Symptoms
- Battery percentage decreases even when the car isn't being driven
- Drop is more noticeable over several days parked
- App shows the car checking in or updating periodically
- Loss seems worse in very hot or cold weather
Likely causes
- CommonBackground climate or battery conditioningMany EVs automatically run battery thermal management to protect the battery in extreme temperatures, which uses some charge.
- CommonPhone app or software checking in periodicallyConnected car features like remote monitoring apps cause small periodic power draws.
- PossibleSentry mode, dashcam, or security features left onCamera-based security features that record while parked can use meaningfully more energy than idle stand-by.
- Less commonParasitic drain from an aftermarket accessoryA poorly installed accessory drawing 12V power can add to the drain.
What to do
- Check if any security camera or 'sentry'-style monitoring feature is active and consider disabling it when parked long-term if range loss is a concern.
- Note the outdoor temperature, since extreme heat or cold triggers more background battery conditioning.
- Check the car's app for any scheduled preconditioning or charge settings that might activate while parked.
- If you have aftermarket accessories wired into the 12V system, consider temporarily disconnecting them to test for drain.
- Compare the rate of loss (percentage per day) against your owner's manual or manufacturer guidance for normal standby loss.
- If parking for an extended period, it's often better to leave the car plugged in if possible.
When to call a pro
If loss is far beyond the manufacturer's stated normal standby rate even with monitoring features off, have a dealer check for a parasitic drain.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.