Well, the procedure lasted almost 3 hours (2:55 to be precise) after which I disconnected it from the power supply and watched television while playing Wordfeud (not intensively). After 2 hours and 40 minutes the battery was drained completely, so it didn't benefit from the Battery Doctor treatment. I have read many complaints of others about underperforming batteries, but I have not yet encountered any testimony of the unability to charge an iPhone via USB. In my case I can only charge my 3GS through a netadapter. When I try to charge with an USB-connector the charge symbol (lightning) appears in the small battery-logo, but the battery-percentage is not increasing. Instead, it is decreasing (very slowly). The same applies for my car-charger: the lightning symbol tells me that charging is in progress, but the battery percentage is decreasing (very slowly) !