According to an article in The Register, the Win7 “bad battery” message appears when the battery’s performance falls below 40% of the manufacturer’s spec.

However, users are reporting (according to the article) that this message appears even when the laptop is using brand new batteries.

So…whose data reporting is wonky: the users, the battery manufacturers, or Micro “Cover my asterisk with paper” Soft?

Users have also reported that following WIn7 installs, battery life significantly decreased. Microsoft is flatly denying it, saying that they’re unable to reproduce those results.