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Cell phone battery life: The charge is yours

As more of us gravitate to smartphones with features such as Web surfing, e-mail and video, we're putting more demands on cell phone batteries. While cell phones are evolving, batteries really aren't, experts say.
Image: Low-energy use screen on device
Qualcomm MEMS Technologies, Inc. and Freestyle Audio have developed a waterproof MP3 player that uses Qualcomm's "mirasol" screen technology that sips, rather than drains, battery power. Qualcomm, Inc.

Phone are getting smarter, but are their batteries?

As more of us gravitate to smartphones with features such as Web surfing, e-mail and video, we’re putting more demands on cell phone batteries. And, while cell phones are evolving, batteries really aren’t, experts say. It’s up to the individual user to take charge, so to speak, and do a better job of managing battery life.

“There are ways of improving cell phone battery life, but there are very few ways of improving the batteries themselves,” said Kevin Burden, ABI Research’s mobile devices research director. “Essentially, battery technology is governed by God — there are just no new elements showing up in the Periodic Table.”

Almost all cell phones now use lithium-ion batteries, offering better performance than the nickel-metal hydride batteries that were in many mobiles until a decade or so ago.

“In 2000, a lithium-ion battery provided ample power for cell phones, but the power demand is now above what is available,” said Isidor Buchmann, founder and CEO of Cadex Electronics, Inc. The company manufactures battery analyzers and chargers.

At BatteryUniversity.com, Buchmann’s educational Web site, he notes that the battery industry “is making incremental capacity gains of 8 to 10 percent per year,” which is not fast enough to keep up with the hardware and software changes bombarding smartphones, such as BlackBerrys, iPhones and Treos.

Battery life 'critical issue'
While cell phone talk times generally range from 3 to 7 hours, once you add in extra duties, such as Internet use and video, all bets are off when it comes to figuring out battery life.

“There’s no doubt that batteries are becoming the critical issue with so-called ‘converged’ devices,” said David Chamberlain, principal wireless analyst for In-Stat Research.

“Assuming there are no chemistry or physics breakthroughs forthcoming, there are a couple of directions we can head,” he said.

“One is by having phones with much smarter operating systems that turn off unnecessary functions,” including radios in the phones that power 3G, for a faster data network, as well as GPS and Wi-Fi radios when they are not in use. Right now, it’s up to the user to make those decisions, generally in the phone’s “settings” menu.

Another way to augment battery life is to divide and conquer, said Chamberlain, who describes himself as an “evangelist for the two-device user.”

“I think the (Apple) iPod touch is a reason to start thinking about a device that has wireless data connectivity (to the Internet), but doesn’t necessarily do voice and text,” he said. “That way, our talk-and-text phone can have terrific battery life, while a second device handles the multimedia/navigation/game applications.”

But Chamberlain realizes his may be a lone, or at least lonely, voice in favor of that argument.

Smartphone sales are stronger than ever, in part driven by the success of Apple’s iPhone, as well as by significant and steady price drops on almost all smartphones in the past year.

In the first six months of 2008, 19 percent of cell phone sales were smartphones, compared to 9 percent for the same period last year, according to a recent report by The NPD Group.

Multimedia phones — those that play music, games and videos— are also increasing in popularity.

Better Bluetooth, screen technology
Cell phone manufacturers “are always examining ways to make devices more efficient from a power standpoint,” said Joseph Farren, assistant vice president of CTIA-The Wireless Association, an industry trade group.

There are some efforts to improve technologies that will reduce battery drain. Bluetooth, a short-range wireless technology used for hands-free headsets, is getting more efficient and less power-hungry, for example.

Qualcomm is working on a screen technology called “mirasol” that could help consume “significantly less power,” and help extend cell phone battery life, according to the company.

Mirasol, which now is being used in very small-screen devices, such a lightweight MP3 player, “takes the ambient light around you to power the backlighting of the screen,” said Burden of ABI Research.

“Obviously, Qualcomm’s goal is to get mirasol into mobile phones, but we’re talking at least two years down the road before phones using it hit the market.”

Phone manufacturers “have been somewhat hesitant to tamper with screen technology, because the screen is what attracts consumers,” he said. “When people walk into a store to buy a new phone, historically it’s always been the screen that’s drawn them to the phone that they want to buy.”

More features, less battery life
Burden cites Research In Motion’s BlackBerrys as having a good track record with battery life. Many of its models are rated to have a talk time of between 4 and 8 hours.

But, because new features are being added to some models in order for RIM to stay competitive, battery life is going to suffer, he said.

“If you look at the new BlackBerry Bold, there’s a lot of radios in that, there’s an extremely bright screen — and it probably has the poorest battery life of any BlackBerry that’s ever been built,” he said. “Unlike other BlackBerrys in the past, this one, you better charge up every day.”

The Bold, with Wi-Fi, GPS, video recording, e-mail and Web surfing, is rated for up to five hours’ talk time, and up to 13 hours on standby.

One of the selling points of the Samsung Instinct, an iPhone “killer” sold by Sprint, is that it comes with two batteries, considered very unusual in the industry. Each battery is rated for more than 5 hours’ talk time.

“This device is built for both voice and data needs, so we expect a good battery life experience,” said Michelle Mermelstein of Sprint. “The second battery ensures that you always have the power you need to stay connected.”

Apple’s iPhone 3G battery will provide up to 5 hours of talk time and/or Internet use using 3G, and up to 10 hours talk time using the slower 2G network, the company says.

The iPhone’s battery is built-in and cannot be easily replaced by the user. Apple charges $79, plus shipping, to replace the battery if the phone’s one-year warranty has expired.

The company states “a properly maintained iPhone battery is designed to retain up to 80 percent of its original capacity at 400 full charge and discharge cycles.”

A lawsuit against Apple by one iPhone owner in the United States contended that the company’s battery replacement fee amounted to an annual charge that is not disclosed at the time the phone is purchased. The suit recently was dismissed by a federal judge, who said Apple does provide adequate warning about the phone’s limited battery life.

Tips to prolong battery life
To help prolong the life of your cell phone battery, consider these recommendations:

  • A battery’s life is determined by a combination of the number of times it can be charged and by time itself, says Buchmann of Cadex Electronics. “Batteries age from the day they’re manufactured,” he said. “Even if you’re not using the battery, it ages.” Most lithium-ion batteries will last for between 300 and 500 charges. But if you let the battery run down too much before charging, that can hurt its lifespan, he says.

“If you were to deep-discharge a battery each time before you charge it, you’ll get fewer cycles than if it only discharged a little before you charge again. “So, if you’re at home and near the phone’s charger, or cradle, plug it in. With lithium-ion batteries, you cannot overcharge ... There’s still a lot of confusion about that, from the days when nickel-based batteries were used in phones, and had to be fully discharged once in a while” before being charged again.

  • Heat – especially in the car — is not your cell phone battery’s friend. It’s one of the elements that can shorten battery life the most, Buchmann says, so don't leave a cell phone on the dash or put it in the glove box.
  • Turn off the Bluetooth, GPS, Wi-Fi and 3G radios in your phone when you’re not using them, and dim the backlight on the phone’s screen, says Burden of ABI Research.
  • Turn off “push e-mail,” that is delivered to you as it is sent, and instead manually check for new e-mail. “The more frequently e-mail or other data is fetched, the quicker your battery may drain,” Apple says on its iPhone Web site.
  • And here’s one for the frequent fliers who surreptitiously keep their phones on while they’re in the air: “When you get further and further away from a cell tower, the faster battery life goes down,” says Burden. “When you’re 30,000 feet in the air, you can’t get a signal, because all the signals are near the ground. But you’re phone is trying so hard to pull in a signal, that it drains the battery a lot faster.”