I’m not a mobile Mac user, although I do have an iPad and iPhone, so I was surprised to learn that Apple removed the battery life countdown timer in Lion and Mountain Lion. It now runs like iOS with just the battery percentage. For iPads, iPhones and iPods, this isn’t a big deal, but with a laptop it may be an issue.
Thankfully, there is an app out there that will bring it back. Battery Time is currently in beta status but appears to work just fine. It’s a no frills, super basic app that does just what it says it does: “Show the remaining time your MacBook (or any Apple portable) can run on its battery.”
As with any software that tweaks the operating system, use at your own risk.