I ordered my vamo before Xmas, it came and was great for about 10 min. then died, So got with vendor...solved by sending me a new one (and some free stuff for the trouble) everything was allgood. Two weeks later the new one wont increase past battery rating. 1 batt will not go above 4.2v when its fresh (all checked with miltimeter). If I use 2 batts it works fine. It is probably the voltage booster, the regulation seems to work fine. Opened a ticket 4 days ago, and have gotten no response. I will refrain from saying who they are to give them a chance to make it right, then I will hit the NEG review forum, I will give them until the end of the day. I guess I just needed to vent, this is very frustrating. Hope everyone else is having a better experience with their Vamo.