Have both a bandit and stampede. When running with the 8.4V 3000mah batteries that came with the cars they run great... Long and fast. So on the advice of local hobby shop i purchased 2 5100mah 8.4V batteries. With the bigger batteries I only get about 5 minutes of run time. Manual says i need to regear for larger batteries hobby shop says no. These are all NiMh not lipos and battery protection is turned off. Before i regear i want to ask... Do i maybe have bad 5100 batteries? Is there a resource somewhere that can explain battery use in RC cars. Maybe someone who wants to take the time to educate a newbie?