Samsung Galaxy S21 Series Replacement Batteries

Why Your Galaxy S21 Battery Matters

The Galaxy S21 series has been around for several years now, and Samsung's official software support for these phones has come to an end. That doesn't mean it's time to retire the phone, though. A capable device with a fresh battery can still handle everyday calls, texts, photos, and apps just fine, especially as a secondary phone, a kid's first phone, or a backup device.

What usually does need attention at this point is the battery. Every Galaxy S21 runs on a lithium-ion battery, and after years of daily charging, it naturally holds less charge than it used to. Most Galaxy phones let you check battery health directly in settings, typically under Battery and Device Care, then Diagnostics. A few signs your S21's battery needs replacing:

• Your phone barely lasts half a day, even with light use
• It shuts off unexpectedly, even with 20% or more showing on the screen
• The back of the phone feels warm, or the case looks slightly puffed out (a sign of a swollen battery)
• Your phone only stays powered on while plugged in
• Battery health diagnostics show a Weak rating

Swelling in particular has been reported on multi-year-old Galaxy batteries, so a bulging back or a phone that no longer sits flat on a table is worth addressing right away. In most cases, a new battery brings a still-solid phone right back to a usable, all-day device.

Choosing the Right Battery for Your Galaxy S21

The Galaxy S21 series includes four different phones, and each one takes its own specific battery. The S21, S21+, S21 Ultra, and S21 FE are not interchangeable, so it's worth double-checking your exact model before you order.

• Galaxy S21: fits SM-G991 series models
• Galaxy S21+: fits SM-G996 series models
• Galaxy S21 Ultra: fits SM-G998 series models
• Galaxy S21 FE: fits SM-G990 series models

You can find your exact model number in your phone's Settings under About Phone, or printed on the original box. Every battery on this page is cross-referenced against Samsung's OEM part numbers, so if you're not sure, just match the model number on your phone to the compatibility list on each product page.

Once you've got the right battery, we also carry a few things to make the swap easier:

• A battery installation toolkit with everything needed to safely open your phone and remove the old battery
• A charging brick to get your S21 back up to full power once the new battery is installed
• A USB-C charging cable to go with it

Installing Your Replacement Battery

Replacing a Galaxy S21 battery at home is a manageable project if you take your time and use the right tools. Let your phone's battery drain below 25% before you start, since a fully charged lithium-ion battery is more sensitive to damage while it's being handled. Power off the phone completely and disconnect any cables first.

Keep in mind that opening the back cover will break the seal that gives your S21 its water resistance rating, so the adhesive needs to be reapplied carefully during reassembly. After installing your new battery, it's a good idea to fully charge it to 100%, let it drain completely, then charge it back up again. This helps your phone accurately read the new battery's charge level going forward. If your old battery looks swollen, handle it carefully and avoid pressing or bending it during removal. If you'd rather not tackle it yourself, a local phone repair shop can install the battery for you using the same part.

Not sure which battery or accessories you need? Our customer service team is happy to help you find the right fit before you order.

Frequently Asked Questions

How do I know which S21 battery is compatible with my phone?

A: Check your phone's exact model number in Settings under About Phone, then match it against the compatibility list on each battery's product page. The S21, S21+, S21 Ultra, and S21 FE each use a different battery, so the model number is the fastest way to confirm you're ordering the right one.

Samsung has stopped supporting my S21 with updates. Is it still worth replacing the battery?

A: Yes, in many cases. The end of software updates doesn't mean the phone stops working, and a new battery is one of the most affordable ways to keep using a device that still meets your needs, whether as a daily driver, a backup phone, or a phone for a family member.

How do I check my Galaxy S21's battery health before replacing it?

A: Go to Settings, then Battery and Device Care, then Battery, then Diagnostics. Your phone will show a battery health rating, usually Good, Normal, or Weak. A Weak rating, or noticeably reduced runtime compared to when the phone was new, is a good sign it's time for a replacement.

Do I need special tools to install a Galaxy S21 replacement battery?

A: Yes, most S21 batteries are held in place with adhesive, so you'll need a few basic tools like a suction handle, prying tools, and heat to safely remove the back cover. We offer a battery installation toolkit designed for this exact job, so you're not stuck hunting down tools separately.

Can I return my battery if it doesn't fit my phone?

A: Yes, Battery Mart accepts returns within 60 days of purchase. If you order the wrong battery for your S21 model, just reach out through our contact us page or check our returns policy for the full details.