I have a Samsung Galaxy S5 phone, and I am looking for a decent power bank for this phone. Samsungs are different when it comes to power banks (different than any other phone). Most will quit charging when the phone goes to sleep. There are thousands of posts out there on the Internet about this. From what I read, very few power banks will work with this phone. I was given two different power banks at a trade show and neither of them worked at all. I'd like to buy one, but I'm wondering what ones REALLY work (?) Here's what I know so far.... - The Galaxy's must have at least 5+ volt input (or they won't charge), ideally 5.4 volts - They must have at least 1.5 amps (and I read more like 2.2+ amps is ideal...most power banks are 2.1) - The power pack must be larger than 3600 mAh (otherwise the phone charges the battery, not the other way) So what power bank will truly work with this phone? I'm looking at a 20,000 mAh battery which charges at 2.5A at 5.4 volts, but it ain't cheap (understatement of the month). It's over $100 bucks, but I don't want to buy something I can't use. Anyone have any advice? Samsung Galaxy advice (because these phones are NOT an iPhone!) NOTE...NOT looking for iPhone advice (no matter what version). Completely different charging system.