- In power-saving mode, an electric car can sit for months
- Overnight with all systems active, you will lose 0.5 to 1% power in optimal conditions and 2-4% overnight in sub-zero temperatures
- Lithium-ion batteries are good at preserving power, but like all batteries, they suffer from vampire battery drain
- You can leave your car for a month without worrying so long as you start with 80% charge
How long can an electric car sit without charging? That depends on what power mode it is in, what systems are active, charge level, and outside temperature.
You see, most electric cars have low energy modes for extended periods of inactivity, which can preserve a state of charge in the battery for months at a time. These modes disable power-hungry features to reduce vampire battery drain.
This article explores a few scenarios and provides real-world examples based on me leaving my Tesla Model 3 to go on holiday.
Vampire battery drain
“Vampire battery drain” is the name given to the energy loss that occurs in an electric car battery while parked. Electric vehicles lose battery charge because the ions inside the battery continue to react with each other, using energy in the process.
Energy loss in electric car batteries
The most efficient electric car batteries lose 0.5-1% charge per 24 hours in optimal temperatures.
In sub-zero temperatures, that energy loss increases to 2-4% per 24-hours (this article discusses how cold temperatures affect batteries).
In this video, YouTuber SaskTesla tests leaving his Tesla unplugged in winter overnight to see how much range it loses. He lost 5% charge overnight, and pre-heating uses another 1.5% (in milder conditions, pre-heating uses around 1.1%).
So, leaving an electric car for a week or two in winter should be fine, providing you park up with enough energy in the battery.
Minimum charge level for long periods of inactivity
Tesla recommends starting with a 90% charge for long periods of inactivity. They don’t recommend 100% because this can have a negative effect on battery degradation.
As a general rule of thumb, always start with a 70% to 80% charge when leaving your electric car for more than two weeks. If you are leaving it for a week or so, a 60% to 70% charge should be sufficient.
Never leave your car inactive for more than a week with 20% or less battery. Batteries are less efficient with a lower charge, so the rate of battery loss increases.
Tesla Model 3 parked energy loss examples
During my Tesla Model 3 ownership, I’ve been away from it on holiday twice. Here’s what happened:
- Holiday 1 – 1 week in Barbados during winter in England. Car left on my driveway with 89% battery. When I returned, I had 78% battery (11% energy loss).
- Holiday 1 – 2 weeks in Croatia. Car left at Manchester airport with 83% battery. When I returned, I had 76% battery (7% energy loss).
From my experience, we can deduce that leaving an electric car sitting in winter saps the battery faster due to cold weather (I lost more energy in winter than I did in summer over a shorter period). However, leaving it for a week or two is no big deal.
How to reduce vampire battery drain
Park somewhere warm. Cold temperatures sap power from the battery faster.
Vampire battery drain increases when you connect to your car via your smartphone to access smart features. Use your companion app sparingly, and you’ll use far less energy while parked.
In Tesla cars, you should deactivate Sentry Mode and Keep Climate On mode. This will help to reduce vampire battery drain without deactivating safety features.
Can an electric car sit for months without charging?
In a climate-controlled environment, an electric car starting at 90% can sit for 6 months without charging so long as it is in a power-saving mode. However, in cold climates, this is reduced.
Should I leave my electric car plugged in on holiday?
You don’t need to leave your electric car plugged in when you go on holiday, just like you don’t need to charge your car every day.
So long as you park up with sufficient charge, you can leave your electric car sitting for several weeks without worrying about losing lots of range.