iPhone 8 Plus Battery Replacement: Cost & Guide
A new battery for the iPhone 8 Plus costs about $12 to $25 in parts as a DIY job, versus roughly $89 at Apple. The 8 Plus opens the same friendly way as the rest of the iPhone 8 family, so replacing the 2691 mAh cell at home is realistic for most people in under an hour.
Released in 2017, the iPhone 8 Plus is now approaching nine years old — and that age brings a specific risk worth knowing about up front: these batteries are among the most likely to swell. If the screen on yours is lifting away from the frame, treat it as urgent. The rest of this guide covers how to check, source, and swap the cell safely.
Why the iPhone 8 Plus battery needs attention now
Lithium-ion batteries are rated for around 500 full charge cycles before dropping to about 80 percent capacity. An 8 Plus in service since 2017 has cycled its 2691 mAh cell far past that, so weak iPhone 8 Plus battery life is simply old age. Because the 8 Plus has a large 5.5-inch LCD to power, a tired battery shows its limits fast — you'll feel it during video, navigation, and gaming.
The phone itself, with its A11 Bionic chip, dual camera, and Qi wireless charging, still handles everyday tasks well. That makes a cheap battery swap the obvious move over replacing the whole device.
How to check your iPhone 8 Plus battery health
Confirm the battery is the issue first. Go to Settings > Battery > Battery Health & Charging and check Maximum Capacity, measured against the original 2691 mAh.
- 85-100%: Healthy — look at apps or settings for drain.
- 80-84%: Aging; a swap will noticeably help.
- Below 80%: Worn. iOS usually shows a "Service" note, and this is the right time to replace.
Most 8 Plus units this old read well under 80 percent. A Peak Performance Capability message — noting performance management after an unexpected shutdown — confirms the cell can no longer deliver peak current and should be swapped.
On the 8 Plus, it's also smart to physically inspect the phone while you're in Settings. Set it face-up on a flat table and look across the screen at eye level for any lift at the edges, then flip it over and check whether the phone rocks. Those quick checks catch early swelling that the software readout won't show.
Signs your iPhone 8 Plus battery is failing
- Your iPhone 8 Plus battery draining fast, losing 20% or more overnight.
- Sudden shutdowns at 30-40%, worse in cold weather.
- The phone runs hot during ordinary use.
- Your iPhone 8 Plus battery not charging consistently, or stalling at a set level.
- The display lifting at the edges, or the phone rocking when set flat.
Safety note — read this one: the iPhone 8 Plus is genuinely prone to battery swelling with age. A swollen cell will push the screen up and off the frame, and it is a real fire and injury hazard. If you see any bulging, stop charging the phone, power it down, and replace the battery immediately. Never force the screen back down, puncture the cell, or keep charging a swollen battery.
iPhone 8 Plus battery replacement cost
Here is the realistic 2026 iPhone 8 Plus battery replacement cost by route:
| Option | Typical 2026 price | What you get |
|---|---|---|
| Apple (out of warranty) | ~$89 | Genuine cell, certified install, no battery-health warning |
| Local repair shop | $55-$85 | Aftermarket or OEM-pull cell, usually same day |
| DIY replacement | $12-$25 (parts) | Battery, adhesive strips, and basic tools |
On a phone worth a modest amount secondhand, Apple's $89 is a hard sell. DIY parts cost a fraction of that and fully restore runtime. Compare current cells and tools in our replacement batteries collection.
The exact replacement battery for the 8 Plus
The iPhone 8 Plus uses a 3.82V, 2691 mAh lithium-ion battery. It fits the model numbers A1864, A1897, and A1898 — check yours under Settings > General > About. This cell is larger than the standard iPhone 8 battery, so be sure to order the Plus-specific part.
When picking an iPhone 8 Plus OEM battery, choose a zero-cycle cell with a recent manufacture date. This is doubly important on the 8 Plus: a cheap, poorly made cell is exactly the kind that swells early. You'll also want fresh adhesive strips to seat the new battery securely — our iPhone 8 Plus battery adhesive strips (50-pack) are cut to fit and economical for anyone servicing several phones. Wholesale pricing is available for repair shops.
How to replace the iPhone 8 Plus battery yourself
Here's how to replace your iPhone 8 Plus battery, step by step. As part of the well-documented iPhone 8 family, this repair is friendly for a careful first-timer.
- Power off and remove the two pentalobe screws beside the charging port.
- Warm the lower edge gently, then use a suction cup and pick to lift the display from the bottom. The screen hinges up from the top, where the flex cables are.
- Mind the Touch ID cable. It's bonded to the display and paired to your phone — tearing it disables Touch ID for good.
- Remove the battery connector bracket and disconnect the battery first, ahead of any other cable.
- Pull the stretch-release adhesive tabs beneath the cell slowly and at a low angle. If a swollen battery has broken its tabs, add gentle heat and pry it free with a plastic tool only — never metal, which can puncture the cell.
- Lay fresh adhesive, seat the new 2691 mAh cell, reconnect, and reassemble in reverse.
Honest difficulty rating: 4 out of 10. The opening is straightforward, but the Touch ID flex and the adhesive tabs need patience — and a swollen 8 Plus battery calls for extra care, since a puffed cell is more fragile. Plan on 45-60 minutes.
After the swap: the "Unknown Part" message
On power-up, iOS may show an "Unknown Part" notice and mark Battery Health as unavailable with a service message. This is expected on any iPhone 8 Plus fitted with a non-Apple cell, because Apple pairs batteries to the logic board. The phone charges — including on a Qi wireless pad — and runs normally; you only lose the on-screen capacity percentage. It does not mean the battery is defective.
Repair vs. upgrade: is it worth it?
Replacing a whole phone because of a $20 battery is the wrong math on a device that still does the job. A fresh cell restores full-day runtime and — just as important on this model — removes the swelling risk that comes with an aging pack. It's the greener choice, too: keeping a working iPhone 8 Plus alive keeps it, and the materials inside it, out of the e-waste stream. Repair, don't replace.
Prefer to hand it off? Searching iPhone 8 Plus battery replacement near me will turn up a local shop, though DIY remains the cheapest option. For other devices, see our battery replacement by model guide.
FAQ
How much does an iPhone 8 Plus battery replacement cost?
DIY parts run about $12-$25, a local repair shop charges roughly $55-$85, and Apple charges about $89 out of warranty. Doing it yourself is the cheapest option by a wide margin.
How do I replace my iPhone 8 Plus battery?
Power off, remove the two pentalobe screws by the charging port, lift the screen from the bottom edge, disconnect the battery connector, pull the adhesive tabs, and fit the new 2691 mAh cell with fresh adhesive. Take care with the Touch ID cable near the home button.
Why is my iPhone 8 Plus battery draining fast?
After years of use, the 2691 mAh cell is well past its rated cycle life and struggles to power the large 5.5-inch display. If Maximum Capacity has dropped below 80 percent, fast drain and shutdowns are normal wear that a replacement fixes.
Is a swollen iPhone 8 Plus battery dangerous?
Yes. The 8 Plus is prone to swelling with age, and a swollen lithium-ion cell is a fire and injury risk. Stop charging, power the phone off, and replace the battery promptly. Never puncture or force a swollen cell.
What battery does the iPhone 8 Plus use?
A 3.82V, 2691 mAh lithium-ion cell for the A1864, A1897, and A1898 model numbers. It is larger than the standard iPhone 8 battery, so order the Plus-specific part.
Will I get a warning after installing an iPhone 8 Plus OEM battery?
Yes. Any non-Apple battery triggers an "Unknown Part" message and marks Battery Health as unavailable. Charging — including wireless — and performance are unaffected; you only lose the capacity percentage display.