Prius seldom runs on batteries alone?

As an owner of two Prius, I am very happy. The two cars together have roughly the same fuel consumption of the 300ZX I traded in, and they are a joy to drive (I love maneuverability). Most of all, they are the most reliable cars I've ever had, by a wide margin. To each their own.

BTW... I'm with you on global warming and CFCs, but you're right - let's not get that started. Have you seen NASA's findings on polar ozone depletion at

? Especially interesting is Table 1 on page 59 of the .doc version.

Don't get the Easter Bunny mad at us, though. I need the chocolate eggs.

Mike

Have to break the habit of a lifetime and agree with Ray. My Prius definitely allows me to set 30mph. Haven't tried any lower (except maybe 29mph).

I read Bill's remarks as meaning "really short trips", like those which don't warm up the engine properly and give the mpg time for "recovery".

"We need more reliable, clear numbers" Andrew Stephenson

"I agree, we can wave our hands around and make points both ways, but without real comparative numbers (which I for one do not have) it is all just speculation." Tomes

So basically; No one has any experimental facts to support any conclusion, or theory.

"Polymer Science Engineer here. As a physicist, you might have run across situations where an answer comes through discussion, as well as through a straight answer. The discussion is what occurs here and this is the normal course of events in this Newsgroup. This is not a flaw, it is a feature." Patience Grasshopper

So, this group is just a bunch of old farts shooting the breeze.

For the record, the way I learned science; discussion, speculations, conjectures, 'shooting the breeze' are all excellent ways to think about nature, formulate theories and suggest experiments to test such theories. But as mentor of mine once said, physics is different from logic, mathematics, and theology, in that we run experiments.

Clearly no one has installed an EV button, and utililized it in a consistent fashion (for example turning it on when you anticipate driving for less than

2 miles) and measured the resulting mileage.

Finally, for what its worth to those of you looking for 'hard numbers'; our first tankfull resulted in 44mpg (US gallons, not imperial gallons, of 87 octane regular gasoline), in a mixed highway and city (red lights) commute across gentle small hills of 75 miles per day. I also read that the US EPA will relabel the Prius from 60 city 51 hwy to 44 hwy this coming summer.

thank you for your comments

-princeton

US 2004 Owner's Manual, section 2-6 "Operation of Instruments and Controls, "POWER switch, transmission, and parking brake," "Cruise Control," page 141: "The cruise control allows you to cruise the vehicle at a desired speed over 40 km/h (25 mph) even with your foot off the accelerator pedal."

Myself, I've been able to set the cruise control at 24mph, so I'd guess that the kph is the more important trigger there...

Forgive my bluntness, Mister Physicist, but it seems called for. Either you've not actually been paying attention to what we have been posting, or you're an idiot, or some mixture of both. Data to hand indicate the third condition, plus ignorance and ego.

When are you going to catch on that the Prius "EV" mode does not allow one to use it as you describe? Yes, you could engage "EV" for (say) a series of very short trips. But sooner or later the car's control system would decide the big battery had discharged deeply enough to warrant flipping out of "EV" mode and firing up the petrol engine for a recharge. It does that whether you like it or not, to safeguard the battery (not to mention your ability to drive the car). The length of run just isn't worth it for an average user, the person for whom Toyota make this car. IOW, as you've been told, repeatedly: THE CAR IS IN CHARGE OF STUFF LIKE THAT -- NOT YOU.

If you don't like that you already know one solution. The other is: shun this current Prius generation entirely -- along with us farts here shooting the breeze. I especially like the last bit.

(Trolls. Bah. You just can't get classy/clever ones any more.)

Sometimes. Other times we get experts weighing in as well. It is a sum of all of it.

Yep, looks like we are on the same page here. We have not run this particular test and we have not found it published either, so we are back to our discussion, speculations and conjectures. It is what we have at hand.

We get about the same MPG here between Flemington and Bound Brook NJ and around here. I read that the whole EPA mileage rating system is being revised to project more realistic numbers, rather than their pie-in-the-sky utopian figures that they have been putting out for years. Pegging the Prius at 44 highway is realistic from my experience. Tomes

Yeah, I just looked it up and it is supposed to be 24 MPH on the Prius. That's better than I thought. But still, I would like to see a minimum of 'already engaged in forward motion' rather than any minimum. Tomes

I read it the same way. The first few miles are always killer miles. Tomes

OK, that's what I thought. It uses the electric motor in reverse to generate electricity stored in the batteries. The IC engine remains out of the picture. Now my next question is does it generate more or less than in normal mode? Tomes

I think that's backward - it dumps energy into turning the engine rather than into the battery. Maybe MRV can explain it more clearly. She does that sort of thing so well :-) People who have monitored the battery current with the Ecrostech Miniscanner

report less regeneration in "B." I've never actually checked myself, but if you want numbers I can do that. Mike

Possibly. The brakes are not especially big, and here in the States the rear brakes are drum type. I understand in Europe they are 4-wheel disks. Anyway, use "B" for long descents.

Mike

The gain in highway efficiency is in the ability to use a lower output engine due to the availability of supplemental power from the battery. When operating at cruising speed, the engine will be running at a higher % power level which is more efficient. In this mode, the electrical drive line saves fuel by merely being there if you need it.

Are you sure about this 12 mph or so? It sounds like I'm hearing pad friction at higher speeds.

How do you know it reduces regeneration using B instead of braking? Do you mean braking is more radical (more force) yielding more regenerated power? Guess I'm used to manual transmission and want something to do. But I see the battery charging quickly when the Prius is in B.

I wonder if the US Touring model also has 4-wheel disk brakes?

Thanks, interesting reading there. So now I am re-understanding this as follows: In B mode it spins the IC engine without starting the engine, wasting off excess energy in that spinning. What is not explained to me yet (his section of How B Mode Works was truncated off) is does it generate electricity in this engine spinning (the reverse of how it starts the engine up all the time)?

I think that I gleaned from this stuff that it makes less electricity in B mode due to the spinning waste. Tomes

OK I found this other link that actually explains it pretty well, if anyone cares :-).

is a bit copied out of that:.....Enter "B" mode. As in, "trucks use lower gear". By forcing the wheels to spin the engine and pump air, a good deal of that energy can be turned to heating the air going through the engine instead of heating the brake parts. Since fresh air is always coming into the engine, having it leave as much warmer air provides a convenient place to dump excess energy. In a conventional car the wheels push the engine around through the transmission, but the Prius needs to help that process out a little bit by actually having its combination of electric motors spin the engine. In this case, the valve-timing in the Prius engine is advanced to increase the amount of air taken in and the suction against the throttle flap -- which uses much more energy than the coasting-in-"D" scenario above......

There is a lot more there that I have not copied here, but in addition to capturing some of the energy, it is spinning it off in B mode.

Bottom line is to not use it in the hopes of saving more energy. Tomes

Bill - read this link regarding what it does in B Mode:

answered a bunch of questions for me about 5 minutes ago. Basically, B mode wastes off excess energy by spinning the IC engine. Read on....Tomes

The minimum speed for cruise control has been 25 MPH since cruise control first appeared on Toyotas. My guess is that speed was chosen to prevent someone trying to use it in stop-and-go driving.

Thanks Tomes! That was illuminating and contained many surprises, e.g. "When accelerating... D and B produce the same behavior."

Do you know about "the Great Database Fire" that took out Priuschat? A similar thing happened to one of the chat sites I visit, BoaterTalk. That's one big downside of chat websites versus group (Usenet) news. OTOH I suppose Google could discontinue groups so we wouldn't be able to search back posts any longer.