iPhone 12 Battery Replacement UK: Mini, 12, Pro & Pro Max Guide

If your iPhone 12, 12 Mini, 12 Pro or 12 Pro Max is switching off unexpectedly, draining fast, or showing a Battery Health reading under about 80%, an iPhone 12 battery replacement is usually the fix — provided you order the exact part for your exact model. E-Tech61 stocks three separate battery listings across the range, and capacity isn't the same for all four phones:

The Mini and Pro Max batteries are showing healthy stock levels as we publish this. The shared 12/12 Pro battery is a legitimate, correctly listed E-Tech61 part, but its live stock count doesn't currently confirm ready-to-ship inventory — check current stock on the product page or contact E-Tech61 before ordering that specific one. Prices and stock were checked directly against the E-Tech61 store on 21 September 2026. If you're actually working on a different iPhone model, E-Tech61's iPhone Battery Replacement Guide covers the wider range.

How to identify your exact iPhone 12: Mini, 12, Pro or Pro Max

Ordering the wrong battery is the single most common mistake in this product family, because three of the four phones look deceptively similar from the front. Confirming your exact model before you buy is worth the two minutes it takes.

Screen size is the fastest first check: the 12 Mini has a 5.4-inch display, the standard 12 and 12 Pro both use a 6.1-inch display, and the Pro Max steps up to 6.7 inches. That immediately separates the Mini and Pro Max from the middle pair — but it doesn't distinguish the 12 from the 12 Pro, since they're physically the same size.

For that, check the camera housing on the back. The 12 Mini and standard 12 use a dual-camera system (Wide and Ultra Wide lenses). The 12 Pro and Pro Max add a third Telephoto lens plus a small LiDAR Scanner sensor, giving a visibly larger camera block with three lens openings instead of two. Two rear lenses means a Mini or a standard 12; three lenses plus a LiDAR dot means Pro or Pro Max.

The definitive check is the model number. Go to Settings > General > About and look at the Model Number field (tap it once if it shows the order number instead, to reveal the "M" model number). Compare that against the codes below:

• iPhone 12 Mini: A2176, A2398, A2399, A2400
• iPhone 12: A2172, A2402, A2403, A2404
• iPhone 12 Pro: A2341, A2406, A2407, A2408
• iPhone 12 Pro Max: A2410, A2411, A2412

Apple issues different model numbers by region, so don't assume the UK model matches a single number quoted elsewhere online — checking your own device's Settings menu against Apple's official model-identification page is more reliable than guessing from a number found on a forum. The model number is also stamped in small print on the back of the phone, near the bottom edge, if you'd rather check without powering it on.

iPhone 12 battery capacity and compatibility table

Apple doesn't publish official battery capacity figures for any iPhone. The mAh ratings below come from regulatory filings and independent technical reporting, cross-checked against multiple sources rather than taken from a single figure.

The iPhone 12 and iPhone 12 Pro share the same 2815mAh capacity rating, and E-Tech61 sells one battery listing that covers both. That's a genuinely useful detail when you're deciding what to order — but it describes this specific battery listing, not the whole phone. The 12 and 12 Pro still use different camera assemblies, different rear glass, and other parts that aren't interchangeable just because the battery is. Don't extend "same battery" into "same repair" for anything else on the phone.

Capacity figures above are consistent with reporting from AppleInsider and GSMArena, and the model numbers are cross-referenced against several independent technical listings rather than one source.

Signs your iPhone 12 battery actually needs replacing

A battery isn't always the cause of poor performance, so it's worth confirming before you buy. Open Settings > Battery > Battery Health & Charging and check Maximum Capacity. Apple designs iPhone 12-generation batteries to retain around 80% of their original capacity after 500 complete charge cycles under normal conditions; a figure noticeably below 80%, especially alongside real-world symptoms, is the clearest signal that replacement is due rather than optional.

Practical symptoms worth weighing alongside the percentage:

• Unexpected shutdowns, especially in cold weather or below roughly 20% charge
• The phone dying well before the displayed percentage reaches 0%
• Noticeably faster drain than a few months ago for the same usage pattern
• Apps or the whole device slowing down under load, which can indicate iOS is throttling performance to prevent an aged battery from causing a shutdown
• The phone or case running warm during light use, not just heavy gaming or video calls
• Any visible swelling — a back glass panel lifting slightly, a case that no longer sits flush, or a screen that looks faintly raised at the edges

That last symptom is different from the others: it's a safety flag, not just a performance one. A swollen lithium-ion cell needs more caution than a simple capacity drop — more on that below.

Current E-Tech61 battery options for the iPhone 12 range

Once you've confirmed your exact model, here's what each listing actually gets you.

iPhone 12 Mini — 2227mAh, £14.99. This is the smallest-capacity battery in the range, matched to the smallest phone. Stock is healthy at the time of writing, so this one is straightforward to order now.

iPhone 12 / 12 Pro — 2815mAh, £14.39. Check current stock for the iPhone 12 / 12 Pro battery before you commit to a repair date. This is a legitimate, correctly listed part — not a discontinued line or a catalogue error — but its live inventory doesn't currently show confirmed ready-to-ship stock. If you need it, either check the product page for the latest count or contact E-Tech61 directly to ask about restock timing; fast-moving, model-specific batteries like this one are typically replenished rather than pulled from sale.

iPhone 12 Pro Max — 3687mAh, £17.99. The largest-capacity battery in the range, priced accordingly. This one is also showing healthy stock right now.

Note that price doesn't scale in a straight line with capacity here — the higher-capacity shared 12/12 Pro battery is priced slightly below the Mini's smaller cell. That's simply the live pricing E-Tech61 has set for each listing; it isn't a discount tied to the stock situation. None of these listings currently states what tools or adhesive are included in the box, so don't assume a toolkit is bundled — check the product page's own description at checkout, or see the tools section below for what you're likely to need separately.

iPhone 12 battery replacement cost: part-only price vs professional fitting

Buying the part is the cheapest way into an iPhone 12 battery replacement. At £14.39–£17.99 depending on model, the E-Tech61 batteries above cost a fraction of a professional repair, but that price doesn't include labour, tools, or a warranty on the fitting itself.

Independent UK repair shops typically charge in the region of £35–£70 for a fitted iPhone battery replacement, model and location dependent. Apple's own out-of-warranty battery service costs more again — published estimates vary by source and change over time, so rather than quote a fixed figure here, check Apple's official UK repair estimate for iPhone battery service for a current, model-specific quote. One relevant exception: if you have AppleCare+ and your Maximum Capacity has genuinely dropped below 80%, Apple has long covered that specific repair under the plan at no extra charge.

The practical trade-off is straightforward. Buying the part only and fitting it yourself is the lowest-cost route if you're comfortable with the tools and the risk described below. Paying a local independent shop for fitting adds labour cost but removes the DIY risk and usually comes with same-day turnaround. Apple's own service costs the most but keeps the repair inside Apple's process, which matters if you value that over price. None of these is universally "best" — it depends on your budget, your confidence with small tools, and how much you value speed versus cost. Whichever route you choose, back up your iPhone first, via iCloud or a computer, since any battery service that requires powering the phone off and reopening it carries a small but real risk of the device not returning to service immediately.

Tools and other parts worth ordering at the same time

E-Tech61 doesn't currently list a dedicated iPhone 12 toolkit or battery adhesive alongside these battery listings, so this section covers what the job generally requires rather than linking specific products.

iPhone 12-series batteries are held in with stretch-release adhesive strips, not clips or screws, so you'll need: a full set of precision screwdrivers (the two visible screws at the bottom of the phone are Apple's non-standard pentalobe type, with several tri-point screws inside), plastic opening picks or a suction handle to separate the screen without scratching the frame, tweezers for the battery connector, and fresh adhesive strips to reseal the battery once it's fitted — reused old adhesive won't hold reliably and can leave the cell loose inside the case.

A heat mat or a low, controlled heat source can soften the original adhesive enough to ease the battery out, which matters because pulling directly on a stuck stretch-release tab can tear it — at which point prying the cell out with a metal tool becomes a genuine puncture risk (see safety notes below). If you're not confident sourcing and using these safely, that's a reasonable point to choose professional fitting instead of DIY. Browse E-Tech61's iPhone Parts collection if you also need a screen, camera or other component for the same repair visit — it's usually more efficient to order everything in one delivery than to reopen the phone twice.

DIY difficulty and lithium-ion battery safety

Fitting an iPhone 12 battery yourself is a moderate-to-high difficulty job, not a beginner repair. The hardest part usually isn't the screws — it's removing the old battery's stretch-release adhesive without tearing it, then reassembling the display and frame seal afterwards without cracking anything.

Apple's own guidance on lithium-ion batteries is specific: do not short-circuit, crush, puncture, heat, incinerate or disassemble a battery. A punctured, bent, or overheated lithium-ion cell can swell, leak, vent, or in rare cases ignite. That's why Apple recommends a trained technician for battery service rather than an at-home repair, even though many people do fit these themselves successfully.

If you go ahead, some baseline precautions matter regardless of your experience level: fully power the phone off before opening it and never work on a live battery, work on a clean, flat, non-flammable surface, avoid bending the battery pouch when levering it free, and stop immediately if you see swelling, an unusual smell, or heat during removal — don't keep working on a cell that's clearly damaged. Keep a fire-safe container, such as a metal tin rather than a plastic bag, on hand for a compromised battery, just in case.

It's also worth knowing that opening any iPhone 12 model can affect its water-resistance seal. E-Tech61's battery listings don't claim to restore factory IP68 water resistance, and no aftermarket repair — DIY or professional — can fully guarantee that seal is intact afterwards without factory equipment. If your phone's water resistance matters to you, factor that into whether you fit the battery yourself or pay for professional service. None of this is a reason to avoid replacing an ageing battery — lithium-ion cells are safe when handled correctly, and phone batteries are replaced safely every day. It's a reason to be deliberate about tools, technique and your own comfort level before you start.

After fitting: testing, calibration and battery health messages

Before you fully reseal the phone, power it on and check that it boots, charges, and holds charge normally. If anything looks wrong — the phone won't turn on, charging is erratic, or it runs hot on the bench — stop and investigate before closing the case back up, rather than sealing in a fault.

Expect to see a battery-related message in Settings after fitting a non-Apple battery. Apple's own support documentation confirms that when an iPhone can't verify a battery as genuine, it displays a message to that effect, and the Battery Health screen may become unavailable or show unreliable figures as a result. This is standard, expected behaviour for any third-party battery in any iPhone from this generation onward — it isn't specific to E-Tech61's parts, and on its own it doesn't mean the battery is faulty or that day-to-day performance will suffer. What you lose is Apple's own confidence indicator on capacity, not necessarily the capacity itself.

There's no reliable way to avoid this message with a non-Apple battery, and any claim otherwise should be treated with scepticism. If having a "Genuine" or verified status in Settings matters more to you than the cost saving, that's a reason to choose Apple or an Apple Authorized Service Provider instead of a third-party part. Give the phone a day of normal use before judging the fit — charge cycles, standby drain and any residual battery-usage stats need a short period to settle after a hardware change.

Frequently asked questions

Do the iPhone 12 and iPhone 12 Pro really use the same battery?

They share the same 2815mAh capacity rating, and E-Tech61 sells one battery listing for both models. That's specific to the battery — the 12 and 12 Pro still differ in camera hardware, rear glass finish and other parts, so don't assume the rest of the phone is interchangeable on the strength of this one shared component.

Is the iPhone 12 / 12 Pro battery in stock at E-Tech61?

At the time of writing, the Mini and Pro Max batteries show healthy stock. The shared 2815mAh 12/12 Pro battery is a live, correctly listed product, but its stock count doesn't currently confirm ready-to-ship availability. Check the product page or contact E-Tech61 directly for the latest position before ordering.

How do I know if my iPhone 12 needs a new battery rather than a new phone?

Check Maximum Capacity in Settings > Battery > Battery Health & Charging. A figure well below 80%, combined with symptoms like unexpected shutdowns, fast drain, or performance throttling, points to a battery problem specifically rather than a phone that's simply worn out overall. If the screen, cameras and other components still work well, a battery is usually the more cost-effective fix than replacing the phone.

Can I fit an iPhone 12 battery myself?

Yes, but it's a moderate-to-high difficulty job, mainly because of the stretch-release adhesive holding the original battery in place. If you're comfortable with precision tools and follow the lithium-ion safety precautions above, many people fit these successfully at home. If you're not confident, a local independent repair shop will usually fit the part same-day.

Will my iPhone show a warning after a third-party battery replacement?

Almost certainly, yes. Apple's iOS shows a message when it can't verify a battery as genuine, and the Battery Health percentage may become unavailable afterwards. This is expected with any non-Apple battery and doesn't necessarily mean the part is faulty.

How many charge cycles does a replacement battery last?

Apple designs iPhone 12-generation batteries to retain around 80% of original capacity after 500 complete charge cycles under normal conditions. E-Tech61 doesn't publish an independent cycle-life figure for its aftermarket batteries, so treat Apple's figure as a general benchmark for how lithium-ion cells age, not a guaranteed spec for the replacement part.

What else should I buy alongside the replacement battery?

At minimum, a precision screwdriver set covering pentalobe and tri-point bits, plastic opening tools, and fresh adhesive strips to reseal the battery. E-Tech61 doesn't currently list a dedicated toolkit alongside these battery listings, so source these separately if you're fitting the part yourself, or ask a repair shop to supply them as part of a fitted service.

Ready to order the correct iPhone 12 battery

Confirm your model first — Settings > General > About, or the screen-size and camera check above — then order accordingly. The iPhone 12 Mini and iPhone 12 Pro Max batteries are both showing stock now and ready to order from the table above. If you've confirmed you have the standard 12 or 12 Pro, check current stock on the shared 2815mAh listing before you commit to a repair date, or contact E-Tech61 directly if you need it urgently.

For a full model-by-model cost comparison across the wider iPhone range, see E-Tech61's main iPhone Battery Replacement Guide. If you actually have an iPhone 13 rather than a 12, the specs and battery differ — see the 3227mAh iPhone 13 battery instead.