After Microsoft stated a week ago that it would look into reports of Windows 7 causing premature battery degradation , we’ve been staying up late at night with our frazzled lithium ion cells, reading them stories about Battery Heaven and generally trying to keep an upbeat tone around the Engadget HQ. Well, it turns out not everything is rosy in batteryville, but Microsoft says Windows 7 isn’t the one to blame. According to the company’s testing, the new tool, which reports when a battery is down to 40% of its designed capacity and suggests replacement, hasn’t reported a single false positive