Just wanted to let you know that we've played a few gigs, and the batteries [9.6V PowerEx] are working fine in both of our guitar wireless units. We had to make sure they were cycled a few times first though, as the first time the charge ran out quickly. Now they hold a charge for about 4 hours, which is comparable to a duracell alkaline (so there'll be some future $ saved there!) FYI, my wireless is a sennheiser ew100, and the bass player's is a shure guitarist model. Thanks again, Dave.