Why you shouldn't expect a long-lasting smartphone battery any time soon

It's happened to everyone who owns a powerful smartphone. You wake up in the morning, reach over to your nightstand to pick up your phone, only to realize you forgot to plug in the charging cable. Now, the battery indicator is blinking red. You might as well kiss your productivity on the commute to work goodbye.

Despite the advancements in smartphone technology that can seem near miraculous to many users, battery life is one that never feels quite like it has reached the next level. Do more than check emails and social media throughout the day, and you'll be lucky to get one day's use out of it. Try playing a high-resolution video or a graphics-intensive game for more than 90 seconds, and all bets are off.

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Questions about battery life were popular in a recent Ask Me Anything, or AMA, session on the Reddit network with Dr. Dee Strand, who researches the lithium ion batteries that power smartphones and other modern devices at Wildcat Discovery Technologies in San Diego, Calif.

"Honestly, all I want to really know is when do you think my iPhone [or other smartphone] will be able to go a good two to three days of actually heavy daily use before needing to be charged," asked user ecib.

"I love this question," Strand replied, before bluntly answering, "The answer may be never."

The reasons for this are myriad, but in short, a phone's battery life is only one concern that must be balanced against several others, including shape, size and available features. When it comes down to a battery lasting more than a day versus functional and aesthetic constraints, battery life often falls down the priority list.

"With every improvement in the battery, the cellphone company wants to add more features (and so do you – consumer demand drives more features). Bigger screen, brighter display, more apps, touch screen features, etc.," wrote Strand.

She also cautions that "heavy use" can mean different things for different people. 

"If you're going to use your GPS for eight hours, there's probably no battery that's going to do that," she said.

Using your phone simply for text messages and voice calls, however, can probably guarantee a week's worth of battery use without needing a charge.

Would you buy a thicker phone?

"I think people want thinner phones, and they're not going to be willing to make that compromise and purchase a phone that's maybe half a centimetre thicker," said Patrick O'Rourke, who reviews phones and gadgets at the tech site MobileSyrup.

A phone that's thicker than the most popular models would probably have to guarantee far more than two to three days or battery life to justify a thicker body, he said.

For most people, though, a day's worth of juice is good enough. 

"As long as my phone can last from whenever I wake up until the evening, that's perfect for me," said O'Rourke.

Strand said it's theoretically possible to build a battery that is about the same size as current smartphone batteries but with "twice the energy density," but it wouldn't be tenable and would fry itself in about a month's time.

Strand's work focuses on improving the materials in batteries so that they can hold more lithium, making for a longer-lasting charge, but she says a viable multi-day battery is still several years off.

Extending battery life on the go

Impressive battery life might not be the sexiest smartphone spec, but there's enough demand for it that third-party products have stepped in to try to give phones some extra juice.

Portable power packs plug into your phone and can carry enough power to fully charge a phone a couple of times when you're on the move.

Some phone cases, such as those made by Mophie, contain a battery pack so if you don't mind a thicker device, these products will protect your phone and extend its battery life.

Aside from buying battery-boosting accessories, O'Rourke suggests making sure your phone's battery-saver mode, which usually kicks in automatically when you're almost out of juice, is optimised.

Turning off features like app notifications and cellular data can help extend battery life, but keeping those on are some of the main reasons people would use a smartphone in the first place.

Location tracking, in particular, can use a lot of battery power, especially since it can be used in multiple apps at once.

"A lot of the stuff that people use with their smartphones on a day-to-day basis doesn't work in power-saver mode unless you heavily customize it and leave certain things on, which I guess you can do, but then that kind of defeats the purpose," O'Rourke said.

Models with better battery life

Lithium is the most common material used to power modern batteries because it allows them to charge relatively quickly, and to be recharged a high number of times before they're unable to hold a charge.

O'Rourke recommends looking at a phone's milliampere-hour rating, usually marked as mAh. The higher the number, the better the battery.

• The Samsung Galaxy S7 Edge has a mAh rating of 3,600 and in testing lasted more than a day and a half with moderate use. "That's the best I've ever seen with a smartphone," O'Rourke said.
• The iPhone 6S Plus has a larger battery than other iPhone 6 models, at 2,750 mAh.
• The upcoming LG G5, unlike most modern cellphones, has a removable battery, so you can keep an extra battery handy if the first one runs out of juice. The expansion slot is also used for modular accessories, such as an improved camera attachment and an improved audio speaker attachment.
• For those who like smart watches, the Pebble Time and some other Pebble models advertise a seven-day battery life.

To extend your smartphone's long-term health — i.e. how many times you can charge your phone before it stops holding a charge — Strand recommends this trick: keep your phone 50 per cent charged.

"Batteries are happy kind of in the middle. That's where they're healthiest," she said. "But it's not very practical for your phone. You have to charge it all the way up in the morning so you can use it all day.

"But if you were to leave your phone in a drawer for a month, maybe leaving it half-charged instead of all the way charged would be able to give it a longer life."