BEFORE YOU BUY
Battery health and cycle count: what the numbers mean
The phone looked new. The battery said otherwise. What health percentage and cycle count actually tell you about how hard a device was worked.
By the Savvoo desk · · 14 min read
I bought a phone that looked like it had never been used.
Boxed. Not a scratch on the screen or the body. It had lived in a case since the day it was bought. The listing said hardly used, and every word of that was true. Whoever owned it before me had looked after it properly.
Then I installed an app to read the battery, and found a cycle count that had no business being on a phone that age. Well looked after. Heavily used.
Those are two different things, and only one of them shows up in the photographs.
Battery health is the share of its original capacity a battery can still hold. A phone at 87% holds 87% of the charge it held when it was new. Cycle count is how many full charges it has been through, and it is the closest thing a used device has to an odometer. Between them they answer the question the pictures cannot: not how carefully this was treated, but how hard it was worked.
The short version
85% and up is fine for everyday use. You will not notice it.
Sellers guarantee at least 80% on a phone and 85% on a laptop. Below that, expect a new battery or a lower price.
Cycle count tells you more than age does. It is the closest thing a used device has to an odometer.
Read the real figure yourself in the first week, while you can still send it back.
If the discount is smaller than a replacement battery costs, it is not really a discount.
What "battery health" actually measures
A phone or a laptop will show you two percentages, and they mean completely different things.
The one at the top of the screen is how full the battery is right now. Battery health is something else: namely how much power the battery can hold at all, compared to the day it was made. A device at 87% health, charged to 100%, has a full tank. It is just a smaller tank than it used to be.
That translates straight into hours. If the laptop ran ten hours on a charge when it was new, at 87% it runs closer to eight and three quarters. Same machine, same apps, about an hour and twenty minutes less between charges.
Capacity falls for three reasons, and only one of them is about how much the thing was used. Full charge cycles wear a battery down, which is the next section. Heat wears it down. So does sitting at 100% on a charger for hours at a stretch. Apple puts it plainly: a battery's chemical age comes from a combination of factors including its temperature history and its charging pattern. Which means a device can show a tired battery without having been worked hard. A laptop left plugged in on a warm desk for two years will look used even if nobody did much on it.
(New does not always mean 100%, either. The clock starts when the battery is made, not when you open the box, so a genuinely new phone can read 99% on day one.)
One thing worth unlearning: 80% health does not mean the battery is nearly dead. It means it holds 80% of what it once did. A phone or laptop at 80% still works. It just wants the charger sooner.
What a charge cycle actually counts
A cycle is not the number of times a device has been plugged in. It is the number of times it has used up 100% of its capacity, added together.
Run a phone down to 50% on Monday and charge it back up, then do the same on Tuesday, and that is one cycle, not two. Apple and Google both count it that way. Which is why "I charged it every night" tells you nothing on its own. What counts is how much got used, not how often someone reached for the cable.
Manufacturers publish a target for this, and it is the number worth knowing:
iPhone 14 and earlier: built to hold 80% of original capacity at 500 cycles
iPhone 15 models: 80% at 1,000 cycles
Mac laptops: 80% at 1,000 cycles
Pixel 3 through Pixel 8 Pro: about 800 cycles
Pixel 8a and later: about 1,000 cycles
Samsung does not publish an equivalent figure, which is worth knowing in itself.
Note Apple's own wording, "under ideal conditions." These are design targets, not promises. A hard life gets there sooner.
Lower is healthier. But the count on its own is only half of it, because 200 cycles means something very different on a six-month-old device than on a four-year-old one.
Where to find the number
Two things decide what you can see. The model decides whether the device tracks a cycle count at all. The software version decides what the screen is called and where it sits. A refurbished device often arrives on older software, so update it first, then look.
Mac. Apple menu, then About This Mac, then More Info. Scroll to the bottom for System Report, then open Power. The cycle count and a condition reading are both there.
Windows. Open Command Prompt and run
powercfg /batteryreport. It writes an HTML file to your user folder. Under Installed batteries you will find design capacity, full charge capacity and a cycle count. Windows does not hand you a health percentage, so work it out: divide full charge capacity by design capacity. 61,000 out of 70,000 is 87%. On a few laptops the cycle count comes back blank, and the capacity comparison still tells you what you need.iPhone 15 and later. Settings, then Battery, then Battery Health. Cycle count, plus the battery's manufacture date and the date the phone was first switched on.
iPhone 14 and earlier. Same route, but the entry is called Battery Health and Charging, and there is no cycle count. You get maximum capacity only.
Android. It varies more than it should. Pixel 8a and later show a cycle count and manufacture date under Settings, About phone, Battery information. Some recent Motorola phones do the same. Samsung is inconsistent between models and software versions. On plenty of phones the number simply is not exposed, and an app is the only route.
The pattern in that list is worth noticing. The easier the odometer is to read, the less you have to take the seller's word for anything. On a laptop the history is there in thirty seconds. On many phones it is not, and that is why a stated battery figure carries more weight in a phone listing than in a laptop one. If that is the thing making you hesitate, we go through the rest of it in is a refurbished phone safe to buy?
Is 80% good enough?
80% is not a number anyone picked with buyers in mind. It is the point manufacturers use to mark the end of a battery's designed life.
Worth being precise about what Apple actually promises, because it gets misquoted constantly. The standard one-year warranty covers a battery that is defective. AppleCare goes further, and replaces the battery at no charge if it holds less than 80% of its original capacity. So 80% is the line where Apple itself calls a battery worn out, and the refurbished trade has borrowed it.
The floors then vary by seller and by device, so read the specific guarantee rather than assuming. Amazon Renewed holds 80% across the board, or 90% on its Premium grade. Back Market holds 80% on phones but 85% on everything else, laptops included, and 90% on premium phones. Some sellers fit a new battery and quote 100%.
Our line has not changed: 85% and up is fine for everyday use. You will not notice it.
Between 80% and 85% is where it gets interesting. Nothing is wrong with the device. You are simply buying one that is closer to wanting a new battery than a listing at 90% would be, and a battery replacement has a price attached. Roughly a hundred dollars for a phone, and somewhere in the region of a hundred and fifty to two hundred and fifty for a laptop, though it is worth checking your exact model.
That gives you a straightforward test. If the discount on the lower-health listing is smaller than a replacement battery costs, it is not really a discount.
Below 80%, the seller should be either fitting a new battery or pricing like they haven't. And if the gap between refurbished and new looks smaller than it used to, that is not your imagination. We wrote about why phones and laptops got so expensive this year.
We are building something to do this arithmetic for you. Savvoo is putting together a service that reads live listings, sets the battery figures against the price, and shortlists what actually fits what you need. It is not live yet. Leave your email and we will tell you when it is.
It will be free to use. We take a finder's fee from the seller, never from you.
The bit nobody tells you: it's an odometer
Go back to the phone at the start. Pristine, cased, boxed, honestly described. And underneath all that, a battery that had been through more than a phone that age should have.
The condition grade tells you how a device was treated. The battery tells you how hard it was worked. Everybody assumes those are the same question. They are not, and only one of them is visible in a photograph. (If the grades themselves are new to you, what does refurbished actually mean? walks through them.)
Which is why manufacturers do not rate batteries in years. Apple and Google both quote their figures in cycles, not months, because time is a weak predictor and use is a strong one. Two identical phones bought the same week can be a year apart in wear. The calendar cannot tell you which is which. The cycle count can. Photographs can be flattering, and a grade is somebody's judgment, but a cycle count is a meter reading.
So there are two readings worth taking, and they answer different questions.
How much is left. Set the count against what the device is rated for. A phone rated for 1,000 cycles showing 400 has used about two fifths of its designed life, with the caveat that a rating is a target under ideal conditions rather than a promise.
How hard it was worked. Divide the count by the device's age in years. Somewhere around 300 or more a year is somebody who ran their device down and charged it back up most days. Under about 200 is a lighter life. That one is our own arithmetic rather than anybody's published figure, so treat it as a rough steer. It is enough to tell a device that carried somebody's whole day from one that only took part of the load.
Two honest limits on all this.
A signal is not a verdict. Heat and a permanent spot on the charger wear a battery down without anyone doing much work on the device. A high count is a reason to ask what it was used for. It is not proof it was worked hard.
A new battery breaks the meter. A refurbisher who fits a fresh battery has done you a favor, and in is a refurbished laptop safe? we say a guarantee matters more than a cycle count, which is true when the question is whether a device is safe to buy. But it comes at a cost worth naming: the odometer stops telling you the truth. Sometimes it resets. Sometimes, because the original battery management board stays in the phone, it carries on counting from the cell that was taken out, and the number you are reading belongs to a battery that is no longer there. Either way the rest of the machine keeps its history. The hinges, the fans, the ports and the keyboard all did the miles. You just cannot see how many any more.
There is a sharper version of that on an iPhone. When a battery is not a genuine Apple part, iOS flags it as an unknown part, and on some phones the maximum capacity figure stops showing at all. So you go to check the one honest number and it is not there. The absence is itself information: the phone has been opened. Settings, General, About, then Parts and Service History will tell you what else was swapped at the same time.
None of that is a reason to avoid a device with a new battery. It is a reason to ask what else got checked.
What the number is actually worth to you
Knowing a device was worked hard is only useful if you can do something with it, and what you can do depends entirely on where you are buying.
Where you can make an offer. eBay, private sellers, local pickup, and, on plenty of listings, Newegg. A cycle count that looks high for the age is a specific, verifiable reason to offer less, and it is a better one than "would you take fifty off" because it points at something real. Not every listing accepts offers, so look for the option before you plan around it.
Where the price is the price. Back Market and Amazon Renewed do not haggle, and that is deliberate. Both set minimum standards their sellers have to meet, and the fixed price is part of that bargain. What you have instead is the ability to walk. There is almost always another listing of the same model, and the one with fewer cycles at the same price is the one to take.
After it arrives, this is where the standards start working for you. The same minimum standards that stop you haggling up front are the reason you have a case afterwards. If a device does not meet what was promised, the marketplace steps in between you and the seller. Back Market's published remedies are exchange or refund. Amazon Renewed's are replacement or refund.
Speaking from my own experience, the negotiation can land somewhere other than those two. A device arrived with a defect, I raised it, the marketplace acted as go-between with the supplier, and I kept the device and got back around 15% of what I paid. That is not a published policy and it is not something to count on. It is worth knowing the conversation exists.
Batteries are unusually strong ground for it, because the claim is a number. Arguing about "light scratches" is arguing about taste. A listing that guarantees at least 85% and arrives at 79% is not a matter of opinion.
One thing to understand about the warranty, because it catches people out. Back Market's year of cover excludes ordinary wear, and that includes a battery gradually losing capacity. What it does cover is a battery that fails to meet the guarantee on arrival, and it will repair a battery free if capacity drops below 80% inside the first three months. So the battery is protected early and then it is on you.
Two checks worth doing in the first week, while the return window is open:
Read the battery yourself. Whatever the listing said, look at the real figure using the method for your device above. If it falls short of the stated guarantee, you have a documented discrepancy.
On an iPhone 15 or later, check the dates. That same Battery Health screen shows when the battery was made and when the phone was first switched on. A listing describing a lightly used recent model, on a phone that says it was first switched on two years before that, is telling you something the photographs did not.
None of this is about manufacturing a complaint. It is about knowing that when a device does not match its description, sending it back is not your only option.
How much should any of this weigh?
Less than you would think, having just read three thousand words about it.
A battery is the one part of a used device that is straightforwardly fixable. It has a known price and a known outcome. That is not true of a swollen case, a failing screen, a seller who stops replying, or a phone that turns out to be locked to somebody else's account. Those are the things that ruin a purchase.
So the order runs roughly like this. The return policy first, because it is what protects you if anything below it goes wrong. Then the warranty, and what it actually covers. Then the battery. Then the cosmetic grade, which tells you less than people assume.
A device with a great battery and a two-week return window is a worse buy than one at 82% with thirty days and a year of cover.
One last thing about that return window. It is not just a safety net, it is your inspection period. Everything in this guide can be checked properly once the device is in your hands, and it takes about a minute. Do it in the first few days, not the fourth week.
Or let us do the checking. We are building a service that reads the listings, weighs the battery figures against the price and the return terms, and shortlists what fits. Leave your email and we will let you know when it opens.
You're the second owner now
The odometer does not reset when the device changes hands. Whatever life is left in that battery is yours to spend.
Four things worth knowing, none of which require any effort.
Cap the charge if your device will let you. Recent iPhones have a Charge Limit setting that stops anywhere between 80% and 100% in five-point steps. Most Android phones have something similar, and Macs and many Windows laptops manage it themselves once they learn your routine. The last stretch of a charge is the part that wears a battery hardest.
Top up whenever you like. Lithium-ion has no memory and nothing to preserve. Small frequent charges are gentler than running flat and filling up again, and partial charges do not each count as a cycle. Apple is clear that leaving a phone on the charger overnight is fine; it stops when it is full.
Heat is the real enemy. Apple puts the line at 95°F, above which charging or using a device can permanently reduce its lifespan, and says even storing a battery somewhere hot can damage it for good. Off the dashboard, off the bed, out of direct sun, and keep a laptop's vents clear.
Watch the permanently docked laptop. A machine that sits at 100% on a desk all day is being worn down while doing nothing. Most modern laptops handle this on their own, but if yours has a charge limit setting and it is switched off, switch it on.
None of this will make a battery last forever. It is the difference between a device that still holds a useful charge in three years and one that is looking for a charger by lunchtime.
Battery health: common questions
Does battery health ever go back up? Capacity only falls. What can change is the reported figure, because it is an estimate: iOS periodically recalibrates it and the number may be revised when it does. Nothing you install can restore lost capacity, whatever it claims.
Does a low cycle count always mean a good battery? No, and this is the useful one. Age wears a battery down on its own. A four-year-old device with 150 cycles has spent four years quietly degrading regardless of how little it was used. Cycle count and age have to be read together.
Is a replaced battery a genuine one? Often not, and that is less alarming than it sounds. Back Market's position is that a replacement does not have to come from the original manufacturer, provided the seller has tested it to perform like one. Apple takes the opposite view and flags a non-genuine battery as an unknown part, which on many iPhones removes the maximum capacity reading entirely. So a third-party battery may be perfectly good and still cost you the ability to check it. If a listing says a new battery, it is fair to ask whose.
Do I lose the warranty if the battery was replaced? Ask, in writing, before you buy. A refurbisher's own guarantee normally covers work they did themselves. Where it gets complicated is any remaining manufacturer cover, which a non-authorized repair can affect. It is a question with a clear answer, and a seller who will not give you one has told you something.
Related
Sources
All checked 3 August 2026.
Apple, "iPhone battery and performance" — cycle ratings for iPhone 14 and earlier and iPhone 15 models, the definition of a complete charge cycle, and the one-year warranty covering a defective battery.
https://support.apple.com/en-us/101575Apple, "Charge and maintain your iPhone battery" — heat and lifespan, the 95°F threshold, and overnight charging.
https://support.apple.com/en-us/105105Apple, "Batteries: Maximizing Performance" — operating temperature ranges for iPhone and MacBook, and damage from hot storage.
https://www.apple.com/batteries/maximizing-performance/Apple, "About Charge Limit and Optimized Battery Charging on iPhone" — the 80% to 100% charge limit in five-point steps, and chemical age arising from temperature history and charging pattern.
https://support.apple.com/en-us/108055Apple, "About recalibration of battery health reporting in iOS 14.5 or later" — maximum capacity as a revisable estimate.
https://support.apple.com/en-us/119954Google, "Understand your Pixel battery" — cycle ratings for Pixel 3 through Pixel 8 Pro and Pixel 8a and later, the partial-cycle definition, and the location of Battery information.
https://support.google.com/pixelphone/answer/15738128Amazon, "Amazon Renewed" customer service page — batteries tested to at least 80% of new, or 90% on Renewed Premium.
https://www.amazon.com/gp/help/customer/display.html?nodeId=GRAS7M4E8YJCLWH7Newegg Knowledge Base, "Make an Offer" — buyer offers, counteroffers, and per-listing availability.
https://kb.newegg.com/knowledge-base/make-an-offerBack Market Help Center, "How long can I expect my battery to last?" — the 80% guarantee on smartphones, 85% on all other devices including laptops, 90% on the Extra charge battery option, and free repair if capacity drops below 80% within three months.
https://help.backmarket.com/hc/en-us/articles/360026656374-How-long-can-I-expect-my-battery-to-lastApple, "iPhone Parts and Service History" — the Unknown label shown when a component was replaced with a non-genuine part.
https://support.apple.com/en-us/102658Apple, "AppleCare" — battery replacement at no charge when capacity holds less than 80% of original, stated for both iPhone and Mac.
https://www.apple.com/applecare/Back Market Help Center, "Why is my iPhone showing an Important Message or Unknown Part warning from Apple?" — non-Apple replacements displayed as Unknown Part or Used Battery, and cycle count reflecting the retained battery management board rather than the replacement cell.
https://help.backmarket.com/hc/en-us/articles/4402499904530-Why-is-my-iPhone-showing-an-Important-Message-or-Unknown-Part-warning-from-AppleApple, iPhone and Mac battery service pricing. Apple quotes per model at the point of service rather than publishing a table, which is why the figures in this guide are given as a range.
https://support.apple.com/iphone/repair/service/battery-power