Why would my Prius V suddenly be getting 26mpg

The battery fan intake is located under the right rear seat.

 

Its not the heat causing 26 mpg. 2012 Prius v in Central Texas over 100f for the last few weeks still gets 40 mpg with the ac blasting. Typically 55-60 mph. Parked with ac on will kill a specific trip mpg as will 80 mph.

A hot battery will code and even go into limp mode. The vent is under the rear passenger's seat, best accessed with the rear seat moved forward. Odds are good the blower needs cleaning but its unlikely to be the cause with no codes. To clean it on a v is easier than a hatchback, remove battery cover followed by remove fan.

 

are the radiator fans coming on?

 

I don't know if I'd spend the money on tint. The car is going to need a replacement hybrid battery before too long, it'll be good to have some bucks reserved for that day.

 

I don't subscribe the theory that you must keep the cabin AC-cooled or your battery's going to suffer. The batteries always run a bit warm.

When I had ScanGuage hooked up (on our 2010 hatchback), driving on 80 kmh coastal highway near dusk, ambient temp around 20C, no AC and windows cracked, I'd be seeing battery temps around 35C and battery fan speed 1 or 2 (out of 5?).

 

"Must" is an absolute we can do without. I think Toyota did a good job of setting it up such that if the human occupants are comfortable, the HV battery probably is too.

A car parked in the sunlight in the greater Los Angeles area (O.P.'s location) in summer is going to hit 140°F / 60°C in the cabin pretty quickly. I think a lot of drivers would feel motivated to use the air conditioner regularly in those circumstances.

 

i hope toyota wasn't counting on people to use a/c for battery longevity

 

Run with windows open and the battery cooling air is close to OAT.

 

The one thing that concerned me was coming home on a hot summer day, parking hot car in our garage with west facing solid-cedar doors. It was slow-death hot in there. We got the doors replaced with insulated core steel doors last fall, helped a lot. Also have a thermostat triggered window fan to exchange the air.

Last summer we exceeded LA in a few of our "heat domes". Lytton, BC (in the interior) hit 49.5C one day. Then went up in flames, I believe the next day. A train might have ignited brush.

 

Insulated doors plus ridge vents on our detached garage modulate the temperature fairly well, eliminating the extremes.

 

Air cooling of the hv battery made the car's price point cheap at the expense of the battery especially in southern states.

I would not run the ac at 20c / 68f ambient. We are happy to get 75f with ac in the six months of summer. So is the battery since the ambient is 35c / 95f with the engine running daily for an hour at turnpike speeds. Often at 130 kmh. Which is why gen3 issues showed up years earlier down here. Miles and heat.

In a garage parked it does not matter.

 

well, the op's car has 10 years and 150,000 miles. that's all toyota designed the battery for

 

A prius does not shift..........how long you been driving this car? The Car DOES NOT Shift Gears........ it
has one gear...Drive no shifting......

 

Perhaps he means the CVT is not ‘changing’, just revs.