Back in May 2007, I wrote a feature for Australian Macworld on batteries and power solution. You can read the entire yarn here [22MB PDF].

In that story I recommended that users should regularly cycle your notebook or mobile phone's battery. That means letting it run all the way down and then fully recharging it.

Today, I came past this story over at ZDNet. It seems that Apple has a nifty diagnostic app running on an iPod that can diagnose whether a failed battery's condition has come from neglect or from a defect.

One of the telling things about this particular visit to the Apple Store was something the tech told me. He said that he would replace the battery with a new one because it has be “used correctly.” When I asked him to elaborate on what that meant, he told me that Apple’s notebook batteries last longest when they’re routinely charged and discharged.

Apple's batteries are more sophisticated than a simple collection of single cells. There are "smarts" built into them that retain information like the number of charging cycles and let you check the remaining charge by pressing a small button either on the battery (for older Macbooks and MacBook Pros) or on the unibody for more recent models.

If you're a mere mortal and don't have a fancy iPod gizmo for testing your battery, you can achieve much the same with iStat Pro - a widget created by iSlayer. In addition to all the useful system information it provides it's able to access that interesting battery data.

As it turns out, battery life is very much a "use it or lose it" proposition. In order to get the most out of your battery, both in terms of longevity and capacity make it a habit to run the battery down regularly.