Phantom drain and phantom braking are two different things. This article is about phantom drain — battery loss while the car is parked. Phantom braking, the unintended deceleration during Autopilot driving, is a completely separate topic with different causes and fixes.
Every Tesla owner has had this experience: you wake up, and the battery is lower than when you parked. Sometimes a few percent, sometimes more than 10%, with no driving in between. That's phantom drain (also called "vampire drain").
This article walks through how phantom drain works, the six common causes, five practical fixes, and how VoltKeep automatically detects abnormal drain for you.
What is phantom drain?
Phantom drain is the visible battery loss that happens while a Tesla is parked and "off". You'll also see it called "vampire drain" in English-speaking communities.
Unlike a gas car, an EV is never really off. Computers, the cellular modem, cameras, thermal management, and the security system are always sipping a little power. This is not a malfunction — it's by design. But the amount of drain varies enormously with your settings and environment, which is why some owners feel it's "way too much".
| Condition | Approx. daily loss |
|---|---|
| Sentry Mode off, default settings | About 1–2% |
| Sentry Mode always on | About 5–10% |
| Cabin Overheat Protection on, midsummer | +2–5% |
| Out of cellular range / poor signal | +1–3% |
| 5%+ per day with Sentry Mode off | Investigate |
The 6 causes of phantom drain
1. Sentry Mode
The single biggest power consumer. Sentry Mode keeps the cameras recording and motion-monitoring continuously, which forces the computer and cameras to stay essentially always on. Expect about 1% per hour, or 5–10% per day.
2. Cabin Overheat Protection
Keeps cabin temperature below ~40°C (104°F) on hot days, using either fan-only or A/C mode. Drain is most noticeable in direct sun above ~35°C (95°F).
3. Preconditioning / Smart Summon prep
Heating or cooling scheduled around your departure time, or calendar-linked preheat. The car starts pulling power well before your set time. Many people leave this on without realizing it.
4. Poor cellular reception (underground garages, etc.)
The car constantly talks to Tesla servers over LTE or Wi-Fi. In low-signal areas, the modem keeps searching for a signal and burns more power. That slow, steady drain in an underground garage is usually this.
5. Tesla Mobile Connector left plugged in after charging
On some firmware versions, leaving the cable connected after charging completes can keep the vehicle awake instead of letting it sleep.
6. Aggressive third-party app polling
TeslaMate, TeslaFi, Stats, and even an extra Tesla mobile app on a family member's phone — anything polling vehicle status frequently keeps waking the car up, which accelerates phantom drain. This is the #1 cause people overlook.
If you run TeslaMate, revisiting your polling settings (sleep mode vs active polling) often dramatically reduces phantom drain.
5 ways to reduce phantom drain
- Only enable Sentry Mode where you actually need it: Add your home garage and workplace to "Exclude Locations". Realistically, only switch it on at malls and street parking.
- Set Cabin Overheat Protection to "Off" or "Fan Only": Unless you have pets, kids, or sensitive items in the car, off is fine. Reserve the A/C mode for those specific situations.
- Unplug the Tesla Mobile Connector after charging: When you're back home, don't leave the cable hanging in the car forever.
- Audit third-party app polling: For TeslaMate, lengthen the polling interval; for TeslaFi, lean on "Sleep mode". And don't run multiple analytics apps at once.
- Plug in at 50–60% before long absences: For a week or more away, leave the car plugged in with the SoC limit set to 50–60%. The car will hold steady automatically.
How to visualize and detect phantom drain
You can't tell whether your fixes are working unless you measure. The common options:
- Tesla's own app: Shows current battery, but no historical view of drain while parked.
- TeslaMate: Visualizes sleep/wake state during parking, but you have to run it on Docker yourself.
- VoltKeep: Automatically logs the SoC delta from start to end of every parking session and pushes a notification on abnormal values.
Phantom drain detection in VoltKeep
VoltKeep pulls vehicle data from Tesla's official Fleet Telemetry API and automatically logs battery state-of-charge at the start and end of every parking session. From the delta and the parked duration, it computes a per-hour drain rate, and if that rate crosses a threshold, you get a push notification on your iPhone.
Highlights:
- No server required — it all runs from your iPhone.
- Uses real Fleet Telemetry data, so the values are measured, not estimated.
- Phantom drain detection is included in the free plan.
- Driving data is encrypted with X25519 public-key cryptography; only your device can decrypt it.
Stop guessing about phantom drain.
Auto-logged at every parking session. Notified the moment something looks off.
VoltKeep turns the "I think my battery's draining" feeling into hard data.
Frequently Asked Questions
Is phantom drain a malfunction?
Usually not. It's the cumulative result of normal Tesla behaviors: Sentry Mode, Cabin Overheat Protection, communications, preconditioning, and similar. That said, more than 5% per day with Sentry Mode off is genuinely abnormal and worth a service appointment.
Why does phantom drain feel worse in winter?
Cold weather hurts lithium-ion battery performance and triggers the battery heater to keep cells warm. Losing an extra 2–3% per day in winter is not unusual.
Should I just turn Sentry Mode off entirely?
That's a tradeoff with theft risk. The pragmatic setup is to add safe places (home, office) to your exclude list and keep Sentry Mode active only in public parking. Use VoltKeep to see how much each location actually costs you in battery — that data makes the decision easier.
Can anyone use the Fleet Telemetry API?
Any Tesla owner can, via Tesla's official OAuth flow. VoltKeep uses that official API directly to fetch your vehicle data, so you never hand over a password.