On the GM Chevy Volt forum I frequented for that last 8 years it was neat that GM engineers who designed and built Volts would join in and clear up mysteries just like these, "shouldn't the 12V battery be trickle-charged when the car is plugged in?" or "what is the battery heater trying to do when it's not associated with charging, just protect battery from severe cold damage?" and "what's different with the Canadian model regarding this, can they trickle charge the 12V battery and thus OK to leave them plugged in for many weeks using battery heater during severe cold?" I guess the language barrier etc prevents Japanese engineers from doing the same here? I wonder if there are Japanese Prius forums somewhere online where Toyota engineers engage with questions from owner's...
