Multiple Factors Contribute to Battery Discharge
Electric vehicles (EVs) do not simply stop drawing power when they are locked away. Even when parked, the vehicle continues to consume electricity, meaning the battery percentage can decrease even if the car hasn’t moved. The degree of charge loss depends heavily on the specific make and model of the EV, as well as the operational status of its various systems.
While lithium-ion cells naturally lose a small amount of charge through a process called self-discharge—which involves electrolyte oxidation and reduction—this natural leakage is minor compared to the electricity used by the car’s various systems. The majority of the energy drain comes from electronics that remain active after the doors are locked. While this drain might not be problematic over a weekend, prolonged periods of inactivity, such as leaving the vehicle for several weeks, can accumulate noticeable losses.
Active Systems and Convenience Features Keep the Power On
A locked EV is not fully powered down. Essential systems remain operational. The vehicle’s battery management system routinely checks the battery’s condition, and the high-voltage battery often supplies power needed to recharge smaller, low-voltage batteries used for the locks, computers, and other internal electronics. Both Tesla, with its Model 3, and Rivian, with its R1T, confirm that their vehicles utilize the high-voltage battery to maintain power for the 12V battery.
Beyond core functions, “convenience technology” also contributes to consumption. Connected services allow owners to check the vehicle’s status remotely, pre-condition the cabin, or start the climate control before driving. Tesla specifically points to app requests, infotainment use, and climate functions as sources of power consumption while the car is parked. Furthermore, third-party applications that repeatedly activate the vehicle can exacerbate the drain. For instance, using cabin cooling in hot weather requires significant energy.
Cold weather adds complexity to the issue, as temperature fluctuations can cause the estimated range to drop, even without the vehicle consuming electricity. Owners of the Model 3 can use the Energy app’s Park tab to get a more accurate reading of energy consumed while stationary, which is more reliable than simply observing the range estimate.
Optional Modes and Surveillance Drain Power
Certain optional features represent the largest potential drain. Security systems, such as Tesla’s Sentry Mode, use sensors and cameras to monitor for suspicious activity. Similarly, Rivian’s Gear Guard Motion Cam can record activity around the parked vehicle. While these electronic safeguards offer peace of mind in unknown locations, they require continuous power.
In terms of expected loss, the Model 3 manual suggests that the battery might lose approximately 1 percent per day, depending on the current settings and operating conditions. However, reports have ranged from observed losses of just 0.1% to 0.3% daily for vehicles in a low-power state, while those running energy-intensive functions can lose several percent every day. These figures are not guarantees, as they reflect varying conditions.
It is also crucial to consider the overall battery size when calculating losses. For example, losing 0.5kWh equates to roughly 1.2 percent of a 42kWh battery, but only 0.6 percent of an 80kWh battery, making the same drain more pronounced in smaller city EVs.
Recommendations for Long-Term Storage
If the vehicle will be left unused for an extended period, owners should take preventative measures. It is advisable to deactivate non-essential surveillance systems and climate controls, limit the use of apps that repeatedly wake the car, and ensure the battery has sufficient charge for the return journey. For long-term storage, Tesla specifically recommends keeping the Model 3 connected to a charging source and maintaining a charge level near 50 percent.
