Short answer: It depends.
Long answer: It is a big battery. I think 2-3+ times the capacity of most cell phones? It is as large as could fit the case and the case is as large as practical for the device. The actual run time will then be dependent on usage. The only viable benchmark I can think of for estimating that is the Pandora. The Pyra is -capable- of using more power per minute, but can also do MUCH more per minute than the Pandora. So, doing the same tasks as the Pandora, it should use -less- power overall for accomplishing the same task. Still, if you're doing tasks outside of the Pandora's capabilities on a Pyra, then you should expect less run time per quantity of power. But, the Pyra's battery is about 150% of the capacity of the Pandora's so it might actually run longer still even with the greater load. At release the Pyra won't have much optimization, but that is expected to improve as the community starts kicking in input. Nobody actually has a Pyra in the wild yet, so there isn't any real world experience to reference. Phone module use will impact battery life depending on how the module gets used - always monitoring for a call will require some OS interaction so it won't be in deep standby at that point, but maybe the two smaller cores could be used for that, but nobody has built that yet but maybe someone will someday...
I understand that it can be under clocked, BUT under clocking may actually decrease battery life as the rest of the system could then be using power longer while pending on the SoC to catch up vs leaving it on full cycle and letting it accomplish it's task earlier. However, if using an application that utilizes all available processing power continuously, that could be void for your usage case. But, cycling it down manually shouldn't be necessary as the SoC should go into lower power modes between it's execution cycles if it isn't maxed out, but that may be dependent on software that may or may not exist yet.
So, I'm going to say about 1 hour full tilt with something pulling power from the USB ports, 4 hours of heavy use, 6-10 hours of surfing the web or playing a video, maybe 15-20 hours of audio playback with the screen off, 16 hours of standby with the 4G module monitoring for calls, maybe 1-2+ weeks of standby without the 4G running. Of course none of that has any basis beyond the rule of thumb and everyone's thumb is different unless you don't have thumbs but then using a Pyra without thumbs could be difficult and I'm sorry but there simply isn't a good way to make it more usable without thumbs.
And yes, there was meant to be humor in that reply.
