Prius seldom runs on batteries alone?

I rode in a friend's Prius and he showed me that the engine started up
before he hit 5 mph even under mild acceleration. I thought the
difference between the "full" hybrids like Prius and "mild" hybrids
like the Civic was the ability of the former to operate as a pure
electric over a modest range of conditions. It would seem that the
Prius' all electric performance is very modest indeed. Is this
correct?

 

I believe that the Prius could theoretically start up and mildly accelerate
with the battery powered electric motor alone (assuming it was charged) but
there would not be enough horsepower in the electric motor alone to satisfy
people (and it might not be safe to accelerate so slowly in high traffic
situations). If not accelerating, then the electric motor can sometimes do
it alone.

 

The electric motor has plenty of juice to run the car. There are a LOT of
other factors here...was the heat on? Air Conditioning? lights? Also, the
US models are set up differently from the models used in the rest of the
world...they run on gas more often in North America. This can be changed
by hacking the ECU (and voiding the warranty...)

Also, was the car fully charged? If not, the engine turn on to run the
generator, while the electric motor provides the locomotion. The display
will show you what's happening...

 

You can find more expertise at alt.autos.toyota.prius. They will also want
to know what year, since there are significant differences between the
Classic (2001-2003) and the second generation (2004+). Ours are both
Classics (2002), so I'll go from that perspective.

As the others indicate, there are a lot of variables. Cold weather makes it
much more prone to run the engine in order to produce heat, which passengers
seem to enjoy The state of hybrid battery charge will affect it, too,
including the entirely counter-intuitive behavior of restarting the engine
periodically to bleed off extra charge if the state of charge is high.

Cold weather, particularly as the temperature drops below freezing, will
take the edge off fuel efficiency. I'm barely managing 30 mpg with mainly 3
mile trips in subfreezing weather right now, but when the weather warms up
it will go back into the mid-40s. OTOH, what other car would provide 30 mpg
under those conditions?

Mostly, the hybrid system knows what to do. There have been reports of
misbehavior - especially shuddering when the engine shuts down - that have
been corrected by disconnecting the 12 volt "aux" battery for a few minutes.
Maybe the car should have ctrl-alt-del keys ;-)

Mike

 

"Hachiroku wrote

I have and drive a Prius. It is just how it is set up. My Prius will
start up in electric when the battery is charged enough and accelerate up
to maybe 40 or so on electric alone - but it is painstakingly slow. One
cannot do this in traffic, thus the need to press down a bit harder and
engage the gas engine. I too would very much like for this car to rely on
the electric much more than it does now.
Tomes

 

The point where the petrol engine fires up depends on a mixture
of road speed and load being imposed. "Racing starts" are sure
to get it going at low speeds, in the Mk2 UK "T4" at least. If
just moving away gently from traffic lights (not a common thing

Google for recent (Jan 2007) posts by me under the Subject 'More
on Prius "EV" mode'. Being all-electric is not the point of the
Prius. Being efficient in its use of fuel is. Huge difference.

 

I've heard of Prius people adding another battery pack(in addition to the
stock one) and 120VAC charger to get better use on the electric side,and
reduce gas usage.Then you can plug it in at night or when you have access
to an outlet.

 

Yes, except Honda update as another poster noted.

An after-market switch is available to make the current Prius operate
entirely on electric motors, like a Euro model. After Andrew's test
I thought it would not be worthwhile, but I'm having second thoughts.
Steven Scharf (SMS) posted this URL describing how:

http://www.calcars.org/prius-evbutton-install.pdf

 

ISTR more perspectives on this can be had by browsing around the
website priuschat.com -- mostly by folks who wanted to do it and
are mentioning odd details. In a UK Euro-Prius, the "EV" button
occupies the right-hand position of two switch holes to the left
of the steering column. If similar spaces exist in USian models
that would seem a good place to put the control. OTOH, a couple
of postings mentioned re-using controls on the steering wheel.

 

A good example of all electric performance that goes well beyond *very
modest* is when a Prius is *instructed* to back up an incline such as a
steep driveway. Mine has yet to revert back to engine power when the
accelerator is *pedal to the metal*.

 

Thanks for the thoughtful comments. I am really just curious about
the state of the technology. Not really interested in purchasing any
current hybrid but I would consider it if the right one existed.
Electric performance is not an issue in this regard - like I said, I
am just curious.

More info on the experience I opened the thread with:

The OAT was about 30F/0C. The engine should have been up to temp at
this point. Lights were on and there were three people in the car. I
don't know the state of the battery but he generally drives like an
old man. Also, the car is a new model, about 2 years old with 7000(!)
miles on it. He mostly drives it to the train station and back. He
indicated that it almost never ran on electric alone and showed me
this by gently accelerating from an electric creep. As best I could
tell, the schematic showed power coming from the engine the moment his
foot hit the gas.

 

There was a Web site a couple years ago where a guy who is an Electrical
Engineer hacked into the ECU via the ODBII connector, changed the mode,
and then wrote a program in order to control the ECU from the interior
Real Time with a Toshiba Libretto.

 

Hmmm...I drove a 'classic' for about a week (1999...hey, how'd he do that
when the 'first' year was 2000?) and got to where I could control the gas
engine with my left foot.

Sad thing was, I got better economy for my type of driving with my '95
Tercel Automatic!

 

In cold weather get 30mpg ? uh, the corolla will easily do that.

 

I just got a prius and am a bit disappointed that it doesn't spend more time
in electric only mode.

My question is for those who have modified the car to spend more time in
electric mode: did you get better mileage?

-thanks

-ralph

 

The hybrid controller for the Prius is designed to keep the battery between
45% and 75% charged to prolong the life of the battery, so a modification
that lets the battery get below 45% charge may shorten the battery pack's
life.

Adding additional batteries would theoretically allow the vehicle to spend
more time in electric mode but then the engine would have to spend more time
running to re-charge the battery.

 

Unless the excess of the engine and regenerative braking were underutilized
to begin with.

 

Year number applied in the previous calendar year, maybe?

Quite possible. Driving style is so important. Too many folks
think a hybrid doesn't benefit from being driven properly. Not
true. It's like any other vehicle, that way.

Is the Tercel a small car? The Prius is not. USian Mid-sized,
almost. I see Toyota FWDs being advertised, with mpgs horribly
lower than the Prius, despite related hybrid tech. (Maybe good
for FWDs, though.) Body mass must count for a lot, although of
course FWDs have the extra transmission bits to power.

 

I am betting that the engine/exhaust system was not warmed up yet. It
needs to warm up to get the emissions stuff hot, then it goes into its
normal mode. This is another of the ways that it is set up by design.
Tomes