If the Prius I doesn't have electric air, how does the AC work when in stealth or stop?

This is one of the things that has really been improved in the Prius II. In the Prius I, it depends on if you have pushed the "Max A/C" button or not. If it is pushed, the engine will run to keep the temperature as close to the selected temperature as possible, which on hot days means that stealth mode almost never happens and you can say goodbye to mpg. If it is not pushed, the A/C system allows for bigger temperature differences. In reality, the engine will start to cool the car down, then stop and start again when the car is a bit too hot to be comfortable.

The same goes in the winter. Does the Prius II have electrical heating as well as cooling? That would help mpg on really cold days.

Yepp, bit improvement. Prius II is completely electric as far as cooling & heating.

I think Prius reqired all electric because it is a full hybrid.
If it had a conventional compressor cooling/defrost wouldn't work in stealth mode.
However, remember the energy required for this is not free, there is a cost.
Except for regen braking it is still provided by the ICE whether direct drive or battery.
Which saves more fuel? Direct compressor drive or drawing from the battery?
It may be easier to say battery but I wonder if there's any data available.
Thanks

I'd say battery without a doubt. Battery means the engine will only turn on if it gets completely drained. Direct, however, means the engine is _always_ on. Excess energy is better than new energy, eh?

When the engine idles is when the car is as least energy-efficient. Better to use a few extra horsepower when the engine is used to propel the car, and save that energy in the battery to cool the car when in stealth mode. That must be more energy-efficient.

I'm still wondering about this.
To heat/cool a cabin say 30 degreese difference requres a certain amount of fuel.

Prius takes this from the battery (or generator). While the compressor is drawing energy the battery drains. The engine comes on and consumes more fuel to replace what was lost. If the driving situation requres ICE to also propel the vehicle it is doing so while also replacing spent cooling energy.
Am I grossly incorrect?

At one time I had wished my HCH had an electric compressor but then I realized the extra gas that I consume to make up for a depleted pack.
To charge my pack up from about half drops my MPG by about the same as the compressor load. I now have the option to switch off the compressor in a steep hill climb and still have full battery for assist power.
I like that option better than charging a depleted pack. :rolleyes:
Energy is engergy: and it is not free

The discrepency is in that the Prius is forced to expel much of the stored energy (green bars) in a less efficient manner. This means more forced stealth mode or more use of battery output. When the car is not moving, this helps free up the energy that would otherwise be forced out.

I think this sounds right. But the point is that with electrical A/C, many situations with the engine idling is avoided. A car on standstill with idling engine is the most ineffective way of using fuel (unless you pour it on the ground and light a match). I am sure this would show in a side by side test with two identical cars, except the A/C system.

Hi All:

___Let me add my $0.02 in regards to A/C.

___Look at Krousdb’s latest tanks compared to the great tank he received a few weeks ago. Notice anything different? I haven’t spoken with him via PM this month but I suspect the large hit was caused by the use of A/C. It doesn’t matter if it’s electric or mechanical from a belt and pulley powered directly from the ICE. It is a huge hit and the same amount of energy is used to cool a given volume with a given size A/C unit whether it is electric or mechanical. You might even say the conversion of Rotational Mechanical to electrical to power up an A/C compressor mechanically is an even larger drag then just pulling it off the Belt via pulley directly? I don’t know exactly how the Prius II’s electric A/C works so I might receive a bit of an education right now? Autostop capabilities not with standing, our ICE’s are really too small to carry such a large load without seeing a rather large hit in fuel economy. A 300 HP to spare monster hardly even flinches under similar circumstances given all that excess power just sitting there going to waste anyway. In the Insight, A/C robs me of ~ 30% of my possible fuel economy for the few seconds I have experimented with it last week. If Krousdb’s latest tanks are any indication, you can bet there is at least a 20% hit while using A/C in a Prius II as well.

___Maybe someone should PM Krousdb and find out if it was A/C use that tanked his Prius’ mileage from previous tanks non A/C use and nothing else. Seeing the temperatures he is driving and his comments in each of the tanks data blocks make me believe this is exactly the case.

___What were we discussing again?

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___Waynegerdes@earthlink.net