continue to draw power:

• Scheduled charging or preconditioning: if enabled, these will activate at set times and pull charge out of or into the pack.
• Manufacturer app connectivity: many cars maintain a persistent connection so you can check status remotely. This is convenient day-to-day but draws power continuously over weeks.
• Alarm and security systems: these run all the time but are usually low-draw and harder to disable without affecting safety.
• Thermal management: some battery management systems run the heating or cooling circuit when temperatures are extreme. This is largely automatic, but parking in a moderate environment reduces how often it activates.

Check your owner's manual or the manufacturer's app for any "transport mode" or "storage mode" that reduces parasitic drain during long periods of non-use.

What happens to range in cold weather even when driving?

Range loss in cold weather is not specific to storage, but it is worth understanding before you bring the car back into regular use after a period of low temperatures. Lithium-ion cells are less chemically active when cold, which reduces the energy they can deliver in one go. Heating the cabin uses additional energy, compounding the effect. The car's battery management system may also limit charging speed in cold conditions to protect the cells. Preconditioning the battery while the car is still plugged in, before you set off, is the most effective way to minimise these effects: it warms the cells using grid electricity rather than traction pack energy.

Frequently asked questions

Is it bad to leave an electric car at 100% charge for weeks?

Leaving a lithium-ion battery at maximum charge for an extended period places extra electrochemical stress on the cells and can accelerate gradual degradation over time. Most manufacturers and battery engineers recommend targeting a mid-range state of charge for any storage period longer than a week or two. Check your owner's manual for a specific recommended range.

Can I leave my EV plugged in during storage?

Yes, in most cases. If you leave it connected, use the car's charge limit setting to cap the state of charge below maximum, and check that scheduled charging or preconditioning is disabled so the car is not constantly cycling. Some manufacturers recommend leaving it plugged in specifically so the battery management system can maintain the pack within a safe range.

How often should I check on a stored electric car?

Checking every two to four weeks is sensible for most situations. Each visit, glance at the state of charge in the car's app or on the dashboard to make sure it has not dropped too low. If it has fallen noticeably since your last check, briefly connect a charger to bring it back into the recommended storage range before parking up again.

Will cold weather permanently damage the battery?

Cold temperatures temporarily reduce the performance and apparent capacity of a lithium-ion battery, but this is not permanent. Capacity returns as the battery warms up. True cold-related damage occurs mainly if the battery is charged at a high rate while the cells are very cold, which is why charging speed is automatically limited in winter. Driving and charging gently until the battery reaches its normal operating temperature avoids this.

Do I need to do anything with the portable charger during storage?

Store your portable or granny charger somewhere dry and frost-free during winter months. Inspect the cable and connectors for any cracking or damage before putting it away, and again before first use in spring. Extreme cold can make cable sheathing brittle, so avoid leaving a coiled cable pressed against a freezing concrete floor for months at a time. See our portable EV charger guide for more detail.

Is a trickle charger safe to leave connected to the 12V battery for months?

A purpose-built battery maintainer or "smart trickle charger" with automatic float mode is designed for exactly this use. It monitors the 12V battery voltage and tops it up as needed without overcharging. A basic fixed-rate trickle charger left connected for months without monitoring is less suitable. Check the charger's specifications before leaving it unattended for a long period.

Storing an EV through winter comes down to three essentials: leave the traction battery at a mid-range charge, protect the 12V auxiliary battery from a flat, and check in every few weeks to make sure nothing has drifted out of range. For everything you need to keep charging simple when the car does come back into use, browse our Type 2 charging cables and the rest of our EV guides.