iPhone Battery Replacement
Price: $7.95
Your iPhone Battery Is Dying — But Replacing It Isn’t As Simple As It Used To Be
Your iPhone drains fast. It shuts down unexpectedly at 30%. It gets warm during light use, and it’s started throttling performance so badly that apps take seconds to open. Battery Health shows 79%, and you’re weighing up whether to replace the battery or replace the phone.
Here’s the problem: replacing an iPhone battery used to be simple. It isn’t anymore. From the iPhone 11 onward, Apple serialised the battery’s control board. Fit a non-genuine battery without transferring the original board, and the iPhone displays a permanent warning. On the iPhone 14, it disables Battery Health entirely.
That means the decision isn’t just “which battery do I buy” — it’s “does my model need a BMS transfer, can I actually do that, and is Apple’s $99 service the better call.”
This guide walks through the whole decision in order: confirming the battery is actually the fault, the model-by-model serialisation rules, which replacement to buy, and the honest repair-or-bin maths.
Why Your iPhone Battery Needs Replacing
An iPhone battery is a lithium-ion cell with a small circuit board attached — the BMS, or Battery Management System. The BMS monitors health, manages charging, and reports a serial number back to the iPhone. That last part is what makes modern battery replacement complicated:
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Worn battery — lithium cells lose capacity with every charge cycle. Apple rates iPhone batteries for 500 cycles before they drop to 80% of original capacity. Below 80%, the phone starts throttling to prevent unexpected shutdowns.
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Battery Health reporting “Service” — the battery has aged past Apple’s threshold. Replacement is the fix.
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Unexpected shutdowns at 20–40% — the battery can’t deliver peak current. This happens even when Battery Health reads above 80%.
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Charging stops at 80% — usually Optimised Battery Charging, not a fault. But if that’s off, the cause is usually the charging port or charging IC, not the battery.
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Swollen battery — the cell has failed internally and is producing gas. This is a fire risk. Do not attempt DIY. Take it to a professional.
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Non-genuine battery warning — appears after a non-genuine battery is fitted. Cosmetic on iPhone 11–13. May disable Battery Health entirely on iPhone 14.
Common Symptoms
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Battery drains fast — 100% to 50% in a couple of hours of light use
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Phone shuts down unexpectedly at 20–40%
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Phone only works reliably when plugged in
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Battery Health below 80%, or showing “Service”
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Battery Health shows “Unknown Part” or “Important Battery Message”
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Phone gets warm during light use
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Performance feels throttled — apps open slowly, animations stutter
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Battery drains 30% overnight in standby
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Phone shuts down in cold weather but works fine indoors
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Battery Health disabled entirely (iPhone 14, after non-genuine replacement)
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Screen lifting or back glass bulging — swollen battery, stop using the phone
What Causes These Faults
Normal battery ageing — the most common cause. Lithium cells degrade with charge cycles, and 500 cycles is Apple’s rated lifespan. At 80% capacity, the phone starts throttling.
Temperature exposure — heat accelerates battery ageing. Phones left in hot cars or charged while gaming age faster than phones used in normal conditions.
Charging habits — frequent full discharge and recharge cycles wear the battery faster than partial charges. Keeping the battery between 20% and 80% extends its life.
Failing BMS — the battery’s control board can fail independently of the cell. This usually presents as erratic percentage readings or sudden shutdowns at high percentages.
Charging IC fault — the charging circuit on the motherboard can fail. This presents as a phone that won’t charge reliably, or drains while plugged in. Battery replacement won’t fix it.
Rogue apps or background refresh — a misbehaving app can drain a healthy battery in hours. Check Settings → Battery before assuming the battery is the fault.
Poor signal — a phone searching for signal in a weak area draws significantly more power. Not a battery fault.
Swollen cell — a battery that has failed internally and is producing gas. This is a safety issue, not a repair job.
What the Guide Covers
This diagnostic guide walks through the whole decision in order:
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Confirming the battery is actually the fault
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Battery Health interpretation, including when it lies
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Ruling out rogue apps, charging IC faults, and calibration errors
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Full model-by-model sections for iPhone 6 through iPhone 14
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The serialisation rules for each generation, explained properly
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The BMS transfer process, step by step
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Tools and consumables required per model
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Specific supplier recommendations
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The three ways people destroy their phone doing this job
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Repair-or-replace maths, including resale considerations
Each model section covers the disassembly process, the adhesive type, the tools required, the serialisation rules, and the specific failure modes for that generation.
What You’ll Learn
You’ll learn how to confirm the battery is actually the fault before spending anything, how to interpret Battery Health alongside real-world symptoms, and how to tell a worn battery from a failing charging IC or a rogue app.
You’ll also learn the model-by-model serialisation rules — which iPhones warn about non-genuine batteries, which ones disable Battery Health entirely, and which ones require transferring the original BMS. And you’ll learn the actual BMS transfer process, including how to desolder and resolder the board without destroying it.
You’ll also learn the three failure modes that account for most DIY disasters: tearing the display flex cables, puncturing the battery, and losing screws. Each one is avoidable with the right technique.
Repair or Bin?
Most iPhone battery replacements are worth doing on phones under four years old that are still fast and in good condition.
For iPhone 6 through 8, DIY is a clear win. A replacement battery is $12–$25, the job takes 20–30 minutes, and there are no serialisation complications. Any reputable aftermarket battery works with no warnings.
For iPhone X through 13, DIY is still cheaper than Apple’s service — a battery is $20–$45 — but you’ll likely accept a permanent non-genuine battery warning unless you transfer the BMS. The warning is cosmetic and Battery Health still works on these models.
For iPhone 14, the maths is closer. A battery is $35–$55, and if you don’t transfer the BMS, Battery Health may be disabled entirely. Apple’s $99 service includes a genuine battery and no warnings.
Where the maths changes is the phone’s overall condition. A battery replacement on a phone with a cracked screen, failing charging port, or slow performance is money spent on a machine near the end of its life. If the phone is over five years old or has other faults, weigh the repair cost against a newer used phone.
The guide includes a full repair-or-replace framework, plus a resale consideration section — because the non-genuine warning displays in Settings and reduces resale value.
Frequently Asked Questions
How do I know if my iPhone battery needs replacing?
Check Settings → Battery → Battery Health. Below 80% means the battery is worn. But also go by symptoms — unexpected shutdowns at 20–40% or rapid drain indicate a failing battery even when Battery Health reads above 80%.
Can I replace an iPhone battery myself?
Yes, on most models. iPhone 6 through 8 are easy. iPhone X through 13 are moderate to hard but doable with the right tools. iPhone 14 is hard, and Battery Health may be disabled after a non-genuine replacement.
Why does my iPhone say “Unknown Part” after a battery replacement?
The iPhone doesn’t recognise the battery’s serial number. This happens when a non-genuine battery is fitted without transferring the original BMS. It’s a warning, not a fault — the battery works normally.
Can I avoid the non-genuine battery warning?
Yes, by transferring the BMS board from the original battery to the new one. This requires desoldering and resoldering, and most people can’t do it. The alternative is paying Apple for a genuine battery service.
Is it worth replacing an iPhone battery or buying a new phone?
Replace the battery if the phone is under four years old, still fast, and in good condition. A $20–$55 battery extends the phone’s life for another two to three years. Buy a new phone if the phone is over five years old or has other faults.
How much does Apple charge to replace an iPhone battery?
$89–$99 in most regions for out-of-warranty battery service. It includes a genuine battery, professional fitting, no warnings, and a warranty on the work.
Get the Complete Guide
This guide gives you the full diagnostic sequence, the model-by-model serialisation rules, the BMS transfer process, the supplier recommendations, and the honest repair-or-bin maths.