My BlackBerry seems to need charging a lot more often lately. Now that I think about it, the original battery is at least two years old, maybe close to three. But aside from the age of the battery, I really have no way of figuring out whether it’s time to replace it. And because I bought a spare battery well after the original one, even looking at the purchase dates wouldn’t clear up the confusion, since the dates say nothing about which battery was used and for how long.

With this in mind, I find it a bit surprising that virtually every rechargeable device provides a status indicator for how much battery life is left on a particular charge, but there’s no information about when the battery needs to be replaced. For batteries that aren’t rechargeable, like those in alarm clocks and VCRs, the idea of a “Replace battery” message seems well accepted. But for more advanced devices that are recharged over and over, the customer is left guessing. Long-term, this hurts the user experience as the battery ages and battery life drops, all the while providing no information to the user about what’s going on.

Most rechargeable batteries are the Lithium-Ion type and have a microprocessor that tells the host device how much charge they have left. So it shouldn’t be all that difficult for the battery to record how many hours (or charges) that it’s been through. When this reaches a certain level, the device could tell you that it’s time to order a new battery, since the battery life is about to decline. Perhaps some devices already work like this, though I’ve never seen one.

For a reasonable reference point, designers of rechargeable products might look to digital projectors, which typically record each hour that the lamp has been used, and remind you to replace it when it gets beyond a certain point. Granted, projectors represent a less complex scenario, since the bulb stays in place until it burns out. There’s no reason for users to swap it with a spare, like they do when using mobile devices. But the takeaway is the same: if a key component is going to wear out over time, the best approach is to give users a heads-up about it. That way, they can take action at the right time, and they’ll be less likely to blame the product itself when things stop working like they’re used to.