It seems that when I charge my phone slower via USB it will hold a charge for a longer period of time when compared to charging more quickly via the wall outlet. To quantify a longer period of time: a typical wall outlet charge will deplete to 20% by the end of a normal week day (about 15 hours). A USB charge will last me over 24 hours on the same week day and then some (about 28 hours). Has anyone experienced this? I have a friend with a Droid who has tested my theory and agrees. We thought perhaps the slower charge is more efficient and less of a strain on the battery.