If you don't wanna spend too much the over lander 80 watt ac chargers work for me like this one http://www.modelsport.co.uk/index.php?product_id=379060&gclid=CIncpNufw8ECFWcUwwoduzwAbQ
If you want something with a bit more umph, I use this: http://www.hobbyking.co.uk/hobbyking/store/__17422__TURNIGY_MEGA_400W_V2_Lithium_Polymer_Battery_Charger_Version_2_.html and this: http://www.hobbyking.co.uk/hobbyking/store/__20611__Turnigy_1080W_100_120V_Power_Supply_13_8V_18V_60amp_.html You need both, but you can charge massive batteries with it, or smaller ones quicker.