i'd find another hobby shop. good luck with those.
*edit*
from castle creations...
10. I’d like to make sure I’m getting everything I can out of my Monster Max system. What are the best batteries to use?
With our combo, most people will find that NiMH cells are useless as they can’t handle the continuous or burst currents the Monster Max will draw for very long. If you use a lower kv motor, and gear lightly though, you can use NiMH cells. The best NiMH cells on the market for 1/10th scale vehicles are currently IB3800s, IB4200s, GP3700s, GP4300s, Elite 4000s, and Elite 4500s. The best lipo packs on the market right now that we’ve tested thoroughly are the Tanic 5000, NeuEnergy 5000, FlightPower Evo 25 5000, FlightPower Evo 30 4500, and MaxAmps 6000 and 8000 packs. This is not to say these are the only packs that will work, these are the only packs we’ve tested that we KNOW work. Feel free to give us a call if you’d like to know if your particular pack is going to handle the discharge currents these systems are capable of.