We regularly test the four most popular browsers for speed, but what about battery life? If you're on a laptop, an extra 20 minutes can make a pretty big difference. Weblog 7Tutorials did a battery life test of each browser, and found that Internet Explorer was the most likely to give you a noticeable battery boost.
They used the Peacekeeper battery test on Internet Explorer, Chrome, Firefox, and Opera, on a clean install of Windows 7 using the Power Saver power plan, and ran it three times to get an average for each browser. Internet Explorer 9 came out ahead, providing 104 minutes of battery life in the Peacekeeper test, with Opera not far behind at 100 minutes. Firefox lagged behind a bit at 92 minutes, while Chrome got almost 20 minutes less, lasting only 85 minutes.
Obviously, your mileage will vary on this, but it's a good thing to know if you're in a bind and need to squeeze every ounce of battery from your laptop. Hit the link to read more about their methodology and the results.