Any peak detecting computerized charger with a display screen will work. The Imax B6 is a cheap one that will work fine. It's sold under several different brands for about $30. If you plane to use high performance lipos soon, I'd spring for something better like a Hyperion or Electrifly Triton EQ. Just make sure you are getting a charger that can cycle/discharge batteries since that is the only trustworthy test of a battery's reliability and your current use. I once bought a new Spektrum branded 4 cell pack from the hobby shop and found in the cycle test that it only delivered 20% of its rated capacity. It looked fine in the voltage test, and I would have flown with it otherwise. Having a charger that could do a discharge test saved me an airplane.