Hot traction battery!

OK, that's interesting. If I understand you correctly, once the system is in battery protection mode, it effectively removes the a/c from the battery load. They really seem to have done a good job with protecting the various elements of the HSD.

Would it seem reasonable that increasing the a/c electrical load could have contributed to putting the system into battery protection mode in the first place?

Another consequence of overloading the a/c by switching to 100% hot humid outdoor air which could be more significant, is that the temperature inside the car will rise. This will limit the ability to cool the battery whether in normal mode or in battery protection mode.

I wonder if Toyota programmed anything in to force minimum outdoor air under conditions where more outdoor air would be a problem?

 

My gen III does not vent battery outside. It has the duct that vents beside the tray liner in the spare tire well. Is this normal? My gen II's vented outside

 

Mine's the same. It looks to vent indirectly, air pumps out into zone beside the 12 volt, and there's a flap and opening to outside in there.

 

Change your vent directions. Use vent as well as floor vent. You split the air flow that way so cold air reaches the back. Also the front side vents face toward the window so they blow toward the back seat. I have never had a issue with temps this way. Usually the entire car is equal temp. Tinting your windows as well helps keep the heat out. And if you have a tonneau cover use it to keep sunlight from beating down on the batt pack.

 

This is what I did :
Adding an additional fan to the Traction Hybrid Battery? | Page 2 | PriusChat

Im from Phoenix, AZ. A typical 110 F day means your cars interior temp will be 120F +. Once you turn your car off your Hybrid Battery fan stops working causing the battery temp to increase. My MPG's increased 2 mpgs since.

 

When batteries overheat, it's time to have them tested.

 

At what temperature do they overheat?

 

To the OP, I'd keep my initial reaction much simpler.

If this is a 2010 Prius, BUT this is the first time you have driven it during the "hot" season, than I'm assuming you bought it used.

The previous owner may of had dogs, or what not.

The first step I would take would be checking the battery cooling fan and intake and making sure they are all clear and clean. There are threads on doing this.

If you determine the fan is clean, the intake clear? Then I think you can start worrying about specifics in regards to your battery itself. But the first step I would take, would be making sure the fan is clean, and the intake is clear.