What happens to your Macbook Air battery in a year

I love my 2010 Macbook, but lately she’s become less of a workhorse¬†and more of a gentle farm pony you feed carrots to at the barn.¬†She tires easily and she doesn’t like to be far away from an outlet. While years of proper care and letting the battery cycle have kept the laptop in good shape, it’s never that surprising when laptop batteries degrade over time.
University of Washington PhD candidate and avid dataviz blogger James Davenport conducted a year-long observation of his new Macbook Air, which focused on monitoring battery efficiency and capacity as it shifted over the first 365 days of use. Of course, the MacBook Air has always been heavily praised in the battery life department, and the 2012 Macbook Air at times exceeded its promise of up to 7 hours of battery life. While those initial tests seemed promising, Davenport’s careful monitoring of his Air showed that over time, the results changed.
Within a year of use, Davenport’s Air dropped down more than 15 percent in capacity, leaving its overall charge power under 85 percent of its initial capacity. After staying at maximum capacity for the first month, the rate decreased steadily over time, with an average cycle dipping a few percentage points roughly every four weeks.


Even more stark was the reduction in capacity compared to Davenport’s previous computer, a 2009 Macbook Pro. While the Air boasts better overall battery performance, Davenport’s records show that his old Pro had a better consistency in its battery retention, hovering above 90 percent capacity until the end of its life some three years later. The only immediate discernible difference between the two is wattage — the elder computer uses 60 watts while the younger has 30 watts — but it could also be how the battery operates within the system as a whole that contributes to the decay. But frankly, if the new Macbook Air follows the same trend as Davenport’s, that glorious “all-day” battery may begin to show some big wear in a short time.
It seems, though, that Davenport’s efficient MacBook Pro is the outlier — not necessarily the dwindling Air. The average life expectancy of a lithium-ion battery is roughly two to three years, even with regular battery cycle maintenance. Apple doesn’t prefer to measure battery life in years — rather, it prefers cycles. All Apple laptops built after 2010 have an estimated life of 1000 charge cycles, and the company has an extensive page that stresses routine care and maintenance.
In my personal experience, my farm pony still does really great out of the barn. After 1098 charge cycles, I still get between three and a half and four hours of unconnected time and I’m running it nearly all day. But Davenport’s research into his own battery behaviors makes me wonder whether there was more that I could do to extend the battery of my laptop, or if it’s all the product of age.
Still, it wouldn’t hurt to try to extend my battery life, so maybe I’ll be able to spend more time away from the nearest outlet. And if you can find me a laptop battery that stands the test of time, then sign me up!