It isn’t a hybrid and the car systems are not designed to support vehicle motion when the engine is off. Could be the brake booster, power steering, etc.
He was responding to post #11. There is still a drain on the HV battery to keep the 12V charged and power accessories. Ever leave the AC on full blast at a long light? That'll drain the HV battery down decently fast. But at that point the efficiency loss is comparable to an alternator anyway.
I think PRIUS A/C is more efficient than on a normal petrol car. In your petrol car, the A/C compressor and fan(s), as well as ventilation fan keeps running, and some older engines have an idle-up solenoid to keep it running smoothly while the compressor is running (newer cars, the computer works that out), and yes, the alternator is under a larger load for the A/C.
I mentioned my Civic Hybrid in the opening post.. The Civic Hybrid with MT had auto stop under 20 MPH.
The A/C compressor in the Gen 4 is stupidly efficient. It cools down reasonably quickly in Eco Mode (but with just me in the car. A full load might be different but it hasn’t gotten really hot yet and it’s almost the end of summer). If I drive a long enough distance (e.g. 50-100km in a day), the AC load ratio in my Prime is in the single digits even when it’s 25°C outside. Once it rains and it needs to run more often to dehumidify, it goes up to 15%, even 20% on shorter trips.
The Prime or Gen 4? I think you own both. The Prime has a heat pump and the Gen 4 has an electric air conditioning system.
Is that a displayed value in the dash? Do you know the impact of those percent values, on EV range, or mpg?
Tangent to Mendel's question, I just posted interesting data on effect (or non-effect?) of AC load ratio in another thread: What is your miles/kWh (total average electricity consumption) on the "Drive Monitor 2" | Page 6 | PriusChat
What is the "GOM" factor, and why should it be increasing? I've got a few things that could use increasing...
My guess o meter read 34.2 this morning . But today is a day off of work, so I won’t use that. Maybe it’ll increase today since it showed 7.7 miles / kWh for the drop off kids at school.
Guess-O-Meter in PRIME is predicted EV range displayed based on the past performance (supposedly factors such as temperature, AC use, terrain, road condition, driving techniques including speed, acceleration, braking, EV use, etc are taken into the calculation). More efficiently the car drives in EV mode, more GOM range for future use is the premises. Therefor, having 100% AC load ratio should be penalized compered to 0%. But under artificially increased EV efficiency at it's max 99.9miles/kWh, it had no effect. Essentially, the car is smart enough to know that I was cheating.
Here is data for the real effect of AC load % on EV range on PRIME I posted on different thread while back. They are not GOM range, but actual EV range I measured from a full charge to empty. In general, higher the AC load ratio, less EV range I could drive from a full charge.
You could be running the AC steady, different days, get different "AC load ratios"? You mentioned it's higher on humid/rainy days. On ours I can varying ACWatts values with the ScanGuage, and the compressor is also running sporadically, cycling maybe once per minute. That was some time back, I had problems with constant SG hookup. And the Prime AC is a different concept too. But yeah maybe similar, in that it's impact can vary.
Sorry we are off topic from the Auto Stop Start in non hybrid. I never owned any non-hybrid car that was equipped with auto stop. The humid/rainy days comment was from @Tideland Prius. Wait for his response. As for my data, I almost always kept my AC setting at 70F AUTO with Eco setting, S-Flow enabled to driver side. The load ratio is variable depending on how hard it has to run to keep that setting, but I don't have temperature or weather data corresponding to those data points. Although the data are from late Aug to early Nov, thus non of extreme cold winter days are included but some are cooling while others are heating. In fact in my climate I can have a day when I need heating in morning commute and cooling in afternoon. I would assume AC (cool) has to work harder on hotter more humid days, and AC (heat) has to work harder on colder cloudy days.
Yeah, I'm enabling topic drift in a big way, will shut up after this. Just would say: we almost never use AC. I'm cognizant it it needs a little excercise, to keep the oil circulated, so I do make a point to run it occasionally. Probably sees more use in winter. Our 3rd gen will stealth-run the AC if vent mode is set to Heat/Defog (as evidenced by SG showing an ACWatts value other than zero, off and on). Sometimes. Even though the AC button is not lit. And we will use it intentionally, pushing the button, if all else fails, typically in heavy rain through winter. With your Prime you use it round the clock, AND get 90 plus mpg? I'm a little stressed here, lol.
So all this AC talk should most likely be in a different thread, but... AC is a factor in "stop-start". I'm seeing that if AC is on full blast some of these stop start systems will not stop. Hybrids are a little like NASA in that the technology used in hybrids is filtering down to non-hybrids blurring the line a bit. Our Elantra has electric PS, for example. CAFE were set to make a big jump (not sure if that has changed with our current leadership). CAFE should be motivating car companies to make vehicles more hybrid like. If the RAV4 is any example the hybrid penalty has been eliminated. If that RAV4 Hybrid could pull our boat... Oh getting back to the AC, the implementation on the Camry Hybrid is just amazing. The AC works perfectly and does not have a huge impact on mileage. My Civic could beat the Camry if all the hypermile techniques were used and AC was off but the Civic's milage would tank if the AC was in use, not so much with the Camry.
Start stop systems have been around longer than hybrids. The first in a consumer car, actually the Toyota Crown, with was available in 1974.VW starting offering it a few years before the Prius debuted in Japan. Start-stop system - Wikipedia These systems get a bonus for a car's CAFE value in order to encourage their use. The cost of a hybrid system is still there. The Corolla and Camry hybrids are priced $3000 more than the ICE model. In the US, Toyota is 'paying' for part of the hybrid cost through lower margins. Other markets, like Australia, have a steeper price increase for the hybrid.
I've used A/C since about 1975 - and done some back to back tests - and I've never found it to make a consistent measurable impact on mileage. Only exception was my '77 VW Auto Microbus with a huge YORK Compressor - on the highway, was about the same as if the kids opened all the windows. But around town, yes, had an impact, but then with 2 fairly oversized carburettors, it drank quite heavily either way.
AC systems use a lot of electricity, which isn't free. All electricity must come from regenerative braking (trying to recapture energy created by burning gasoline, or just burning gasoline while driving to generate the electricity. It's a lossy process. No matter which way you look at it, AC consumes power. On my Insight using the AC can bring MPG down by up to 20%. On a larger, more inefficient vehicle like the Prius, the effect will be less noticeable, but it's still noticeable.