| All bars full is rare, but it can happen. One way it occurs is going down a long mountain road. The ECU tries to avoid fully charging the battery (all bars is about 80% charged) or fully discharging it (no bars is about a 40% charge). This is to insure that the traction battery lasts "the life of the car".
JeffD 
With my 2004 Prius - MakesMeLookSmart |