promatch.com and yes they are very good. if you can get them at your track or willing to order online there are very good. i miss their electric motors by the way. 7 cells will give you more punch but not more power or run time. if your looking there you need to go lipo and the orion advantage charger that does nimh and lipo. its an awesome charger especially for nimh cells. the step charge feature for 3300,3600,3700,4200,4300's is AMAZING. once you get the settings right along with my novak smart tray, man my batts rule. but you need to start with a top quality cell, from the previous mentioned batt. companies. ten minutes is very typical of a racing pack charged for racing on a brushed or brushless motor. maybe you get a bit more on a brushless but not much.