HTC EVO 4G review -- Engadget
From review:
"We know what you're thinking, though: what about battery life? Amazingly, we got some three hours and 13 minutes of run time while using the EVO continuously as a 4G hotspot -- and when we say "continuously," we mean we were streaming high-quality audio the entire time. What's more, the phone wasn't even fresh off the charger when we started; it had been on and in heavy use for two hours and four minutes prior. Bottom line, this thing seems to be a champion on a 1500mAh battery; we can't even begin to fathom what a massive aftermarket pack would do to it."
From review:
"We know what you're thinking, though: what about battery life? Amazingly, we got some three hours and 13 minutes of run time while using the EVO continuously as a 4G hotspot -- and when we say "continuously," we mean we were streaming high-quality audio the entire time. What's more, the phone wasn't even fresh off the charger when we started; it had been on and in heavy use for two hours and four minutes prior. Bottom line, this thing seems to be a champion on a 1500mAh battery; we can't even begin to fathom what a massive aftermarket pack would do to it."