If you want a small one just to charge a phone you can get one that will also jump start a car for extra utility. Hard part is remembering to recharge it regularly.probably not helpful, but....
my parents have an auto-on gas powered generator for the house and they love it.
I have looked at those power banks to have at hte house to run maybe a TV, charge phones, etc. I need to get one, this is a good reminder.
I do have a number of small "power banks" like the size of an iphone that i've taken on trips and to concerts/festivals and they have been really helpful at getting through a 12 hour day when you need your phone.
Solar GeneratorI am talking one that will not only charge some phones but, one that will run a refrigerator for a period of time, tv's, some lights, maybe a fan. Looking at solar as an option. Silent and doesn't require a utility hook up. Somewhat portable, doesn't use gasoline.