<9000 miles and already having an engine/electric motor issue

Well,I doubt you'll embarrass the specialist.I worked on foriegn cars for 6 years (35 yrs ago,ha),and I would've been happy for you to tell me the fix.It's been my experience over the years,that I had to find someone with exact experience with the problem I was having.( and I've schooled some of my mech. friends on fixes I've found on forums)Me personally,unless I'm shown or taught,I'm not good at figuring things out.Yes, he and toyota could've handled it better,but the next person he advises on this issue might think he and Toyota were great.

steve......goin out check my vent

 

Well at least now you can trade it for the Hyundai

 

Glad you got it resolved, and it sounds exactly like a hot battery. The resolution seems to be exactly that. Also you said something in your fist post that concerns me you may not understand the hybrid system fully, which is OK since it is extremely complex.

If your battery is full, the engine will run. Toyota designs the car so that the maximum battery state of charge is never more than 80% and tries to keep it in the low 70% to 60% range. It also never goes below 40% unless you run it out of gas, and then you can discharge down to 10% or 15% and cause permanent irreversible damage to your battery which you have also done. One time, you might not notice, but do it a few more times and will most likely encounter battery problems in the higher mileage. The display you see with the battery shows 1 bar at 40% and full bars at 80%.

So when the battery gets charged all the way up, the engine is spun as an air pump to waste energy. This means high rev's. In the Prius the engine rpm is not related to the pedal or to the speed. This is not your conventional car. Just like when the battery gets too low, the engine will turn on and rev up to charge it even if you are stopped. It is nothing like a start/stop mild hybrid or anything else on the road that doesn't use the Toyota design.

Another thing to consider is that when the battery gets charged, it gets hot. Just like when you charge your cell phone, it gets hot. Charge your laptop, it gets hot. Charge your Prius, it gets hot. The hotter it gets the less the computer will use the battery to drive the car and allow it to cool off. It will then run the vent fan and try to cool it down. In this mode, your acceleration will suffer and your mileage will plummit as if it wasn't a hybrid because essentially the car is saying "hey this battery needs time to cool down, don't use it" and Toyota designed such an awesome system that it can.

The inability to go into EV also indicates a hot battery.

If this is something you want to monitor, I would recommend getting an OBDII scanner like the ScanGauge.That will show you the battery temperature, not displayable anywhere else.

Honestly, don't worry about it. The car takes care of itself. Keep the vent clear, and if you notice the symptoms of a hot battery take that into consideration.

You also said that you are near Miami and you did not have the AC on. Batteries like temperatures humans like. Too hot and they are sad. Too cold, and they are sad. Your batteries are wrapped in a metal box and shoved under the floor and then made to work hard. Like if you were put in a boiler room and told to run on a treadmill. You could do it for a while, but you would get hot and wear out quickly. The solution is to get some cool air in there. Running the AC is best because the vent can suck in cool air. Second best is to roll a window down so that the air forces into the vent.

 

Shouldn't the "hybrid system overheat" message comes on in this case?

Also, what's the best cabin temperature for the battery?

 

Batteries like human temperatures. Room temp is perfect for batteries, so 25C. Consider they are being worked in an enclosed space, so a couple C lower would be optimal. This doesn't mean you have to run your AC at low so that your hybrid doesn't explode, it just means that to prevent hot batteries, and to prevent loss of power, and to maximize the life out of your batteries, you should treat them nicely. If you ignore it the car will still work fine for a long time, it protect itself. But the vehicle will more than likely not achieve the higher end of lifetime projections.

 

And to answer the overheating message question it will not come on because it is not overheating. It is just very hot. Only after the inverter reaches 112C will you get that message. The battery will not throw the message directly. It tells the HV ECU how hot it is, and the HV ECU then dishes out motive power responsibility accordingly. So if the battery is hot, it decides to let the engine do more work until the battery cools down some, hence the lack of power. The inverter is still a happy temperature, no message. It is not a critical failure to have a hot battery, it is just not ideal.

 

Thanks, good to know.

 

It's not that much about the cabin temperature. It's more about exhausting the heat away from the battery pack that it generates while working. Put some duct tape on your mouth and run a marathon. See how well you perform

 

My question was more about what should the cabin temperature be even if the cooling duct was not blocked. Even without duct tape on my mouth, I wouldn't run a marathon in the death valley. Then again, I wouldn't run a marathon anywhere, that's why I bought a car.

 

Set the A/C to auto mode, around 75° with the ECO mode active. That should be the best balance between keeping cool and minimizing it's impact on MPG's. They say the best temp is around 75° to 80° for the battery itself. Always make sure the vent for the battery isn't blocked by anything.

 

I just posted this exact same problem on the aus site yesterday. My problem is identical, it is adhoc, the over revving occurs maybe once a week and usually only lasts 30 or so minutes, I know where my vent is and it is clearly not blocked. Mine also will not go back to EV mode whilst playing up. The over revving is more like an extra 'pulse' that lasts a few seconds after you take your foot off the accelerator, this is combined with the louder noise coming from the battery cooling fan and the petrol motor remaining on. Toyota also say they can't do anything unless it happens whilst they have the car. I am thinking of recording the issue via video with good sound, next time it occurs. I note the posts above are around 6 months old, as anyone else had this issue since with the Prius C?

 

Hello. I have a 2012 Prius c with 31500 miles. I also recently noticed an RPM increase when letting go of the gas pedal at highway speeds. I read it could be a BLOCKED vent and its funny I have a plastic bag with a jacket on the floor behind the drivers seat. I'm going to clear it out in the am to see if it goes away. It revs up pretty good when it should be going down upon letting go of the accelerator. Will keep you posted.