I have some bad news about the Pentax Q. The new batteries worked ... for a while ... But now the camera refuses to turn on again. I have cleaned the electric contacts inside the battery compartment, I have heated up the the camera a little bit by leaving it in front of my laptop exhaust fans (while playing video games so hot air was coming out) and I left a fresh battery in the camera in the hopes that it will charge the CMOS battery enough. But it did not work.
My personal theory right now is that the camera mainboard is trying to draw to much power trying to power itself on and charge the CMOS battery and it puts a strain on the batteries themselves, unable to cope with more then 3.7 Volts that it is rated at even a brand new battery will fail and hence after a bit of effort the camera will not turn itself on even with a fully charged battery.
This makes the Pentax Q unreliable and, unfortunately, a very cute decoration. It's not the end of the world for me BUT all the other Q successors, Q10, Q7, Q-S1, are made with the same design and same limitations. That is they are so compact and fabricated with very tight tolerance, with ribbons that are soldiered and to fragile to be fixed, with very difficult to access and almost self-destruct CMOS battery design that it's to risky to even try and replace them.
I am not sure I will try to get another Q or Q7 because of this, which is sad for me.
Alternatively there is Panasonic GM1 and GM5 and GF series that are almost as small but you will have 2x crop factor instead of 5.5x and 4.7x, and the lenses are not AS small (but small enough).
Buyers beware that the Pentax I camera will not last indefinitely and it's not because of the the external battery but because of the internal battery.