All handheld devices like the PDA (Personal Digital Assistant) run on battery power. Whether it's by dry cell, alkaline or other more advanced types of battery, if it's handheld, then it's got to be battery-powered. This means that unless you have the PDA hooked up permanently to an AC power connection, sooner or later, it is going to run out of power. How long it will function before the battery runs out is, therefore, one of the most important things the user needs to know.
Many PDAs running the Palm OS use ordinary AA-sized batteries. Even then, they offer excellent battery life, often running for weeks before needing a replacement. This is because Palm PDAs (with the exception of the Palm IIIc) don't use colour screens and they have less substantial hardware (slower processor, less RAM, etc...). However, some Palm PDAs like the Palm IIIc come with a built-in rechargeable battery. In the Palm IIIc's case, it's because the use of a colour screen brings about a substantial increase in power requirement and using normal AA-sized batteries would have meant an extremely short battery life.
That's why when Microsoft launched the Pocket PCs, all of them came with built-in rechargeable batteries. Even then, their battery life is comparatively short in contrast to Palm PDAs. For example, the Casio E-115 only has a battery life of 6 hours and that's with the backlight set to minimum and without the use of any CompactFlash devices. Of course, real life usage would normally reflect 4-5 hours, rather than the rated 6 hours.
Other Pocket PCs have longer battery life but not significantly so. Pocket PCs from the HP Jornada 54x series have a battery life of 8 hours and that's primarily because of their CSTN screen which consumes less power. The newer Casio E-125 Pocket PC also has a battery life of 8 hours, which isn't that much of an improvement over the E-115. Only the new Compaq iPAQ has a significantly longer battery life - 12 hours. However, that's the official word. My brother's iPAQ H3670 lasts only 3-4 hours with sidelights set to minimum!
So, what it boils down to is the fact that Pocket PCs generally don't last long. Now, as a handheld device can only be as good as its battery life, that's a real disadvantage when compared to Palm PDAs. For many users, 6 hours is normally quite acceptable (though inconvenient). But there will be quite a few occasions when a much longer battery life is critical. Examples include when you are on a long flight or when you are off camping. And let's not forget using power-hungry CompactFlash devices on the road. It would be impossible to charge your Pocket PC's batteries and if they only last 6 hours, it wouldn't be long before you are out of business. :)
In light of this, what can we do to assuage this inconvenience?