RE: How do I make an E-maxx's runtime longer?
With 6 cells per pack, the E-Maxx is very quick and very fast. A blip of the throttle in first gear will flip the truck over backwards. It will climb anything and jump 10 feet in the air off of a skateboard ramp (and usually survive unharmed).
With 7 cells per pack, it becomes insanely fast (just over 30mph) with ridiculous acceleration.
However, the E-Maxx can destroy battery packs very easily. To avoid doing this, when you notice that your E-Maxx starts to slow down significantly, stop using it at once.