Old smartwatch and fitness tracker second life: match the job to the battery it has left

Repurpose · 7 min read

Can an old smartwatch still be useful? Yes — but the useful question comes second. The first question is what charge the battery can still hold, because the same retired watch is a good overnight sleep tracker with a healthy battery and a poor one with a tired battery, while a tired battery is no obstacle at all to a watch that lives on its charging dock as a clock. Battery first, job second. Everything below follows that order.

Health note: most smartwatches carry heart-rate sensors, and some add blood oxygen and ECG. Those are wellness indicators for everyday curiosity, not medical instruments, and spot-checks from an old watch do not substitute for a doctor's advice.

Start with the battery check

On an Apple Watch, battery health is checked on the watch itself at Settings > Battery > Battery Health, which shows maximum capacity — the battery's capacity relative to when it was new. The watch alerts the wearer when capacity is significantly reduced. On any brand, the practical test is just as telling: charge it fully, then see whether it gets through a full day, through a single night, or only through a few hours off the dock. Write the result down. That one result — a day, a night, or dock-only — assigns the job.

Job 1: the dedicated sleep tracker

A retired watch solves a timing problem the everyday watch has: worn all day, its battery is low by bedtime, so it charges overnight instead of tracking. A retired watch has no other job. Charge it briefly each morning — the Galaxy sleep-tracker routine suggests about 30 minutes — leave it on the dresser by day, and wear it only at night. Its heart-rate sensor, SpO2 monitor, and accelerometer still work for sleep tracking.

On Apple Watch, the Sleep app lets the wearer create bedtime schedules and sleep goals; worn to bed, the watch estimates time spent in each sleep stage — REM, Core, and Deep — and when the wearer may have woken up, with sleep trends over the past 14 days viewable. Two limits are built in: if the watch is charged less than 30 percent before bed, it prompts for a charge, and the watch must track sleep for at least four hours a night to return sleep data. Sleep Focus silences notifications overnight, and the haptic alarm in Silent Mode wakes the wearer without sound — a genuinely better alarm clock than a phone across the room.

Job 2: dock-bound jobs for a tired battery

A watch whose battery is too weak for whole-day wear can sit on a stand or charging dock with the always-on display enabled and work as a desk clock or bedside alarm; raise-to-wake is worth turning off on a docked watch, since nothing is raising it. Keeping the screen on while charging makes the same bedside-clock job work on other brands as well.

Docked does not mean idle. A Samsung Galaxy Watch has a built-in Camera Controller app that works as a Bluetooth shutter for the phone camera, and a Pixel Watch uses Google's Camera app for the same job; a watch can also serve as a music playback controller or a presentation clicker. An old Apple Watch can even run the Hue Essentials app to control Philips Hue lights without a phone. None of those jobs cares that the battery is tired, because the dock is never far away.

Job 3: the beater watch

With a battery that still lasts the day, the honest job is risk transfer: an old watch can be reserved for higher-risk activities so the newer watch stays pristine, with workout data still syncing to the iPhone. Compatibility varies by model — most Apple Watch features in this role need Series 4 or later, and an older model such as Series 3 is limited to basic metrics. Basic is enough for a beater: steps, time, and a workout record are the job, and a scratch on this watch costs nothing.

Handing it on: export, erase, unpair — in that order

When the watch leaves the house, the order of the steps matters more than any single step. Data first, while it can still be saved. Erasing second, on the device. Removal from the account last — because removing a device first can delete data that has not been synced, and, on Apple Watch, erasing on the watch alone does not do the job unpairing does.

1. Export the health history. For Apple health data, open the Health app, tap the initials at the top right, and choose Export All Health Data. For Fitbit, request an account data export at fitbit.com through the settings gear, then Settings, then Data Export, then Request Data; Fitbit emails a confirmation and then a download link, which can take a few days. Wait for the download before continuing. Check: the export file is saved somewhere other than the watch or phone being handed on.
2. Erase on the device — Fitbit first, before account removal. Google's Fitbit guidance is explicit: if the device will be given to someone else, erase the data on the device before removing the device from the account, because removing a Fitbit device from an account deletes any data that has not been synced. A Fitbit is then removed in the Fitbit app through the Today tab, Devices, the device image, and the remove option. Check: the device itself shows no personal data before the account step begins.
3. Unpair an Apple Watch; do not just erase it. Unpairing an Apple Watch from the iPhone erases the watch, removes it from the Apple account, and removes Activation Lock, so someone else can activate it. Erasing on the watch itself, by contrast, erases content but leaves the watch paired — that route is only for an owner keeping the watch. Cellular models prompt whether to keep or remove the cellular plan during the erase or unpair. Check: the watch no longer appears in the Watch app, and it offers its first-time setup screen.
4. Confirm the handover. The next owner should be able to pair and activate the device without any prompt for the previous owner's account. Check: activation completes under the new owner's account, with no Activation Lock or leftover account message.

What success looks like: the health export is saved, the device itself is empty, the device is gone from the old account, and the new owner activates it cleanly on the first attempt.

When to stop: trade in, donate, or recycle

Some watches should not get a second job. A swollen battery, a watch that gets hot in normal use, or one that shuts down unexpectedly is finished, and the routes are documented ones. Apple recycles an Apple Watch for free if it is not eligible for trade-in credit. Fitbit recycling runs through Google's recycling program, which provides a free shipping label in the U.S. Garmin's Consumer Product Recycling Program accepts shipped-back watches at the owner's shipping cost, and Garmin owner's manuals carry the model-specific data-wipe or master-reset instructions — worth following before any Garmin leaves the house, because Garmin has no upgrade or trade-in program for its outdoor watches, so reuse, giveaway, or recycling are the only end-of-life routes.

FAQ

How is Apple Watch battery health checked? On the watch, at Settings > Battery > Battery Health. The figure shown is maximum capacity, relative to when the battery was new.

Can an old smartwatch still track sleep? Yes, if the battery lasts the night. Apple sleep tracking needs watchOS 8 or later and at least four hours of tracked sleep a night; a retired Galaxy Watch does the job on a charge-by-day, wear-by-night rotation.

Should a Fitbit be erased before it is given away? Yes — and before it is removed from the account, not after. Removal deletes unsynced data, so the sequence is export, erase on the device, then remove.

Does Garmin have a trade-in program? No. Garmin's own forum answer confirms there is no upgrade or trade-in program for its outdoor watches; the routes are reuse, giveaway, or its recycling program.

— Dex Carter, Tech Writer

Next: turn an old tablet into a dedicated e-reader →