I Blame the Battery Bar

Many standards in modern software have existed for so long that we take them for granted. Take for instance the notion of saving files. In About Face: The Essentials of User Interface Design, Alan Cooper argues that explicitly asking the user to save a file is a complete waste of time. And he's right.

The idea of saving files lives strictly in the digital world. When you write something down in ink you expect it to still be there when you come back tomorrow. Why shouldn't you expect the same from your digital documents? Why force the user to explicitly save files? Nevertheless whenever you close a Word document (or almost any other kind of document for that matter) you are constantly bombarded with dialogs demanding to know if you want to save your file when the computer should already know the answer (you just spent time creating it, I'm pretty sure you want to save it). A decade later, designers are finally starting to catch on and new applications like Google Docs save files and revisions automatically. This saves you not only extra clicks but also protects you against losing work in a computer crash.

Misguided standards are by no means limited to the desktop world. They're making a land in mobile as well. One of my biggest issues with my Nokia N93 is the amount of battery its more exciting features consume. It's great that I can listen to MP3s while playing 3D games but I'm constantly worried about whether I'll have enough battery left to make it through the rest of the day. Sure, I've got the standard battery meter to tell me how much juice is left but I find it leaves a lot to be desired. And that's where I take issue against one of the modern cell phone's most typical features: The battery life bar.

Think about your cellphone. Can you assign some sort of meaningful amount of time to the different levels of batteries your phone displays? At which point do you start worrying about the amount of battery life you have remaining? Do you know how long your phone will last while when using its advanced features? How long will it last in standby mode?

If you are like me and have a new phone, you probably had some trouble picking a definite answer to those questions. The function of the battery meter is to tell you how much battery you have left. Is it doing its job? And more importantly, is it doing it well? Not really. Then is it possible for our cellphones to give us a more accurate picture of the remaining battery life of a phone? Yes.

The immediate problem with the battery bar is its lack of precision. With only five bars to represent all battery life, each bar must represent 20% of theoretical battery life. Imagine you have one bar left. What exactly does that mean? 20% battery remaining? Or 2%? With only five bars to work with, the phone is unable to visibly inform you how much power is really still in there.

The solution to this problem is painfully obvious. Remove the battery bar and replace it with another widget that can represent battery life with greater accuracy. For instance a number representing the remaining percent of battery. With the numbers 100-0 to work with you'll at least know when you have 20% left and when you only have to 2%. Using a larger scale also helps increase the visibility of the change in battery life. Instead of getting alarmed when you drop and entire battery bar you can see your cell phone's battery slowly decreasing as the numbers count down. Why not even go a step further and display an estimated amount time left until the battery runs out? If you knew your cellphone had exactly thirty minutes of talk time left you would in a much better position to place your last few calls then you would ever be with 'two bars'.

That the battery bar has developed into a standard should be something for a wake-up call for mobile developers. Before implementing anything sit back and ask yourself what problem you are solving and whether you've chosen the right solution to it or just created a new problem. Mobile phones are very personal devices. Put the person first in design.

-jb