I'm a new 2008 Prius owner. I have noticed when the battery gets completely recharged it seems to make a noise. I can't really describe the noise but it's enough to make me want to take the car out of "B" mode when I'm going down a hill. This happened when I rented a prius last month too so I'm wondering if it's normal and if it's OK to stay in B mode when the battery is fully charged? Thanks, Angela
There is a fan in the battery pack to keep it cool. This is probably what you are hearing, if the sound is coming from the rear of the car (vent is on the right side of the rear seat). If the noise you hear is coming from the engine compartment, it's the engine spinning very fast. The car uses the engine to dump energy in "B" mode, and the engine can spin up to 5000 RPM during this mode. That makes more noise than most owners are used to. It will not cause any problems or damage. It's normal operation, though usually you wouldn't hear it unless you were descending from a high mountain pass.
That all sounds normal. (You usually don't have it in "B", right? Only when coming down a long steep hill?)
