Lenovo claims battery life crown from HP

Computerworld - Lenovo Group Ltd. this week quietly claimed that its latest ultraportable laptop, the ThinkPad X201, has set a new endurance mark.

According to Lenovo, the base X201 laptop can run for up to 11 hours with an optional nine-cell lithium-ion battery. Using the low-wattage Core i7 LM processor would extend the new laptop's life without a battery recharge to 12.2 hours, said Lenovo's senior worldwide product marketing manager, Mika Majapuro.

With the nine-cell battery, the X201 and X201s still weigh just 3.5 and 3.1 lbs., respectively, according to Lenovo.

Lenovo tested the laptops using the MobileMark 2007 benchmark. The company is also offering another set of batteries with a slightly lower runtime, but which will guarantee the promised runtimes for three years. The batteries are available on all T-series and X-series ThinkPads.

Strong endurance and high capacity (the number of times a laptop battery can be recharged and maintain its runtime) represent the holy grail of PC vendors, who normally have to heavily trade one for the other.

For example, lithium-ion batteries are notorious for wearing out quickly, with battery life commonly shrinking by one-third or a half after a year or two. Every lithium-ion battery recharge generates heat, which degrades the charge-holding material -- the Lithium cathodes -- inside the battery. Packing more cathode cells into a battery to increase runtime tends to result in more heat, which cuts the battery's life span further, according to Robin Tichy, a technical marketing manager at battery manufacturer Micro Power Electronic Inc.

The Lenovo ThinkPad X201.

Similarly, increasing voltage to more quickly recharge batteries -- a feature sought by on-the-go businesspeople -- tends to shorten life span, because of the heat and the extra metal needed to collect that current.

"There is no super magic formula where you can suddenly get fast charges without sacrificing something else like capacity," Tichy said.

Improvements in battery technology have lagged over the past 20 years, she said, noting that the capacity of state-of-the-art lithium-ion batteries has increased by only about 3% a year during that period. "We're just looking at incremental improvements," she said.

Lenovo's changes

Majapuro credits the endurance and capacity boost in Lenovo's new laptops to a pair of steps taken by the company's developers.

First, the development team improved the power managers in the T- and X-series ThinkPads to enable devices to adapt their recharging styles to their users. For instance, if users generally keep their laptops plugged in for a long time, the batteries will be charged more gently, which extends battery lifetime.

Second, to ensure its three-year batteries last as guaranteed, Lenovo doesn't let its ThinkPads tap 100% of the battery in the beginning. "We don't give all of the capacity at once to a customer," Majapuro said. That leaves cells fresher for a longer period of time.