[Wireless Japan] DoCoMo Develops 'Intelligent' Li-ion Battery Pack

Jul 23, 2008
Kouji Kariatsumari, Nikkei Electronics
The evaluation board for the exhibited battery pack
The evaluation board for the exhibited battery pack
[Click to enlarge image]
The deterioration of the battery indicated on the cell phone display
The deterioration of the battery indicated on the cell phone display
[Click to enlarge image]

NTT DoCoMo Inc unveiled a battery pack that can detect the deterioration and troubles of a Li-ion secondary battery used in a cell phone July 22, 2008.

The company exhibited the "intelligent battery pack" at Wireless Japan 2008, which is an exhibition of wireless technologies and runs from July 22 to 24 at Tokyo Big Sight.

NTT DoCoMo developed the battery pack in response to the explosions and fire accidents of Li-ion secondary battery packs for cell phones that occurred in 2006 and 2007.

"As a measure to enhance the reliability of battery packs, we will start to employ the new battery pack in our new models within a year," said Kazuhiko Takeno, director in charge of technology promotion, the Mobile Device Development Department of NTT DoCoMo.

The company developed the intelligent battery pack with Mitsumi Electric Co Ltd by adding functions that detect the troubles and deterioration of the battery, measure a remaining battery level and manage other information to the existing protection circuit module.

Though the company did not reveal the details, the battery pack is equipped with an 8-bit microcomputer and can detect the troubles and deterioration of the battery based on the information of the battery's voltage, current, temperature, etc.

The status of the battery is recorded in the battery pack; therefore, even if it is used in other cell phones, the status, such as the deterioration of the battery, can be assessed. Furthermore, it can notify the users of the time and date to recharge the battery and suggest replacing the battery or going to a shop to solve a battery problem.

To enhance the reliability of battery packs, NTT DoCoMo is planning to adopt a new evaluation test method for battery packs as well as to make them "intelligent."

After the reliability is ensured by those measures, "We will start working on increasing the battery capacity, which is now suspended," Takeno said.