My last ? Of the night. I just bought my 2008 2 days ago and am really not understand how all this works.
Well, there are 2 batteries....I going to assume you are asking about the big Hybrid traction battery. In reality there is no need to keep the HV batt full, as the car will automatically charge it up when needed, by starting up the engine. Actually you really don't want to park with a full battery in the hot summer heat. Best to run air conditioning in summer which cools you and your battery, and also A/C tends to keep the battery less than full state-of-charge in summer. In the winter with heat on, you may notice the heater makes the engine run which has the side "benefit" of keeping the battery in the green full state of charge. Don't try this in Texas summer though for the reasons mentioned above .
Unless you have a substantial downhill run, the battery will rarely get above 6 bars. This is part of the system firmware to extend the battery life by avoiding overcharging. Similarly, you won't get less than 2 bars very often...which avoids over-discharging. There is a lot of information on here about high mileage techniques, so good luck!
