Extended batteries are the most popular accessory for those who want to increase their HTC EVO 4G's battery life. The batteries come from different companies in different capacities and for different prices, and G&E has probably covered all of the standouts by now.
But what about extra standard batteries as a way to get more use between charges?
For people who don't want to fatten up the EVO's profile with an extended battery and replacement back cover, carrying around a spare 1500mAh standard-capacity battery is an appealing option. There are higher capacity slim batteries that are the same size as the stock one (e.g., 1750mAh Seidio, 1800mAh Mugen), but many them aren't worth their high cost.
Fortunately, a standard 1500mAh spare battery for your EVO doesn't have to cost more than about $5. Why? Because there's really nothing special about it. It's not unique or exclusive to the EVO; it's the same one used by the HTC Hero, Touch Pro2, Droid Eris, Droid Incredible, and many other phones.
Batteries marketed for the Touch Pro2 are usually the least expensive, which is why you can get a 1500mAh spare battery for your HTC EVO for so little.
DealExtreme, for example, has one for sale right now for $5.01 with free global shipping. If you buy 3 or more, you can get each one for even less than that—as low as $4.04 apiece! Bulk rates are subject to a $1.70 shipping charge, which is still a steal.[DealExtreme]