No battery, no matter the type, will normally swell. If it swells, discharge and dispose of it and get a new one. I am guessing it is LiPo, in which case you can soak it in salt water for 24 hrs, then just throw it away. Clip the connector off and keep it before you chuck it, so you can reuse it. What was the circumstance under which it swelled? Always great to meet a fellow Tennesse native! I'm from McKenzie, but spent the last 8 years before I moved away in Paris. My dad goes to Dickson often for his job. Cheers and happy flying!