Auto-AC Button on Steering Wheel

[doubleg2005]

Originally Posted by Sheepdog

80* is surprisingly cool when it's triple digits outside!

+1
yesterday after my teacher inservice i got back into my car (3pm-ish) and the MFD thermometer read 133*

took 45 minutes for the A/C to get the temperature down to 80...
but it DID slow down as it approached 80 inside, just as it's supposed to. then there's the fact that the outside temp finally "cooled down" and settled in at 104. a 24* differential from inside to outside is pretty significant if you ask me. good thing Pablo's AC is so effecient!

[rigormortis]

Originally Posted by qbee42

This is misleading. The Prius uses heat from the ICE to warm the cabin when heat is required, and uses HV electricity to cool the cabin when A/C is required. Both of these conditions use energy, which ultimately came from burning gasoline. Best mileage will come from not needing to heat or cool. If you raise the temperature setpoint when cooling, the Prius will allow the cabin to warm by reducing the amount of cooling. The converse is true when heating in the winter.

If you rapidly raise or lower the setpoint, it is possible the Prius may use heat or cooling to get there, rather than waiting for ambient conditions to do the job. This is because the Prius uses a proportional control system, either PI or PID, to control heating and cooling. Outside air temperature, humidity, cabin temperature, setpoint, and solar intensity are all used as control inputs and influence the decision of when and how much heating and cooling is needed.

There are a couple of special cases that may be confusing you. Cabin air is used to cool the traction battery. If you allow the cabin to get too warm, it will interfere with operation of the traction battery. The other special case is max heat with a cold engine. There are two electric heating elements that come into play in this special case, thereby using HV electricity for heat.

Other than that, your cabin temperature setting has nothing to do with fuel economy.

Tom

try it sometime. it has been my observation that at times the internal combustian engine will fire up for no other logical reason other then to keep the cabin warm.

now if the internal combustion engine fires up at longer intervals like at least 5-10 minutes, its pretty obvious that its charging the battery up

but if you keep the cabin air temperature down, the engine will only stay on for a couple minutes, here and there, and then shut down for the 30 minute period


the prius's traction battery fully charged (as defined as 70 %, heh) has enough energy stored in it to keep the car in full ready mode, in park, for at least 30 minutes without needing the internal combustion engine to charge it.

find a couple stop watches and you will notice that the gasoline engine will fire up more often in a prius car with its cabin temp set higher then the other prius car with its cabin temp set lower

can you hear the battery cooling fan? i have never heard it comming on

most of the time on my 30 minute lunch breaks at 2:35 am in the morning
i sit in my car in full ready mode (because at 30-45 minutes in accessory mode is kind of pushing it), 5 days a week, and theres a direct link from what i have seen so far

after you have tried this and it seems to be the case please report back on the following section

totally unproven theory section
=======================
the prius fuel tank has a sensor in it to correct the fuel level when you go up and down hills, the headlight sensor will adjust the HID lights as you go up and down hills, these sensors report back to the prius and the prius takes this information and forces your car to burn gasoline @ 25 mpg uphill to keep the battery safe so it lasts a long time

[qbee42]

Originally Posted by rigormortis

try it sometime. it has been my observation that at times the internal combustian engine will fire up for no other logical reason other then to keep the cabin warm. <snip>

This is unquestionably true in the winter, when the ICE is supplying heat for the cabin, but I assume you are discussing summer cooling. With cooling, the situation you describe comes from removing humidity. The Prius climate control system uses a sensor to detect humidity and runs the A/C compressor as needed to keep the humidity to a reasonable level. If the conditioned air feels to cold when it enters the cabin, you raise the setpoint. Now the controller has a dilemma: cut the cooling and allow the humidity to rise, or add heat from the ICE. In this case the A/C controller will reheat the cold air with heat extracted from the ICE. This kind of operation is common with air conditioning systems running in hot humid weather. The same thing happens when you run defrost in the winter.

Tom

[DaveinOlyWA]

just returned from a 900 mile trip over 5 days and we also started AC at 70... but as the drive goes on and the humidity of the air goes down and cabin temp equalizes, (not easy because of the radiant energy of full sun) our comfort needs eventually had us at 75º... now that might not seem good to most, but keep in mind, temperatures are all relative and based on what you are acclimated to. daily average high temps in summer around here is 77º

in the south where temps are much higher, one could probably set temps to 80 and be ok.