Galaxy S21 Plus Battery Replacement: Cost & DIY Guide
A Galaxy S21 Plus battery replacement runs about $79-99 at Samsung or a repair shop, but the battery itself is only $15-30 if you do the swap at home. It's a genuinely DIY-doable job for a careful beginner, since the S21+ opens from the back rather than the screen.
The S21 Plus hit shelves in January 2021, so most units are now four to five years old, which is exactly the point where lithium cells fall below the 80% capacity mark. If your S21+ used to last all day and now needs a lunchtime top-up, the battery, not the phone, is the thing that's worn out.
How to check your Galaxy S21 Plus battery health
Samsung includes a battery health tool, and the path depends on your One UI version. On One UI 5 and later (Android 13+), open Settings → Battery and device care → Battery → Diagnostics and look at the "Battery health" line. It reads as a simple grade: Good, Normal, or Weak. A "Weak" result means the cell has degraded far enough that a replacement is the sensible move.
If your phone is on an older One UI release, there's no built-in percentage figure, so don't try to eyeball it. A free tool like AccuBattery measures your real capacity against the factory 4800mAh spec across a handful of charges. Once it's reporting you're holding meaningfully less than 80% of that design capacity, the battery has reached the end of its practical life. It's also worth checking Battery → Usage since last full charge to make sure a background app isn't the real reason for the drain before you open the phone.
Signs your Galaxy S21 Plus battery is failing
Degradation tends to arrive as a set of nagging symptoms rather than one dramatic failure:
- Galaxy S21 Plus battery draining fast during ordinary use, or heavy overnight standby drain.
- Unexpected shutdowns while there's still 20-40% showing, particularly in the cold.
- The phone runs warm during simple tasks and charges more slowly than before.
- A Galaxy S21 Plus battery not charging reliably, or a percentage that leaps up and down.
- It only powers on while connected to a charger.
Safety note: if the 6.7-inch display starts to lift at an edge or the back panel bows outward, stop using the phone immediately. That's a swollen battery expanding inside the frame. A puffed lithium pack can rupture or catch fire, so never puncture, bend, or press on it. Shut the phone down, keep it clear of flammable materials, and replace the cell without delay instead of continuing to charge it.
Galaxy S21 Plus battery replacement cost
Here are the realistic 2026 numbers. The Galaxy S21 Plus battery replacement cost is driven almost entirely by labor, since the part is cheap.
| Option | Typical 2026 price | What you get |
|---|---|---|
| Samsung / uBreakiFix (authorized) | $79-99 | Genuine cell and a repair warranty, but you book ahead and wait |
| Local repair shop | $50-80 | Often same-day, though quality depends on the technician |
| DIY (parts only) | $15-30 | Battery and adhesive, plus roughly an hour of your time |
Notice how little separates the S21+ from its smaller and larger siblings on price; the battery is inexpensive across the whole S21 line. If searching "Galaxy S21 Plus battery replacement near me" only surfaces $80-plus quotes, doing it yourself keeps almost all of that money in your pocket for the cost of a part and a set of adhesive strips.
The exact replacement battery for the S21 Plus
The S21 Plus carries a 4800mAh lithium-ion battery, Samsung part number EB-BG996ABY. Note that this is a different capacity and part from the smaller S21 (4000mAh) and the Ultra (5000mAh), so don't mix them up. The EB-BG996ABY fits every regional variant, sold as SM-G996, SM-G996B, SM-G996N, SM-G996U, SM-G996U1, and SM-G996W. When you shop for a Galaxy S21 Plus OEM battery, confirm both the 4800mAh rating and that part number so you get the correct cell for your exact model.
You can find compatible cells in our replacement batteries collection. Because PhonePartPro serves both retail buyers and wholesale repair shops, even a single battery is priced at parts level rather than the marked-up rate you'd pay over a repair counter. Steer clear of listings boasting inflated capacities above 4800mAh, which almost always signal a lower-quality cell that will degrade sooner.
Replacing it yourself: step overview and honest difficulty
Here's how to replace a Galaxy S21 Plus battery at a glance. Gather a hair dryer or heat pad, a suction cup, thin plastic picks, a small Phillips driver, and fresh adhesive strips first.
- Soften the back glass with even heat, then use a suction cup and pick to cut through the adhesive and lift the rear panel away carefully.
- Remove the wireless-charging coil bracket and disconnect the battery connector before touching anything else, so the board is unpowered.
- Free the old battery. The S21+ cell is held by pull-tabs and adhesive. Draw the tabs out slowly and steadily; if one tears, work a little high-strength isopropyl alcohol under the edges to loosen the bond. Never lever a swollen cell with a metal tool.
- Fit the new 4800mAh battery, reconnect it, and confirm the phone powers on before sealing anything.
- Re-adhere the back glass with new strips and press evenly for several minutes.
Difficulty: moderate (about 5-6/10). The S21+ has a flat back panel, which is a touch more forgiving than the Ultra's curved glass, but it's still glued glass that cracks if you skimp on heat or rush the pry. Give yourself 45-60 minutes and a clear, well-lit workspace. For a first-time repairer who works patiently, it's very achievable.
After the swap: calibration and warnings
Samsung phones don't display a permanent battery-servicing flag the way an iPhone does, although some software builds show a brief genuine-parts notice. What matters more is running a calibration cycle. With the new battery installed, charge to 100%, then run the phone down until it powers off on its own, and finally charge it uninterrupted back to full. That recalibrates the fuel gauge so the percentage tracks the fresh cell correctly, clearing up the erratic readings a new battery can show in its first day of use.
Once calibrated, both the on-screen estimate and the Battery health diagnostic will reflect the true capacity you've just restored.
Repair vs. upgrade: a small part or a big bill?
The S21 Plus is still a strong daily phone in 2026, with a bright 6.7-inch 120Hz display, capable cameras, and more than enough performance for everyday tasks. The one part that genuinely wears out is a consumable cell that costs less than dinner for two. Putting $15-30 into a battery rather than $800 into a new flagship is the obvious math, and it keeps a solid phone out of the e-waste pile.
That's the case for repairing instead of replacing: one tired component shouldn't send a working phone to recycling. Restore the Galaxy S21 Plus battery life you had when it was new and you buy yourself another couple of years for the price of a phone case. Browse more device-specific walkthroughs in our battery replacement by model hub.
FAQ
How much does a Galaxy S21 Plus battery replacement cost?
Roughly $79-99 at Samsung or an authorized shop, $50-80 at an independent store, or just $15-30 in parts if you do it yourself. The cell is cheap; the shop price is mostly labor.
How do I replace a Galaxy S21 Plus battery?
Heat and lift off the back glass, disconnect the battery connector, release the old 4800mAh cell with its pull-tabs (or isopropyl alcohol to break the adhesive), install the new battery, verify it powers on, and reseal with fresh adhesive. Budget 45-60 minutes.
Why is my Galaxy S21 Plus battery draining fast?
After four to five years the original cell has lost capacity. Check for a misbehaving app under Settings, Battery and device care first, but if a "Weak" health grade or an AccuBattery reading confirms wear, a new battery brings the runtime back.
What battery does the Galaxy S21 Plus use?
A 4800mAh lithium-ion pack, Samsung part EB-BG996ABY. It fits variants sold as SM-G996, SM-G996B, SM-G996N, SM-G996U, SM-G996U1, and SM-G996W. It is not the same battery as the standard S21 or the Ultra.
Is it worth replacing the Galaxy S21 Plus battery in 2026?
Yes. The S21 Plus still runs modern apps smoothly, so a $15-30 battery is far cheaper than a new phone and keeps a capable device working instead of heading to the landfill.
Why is my Galaxy S21 Plus not charging?
Try another cable and clean out the USB-C port, since debris is a frequent cause. If it still won't charge or drains quickly, a worn or swollen battery is the likely culprit and should be replaced promptly.