If your phone’s swollen battery tries to pop up from the screen, it’s because you didn’t charge it enough

Every now and then, one gets to use a gadget from way back, from the old days. It’s amazing how you can fire up that ancient box-like TV you found in your grandpa’s garage. Unlike this immortal beast, your modern, fancy phone is fragile as snow on a May day.

One fine day in the future, your grandchildren (or you) will inevitably put their hands on your sacred drawer (the future equivalent of the current-day garage) and they’ll find a phone with a battery so swollen that it actually tries to pop up from the front, damaging, deforming and, ultimately, cracking the screen.

Why? It’s because you didn’t charge your phone often enough.

Jokes aside, if you wish to hold on to your old phone for whatever reason, there’s the real possibility of all the wrong things going for your battery (and screen, as we’ve just discussed).

The old phone may have some sentimental value for you, or you want to sell it for ten thousand dollars in the year 2060, hoping that there’ll be some kind of nostalgic wave for phones from 2024, a phone renaissance if you will. I’m kind of skeptical about that last point, but, hey, you’re calling the shots!

Whatever the case is, if you want to preserve your smartphone throughout the years, you’ll need to know more about its battery and what can make it swollen.

There’s a wonderful, informative, and detailed article by iFixit about swollen phone batteries for their “How Tech Works” series.

What I like most about it, is that it’s written in simple, clear language that won’t alienate even those among us who are on the opposite side of the tech-savvy spectrum.

The article outlines that most modern gadgets use lithium-ion polymer batteries (LiPo for short).

A LiPo battery is made of a tightly wound roll of thin metals and plastics coated with chemicals. This roll is placed in an aluminum pouch with a measured amount of gel-like electrolyte. The pouch is then vacuum-sealed and heat-sealed to make it airtight, forming the finished battery.

The gel electrolyte inside the battery is essential; it allows lithium ions to move, which is necessary for the battery to work. In theory, the airtight pouch keeps the amount of gel electrolyte stable.However, in practice, the gel electrolyte can break down and turn into gas, primarily carbon monoxide and dioxide. This gas gets trapped in the airtight pouch, causing it to swell as pressure builds up. Although it may seem concerning, the swelling pouch acts as a safety feature, containing the gas and preventing it from leaking into the environment.

The breakdown of the electrolyte into gas is mostly irreversible; once it happens, the gas cannot be turned back into the gel. Nevertheless, the battery can still function. A small amount of electrolyte turning into gas during charging and discharging is normal and doesn’t affect the battery’s performance. However, if a large amount of electrolyte decomposes, the battery can no longer function properly, leading to a failure.

These conditions will accelerate electrolyte decomposition and battery swelling:

• The battery gets really hot (>194 °F [ca. 90 °C]);
• The battery gets overcharged (because of bad/wrong chargers);
• The battery is physically damaged, shorting out internal layers;
• The battery gets deeply discharged for a long period of time (yes, this includes the phone you’ve forgotten about, sitting at the far end of the drawer you open twice a year).

Depending on the battery capacity, build quality, and specific chemistry, the deep discharge can take weeks… or years. Even if there isn’t swelling, it doesn’t mean the battery’s undamaged—it’s possible that the pouch is no longer airtight and the gas has vented out.

How to prevent the battery from swelling?

To prevent a LiPo battery from swelling, you can simply check and recharge your old devices every now and then. It may sound like a hassle, but that’s the price we must pay, we must sacrifice some time. Actually, it’s not that much.

Every four months (that’s three times a year), you need to take your old phone, turn it on, charge it to 80%, then turn it off and set a calendar reminder for after 120 days. You’ll get used to it.

I’m dead set to do so with my old phone, once I transfer all my files, accounts, and data to my new Oppo flagship. I won’t be parting with my good old Pixel anytime soon – I just might use it for some rooting/OS experiments. But that’s a story for another time…