What reverse wireless charging does

Reverse wireless charging lets your phone act as a wireless charger for another device. Instead of only receiving power through a charging pad or cable, your phone can send power out wirelessly to charge earbuds, smartwatches, or another phone placed on its back. The phone becomes both a battery and a charger at the same time.

The technology uses the same wireless charging standard that charges your phone — usually Qi, the most common standard worldwide. When you turn on reverse charging, your phone's battery powers a coil in the back of the device that sends energy to another device's receiving coil. It is the same principle as a regular wireless charger, just running in the opposite direction.

Key Takeaways

  • Reverse wireless charging lets your phone charge other devices wirelessly, but it drains your battery faster than normal use.
  • Only certain phones have this feature — Samsung Galaxy S21 and newer models, some Google Pixel phones, and a few others — so check your phone's specs before assuming you have it.
  • The charging speed is slow, typically adding only 5 to 15 percent battery to a smartwatch or earbuds in 30 minutes.
  • Turning on reverse charging while your own battery is low can leave you without power when you need it, so use it only when your phone is well-charged.

Which phones actually have reverse wireless charging

Reverse wireless charging is not standard on most phones. Samsung includes it on Galaxy S21, S22, S23, and S24 models, as well as some Galaxy Z Fold and Z Flip foldable phones. Google added it to Pixel 8 and Pixel 8 Pro. A few other manufacturers have included it, but the feature remains uncommon.

The easiest way to check if your phone has it is to search your phone's model number plus "reverse wireless charging" or look in your phone's settings under Battery or Device Care. If the feature exists on your phone, there will be a toggle to turn it on. If you do not see a setting for it, your phone does not have the capability.

How slow the charging actually is

Reverse wireless charging is noticeably slower than plugging a device into a wired charger. A smartwatch or pair of earbuds typically gains 5 to 15 percent battery in 30 minutes when charged this way. A second phone would charge even more slowly — often taking an hour or more to add 10 to 20 percent.

The slow speed happens because wireless charging itself is less efficient than a wired connection, and reverse charging adds another layer of power loss. Your phone has to convert its battery power into a wireless signal, and the receiving device has to convert that signal back into usable power. Each conversion wastes some energy as heat.

For this reason, reverse charging works best for small devices like earbuds or smartwatches that have small batteries. Trying to charge a second phone this way is usually impractical unless you have hours to wait.

The real cost to your phone's battery

Using reverse wireless charging drains your phone's battery much faster than normal use. Sending power to another device while your phone is also running its own screen, apps, and systems means your battery loses charge at roughly double or triple the normal rate. If your phone is at 50 percent and you reverse-charge a smartwatch for 30 minutes, you might drop to 35 percent or lower.

This matters because every charge cycle — draining and refilling your battery — causes a small amount of permanent wear. Frequent reverse charging sessions add up over months and years, slightly reducing how much total charge your battery can hold. If you reverse-charge several times a week, you will notice your phone's battery capacity declining faster than it would otherwise.

When reverse charging makes sense

Reverse charging is most useful in specific situations: your friend's phone dies at an event and you have a full battery, or your earbuds run out of power mid-day and you need them working again. It is a convenience feature for emergencies, not something to use regularly.

The best practice is to turn it on only when your own phone battery is above 50 percent, and only when you do not expect to need your phone heavily for the next few hours. If you are out for the day and your battery is already dropping, do not use reverse charging — you risk leaving yourself without power when you need it most.

Reverse charging versus carrying a portable battery pack

A small portable battery pack (also called a power bank) does the same job as reverse charging but more efficiently. A 10,000 mAh power bank can charge a smartwatch or earbuds multiple times and will charge a phone much faster than reverse wireless charging. It also does not drain your own phone's battery.

The trade-off is that you have to carry an extra device. Reverse charging requires nothing extra — just your phone. For people who travel light or only occasionally need to charge another device, reverse charging is convenient. For people who regularly charge multiple devices or need fast charging, a power bank is the better choice.

Frequently Asked Questions

Does reverse wireless charging damage my phone's battery?

It does not cause when ready damage, but frequent use speeds up normal battery wear. Every charge cycle — whether your phone is charging or sending power out — causes tiny degradation. If you reverse-charge once or twice a month, the effect is negligible. If you do it several times a week, you will notice your battery capacity declining faster over a year or two.

Can I reverse-charge while my phone is also charging?

Most phones do not allow it. If your phone is plugged into power, the reverse charging toggle will be grayed out or disabled. This is a safety feature to prevent overheating and excessive stress on the battery.

Why is reverse wireless charging so slow?

Wireless charging loses energy during transmission, and reverse charging loses even more because the power has to convert twice — from your battery to a wireless signal, then from that signal back to usable power. Wired charging is direct and more efficient, so it is always faster.

What devices can I reverse-charge?

Any device with a Qi wireless charging receiver can be reverse-charged. This includes most modern smartwatches, wireless earbuds, and phones made in the last few years. Older devices or budget models may not have wireless charging built in, so check the device's specs first.

Should I turn off reverse charging to save battery?

Reverse charging only drains your battery when it is actively turned on and another device is placed on your phone's back. straightforward having the feature available does not use power. You can leave it on in your settings and only use it when you need it.