Quote Originally Posted by baja_yu View Post
Why would they hold back on features and functionality to get you 3 or 4 days when they know you'll take one.
Because it isn't their decision to make.

The manufacturers are very limitted in what battery life they can offer. They are using the best battery technology in existence today, and are making a trade-off between size and battery life. The charge on any device is dependent on how they make that decision. After all, any of these devices could be made to run for weeks at a time, though you'd be hard pressed to carry the battery around.

A manufacturer doesn't make a 5mm thick smartphone with all the features and a week long battery life, not because they don't want to, but because they can't. No current battery could last that long at the power usage of those phones and in the size allowed. On the other hand, no manufacturer is building the batteries, exactly. They might say, "the battery must be this size.", but they can't say, "the battery must be this size and must last for two weeks" unless they have a LOT of space to work with. Once they know the size of the space, they know the limitations on the battery. Once they also know the power consumption metrics for the hardware, they know the length of time the device will remain powered within the limitations of the battery. Those are pretty tight bounds, too. Lithium batteries are as good as it currently gets when it comes to energy density, and that's what's used in the phones. What you currently get is the best you can get in that form factor. To extend the life, you have to drop features or increase the size of the phone. Neither is appealing, so we are stuck with what we have.

If a new battery technology came out with 2x the energy density, then we could have longer life in the phone with the same form factor and feature set. At that time, the only reason that a manufacturer would stick with the weaker battery would be if the new batteries were prohibitively expensive.

Our devices are largely constrained by our ability to power them.