ThunderBolt battery could pose problems for users

Computerworld field tests show battery in HTC ThunderBolt on Verizon LTE network averages less than 5 hours per charge

Independent speed tests for the HTC ThunderBolt smartphone on the Verizon Wireless LTE 4G network show it runs many times faster than on older 3G networks for Web browsing, emailing, streaming video and music and playing online games.

At the same time, though, its battery life comes up shorter -- sometimes much shorter -- than advertised, according to initial Computerworld field tests.

In four field tests over several days, battery life on a review unit of the ThunderBolt averaged only 4 hours and 22 minutes between charges, two hours below the advertised 6.3 hours for the device's 1400 mAh battery.

The faster battery drain came from relatively heavy video and music downloading, though the tests also included typical voice calls, texting, e-mailing and Web browsing tasks.

The testing was done as the phone occasionally moved between 4G LTE and 3G cell zones in the Boston suburbs.

Four hours and 22 minutes of battery life is not out of line with the findings of various online reviewers who also pushed the ThunderBolt by receiving heavy downloads of music and video, as well as using it for videoconferencing on LTE.

Some bloggers have offered workarounds -- by shutting off the LTE connection or buying a longer-life battery.

However, our experience with the ThunderBolt found that even in 3G zones, the battery life can be quickly sapped by multimedia data. (The ThunderBolt's voice traffic runs over CDMA for now, separate from LTE data traffic.)

In a separate test of battery life, Computerworld also tried out ThunderBolt's Mobile Hotspot capability. Using the ThunderBolt as a Wi-Fi hotspot, we started with five devices connected over Wi-Fi to the ThunderBolt. The smartphone was also connected to the LTE cellular network in Framingham, Mass.

In the mobile hotspot test, the ThunderBolt's 1400 mAh battery was drained to less than 15% in just two hours. That quick battery drain may be why Verizon suggests connecting the smartphone to a wall charger when using it as a mobile hotspot. (A warning on the phone says: "Mobile Hotspot may use more battery. You may want to connect the phone to a power supply."

HTC and Verizon don't appear to have any official statement of ThunderBolt's battery life when used as hotspot without a power connection.

LTE, battery background

Several early testers of the ThunderBolt found LTE speeds are the device's most striking feature. Network World reviewers reported an average of 12 Mbit/sec downlink speeds on five tests over LTE in Framingham, Mass., while a Computerworld reviewer got 16 Mbit/sec download speeds and 19 Mbit/sec upload speeds in the New York City area.

That Computerworld reviewer found the LTE speeds were 20 times faster than Verizon's 3G speeds, which are far more widely available than LTE. LTE networks are now available in some 40 cities.

In a Wall Street Journal review of ThunderBolt, Walt Mossberg found LTE speeds averaged more than 12 Mbit/sec for downloads and more than 4 Mbit/sec for uploads in Washington and Orlando, Fla. That's about eight times faster than the ThunderBolt performed over 3G, he said.

But with such speeds come multiple costs, including the reduced battery life. Some Android observers suggest that the ThunderBolt came to market later than expected to allow its battery to go through rigorous testing.

When the ThunderBolt was launched on March 17, Verizon said the unveiling came once testing was done, and didn't comment further.

At the time of launch, Verizon said ThunderBolt batter life was up to 6.3 hours, presumably for non heavy voice, Web browsing, texting and game-running uses.

Prior to the release of the smartphone, some analysts already speculated that heavy multimedia use on LTE networks would burn up the phone's battery life in far less time than 6.3 hours.

LTE is fast enough in lab tests to support graphics and high definition movies, and even interactive gaming and real-time videoconferencing. Mobile 3G networks, on the other hand, can't always support video streaming and videoconferencing capably.

Even after various field tests by Computerworld and others, it remains unclear exactly what impact LTE speeds and download capabilities have on ThunderBolt's battery.

Battery life is also hurt by ThunderBolt's large 4.3-in. screen that generally produces brilliant, clear color and smooth video. Video content streamed in high definition would also adversly affect battery life. And, the phone relies on a power-hungry 1GHz Snapdragon processor to support video and real-time gaming.

Mobile Hotspot test

In the mobile hotspot test, we tried to maximize data downloadeds to the ThunderBolt, by running videos streaming from Netflix and YouTube and music from Pandora onto five devices connected to a device via Wi-Fi. The ThunderBolt served as the Mobile Hotspot to all five devices.

Three of the Wi-Fi connected devices were laptop computers (two Macbooks and an HP Envy) and two were Apple handhelds--an iPhone 4 and an iPod Touch.

In the two hours of draining the battery as a Wi-Fi hotspot, two of the devices -- the iPhone and the HP laptop -- kept a fairly consistent connection to Netflix movies "The Sting" and "Prince of Persia." Still, those movies were each interrupted with one or more brief pauses. "The Sting's" connection reported three searate slowdowns.

The Pandora music connection via the iPod Touch was consistent for two hours over Wi-Fi to the LTE-connected ThunderBolt.

But in the case of the two MacBooks, one user stopped using the Wi-Fi connection after 45 minutes due to repeated slowdowns of a YouTube streaming video and loading of other Web pages.

The other MacBook user loaded the movie "Food Inc." from NetFlix but got a slow connection report after only nine minutes (while all the other four devices were still connected via Wi-Fi). NetFlix then re-calibrated to improve the connection, which took five more minutes. After that, the movie ran five more minutes before Netflix again said the network connection was too slow. Recalibration took another 10 minutes.

On a third try, "Food Inc." ran three more minutes before timing out again, and then the Safari browser supporting Netflix on the Wi-Fi connection froze and the user dropped off the Wi-Fi connection entirely.

After two hours, only three of five users retained a Wi-Fi connection to the ThunderBolt for bandwidth-rich content. Only the music connection was consistently smooth. (Music, as expected, takes up much less bandwidth than video.)

The Mobile Hotspot monitoring tool in the ThunderBolt was clear and helpful for noting which devices were connected.

However, Verizon had said it was offering the hotspot ability for free in the first month for use with up to eight devices. Yet, the ThunderBolt review unit deployed in this test would only accept up to five devices. (A Verizon spokeswoman said it should have accepted eight, but we couldn't figure out how to override the advisory on the phone, "Max. connections 5 users," despite repeated tries.)

Verizon is offering the hotspot service for free until May 15, but still hasn't said what the price will be after that. If the Mobile Hotspot service proves to be inconsistent for five devices for free, as Computerworld discovered, you will get what you pay for.

The Mobile Hotspot test aimed to exhaust the ThunderBolt battery as quickly as possible, which is why video and music content was chosen. Thus, it may not be the most likely real-world test.

A more likely typical use case would be for several workers on a road trip to use the hotspot to call up less bandwidth-intensive email or Web-based sales presentations. However, the ThunderBolt (and many smartphones) is marketed as offering access to video content. With the abundance of ordinary Web sites deploying streaming video or training materials, traveling workers may need plenty of bandwidth for work-related uses.

Furthermore, one could wonder how easy it will be to find a receptacle to plug in a ThunderBolt for added power.

Even so, the result from this informal field test shows the power of Wi-Fi and LTE when delivered to a smartphone. Two users were able to watch movies for almost two hours, even though they may have sapped the Wi-Fi bandwidth from the others.

Single ThunderBolt test

In a field battery test of one ThunderBolt review unit, we tested the effect of heavy movie use on the battery. Computerworld reviewer Dan Rosenbaum got more than a full day out of the battery with light to moderate use, even while on the LTEservice.

Rosenbaum did note that Android phones (ThunderBolt runs Android 2.2) tend to run through batteries more quickly than others and he warned users to make sure the ThunderBolt is fully charged over a few hours to get a full day of use.

One of the worst reports came from PC Magazine, which reported only 2.5 hours of LTE streaming before the battery was drained.

Various bloggers have suggested steps that can be taken to cut off LTE to extend battery life, reverting the ThunderBolt to 3G-only, while hoping that HTC can one day extend its battery life.

A Fox reviewer found he couldn't get more than 4.5 hours on LTE with ThunderBolt, and complained there was no easy way to switch 4G on and off.

Other 4G smartphones like the HTC Evo 4G and Google Nexus S 4G have a widget to disable 4G, extending battery life, he noted. Verizon's official position is that the LTE cannot be turned off and Verizon did not comment on the Web reports of a workaround.

An $44.95 extended life battery from Seidio Innocell with 1600 mAh will add 200 mAh, a 14% increase in available power. It is the same physical size as the stock battery.

Verizon also sells an extended life 2750 mAh ThunderBolt battery for $49.99 that has nearly double the stock battery's power. It adds an ounce of weight and comes with a new back that makes the phone somewhat thicker.

The Computerworld field tests of the single ThunderBolt review unit occurred over four days, and were admittedly designed to consume a heavy amount of data without being unrealistic. (For example, an unrealistically heavy use would be playing Pandora music blaring in the background, while also watching a YouTube video with the sound turned up.)

The lowest amount of battery life over the four days of tests was shown to be only 3 hours, 41 minutes after a full charge. About 90 minutes of that total was devoted to watching several YouTube videos, the first 30 minutes over LTE 4G with the ThunderBolt and 60 minutes over 3G. The remaining 2 hours, 10 minutes was spent browsing news Web sites with Pandora playing in the background over 3G.

About 20 minutes was spent with Pandora music playing while driving and the rest while stationary.

The 3G connections were made in a suburban house with three out of four bars of radio reception. If the radio has to work harder to keep a constant connection, that could have a small impact on battery life.

When asked about the battery life of the ThunderBolt, an HTC spokeswoman recommended the upgraded battery on sale at Verizon stores, but did not comment on whether any upgrades to the actual phone are underway that could improve battery life.

"Battery life is always a concern when it comes to new technologies and innovations," the HTC spokeswoman said. "The HTC ThunderBolt is no exception and while we strive to enable the most [battery] life, the actual amount of time is directly related to usage scenarios."


The Computerworld battery field tests of the ThunderBolt are just initial tests on a single device.

Still, they are not out of line with the results of tests by various bloggers and others that found the device offers about four hours of battery life over LTE, even for typical uses, well below the advertised 6.3 hours.

The Computerworld field test found that the battery drained quicker than advertised even in 3G.

Computerworld's Mobile Hotspot field test of the ThunderBolt might be deemed irrelevant by some, since Verizon recommends connecting the phone to a power outlet when it used as a mobile hotspot. Still, it is worth noting what the battery life would be if several Wi-Fi users suddenly found themselves working on a media-rich presentation in a crowded airport without a power outlet nearby for the ThunderBolt.

The striking speed of the LTE network seems to be undermined by ThunderBolt's battery life.

The battery issue will not be as pronounced with various LTE laptop modems that Verizon is announcing this week because laptops have larger batteries and are often used near a power outlet.

But smartphones are intended to be more mobile and usually recharged overnight.

Matt Hamblen covers mobile and wireless, smartphones and other handhelds, and wireless networking for Computerworld. Follow Matt on Twitter at @matthamblen, or subscribe to Matt's RSS feed . His e-mail address is

Copyright © 2011 IDG Communications, Inc.

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