If you're just looping through a browser, loading a new page when the last page completes rendering, you could be punishing faster phones in your testing methodology.
Say phone A is twice as fast as phone B.
If you're just looping as stated above, phone A is putting in twice the work of phone B per hour, which of course will use more resources.
Web page loading is a variable resource task - the faster the phone, the higher the rate of resource utilization - unlike playing a video, which uses the same resources for both phone A and phone B (provided both phones are capable of playing the video).
If phone A taks 20 seconds max to load a page and phone B takes 40 seconds, the only fair way to compare battery life would be to request a new page every 40 seconds - but in real world usage even that is fallacious.
In the real world, a user might browse a dozen pages, consume content, and put his/her phone back to sleep.
Some pages would begin to load and the user might hit a link without waiting for the page to completely load; for other pages, the user might find something of interest and the phone would load the page and simply idle as the user consumed the content at human speed.
So, what's the trigger you use to load the next page? A realtime wait, or a continuous loop?