Picture this: You're watching your favorite movie on Netflix when you suddenly get a notification on your phone.

"20% battery remaining."

20% should be enough to get you to the end of the movie, right? You clear the notification, hit play, and three minutes later- your battery drops to 0%, your phone shuts off, and your movie is brought to an unexpected end.

Random shutdowns are an all too common issue on smartphones, but they are preventable. In this article, we'll explain why they happen, how you can prevent them, and share a device with you that can extend your cell phone battery life to the end of the day.

Why Does Your Phone Suddenly Die at 20/30/40% Battery?

1. The Battery Percentage Is Inaccurate

You may have never given it much thought before, but your battery's percentage isn't 100% accurate (pun intended). There's no magic way to know exactly how much percentage of a charge is left on your phone battery. Instead, a (very accurate) measurement is made using algorithms from chemistry.

Without getting too deep into the nitty-gritty, batteries are made possible through chemical reactions. Like most science, these reactions are measurable. Your smartphone has a "fuel gauge" of sorts attached to the battery that, using chemistry formulas, uses the present interactions (both electrical and chemical) to estimate a battery percentage.

As you can safely assume, this is a sensitive process that can be affected by things like temperature, the age of your battery, the quality of the fuel gauge, and so forth. While most major smartphones show accurate battery percentages, errors can arise that reduce the accuracy, resulting in unexpected shutdowns.

2. Something Abnormal Is Draining Your Battery Too Quickly

This is another common reason for a sudden smartphone shutdown, and that's less-than-ideal conditions. Not only can certain factors affect the accuracy of your battery percentage, but they can also impact the battery itself. When the battery percentage is accurate, but you notice your phone battery draining fast, one of these issues is likely the cause.

Temperature is probably the most common reason that smartphone batteries die unexpectedly. As mentioned, your battery is made possible by chemical reactions. If your phone becomes too cold, the reactions can slow down, causing your battery to shut off suddenly even when it still has 30 or 40% juice. If it becomes too hot, then the reactions can become dangerous, and your phone will shut down preemptively.

Internally, there could be a software issue that's draining your battery faster than normal. This could be an app running in the background, like a mobile game, malware, or even a simple software bug that needs to be patched.

3. The Lower Your Battery Percentage, The Lower Its Voltage

Thirdly, it could be your battery's voltage affecting its ability to power your smartphone. Voltage is the amount of power your battery is currently putting out.

You can think of voltage like water pressure: The more water you have the more pressure you have, and vice versa. That's why a leak in a water tower would flow with a lot of force, while a leak in a coffee cup would just drip onto your table.

Voltage works in a very similar way. When your battery is on a 100% charge, your phone can perform heavy tasks more easily. At a 20% or 30% charge, however, things start to slow down, and normal usage (like gaming or video editing) is too much for the phone to handle, so it suggests low power mode. If you ignore that notification, your phone may abruptly die.

4. Your Battery Is Old

Last but not least, your phone battery could just be old. Smartphone batteries are only good for about two years of use, at which point they need to be replaced. This is why so many people stick to a two-year cycle when upgrading their smartphones.

It's important to note, however, that you generally do not have to replace your entire phone when the battery gets old. Unless you're itching to grab the latest phone, swapping out your battery is generally the better way to solve an aging phone's woes.

If you own an iPhone, you can easily check your battery's health in the Settings app. Just go to Settings > Battery > Battery Health and check Maximum Capacity. Around 80% capacity is when you can start to expect random shutdowns and other degradation issues.

How To Prevent Your Phone From Shutting Off Suddenly at A 20% or 40% Charge?

1. Update Your Phone

Another way to prevent unexpected shutdowns is to update your phone's software. Although annual updates bring exciting features and new emojis, the smaller updates bring really important changes to your phone as well, like security and performance improvements.

These minor updates, while not as newsworthy, often fix bug-related issues like unexpected shutdowns. They can improve the accuracy of your battery percentage and reduce the amount of energy required to power certain processes, helping you get more out of every charge.

2. Restart Your Phone When The Battery Is Low

We mentioned above in Point #2 that a possible cause of a quickly-depleting battery is a process running in the background. This could be an app searching for Bluetooth or using your location, malware, a game you forgot to close, and so on.

These processes all use up lots of energy, which can result in your phone dying randomly. To prevent this from happening, you can restart your phone when you notice the battery getting close to 20%.

Restarting your phone is a surefire to close all processes currently running on your phone. Once it turns back on, all of your previously running apps should now be closed. This will extend your battery life and reduce the chances of your phone dying when you aren't expecting it.

3. Charge Your Phone As Soon As Your Battery Gets Low

Of course, this is the simplest and most effective solution to a phone that unexpectedly dies, and it's the only method guaranteed to work (assuming your battery is still functioning). Plugging your phone into a charger warms the battery up, beating the cold, allows it to run on external power, and, of course, it prevents your phone from dying due to low battery.

Although this is a guaranteed solution, you might not always have a wall outlet nearby. This is why carrying a portable battery around has become the norm for so many people. It provides enough extra charge that you don't have to worry so much about your phone dying.

Not all portable batteries are created equal, however. Some are bulky and hard to remember. You can easily forget to charge a portable battery, rendering it useless. And it makes it harder to use your phone, as your phone ends up tethered to the battery. Luckily, there's a better power bank solution.

4. Recalibrate Your Battery

Fully charge the battery, then let it drain until your phone shuts off. If it shuts off before the specific percentage, be it 30%, 20% or 1%, plug it in for about a minute, then drain it again. Keep plugging and unplugging until the battery shuts off at the accurate percentage. 

5. Replace Your Battery

If none of the above solutions work, it could that the battery is defective. The last thing to do is repair or replace the battery. Most smartphone manufacturers will do this for you, even out of warranty. You can expect to pay around $50 for the service depending on the size of your smartphone's battery.

Many people assume that the lifespan of a smartphone is around two years because this is when they start noticing issues with performance, shutdowns, and overall reliability. However, more often than not this is a result of battery issues.

Your smartphone's battery is really the only part of the phone (aside from the screen) that noticeably degrades with time. That means, aside from software updates, you can get quite a few years of use out of a smartphone by simply replacing the battery. Not only does this save you money, but it's also better for the environment!

The Magnetic Wireless Charger That Keeps Your Phone Alive: MagEZ Battery Pack

MagEZ Battery Pack provides you with the extra power you need to keep your phone from dying when you least expect it. It's a magnetic wireless charger that also acts as a magnetic power bank for your phone. When you want to charge it at home, you simply place it on the MagEZ Slider wireless charging stand to instantly start charging it.

The wireless power bank may look small, but it packs a punch. When you bring it with you to work, the mall, or the movies, you get an extra 30% of battery life. That's enough to get most major smartphones to the end of the day without ever needing to plug your phone in.

Stop Your Phone From Randomly Dying Now

Having a phone randomly die is annoying at best and stressful at worst. With the tips and tricks we've outlined above, as well as by using the MagEZ Battery Pack, you can dramatically reduce the chances of your smartphone unexpectedly dying.