My P90D with 72 amp onboard charger will be my first Tesla, so I have no past experience with charging. I'm wondering if you can tell the car at which rate to charge. I will have the High Power Wall Charger on a 100 amp circuit. If I don't want to charge at the full capacity of the wall unit all the time, can I dial it back with any controls in the car/touch screen/iPhone app? Total newbie question, I know.