Before I go into any definitive realization about what I am about to explain, I want to point out that I'm still a beginner to driving my Hybrid. But I realized something today on my morning commute. I read a thread on this forum about the battery calibration and it answered my question as to why my car was charging when I accelerated and wouldn't charge when a braked. The car's battery is no different, in principle, than a camcorder bat, etc. Well in a traditional Metal halide battery there is memory. I can imagine that with a battery designed to last the lifetime of a car, this had to be specifically addressed, hence "annual battery calibration." With this in mind I realized, if the car's computer has to check for battery functionality while it's being used, ideal conditions for testing get thrown out the window. I thought about another post I read about how accel & braking hard will increase mpg. Well if the computer wants the best measure of the batteries capability to push and pull current, pushing the car to extremes helps better calibrate it. So in a nut shell, if you realize your car is recalibrating, drive it hard . If anyone has tried or wants to try this to test it out let me know.