Ok here is what I found out when I used the "cube"
Since I have the factory battery still this "cube" can "just" refill it back to full strenght no more Once you charge "almost " a totally dead battery "the cube" can recharge you back but thats it then it needs a recharge itself.
It takes about the same amount of time to charge from the "cube" as it does from wall charger.
It takes over an hour to recharge the "cube" totally full again.(I forgot exactly how long just know its over an hour ) ha
When "cube" is fully charged it says to unhook from computer so I haven't left connected after it got its full charge on.
If you do bump charge with the "cube" , the cube shuts itself off when the battery is full.
My phone was off when I recharged with the "cube"
The little lights on the "cube" let you know how much of a charge it still has left.
Bacically it like having an extra factory size battery with you , I can see it helping when not able to charge phone due to not being able to plug phone in or being in a car that doesn't have a cigarettte lighter in the car. But an extra battery would work too just another way of doing it I guess , LoL