The Green Lasers
The Apple Watch features a sophisticated optical heart rate sensor on its underside. Throughout the day, the watch constantly fires bright green LED lights into your wrist to measure your blood flow and calculate your pulse. While this is critical for athletes tracking their cardiovascular health, the constant activation of these high-powered LEDs consumes a massive amount of electricity. If you exclusively use the Apple Watch to check text messages and read emails, and you absolutely do not care about fitness tracking, the heart rate sensor is pointlessly draining your battery. You can completely shut down the hardware.
How to Turn Off the Heart Rate Sensor
You can cut power to the optical LEDs via the privacy settings.
- Open the Settings app directly on your Apple Watch (the grey gear icon).
- Scroll down the main list and tap on Privacy & Security.
- Tap on Health.
- Tap on Heart Rate.
- You will see a master toggle switch labeled Heart Rate.
- Toggle this switch to the Off position (the green background will disappear).
Maximum Battery Life
The change is absolute. The Apple Watch will immediately cut power to the sensor array. If you take the watch off your wrist and look at the back, you will never see the bright green lasers flashing again. While the watch can no longer calculate your active calories burned or track your workouts, you will experience a noticeable increase in overall daily battery life.