Where is this battery draining code from?

I think battery falling like that can only be either a horribly wrong value for the battery calibration (and relatively low charge being shown as full) or GPS being active. There is just no hardware taking that much power besides full power backlight, but I suspect you would have seen that at some point. Do you have agpsdata configured for autoupdating? Maybe there is some bug not turning GPS off after the update.