Browser company Opera has come out swinging against Microsoft's recent claims that its Edge browser offers the best battery life for Windows 10 PCs. Opera claims its own tests show that its browser beats Edge in battery use by over 40 minutes.

Microsoft announced its battery test results earlier this week. It stated:

We connected a Surface Book to specialized power monitoring equipment and measured the actual power usage during typical browsing activities in the latest stable versions of Microsoft Edge, Chrome, Firefox, and Opera. We then automated each browser to perform the same series of activities: opening websites, scrolling through articles, and watching videos, opening new tabs for each task. We used the same websites you spend your time on – Facebook, Google, YouTube, Amazon, Wikipedia and more.

In its own blog post, Opera claimed that Microsoft did not reveal the full details of its test methodology, so it was unable to replicate Microsoft's results. Instead, it used its own test and revealed its methods, which included the use of a Lenovo Yoga 500 laptop, running on Windows 10 in a balanced power profile.

The final result, according to Opera, were as follows:

Opera Developer (39.0.2248.0) with native ad blocker and power saver enabled is able to run 22% longer than Microsoft Edge (25.10586.0.0) on a laptop running Windows 10, 64-bit, and 35% longer than the latest version of Google Chrome (51.0.2704.103)

The company ended its blog post with this statement:

The browser is by far the most used application on both laptops and desktop computers, and for users it is undoubtedly beneficial that browsers are improving and competing. However, if Microsoft really wants to prove that its browser performs better than others (in any regard), the company should be transparent about its methodology so that others can replicate it. Better luck next time, Microsoft!