You park at 68% on Sunday night. Sentry mode is off. The car sits in your garage, untouched, for nine hours. Monday morning the app shows 61%.
That is seven percent gone while the car did nothing you asked it to do. No trip, no climate request, no charging session. This is vampire drain, and it catches almost every Tesla owner off guard at least once.
The frustrating part is that most owners assume Sentry mode is the only culprit. Turn it off, they think, and the drain stops. It often doesn't. There are at least five other processes that can eat your battery overnight, and most of them are invisible unless you know where to look.
I had this exact conversation with a friend who parks his Model Y in an underground garage in Istanbul. He'd disabled Sentry mode after reading that it was the main battery drain, and he was still losing 2% a night. Three weeks of checking settings later, it turned out to be a combination of weak cellular signal underground and a tracking app polling every three minutes. Neither of those shows up anywhere in the car's own settings screen. You have to go looking.
What vampire drain actually is
Vampire drain is the battery percentage your Tesla loses while parked, not driving. Every car with a 12V system and a connected computer loses some charge just staying "awake" enough to respond to your phone, check for software updates, and run background safety systems.
A small amount of this is unavoidable. Gas cars lose nothing because they don't need to stay connected to anything. A Tesla is a networked computer on wheels, and computers draw power even at rest.
The question isn't whether your Tesla loses charge overnight. It's how much, and whether that amount is normal for your model, year, and climate.
Tesla doesn't make this easy to understand on its own. The app shows you a percentage, not a reason. There's no notification that says "preconditioning ran at 3am" or "modem reconnected 40 times last night." You're left reconstructing the cause from indirect evidence, which is exactly why this topic generates so many confused forum posts and so few clear answers.
The usual suspects beyond Sentry
Cabin overheat protection
If you parked in direct sun and the cabin temperature crosses a threshold (usually around 40°C), your Tesla can turn on the climate system briefly to vent heat, protecting the interior plastics and your dog if you forgot them inside for a minute. This pulls real power, sometimes 1% to 2% in a single afternoon.
Check Controls > Safety > Cabin Overheat Protection. If you don't need it active while unoccupied in summer, you can set it to "No A/C" mode, which just vents air without running the compressor. That alone can cut parked-hot-day drain significantly.
This matters more in places like Izmir, Adana, or anywhere with long, hot summers and street parking without shade. A car parked in direct sun at 38°C ambient temperature can see cabin overheat protection trigger two or three times over a single afternoon, each cycle pulling a small amount of charge. Over a week of hot afternoons, that adds up to a noticeable chunk of your total drain, and it has nothing to do with Sentry, apps, or software bugs.
Climate keep-on and scheduled preconditioning
If you've set a departure time or a climate schedule, the car will start conditioning the cabin and the battery ahead of that time, even if you end up not driving. A missed scheduled departure that still triggers preconditioning is one of the most common silent drains owners report, especially after a software update resets a toggle they didn't notice.
Check the Climate tab and the Schedule tab in the app, not just the car's screen. These settings have moved between app versions and it's easy to have a stale preconditioning schedule lingering from months ago.
Dog Mode and Camp Mode deserve a specific mention here too, since both keep the climate system running continuously rather than in short bursts, and both are easy to leave armed by accident after a trip where you actually needed them. If your drain is unusually high and you used either mode recently, double check it actually turned off. We cover exactly when these modes are safe to trust in our Dog Mode and Camp Mode guide.
App polling
Tessie, TezLab, Stats for Tesla, and similar apps need to wake the car's computer to pull live data like location, temperature, and odometer. The car has to come out of deep sleep to answer that request, and waking up itself costs power, often more than answering the actual request.
If you poll every 5 minutes for live tracking, you are preventing the car from ever reaching its deepest, lowest-power sleep state. This is one of the most overlooked causes because owners blame "software bugs" when the real cause is the monitoring app they installed to catch problems. We cover how the major apps differ in polling behavior in our comparison of Tesla apps.
LTE modem wake cycles
Your Tesla's cellular modem periodically checks in with Tesla's servers even when you're not using the app. On weaker signal (parking garages, rural areas, certain carrier dead zones), the modem retries connection more aggressively, which draws more power than a clean handshake would.
If your garage has poor cell signal, connecting to home WiFi (Controls > Wifi) instead of relying on LTE can measurably reduce this specific drain. It's a five-minute fix that people skip because they assume LTE just works in the background for free.
Underground and multi-level parking structures are the worst case for this. Concrete and rebar block cellular signal far more than most people expect, and a car parked on level B2 of a shopping mall garage might retry its connection dozens of times over a few hours. If you regularly park somewhere like this overnight, home WiFi isn't an option, but you can at least confirm the signal problem by checking Controls > Software for a weak signal indicator, and factor that into your expectations rather than assuming something is broken.
Software bugs after an update
Tesla pushes frequent over-the-air updates, and not every release is drain-neutral. Several updates in the last two years have introduced temporary regressions where background processes didn't sleep properly, causing drain spikes of 3% to 5% per day that resolved only after the next patch. We track which releases caused trouble in our software update history recap.
If your drain suddenly got worse right after an update and nothing else changed, this is the likely cause, and the fix is usually patience, not a service visit.
The pattern is almost always the same. A new release ships, owners start comparing notes within days on whether their overnight percentage loss went up, and within two to four weeks a follow-up patch quietly fixes it without ever being called out in the release notes as a battery fix. If you want to know whether a specific update you just received has this kind of history, checking owner reports from the days right after release is more useful than anything in the official changelog.
Typical drain ranges by model and year
Not all vampire drain is equal across the lineup. Older hardware and larger infotainment systems tend to draw more at rest.
| Model and year | Typical overnight drain (parked, no Sentry) | Notes | |---|---|---| | Model S/X (2016 to 2020, pre-refresh) | 2% to 4% | Older MCU1 computer sleeps less efficiently | | Model 3/Y (2018 to 2022) | 1% to 2% | Better sleep states, still LTE-dependent | | Model 3/Y (2023 to 2026, Highland/Juniper) | 0.5% to 1.5% | Newer computer, improved deep sleep | | Any model with cabin overheat protection active on a hot day | add 1% to 2% | One-time event, not daily baseline | | Any model actively polled by a third-party app every few minutes | add 1% to 3% | Prevents deep sleep entirely |
If you're seeing numbers two to three times higher than your row in this table, consistently, over a week, something specific is wrong rather than normal background behavior.
It helps to translate percentage into something more concrete than an abstract number. On a Model Y Long Range with roughly 530 km of rated range, losing 2% overnight is about 10.6 km of range gone before you've even touched the accelerator. Losing 5% is closer to 26 km, enough to change whether you need a top-up charge before a trip you'd otherwise have made comfortably. Thinking in kilometers rather than percent makes it easier to decide whether a given drain rate is actually a problem for how you use the car.
How to diagnose it using the app's charging history
Tesla's own app gives you more than enough data to self-diagnose before calling service. Here's the process that actually works.
- Open the Tesla app and go to your vehicle's Charging tab.
- Scroll to charging history and look at the percentage reading right before you left the car and right when you returned, ignoring any charging sessions in between.
- Note the exact hours parked. Drain scales with time, so six hours and eighteen hours are not comparable without doing the math per hour.
- Divide the percentage lost by the hours parked to get a per-hour rate, then multiply by 24 for your daily rate.
- Repeat this for three or four different parking sessions, ideally some at home and some elsewhere, to see if the drain is location-specific (a signal issue) or constant (a settings or software issue).
- Cross-check against the Cabin Overheat Protection and Schedule settings mentioned above for the same dates.
- If a third-party app is installed, pause its tracking for 48 hours and re-measure. If drain drops noticeably, you found your cause.
This process takes about a week of casual observation but gives you a real number instead of a guess, which matters if you do end up contacting Tesla service.
A few extra checks are worth doing at the same time. Look at whether the drain is worse on nights after a long drive versus nights after the car has been idle for days, since a battery that recently finished fast charging or a long trip can run background balancing and cooling for a while afterward, which looks like drain but is actually the battery management system doing its job. Also note the outside temperature for each session, since cold nights alone can account for a noticeably higher reading even with every setting turned off, something we go into in more detail in our cold weather range loss data.
When it signals a real fault versus normal background use
Most vampire drain complaints resolve to one or more of the causes above, not a hardware fault. But there are a few patterns worth flagging to a service center.
A drain rate that climbs steadily over weeks with no change in your settings or apps, rather than staying flat, suggests a degrading 12V battery that's struggling to hold its own charge and pulling more from the main pack to compensate. We go into the warning signs for this specific failure mode in our 12V battery guide.
A drain rate above 5% per day that doesn't drop even after disabling every app, schedule, and overheat setting, sustained for more than three or four days, is unusual enough to warrant a service ticket. Bring your per-hour measurements from the diagnosis steps above. A specific number makes the visit faster and harder for anyone to wave away as "normal."
| Signal | Likely explanation | Action | |---|---|---| | Drain is flat around 1% to 2% nightly, every night | Normal background behavior | None needed | | Drain spikes only on hot, sunny days | Cabin overheat protection | Adjust or accept as a one-time cost | | Drain is high only in one parking spot | Weak cellular signal | Switch to WiFi if available | | Drain is high everywhere, every night, started after an update | Software regression | Wait for the next patch | | Drain climbs week over week with no setting changes | Aging 12V battery | Book a service inspection | | Drain stays above 5% even with every app and schedule disabled | Needs investigation | Contact service with your measured numbers |
Service centers see this complaint often enough that having your own data, rather than just "it feels like it loses too much," tends to get you a faster and more accurate diagnosis on the first visit instead of a shrug and a "that's within spec."
The soft takeaway
Most vampire drain is explainable, fixable in five minutes, and not a sign anything is broken. The habit that actually helps long term is simply checking your charging history every week or two, the same way you'd glance at your fuel gauge in a gas car. If you want that check automated instead of something you remember to do manually, that's exactly the kind of quiet background task Volt is built to handle for Tesla owners who'd rather not think about it.