I know you probably don't want to spend any more money, but a computerized charger will let you know for sure if your batteries are good. I see them frequently used on here for $30-$40, so it's not a huge investment. The ability to peak charge and do cycle testing tells you conclusively how good your batteries are instead of just guessing and hoping. There are considerably fewer unexplained losses of control talked about on the forums now than there were 8-10 years ago. Many would say that 2.4ghz radios are to thank for that, and I'm sure they are a factor. But about the same time those gained popularity, computerized chargers became a lot more commonplace. I actually think that has been a bigger factor, and RC pilots are finally making sure that their batteries are both charged fully and performing up to standard before taking off. Along with that, a $5 harbor Freight electrical multimeter will let you check voltages at your receiver and find problems before they cost you a plane.