How to Check iPhone Battery Health Before Selling in 2026

It takes about ten seconds, and it's the one spec a buyer checks first.

1. Open Settings.
2. Tap Battery.
3. Tap Battery Health & Charging (iOS 16 and later) or Battery Health (iOS 14-15).
4. Read the Maximum Capacity figure.

That percentage is how much charge your battery holds today versus the day it left the factory. A new iPhone reads 100%; every charge cycle nudges it down.

A few other lines on that screen matter to a buyer:

• Peak Performance Capability notes whether iOS has ever throttled the phone after an unexpected shutdown.
• Optimized Battery Charging delays topping past 80% until you need it. Leave it on.
• Newer iOS builds add an 80% charge limit toggle that slows wear further.

Battery Health lives on any iPhone 6 or later running iOS 11.3 or newer. If it's missing, update iOS under Settings > General > Software Update. An iPhone 5s or older won't have it, and those models are worth little today regardless. Knowing your number before you request a quote means the condition you pick on GadgetRenu's iPhone page matches what inspection finds, so the offer doesn't move later — and a higher reading points you to a higher condition tier and a bigger check.

100% is new and lower is worse, but the shape of the decline is worth understanding.

Every iPhone runs a lithium-ion battery that ages with use. A charge cycle is one full battery's worth of discharge, whether that's 100% to 0% once or 100% to 50% twice. Apple rates iPhones through the 14 to hold 80% capacity after 500 cycles; for the iPhone 15 and later it doubled that to 1,000 cycles (Apple, 2024). At roughly one cycle a day, an older iPhone reaches 80% in about a year and a half, while a 15 or newer can stay above 80% for closer to three years.

Here's how the ranges tend to play out:

• 95-100% — barely worn, typical under a year of use. No effect on value.
• 90-94% — normal for one to two years in. Slightly shorter screen time, still full value.
• 85-89% — a couple of years of use. You may charge mid-afternoon. Little to no effect on most offers.
• 80-84% — the cell is getting tired and you're near Apple's service line. A small deduction is possible.
• Below 80% — Apple's replacement threshold. iOS flags the battery as significantly degraded, and on phones that have had an unexpected shutdown, Performance Management can cap peak speed. Refurbishers price in a battery swap at this point.

Model and storage decide most of your payout; battery health adjusts it at the edges. Start with what a healthy, Excellent-condition iPhone earns at GadgetRenu right now:

Current GadgetRenu Excellent-condition offers as of August 2026; "max" means top storage, unlocked. Lower storage, cosmetic wear, or a carrier lock bring these down.

Against those anchors, battery health is a minor adjustment. Based on GadgetRenu's own grading, a battery in the 80-84% range shaves roughly 5-10% off an Excellent offer, and below 80% roughly 10-15% — the cost a refurbisher expects to spend replacing the cell. On a $538 iPhone 15 Pro that's about $25-80. Real money, but far less than the $133 gap between a 15 Pro and a 14 Pro. And because GadgetRenu pays cash — not store credit — that higher-health offer lands in your account, not on a gift card.

Should You Replace the Battery First?

Almost never. Apple's out-of-warranty battery service runs about $89-119 depending on the model (Apple's published pricing). A fresh cell rarely lifts a used-phone offer by that much, so you'd usually spend more than you'd recover. Let the refurbisher handle it at wholesale cost and sell as-is.

Where Battery Ranks Among Value Factors

• Model/generation — the largest lever (the 15 Pro-to-14 Pro gap above is $133).
• Storage — higher tiers add a solid chunk.
• Cosmetic condition — a cracked screen is the harshest single hit, often cutting value by a third or more.
• Carrier lock — a locked phone trades below an unlocked one.
• Battery health — real but secondary unless it's badly degraded.

Don't let 83% stop you from selling; that phone is worth nearly full value. See how much your iPhone is worth for the full picture.

Samsung buries this deeper than Apple does, and it usually won't hand you an exact percentage on older hardware. Best options, roughly in order:

• Settings (Galaxy S24 and later) — One UI 7 and 8 now surface a proper maximum-capacity percentage, cycle count, and manufacture date under Settings > Battery > Battery information, closer to Apple's style. The screen is rolling out unevenly by region and firmware, so it may appear or vanish with an update.
• Samsung Members app — open it, go to Get Help > Interactive checks (or Phone diagnostics), and run the Battery test. It reports a status like Good, Normal, or Weak rather than a number. Good/Normal maps to a healthy cell; Weak means real degradation that will show up in an offer.
• AccuBattery or similar — estimates capacity by measuring real charge sessions over a few days. Less exact than a built-in reading, but a fair ballpark.
• Diagnostics dial code — on some models *#*#4636#*#* opens a hidden testing menu with battery details. It's hit or miss across carriers.

Samsung publishes less than Apple about per-model cycle life, but its recent flagships are built to stay healthy across several years of normal use. Selling one? GadgetRenu's Samsung page tests the battery at inspection like every other spec.

Pixels are simpler on recent hardware. On the Pixel 8a and later (Pixel 8a, the Pixel 9 line, and the Pixel 10 line) running Android 16, open Settings > Battery > Battery health and tap Battery capacity for an estimated percentage much like the iPhone's Maximum Capacity — it flags the cell as Reduced once it falls below 80%. The Pixel 8 and 8 Pro and older models (Pixel 4 through 7) don't surface a health percentage natively — your best bet is AccuBattery over a few charges, or the *#*#4636#*#* diagnostics menu on models that support it.

Google backs its newer Pixels with long update commitments and multi-year battery designs, so a well-kept Pixel 9 usually still reads healthy at sale time. The dollar swings are smaller than on iPhones simply because Pixel resale values sit lower — an Excellent Pixel 9 Pro runs $362 at GadgetRenu as of August 2026 — but the battery-health effect is proportionally similar. Get a Pixel quote to see yours.

If you'll sell in the next few months, a few habits help at the margins. Nothing reverses aging, but you can slow it.

• Turn on optimized charging. iPhone: Settings > Battery > Battery Health & Charging > Optimized Battery Charging. Samsung: Settings > Battery > Battery Protection (set an 80-85% cap). Pixel: Settings > Battery > Adaptive Charging.
• Keep it cool. Heat is what actually kills lithium-ion cells. Skip the hot dashboard, pull the case off if it runs warm while charging, and don't game or record video plugged in.
• Stay in the middle. Batteries age slowest between about 20% and 80%. Routinely draining to zero adds stress.
• Use a decent charger. The manufacturer's brick or an MFi- / Samsung-certified third party (Anker, Belkin) is fine; unknown no-name chargers can run hotter than needed.

Be realistic about the payoff: careful habits might preserve a couple of extra percentage points of health over a year, not rescue a tired battery. The bigger lever is timing. A phone at 90% today outsells the same phone at 85% six months from now, and models keep dropping in price as replacements launch. A GadgetRenu quote locks today's value for 14 days — enough time to ship with the free insured USPS label from anywhere in the country.

It's a fair worry, and it's worth being specific about how to shield yourself. Some operators quote high to win the shipment, then cut the offer after "inspection," and battery health is an easy line to cite — most sellers never checked it and can't easily contest a number.

Screenshot your battery health before you ship. This is the whole game. Capture Settings > Battery > Battery Health & Charging and save it with the date. If anyone disputes the reading, you have proof. Then wipe the iPhone and you're ready to box it up.

Describe it honestly in the quote. Pick the condition that matches what you see. A screenshot plus a matching description is hard to argue with.

Pick a grader that shows its work. GadgetRenu photo-documents each inspection and measures every battery, and if the grade differs from what you described, it contacts you with the number and the effect on your offer before any payment goes out — you decide from there, no bait-and-switch. (That's how GadgetRenu runs it; other companies vary, so read their terms.)

The rest of the process is built to remove surprises: a roughly two-minute quote up front, the 14-day price lock, free insured USPS shipping, and cash — not store credit — within three business days of delivery via PayPal, Zelle, Venmo, Cash App, or check. For related reading, see How Much Is My iPhone Worth? and How to Get the Most Money for Your Used MacBook.

What battery health is too low to sell?

Below 80% is Apple's replacement threshold and where offers typically dip around 10-15% (GadgetRenu's own grading). Above 85%, the effect is minimal; 80-85% is a gray zone with at most a small deduction. You can still sell at any level — a low reading lowers the price, it doesn't disqualify the phone.

Can battery health go back up?

No. It reflects one-way chemical aging of the lithium-ion cell. A small ±1% wobble is just iOS recalibrating how it measures capacity, not real recovery. The only reset is a physical battery replacement.

How many charge cycles does an iPhone battery last?

Apple rates iPhones through the 14 for 80% capacity at 500 cycles and the iPhone 15 and later at 1,000 cycles (Apple, 2024). At about a cycle a day, that's roughly 1.5 years on older models and up to about 3 years on newer ones. Charge twice a day and you'll hit it sooner.

Does fast charging wear the battery faster?

Not meaningfully. Apple and Samsung fast-charge quickly to about 80%, then ease off to limit heat — which is why the last stretch is slower. The manufacturer's charger or a certified third party won't degrade the cell faster than slow charging.

Should I stop charging at 80%?

For longevity, 20-80% is the sweet spot, and Optimized Battery Charging (iPhone) or Battery Protection (Samsung) automates it. Over a few months before selling it might save a percentage point or two — helpful, not decisive.