The IMP52D took 105 minutes to fully charge of my iphone 4 from 34%. It costs half of the charger power(2 LED lights out of 4 were off). I would suggest that the battery pack should contain its own wall charger. The charger can charge iphone 4 two times only. As far as I know, iPhone 4 battery capacity is 1420mah so the itorch could charge the cell 3 times. So I would suggest to improve the battery power on this version. But overall, I like it and I will rate (4), if it could charge more times, I would rate it (5) stars.