HR, you are correct on the 2.5v limit stuff (although it doesn’t completely kill the batt if you drop below this!) Since the batts hold a resonably flat discharge curve (same as NiMH) you can fairly easily tell when the voltage drops! As a rule of thumb as soon as the car drops speed you can recharge (doesn’t matter when you charge Li cells ie. part charge). Just make sure you have a decent charger! The cars are close to the limit for the max discharge rate so if you are running at full throttle the whole time you may run into some longetivity issues!
