Immediately after each flight you need to check your battery voltage UNDERLOAD!!

"Voltwatch" has no load, which is great if you are going to fly your plane under NOLOAD. If you have a bad cell Voltwatch won't help you.

Try something like this ,, http://www.horizonhobby.com/Products...?ProdID=HAN171

It is $40, but when compared to the cost of your airplane,,,, it really sucks to lose an airplane because of batteries run too low.

Also very important to charge and maintain your battery PROPERLY.