Over the years I have accunulated about 1000 flights on 4 Lazy Bee's powered by the same Magnum 15 engine and the same radio gear HiTec Focus AM 3CH powered by 4 alkaline batteries. I get about 46 flights that are 12 minutes in length and I have never experienced battery failure or problems. I use alkalines as I can go flying in a moments notice and do not have to worry about charging batteries. I believe this has worked for me because I use a lot of foam to wrap the batteries in and I replace the 4 cell holder each year as the plastic wears out and breaks from the spring tension. For me it has worked well.
Thanks for your time....Brian