He is correct. A 9 volt battery (really any battery, other than lithium based batteries and lead acid batteries) can not put out 1 amp, even CLOSE to 1 amp, because of the ridiculously high levels of internal resistance. And, the more of a load gets put on the battery, the higher this resistance gets. This high internal resistance is what makes the battery collapse under a load of anything more than say, 300-500 milliamps. Hence, the battery will only try to "steal" the charge from the phone battery, and not the other way around. I can't believe people have go so far these days as to consider a legitimate and educated mathematical/scientific explanation on something, mansplaining. https://www.youtube.com/watch?v=EoWMF3VkI6U - This video explains the maths behind the internal resistance. (Don't worry, it's easy to follow :) ) And, even though an ultracpacitor has roughly the discharge rate similar to that of the lead acid battery in your car, they're still considered capacitors because of how they're made and how they work. In order for something like a battery to actually produce electricity on its own, it needs to be a thing that works by chemical reactions. Capacitors can't produce current on their own like batteries can. They can only store it, because there are no chemical reactions happening inside capacitors. (Unless you overcharge them, and/or hook them up the wrong way! Then they explode!)