I have two sets of Energizer NMH and two chargers, 8hr Energizer and 8 hr Rayovac. One set of batteries seems to have a better charge (car runs noticibly faster). I have yet to test it with a volt meter but I will do that tonight. I have charged each set on different chargers and the same result exists. Seems to be battery related. The only difference between the two battery sets is the silver wrapping. The set that runs better has the dull silver finish and the other set has the shiney silver finish. Anyone else with the same observations?