I have understood that the batteries can stand it if you charge em even if they arent totally empty. (please correct me if im wrong)

If you buy a few extra batteries, you may need 2 per day, 3rd one for extreme days. Well, when you get home, just charge the first battery and before you go to sleep put the another one to charge for night.

I havent got the device yet, but I habe been thinking it will be something like that for me.