Apple Watch Power Reserve Mode: What It Does & How to Use It

Yes, you can and should use Apple Watch Power Reserve mode when your battery is critically low and you need to stretch it until your next charge. It turns your watch into a basic timepiece, disabling all apps, notifications, and sensors to maximize battery life. Here’s everything you need to know about when to use it, how to turn it on, and what you lose while it’s active.

What Is Power Reserve Mode?

Power Reserve is a built-in battery-saving feature on all Apple Watch models (Series 0 through the latest). When enabled, the watch stops running watchOS entirely and shows only the time in a minimal, monochrome display. It’s designed for emergencies—when you’re away from a charger and need to keep the watch alive for hours or even days. Apple states that Power Reserve can extend battery life significantly, but the exact duration depends on the model and battery health. For example, a Series 8 with a full charge might last several days in Power Reserve, while an older Series 3 might only last a day or two. The feature is not meant for everyday use; it’s a last-resort tool.

How to Turn On Power Reserve Mode

There are two ways to activate it, both requiring you to have the watch on your wrist and the screen awake.

• From the Control Center: Swipe up from the bottom of the watch face (or press the side button on watchOS 10 and later to open Control Center). Tap the battery percentage icon (a circular battery symbol). Then tap the “Power Reserveâ€� slider, and confirm by tapping “Continue.â€�
• From the Side Button (older models): On Apple Watch Series 3 and earlier, press and hold the side button until you see the Power Off screen. Then force-press the “Power Offâ€� slider (or tap it and hold) to reveal the “Power Reserveâ€� option. Tap it and confirm.

Once activated, the watch screen goes black except for a small digital time display. To see the time, press the side button or tap the screen—it shows for a few seconds, then goes dark again to save power.

What Happens While in Power Reserve?

Essentially, your Apple Watch becomes a dumb digital watch. Here’s what stops working:

• All apps, including complications, stop updating.
• Notifications, alarms, and timers are silenced (alarms won’t sound).
• Heart rate, GPS, and other sensors are disabled.
• Wi-Fi and Bluetooth are turned off, so the watch disconnects from your iPhone.
• You cannot use the Digital Crown, side button, or touchscreen for anything except viewing the time.

The watch also stops tracking your activity, so any workout or step data will not be recorded while in Power Reserve. If you try to use Siri or open an app, nothing happens. The only function is time display.

How to Turn Off Power Reserve

Exiting Power Reserve is simple but requires a physical action:

1. Press and hold the side button (the long, flat button on the right side) for a few seconds.
2. You’ll see the Apple logo and the watch will restart.
3. After booting up, the watch returns to normal watchOS, and you can use it as usual.

If the battery was completely drained before entering Power Reserve, the watch may show a red “low battery� icon instead of the time. In that case, you’ll need to charge it for a few minutes before it will turn on.

When Should You Use Power Reserve?

The obvious scenario is when your battery is below 10% and you’re far from a charger. But there are other practical uses:

• Long flights or overnight travel without a power source.
• Outdoor adventures like hiking or camping where you need to conserve every bit of juice.
• If you forget your charger on a trip and need the watch to last until you can buy one.

However, don’t use it just to save battery during a normal day. The feature disables all smart functions, so you’ll miss calls, messages, and health tracking. It’s better to enable “Low Power Mode� (available on watchOS 9 and later) if you want to retain some functionality while saving battery. Low Power Mode disables the always-on display, background heart rate, and some other features, but you can still use apps and receive notifications.

Common Problems and Misconceptions

Many users think Power Reserve will automatically turn on when the battery hits a certain level—it does not. You must activate it manually. Another misconception is that you can still use the Digital Crown to scroll or the touchscreen to interact—you can’t. The watch is locked into time-only mode.

If you find that Power Reserve doesn’t activate, make sure your watch is not in a low-power state that prevents the Control Center from opening. Also, on older watchOS versions, the gesture to access Power Reserve via the side button was different. If you’re unsure, check Apple’s support page for your specific watchOS version.

One real problem: if your battery is so low that the watch shuts off completely before you activate Power Reserve, you can’t turn it on. The watch will show a red battery icon, and you’ll need to charge it for at least 10 minutes. So it’s best to activate Power Reserve before the watch dies.

Power Reserve vs. Low Power Mode

It’s easy to confuse these two, but they serve different purposes. Here’s a quick comparison:

• Power Reserve: Extreme battery saving, only shows time, no connectivity, no sensors, no apps. Available on all watchOS versions.
• Low Power Mode: Introduced in watchOS 9, disables always-on display, background heart rate, and some other features, but you can still use apps, receive notifications, and make calls. It’s like the iPhone’s Low Power Mode.

Use Low Power Mode for everyday battery extension (e.g., a long day out) and Power Reserve only for emergencies when you need to stretch the last few percent.

Battery Life and Charging Tips

While in Power Reserve, your watch’s battery drains very slowly. Apple doesn’t publish exact numbers, but anecdotal reports suggest a fully charged watch can last anywhere from 24 hours to several days, depending on the model and battery health. To maximize the time, keep the watch away from extreme temperatures (both hot and cold) and avoid pressing the side button repeatedly to check the time—each press wakes the display and uses a tiny bit of battery.

When you finally get to a charger, plug in your watch and let it charge until it turns on automatically. If it doesn’t, press and hold the side button to restart it. Note that charging while in Power Reserve is fine; the watch will exit Power Reserve and boot up normally once it has enough charge.

Frequently Asked Questions

Does Power Reserve mode stop alarms?
Yes, all alarms and timers are disabled. If you rely on your watch to wake you, don’t use Power Reserve overnight—use a regular alarm or keep your phone nearby.

Will my activity rings still close in Power Reserve?
No. The watch doesn’t track any movement or heart rate data while in Power Reserve. You’ll miss out on those ring progress and any workout data.

Can I still use Apple Pay in Power Reserve?
No. Apple Pay requires the watch to be in normal mode with a connection to your iPhone or the watch’s own NFC. Power Reserve disables all that.

Does Power Reserve work on all Apple Watch models?
Yes, every Apple Watch model has Power Reserve, but the exact activation method may differ slightly on older models with earlier watchOS versions.

Can I charge my watch while it’s in Power Reserve?
Yes, you can. Just place it on the charger. It will charge normally and boot up once it has enough power.

Why doesn’t my watch automatically enter Power Reserve when the battery is low?
Apple designed it to be manual. The watch will show a low-battery alert, but it won’t enter Power Reserve unless you initiate it. This prevents you from being stuck without any functionality if you didn’t intend to.

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