How does the n900 camera compare with the k850i and more modern camera phones? You would recommend I purchase 2 batteries then? Keep them both fully charged and when one runs out, switch over? The battery life on my phone lasts about 5 days if it's left always on, I'm guessing the n900 will no where near touch that, even if I don't do much on it at the time. That's a shame. Is it possible to buy a third party battery which is more efficient?