With moderate use after 12 hours, I'll be between 65-55% left. I can easily go all day without even thinking about charging it. I'm on CM7.2.1 with chads incredikernel and voltage tweaks. This thing is tweaked to get the max battery life so thats a factor as well but even if you don't tweak the bejesus out of it I still recommend the 1800 battery from htcexpress. The phone shouldve come shipped with this type instead of the crappy stock battery it comes with. Like broken said I cant compare either, Ive never used the seidio 1750.