Fact: the more stuff you have running on your laptop, the shorter your battery life will be. Constant use of the CPU, GPU and RAM draws more power and drains the battery that much more quickly. And when we're using our laptops, many of us carry over our desktop web browsing habits, which means we have a dozen (or two) tabs open at any given time. And that's not so good for battery life either.
The correlation between too many tabs and shorter battery life might seem obvious, but it's hard to know exactly how much of a difference each tab makes. So Wired hooked up a MacBook Pro to another laptop and used Watts Up Pro to measure power usage while increasing how many tabs were open on the testing laptop.
Chrome and Safari performed nearly identically, with Chrome drawing maybe a tenth of a watt more power initially but eventually evening out. Firefox actually started out drawing a solid half watt more power than the other two browsers, but drew less over time; at the 30 watt mark it began to dip below Chrome and Safari's power usage.
With a little math, Wired worked out how much power each additional tab used in relation to the MacBook Pro's battery. Having 100 tabs open at once will shave an hour off your total battery life. Not so bad, right? 10 or 20 tabs may be common, but 100 is a little extreme, especially for a laptop screen.
Head over to Wired for more browser vs. battery charts and graphs.