I number my batteries and make sure to run them dry, or to stop, etc. I never fast charge them or abuse them. If you're short on batteries, the Turnigy-Nanotech lipos can be purchased from www.hobbyking.com
for about $9.00 US. The IMAX does a great lipo balance charge for lipos. Make sure to order from the "US Warehouse" option, so you get them quicker. It sounds like you don't have enough batteries.