We have used NimH batteries for years in our systems, and we have at least 24 v75 mics. We purchase them from Thomas Distributing, both the batteries and the chargers that charge 8 at a time. The brand that we have had the best luck with has been the PowerEx 2700's, but we have used other brands as well, including Duracell. The display's on the mics usually report more time than you actually get out of them, it seems I read this was normal compared to regular barreries. I will add that all of our mics are set to the powersave setting, which works fine, because our microphones are usually within 50 feet of the receiver.....