I also said these words a year ago when I started. I charged 12 hours and flew 4 or 5 flights at a time. One day I noticed my plane seemed to be hit with "interference" so I landed. Luckily I was right at the runway. I had very slow response and it seemed intermittent. I discovered at rollout that I had no more control, but luckily it froze at idle as I turned on the ground. My battery was dead. It went from seeming fine to DOA in about 1 minute. Turns out that is how they die! Scary, huh? I bought a battery testing ESV for less than $20 and check my batteries before every flight. Cheap insurance- spend the $18 bucks. You can buy those little on plane battery meters for about the same which may be more convenient for checking between flights, (though you will likely buy the meter later anyway). If my plane had been racing toward the pits wide open when the battery died that cute story could have been a horror story. I later lost a plane from a battery wire breaking in flight, and it was terrible watching it fly past the pits and over the parking area over people's heads under no control. I must have seemed quite mad to the bystanders, running after it screaming at the top of my lungs, "I don't have it! Lookout!" At least that time I knew I had done everything possible to be safe...
Spend the $18!!! (Or borrow one before every flight!)
Tom