Microsoft has a big battery problem. Literally.

The company’s premium line of Surface tablets and laptops are generally beloved by users—for a while. But within a few years of use, many Surfaces are plagued by a problem that renders them completely unusable. In the callously creative language of the internet, this problem is called a “spicy pillow.” In more banal terms, it’s a swollen battery.

Swollen batteries have been found in almost every model of phone, tablet, or laptop from almost every electronics manufacturer. But if it’s a competition, Microsoft Surfaces are gunning for the podium. Not only are Surface batteries swelling at abnormally high rates, but the Surfaces are designed not to be serviceable, so a swollen battery is often the death-knell for these expensive devices. The cherry on top of the spicy pillow is Microsoft’s refusal to acknowledge the problem.

The most commonly affected models are the Microsoft Surface Pro 4 and original generation Surface Book, but swollen batteries have been reported in the Surface Pro 5, Surface Pro 6, Surface Pro 7, Surface Book 2, Surface Laptop 1, and other models.

Bulging Batteries in Microsoft Surfaces

Lithium-ion batteries are the most common type of battery in consumer electronics today. Like anything else at the mercy of entropy, Li-ion batteries get worse over time. A new battery that holds five hours worth of charge may hold just three hours after a few hundred charge cycles. This degradation is normal, though it can be mitigated with proper battery care.

What isn’t normal is when Li-ion batteries swell. This happens when the battery’s planned chemical reaction is compromised and gaseous by-products are produced, mostly carbon dioxide (CO₂). The mixture can also include the toxic gas hydrogen fluoride (HF) and potentially toxic gas phosphoryl fluoride (POF₃). With nowhere to go, these gases exert pressure on the battery pouch and cause it to swell. When the battery swells enough to reach the walls of its enclosure, it keeps pushing.

If you’ve ever noticed an unexplained bulge in your laptop or tablet, it is likely caused by a swollen battery. The bulge can be subtle—perhaps you’ve noticed your laptop doesn’t quite sit flush with your desk anymore—or it can be painfully obvious, going so far as to split apart the chassis and reveal the spicy pillow inside.

The battery in Microsoft Surface Pro and Book devices is located behind the touchscreen display, and swelling is often preceded by noticeable splotches of discoloration on the screen. These splotches may move over time as swelling increases. Surface Books also have a second battery underneath the keyboard base (see pictures above).

Surface users who notice a swollen battery should stop using their devices immediately. The Surface should be handled with care, as the battery can ignite and release toxic gas. This applies to any device with a swollen battery, and owners of these devices will have to repair, replace, or recycle it once the battery swells.

Here’s where the trouble is doubled for Surface users, as Microsoft Surfaces are not designed for battery replacements. They’re not the only consumer devices that are difficult to service; the whole category of thin-and-sleek premium electronics—including Apple MacBooks—is notorious for difficult user repairs. However, the Microsoft Surface line is particularly egregious, as Microsoft itself will not replace batteries in its own products. If you need another battery, Microsoft will sell you another Surface. Apple, for comparison, will replace its own MacBook batteries for $200 or less.

That’s not to say it’s impossible to replace a Surface battery. You can always bring your device to a third-party repair shop or give it a go yourself—here’s a step-by-step iFixit guide for the Microsoft Surface Book. But be warned—it’s not an easy repair, and if you mess it up, you could permanently disable your device. Abdullah Mamun, owner of RxTech Repair in Orange County, California, strongly advises users not to attempt to replace Surface batteries themselves.

“If it’s your first repair, it’s going to be difficult,” he cautioned. “You’re probably not going to have a good time.”

How Many Surfaces Suffer Swollen Batteries?

We searched through dozens of threads on the Surface forums, Surface subreddit, and Microsoft community forums, and encountered hundreds of users reporting swollen batteries (here’s a particularly lengthy thread). That was just a small sample of the online discussion. Of the 257 cases of swollen Surface batteries we recorded, 101 were for Surface Pros (gens 3 through 7), 87 were for Surface Books (gens 1 and 2), 6 were for Surface Laptops (gens 1 and 3), and 63 were for unspecified Surface devices.

One Surface user we spoke with is an IT team lead for a software development company. John (not his real name) administers 60 Surface Books, split between 25 Surface Book 1s and 35 Surface Book 2s. Since first deploying the Surface Books in 2017, John has seen 13 of the devices affected by a swollen battery (encompassing both Surface Book 1 and 2 models and both screen and keyboard batteries). His company’s sole Surface Pro 4 also swelled, making for a total failure rate of 23 percent. In contrast, John also administers around 90 Dell laptops and has experienced swollen batteries in five of them—a 5.5 percent failure rate.

“Quadruple the failure rate is pretty bad, and to make matters worse, the Surface devices have to be completely replaced. We can just swap the batteries out on the Dells,” John said.

Mamun can also attest to the uncommonly high rate of Surface battery failure. His repair shop has replaced hundreds of swollen batteries on Microsoft Surface Pros—more than for any other brand of device—and it remains one of his most popular repairs. It’s also one of the hardest.

“It’s an extremely difficult repair to do,” Mamun said. “Without having a lot of experience, you’ll most likely break the screen trying to get to the battery. I myself have done over 500 of these and I used to break these screens all the time.”

The Surface Pro 4 is the most common device Mamun sees with swollen batteries, but his shop RxTech Repair also regularly replaces swollen batteries on the Surface Pro 3, 5 and 6. After receiving many customer requests, he has recently begun offering the service for the Surface Book as well, though he considers it an even trickier repair than the Surface Pro.

Why is swelling so prevalent on Surface batteries? In the case of the Surface Pro, Mamun suspects the culprit is poor thermal design. The Surface Pro’s heatsink—a block of metal found in many electronic devices that draws heat from the processors—is positioned directly atop the batteries. Heat accelerates battery deterioration, so placing the heatsink right on top of the Li-ion battery pouches is a strange design choice.

“It just doesn’t make any sense to me why the heatsink goes over the battery, because you don't want the battery getting hot,” Mamun said. “In my experience, I don’t really see any other devices where the heatsink goes over the battery.”

Could the justification be that the Microsoft Surface Pro is simply so slim that there was nowhere else to put the heatsink? No, Mamun emphasized. “There’s plenty of real estate where [Microsoft] could have put the heat sink that wasn’t on the battery.”

This explanation doesn’t transfer to the Surface Book, as its heatsink is located below the Li-ion batteries in the touchscreen. But that doesn’t absolve the Book of other thermal issues, according to Mamun.

“It’s a better design on the Surface Books than the Surface Pro, but [the batteries] do still bloat,” he said. “And even if the heatsink is not directly on top of [the batteries], if heat doesn’t have a way to escape, the heat is still in the device.”

Battery deterioration doesn’t always lead to swelling, and batteries may fail without any visible sign. In Mamun’s experience, Surface batteries tend to fail much faster than other devices.

“A device has a certain amount of charge cycles,” Mamun explained, referring to the number of times a battery is charged and discharged over its lifetime. “For most devices that I see, their batteries start failing after about 800 to 1000 charge cycles. For Surfaces, I see that around the 200 to 350 mark. I have a feeling that has a lot to do with how those Surfaces are designed.”

Are Swollen Batteries Dangerous?

Swollen batteries are not merely an aesthetic issue—they also pose a potential safety hazard. The inherent danger of Li-ion batteries exploded into the public consciousness with the Samsung Galaxy Note 7 smartphone from 2016, which was hastily recalled worldwide when at least 35 units caught fire. Major airlines banned the device from flight, and one user was hospitalized due to smoke inhalation. The problem was traced back to defective batteries.

While illustrative of the potential dangers of Li-ion batteries, the Note 7 recall was caused by a design flaw that led to internal shorting in the batteries, which discharged their stored energy very quickly. Battery swelling is a different problem, and the question of whether swollen batteries are dangerous depends on who you ask.

Microsoft does not consider swollen batteries a safety concern, and states the following on Caring for your Surface battery:

Battery expansion from deterioration does not present a safety concern and is most often caused by the formation of non-flammable carbon dioxide (CO₂) gas. If you have a device where the battery has expanded visibly beyond the mechanical enclosure, we recommend you stop using the device. You should handle the device with caution to prevent putting pressure on or risk puncturing the battery cell. [Emphasis added]

To Surface users with swollen batteries, this messaging doesn’t provide much in the way of clarity or comfort. It’s a bit like meeting an unfamiliar dog and being told by its owner “Don’t worry, he won’t bite; just keep your fingers away from his mouth.”

Microsoft’s competitors have made similar statements about swollen batteries. Dell, for instance, has this to say in its laptop battery FAQ:

While a swollen battery pack does not represent a safety concern, you should not use damaged or swollen components. [Emphasis added]

HP says this:

A swollen battery does not present a safety issue… In order to protect your hardware from potential damage, HP recommends that customers experiencing battery swelling discontinue use of the notebook until the battery can be replaced. [Emphasis added]

Lenovo deviates from the script and admits a small possibility of risk:

In most cases, a swollen battery which has resulted in mechanical damage to your system does not present a safety risk, as the swelling is primarily from harmless carbon dioxide (CO₂) gas generation. However, in some rare instances, excessive swelling may lead to hazardous conditions. Therefore, Lenovo recommends treating all excessively swollen batteries carefully to avoid puncture or further damage. [Emphasis added]

For those planning to get up close and personal with swollen batteries, the safety messaging is far different. iFixit, a popular wiki that provides electronics repair manuals, takes a different stance from Microsoft and other laptop makers:

A SWOLLEN LITHIUM-ION BATTERY MAY CATCH FIRE OR EXPLODE. PROCEED WITH EXTREME CAUTION AND AT YOUR OWN RISK WHEN REMOVING A SWOLLEN BATTERY FROM AN ELECTRONIC DEVICE. [Original emphasis]

BatteryWorld, a large Australian battery provider, also urges caution:

Swollen batteries, while not common, are a significant risk… Even if your device still works, the battery must be replaced immediately. Using the device or leaving it connected to power can be dangerous. [Emphasis added]

Mamun, who has personally replaced hundreds of swollen batteries, has not experienced any physical injury from the procedure. However, safety is always top of mind. When swapping swollen batteries, Mamun wears protective equipment including gloves and safety glasses. He keeps a fume extractor on-hand for accidental punctures. He doesn’t use metal tools. He is very cautious when applying heat, which for Surfaces is necessary to loosen the strong adhesive holding batteries in place.

“If you heat it too hot, the battery can explode,” he said. “I’ve seen batteries explode in my time as a technician. I do most of these repairs myself because I don’t want other people to take the risk.”

John, the IT lead, has comfortably replaced several swollen batteries in Dell laptops (they are designed to be replaced) but abandoned his single attempt on a swollen Surface Book, wary of the danger and unwilling to use the force and heat necessary to pry the battery out.

One user on the Microsoft support forums posted pictures of his Surface Pro 4 in the aftermath of a swollen battery fire. It’s not clear exactly how the fire began, but a response from a Microsoft agent places the fault with the user: “An examination by Microsoft determined the battery in this particular device was punctured by an external object inserted into the device.” The agent went on to advise users not to attempt swollen battery replacements themselves.

How is Microsoft Responding to the Surface Battery Problem?

Of the Surface users who report swollen batteries, many experience the issue a few years into owning their device. While Surfaces are warrantied for one year, Microsoft appears to have extended the warranty to three years for swollen batteries. There is no official record of this policy, but it is consistent with dozens of user reports. During the three-year window, Surfaces with swollen batteries will be replaced at no cost to the user.

Beyond this unofficial three-year warranty, Microsoft’s response to swollen Surface batteries has been mixed. Some users report that Microsoft has replaced their devices for free beyond three years. Other users are only offered the option to purchase a refurbished replacement device at a cost of $499 (Surface Pro) or $599 (Surface Book). The replacements are warrantied for just 90 days, and several users have reported swollen batteries on replacement devices as well.

The users that received free out-of-warranty replacements all seem to have been supported at Microsoft’s physical retail stores, and universally praise the in-store customer service. Unfortunately, Microsoft closed all of its stores in the midst of the pandemic and has no plans to reopen.

We spoke with a former employee of one of Microsoft’s specialty stores, which is what the company called kiosks that were not full retail stores (Microsoft closed its specialty stores in August 2019, nearly a year ahead of the full shutdown). The employee (who requested anonymity) recalled just how prevalent the swollen battery problem had been during his nearly two years at the store before it was closed.

“We were getting absolutely spammed,” he said. “On a low week, probably three or four times a week. On a high week, probably two a day. It was a very common issue.” The Surface Pro 4 was the biggest offender, he noted, but his store also saw plenty of original Surface Books and a smattering of other Surface models. Regardless, it was store policy to ensure customers left with a free replacement.

“No matter what store in the country, if there was a swollen battery that came in, you processed it right away and took care of the customer. No questions asked,” he emphasized. “The liability of letting them go home with that device was way too great.”

With retail stores closed, the only remaining option for Surface users is Microsoft’s phone support. By all accounts, it’s a distant cry from the superb in-store service.

This was the last straw for John, the IT team lead with 13 swollen Surface Books: “We don’t plan to buy any more Surface Books for several reasons, one of which is definitely the battery issues. The failure rates are much too high for a business to have to deal with. The nail in the coffin was when Microsoft closed down the stores and we had several mediocre-to-poor phone support experiences. It all came to a head when their business support phone lines were playing a message indicating their phone system was down for several days (yikes!) and that I should enter a support case online, which I did, and the follow up was incredibly slow and poor.”

Officially, Microsoft is keeping mum about its swollen battery problem. The update pages for the Surface Pro 4 and Surface Book list “no known issues” for either device. Microsoft declined to comment for this article, responding only with a link to the webpage Caring for your Surface battery.

Despite their silence, Microsoft is clearly aware of the battery problem. For one thing, their erstwhile retail stores were getting spammed with swollen batteries and the company had specific procedures in place to handle them, including the unofficial extended warranty. “I don't know how high up it went, but whoever was in charge of retail definitely knew,” admitted the former Microsoft store employee.

More evidence for Microsoft’s knowledge of the swollen battery problem comes from three software features they quietly introduced for Surface devices: Battery Limit Mode, Battery Smart Charging, and Battery Lifespan Saver. Each of these features supposedly improves battery life and performance, though there is scant record of them in the Surface update history, and users were not notified of their introduction.

Battery Limit Mode is a feature that constrains battery capacity to 50 percent, which Microsoft claims will prolong battery life for users who keep their devices plugged in full-time. Also referred to as “Kiosk mode,” this feature was first introduced in updates for the Surface Pro 3 and Surface Pro 4 on September 10, 2018 (though not by name; only later did Microsoft cite these updates in reference to Battery Limit Mode):

To enable Battery Limit Mode, Surface users must enter the Unified Extensible Firmware Interface (UEFI), and depending on their Surface model, a firmware update may first be required. It’s fair to assume that most users do not actively browse their UEFI settings, and even for the technically inclined, the lack of any notification alerting users to Battery Limit Mode has kept it buried. John, the IT team lead administering 60 Surface Books, was unaware of this feature, though he suspects many of his users keep their Surfaces plugged in regularly. The official Microsoft documentation for Battery Limit Mode is dated January 15, 2021.

The second silent battery update was Battery Smart Charging, though its chronology is difficult to determine. According to Microsoft, Battery Smart Charging is “a feature that helps protect your battery from the effects of charging patterns and high temperatures that may accelerate battery deterioration or lead to expansion.” The earliest mention we could find of this feature was on July 9, 2020, in an update for the Surface Book 2 with the terse description: “Improves Battery Smart Charging reliability.” This would seem to imply that the feature was quietly introduced at some point beforehand.

July 2020 is also the earliest we could find mention of the third software update, Battery Lifespan Saver. There is no explicit mention of it on any Surface update page, but it is listed on Caring for your Surface battery. Battery Lifespan Saver continuously monitors the Surface battery, and if “adverse conditions are detected,” it “implements a limited number of permanent reductions in charging voltage.” This permanently decreases battery capacity for the purpose of “limiting conditions that would otherwise accelerate battery deterioration, significantly reduce battery capacity, or lead to battery expansion.”

Battery Lifespan Saver is only available on recent Surface models, including the Surface Pro 7, Surface Pro 7+, Surface Pro X, Surface Book 3, Surface Laptop 3, Surface Laptop 4, Surface Laptop Go, and Surface Go 2. Whether it effectively prevents battery swelling on these models remains to be seen.

What Should Be Done About the Surface Battery Problem?

Microsoft Surfaces are marketed as premium devices, and priced accordingly. A top of the line Surface Book can cost over $3000. Users who’ve paid these high prices are understandably upset when, in just a few short years, their computers become unusable due to swollen batteries. Adding insult to injury, for most of these users, Microsoft’s official response is to offer them the chance to buy the very same device again, refurbished and with a limited 90 day warranty, at a cost exceeding aftermarket value (at time of writing, there are 248 results for “Surface Pro 4” on eBay cheaper than Microsoft’s replacement offer of $499).

Many frustrated Surface users have suggested a product recall in the vein of Samsung’s response to the Note 7, or Apple’s voluntary 2019 recall of certain 15-inch MacBook Pros with an overheating battery problem. However, the comparisons only go so far. In Samsung and Apple’s cases, there were several user reports of fire and injury, and the FAA banned the devices in question from flight. As far as we can determine, there have been no reports of users being physically harmed from swollen Surface batteries, nor have the devices attracted FAA attention.

Another common refrain from disgruntled users is to suggest a class-action lawsuit, a threat which has worked on Microsoft before. In addition to its swollen battery issues, the Surface Pro 4 is also infamous for a flickering screen caused by a faulty LCD display. Thousands of Surface Pro 4 users affected by Flickergate pursued a class-action lawsuit, which was dropped when Microsoft extended its warranty from one to three years for flickering Surface Pro 4 displays.

To date, no class-action suit has been filed for the Surface battery issues. In June 2020, a Facebook group called Microsoft Surface Book Problems With Screen Discoloration and Bulging was formed in an attempt to organize a collective response to the problem. According to group administrator Lindsey Hofstra, several law firms have so far declined to move forward with a class action suit. The private Facebook group currently boasts 530 members and counting.

It’s no surprise that many swollen Surface sufferers have sworn off Microsoft devices, deflated from swallowing the cost of what they perceive to be a defective product. A product that many were genuinely enamored with, until the swelling started.

“They’re super cool devices… but I would never buy one for myself knowing what I know now,” said John, who noted that many of his company’s users love their Surface Books.

Mamun, whose wife happily owns a Surface Pro 4, expressed the same sentiment. “Don’t get me wrong, I love the devices. The devices are amazing. If they were engineered in a way that would be more repairable, I would recommend them a lot more.”

Ultimately, Mamun views the swollen Surface batteries as emblematic of an industry-wide aversion to repairability.

“If enough people complain about this, the tech giants will be forced to make their devices more repairable, make them last longer,” he said. “I want a $2,000 device to last at least a couple of years.”