As a user of smart phone especially ‘Android’ we always wonder as two why it drains so much battery without any apparent use or over simple browsing. Following research may help:

Stanford computer scientist Narendran Thiagarajan and colleagues used an Android phone hooked up to a multimeter to measure the energy used in downloading and rendering 25 popular websites, New Scientist reported. Simply loading the mobile version of Wikipedia over a 3G connection devoured just more than 1 per cent of the phone’s battery, while browsing to apple.com, which does not have a mobile version, used 1.4%. The measurements were then repeated with locally saved versions of the website, facilitating them to separate out the energy needed to render a page from that need to download it. Javascript and CSS files are used in most modern websites that offer additional functions and styles that are not possible using basic HTML. However, the researchers found that several websites they looked at were loading large files that were not being used in the page. For instance, Wikipedia utilizes a custom file Javascript besides a generic library to collapse and expand the different sections on a page, but a great deal of the library goes unused. By rewriting the site’s Javascript to just perform the required function, Thiagarajan and colleagues were able to decrease the energy consumption from 15 to 9.5 Joules. Making similar changes to the CSS files and images, they successfully reduced the total energy used in loading Wikipedia from 35 to 25 Joules, a saving of 29%. (http://www.dnaindia.com/scitech/report_simple-web-browsing-may-drain-your-smart-phones-battery_1677747)

As for the practical solution: Install ‘Advance Task Killer’ from Google Apps a.ka. Market a.k.a. Play. It will keep killing inactive apps and will save battery.