Hello, I've got a 2009 with 140k. I remember going to the beach last summer and thinking something was wrong with the car, as the MGS dropped from approx. 44 to approx. 36 on our (mostly highway) drive down to the beach. My best guess was the 12v battery and never did. However, it tested within range. (although I don't recall testing under load). The rest of the year has come and gone without me thinking about/ noticing this issue at all. Fast forward to this past (very hot) month, and my wife and I both noticed times where acceleration is weak at highway speeds, esp up hills (when ICE is engaged); MPGs has also dropped to approx. 36 again. I had initially chalked up both low acceleration and MPG drop to AC use. However, after my wife mentioned it, started looking through the forum and trying to figure out a solution. Some mentioned the battery fan, but we don't have any purple bar issues (and the issue seems to be ICE related). Elsewhere, I saw acceleration issues tied to overfilling oil and the throttle plate needing cleaning (I just paid someone to do my oil for the first time recently, and they did overfill it... I just bought the stuff to suction the excess out), but that doesn't seem to explain the MPGs. Does the reasoning in the above paragraph seem sound? If so, where should I start? I'm thinking that I reexamine the 12v Thanks
Welcome to PriusChat!! In case you didn't notice this stickied post, please copy/paste/answer as many of the questions as possible. At 140k I would check the fan for buildup, especially is you offer portage to cats/dogs/children or their dander on your clothing. How long are these uphill stretches on the highway, and what is the HV battery state of charge beforehand? How long have you owned the vehicle, and what sort of maintenance have you done thus far? (plugs, injectors, fluids, etc.)
generally, warm weather power woes are related to a weak hybrid battery trying to protect itself. as sfo said above, clean the intake grille and fan. if that doesn't help, prepare for a new hybrid battery down the road somewhere. a bit more complicated, but it might just be corrosion inside the battery. if it is, cleaning things up could be helpful.
