You may benefit by checking out Red's site at www.rcbatteryclinic.com for some good info on battery care. There is probably more missinformation on batteries than on any other topic on the forums. Some common myths such as NiCads having a memory etc. are discussed and information on how to best get long life from your batteries are discussed. In general, batteries will last longer if slow charged as improperly fast charging them will most certainly lower their lifespan and, as you found out, will actually destroy them. Fast charging has its place but is not recommended unless you just can not stand the time it takes to put in a safe charge. Even then, try to limit it to 1C with an occasional slow charge to equalize the cells.