I want to address the rechargeable battery debate here. Our church started to use rechargeable AA and 9v batteries after the economy tanked to save money on batteries. Also, it has been said that rechargeables are a lot easier on the environment.
We use the Maha Powerex 2700mAh AAs and the iPower US 500mAh 9 volt.
I use(d) the 9v batteries in PSM 700r(now updated to Sennheiser) product as well as ULXP product. I have not had a battery die on me yet. I replace my batteries roughly after 2 uses (6-8 hours, depending), alkaline or rechargeable. The cheapest I was able to find good alkalines was about $1; the iPower batteries are $18/ea. So, they make up their value after about 20 charges. Charge time is usually under an hour.
The Powerex are in use for Shure UHF-R transmitters and Sennheiser g3 receivers. Freshly charged, they last at least as long as the Procell or Energizer product. No failures as of yet, either. I bought some extra batteries so that I could cycle through the product and have enough spare in case I did not have enough time between charges. I always slow charge the batteries and it takes anywhere from 1.5-4 hours. Not including the charger, they make up for their cost after 11 uses.
I still use alkaline AA in our UR1 bodypacks, but only because the pack does not latch well when using the rechargeables. Since I change the batteries every time for our Pastor, I am able to use old alkalines in other bodypack situations (baptistry, etc.).
We saved about $1000 this year using rechargeable batteries. Hope that helps.
Michael D. Jaspers
Director of Technical Services
First Baptist Church of Springdale