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
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.
It is my unscientific belief that I regenerate more than I use, based upon
my observation that I am in the green a lot and hardly ever go below half
of the blue. Thus, I would like to use the electric moreso that it does
Doing it (controlling it) manually, however, would open up the possibility
of hurting the battery on both ends inadvertently - by over and under
What I would like is the ability to tweak it within limits. (Adjust it to
be a bit more on the electric side.)
You Prius drivers are almost as nuts as me!
I run a GPS in my Corolla Wagon. The GPS is connected to my
laptop computer and will take voice commands such as 'Where the hell
Now just think how dangerous I'd be in a Prius!!!
You're redesigned Prius actually (according to what I've read and heard)
does go further and faster in all electric mode under similar conditions
than my '03 Prius. As far as installing another battery pack, if it were my
project I would make it so the second battery pack was for *overflow* only
and not to be charged simultaneously or better put, not a priority.
For the past two very cold weeks (mornings 5 degrees and daytime not much
more than 20 degrees) I've been driving with the speedometer set for
kilometers instead of miles. My fuel efficiency *seems* to have improved and
I can only surmise it's because I can only relate to designated fixed speeds
so I tend to accelerate faster than normal. In the past when I'm on the
highway I noticed 62 mph seems to be the sweet spot. It just so happens to
be 100 kilometers per hour. And the double nickel 55 is the double infinity
88 but upright instead. Hey! Gotta keep amused.
All this stuff is technically feasible. The question is whether it is
commercially feasible, that is, whether consumers are willing to pay $2000
to $4000 for the additional battery packs, chargers, etc. and give up trunk
space. My guess is that people would probably give up trunk space but would
be a little more reluctant to part with the additional money since the
payback period may be longer than they intend to keep the vehicle.
The break-even point in terms of fuel costs is somewhere between 3 and 7
years, depending on the cost of fuel, driving conditions, etc. Adding an
additional $2k to $4k may push the break-even point out further than most
people would keep the car. While there are plenty of people who keep their
car for 10 or 20 years, even if all of them purchased the additional battery
capacity, the sales numbers may still not justify an automaker to put it
The exact numbers are not to hand but, in general, the efficiency
of charging from a wall socket is not as good as people generally
think. It may be $cheaper to the householder than what is put in
in fuel tank; but that's a red herring in the efficiency puzzle.
Consider these stages when charging:
* burn fuel at the power station and convert to electricity (hard
to compute the efficiencies if the energy source is, say, hydro
or solar or one of those, so skip them for now);
* convey the electricity to wall socket and charger unit (if long
journey across country, losses not negligible);
* convert electricity to form suitable for battery (low volt DC),
then convert to chemical energy, then back to electricity (huge
Compare this with the clever juggling the full hybrid setup does.
Often the battery stays idle, as engine drives generator and that
drives electric motor. If it does involve the battery, we do not
have to pay for transmission losses. The higher-than-usual Prius
petrol engine efficiency... hmm, I'd be guessing irresponsibly if
I estimated how it matches up to the power station and would like
to know more.
Just a thought, right?
email@example.com (Andrew Stephenson) wrote in
"Jim Yanik" writes:
I suspect that electric generation is more efficient any from 120VAC source
than any hybrid auto,and also outputs far less pollutants.
Transmission losses are present regardless of whether the auto is charged
from the line or not.Losses from corona discharge/leakage are far greater,I
and you neglect the conversion losses that the auto has in going from
electric to mechanical and back,also the self-discharge the batery pack
I considered listing each last tiny cause of inefficiency I could
imagine then decided to group them, eg: "* convert electricity to
form suitable for battery (low volt DC), then convert to chemical
energy, then back to electricity (huge losses overall)". Leaving
it to technically minded readers to fill in details seemed good.
We need more reliable, clear numbers.
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
I'm thinking that I am remembering reading that Toyota is considering the
ability to plug it in for the next version. Dunno if that would actually
There's always a possibility the engine will start anyway even if the car is
sitting still. If both battery packs are topped off ahead of time then
there's no place else to store the electricity. Then the so-called savings
from using AC utility power are diminished. By how much I don't know. All I
can say is if an extra battery pack allowed me to travel 20 miles I would be
hauled off, tarred and feathered by everyone behind me for going so slow.
Doing this has not occurred to me - I will try this. I figure that I
don't need to have the engine running when I am stopped, even if it thinks
that it needs to heat something up. It can wait to do that until I
acceletate and co-use that power.
This is what I am thinking, I just don't know if I am right.
In every case I have read about where people have wanted to tweak or adjust
how the hybrid system operates, their desire has been to have the vehicle
run in pure electric mode for a longer period or distance. I believe that
Priuses sold in the UK have an EV button that forces the vehicle to operate
in electric mode as long as possible, and that real world fuel economy
changes very little by using that mode often.
Unbelievable! 11 answers and counting and no-one answers my original
question! Are you all a bunch of politicians!?!?!?!
OK, enough ranting....
Ignoring, increased wear and tear on the batteries or engine, total energy
equations involving my old coal powered power plant; and any disturbances in
subspace temporal harmonics....
DID THE EV only switch increase peoples mileage? and by how much?
"Ray O" <rokigawaATtristarassociatesDOTcom> wrote in message
Did you actually READ all the responses, to your questions and
the others you no doubt found when you no doubt Googled on the
recent traffic in this NG, and THINK about them?
The implication was that it's not worth doing. The car is set
to care for itself and the battery. "Mileage" is another word
for "efficiency" in this context. Greater efficiency turns on
making better overall use of the fuel put into the tank. Read
my past posts on my EV experiments (see recent Google). EV is
purely there to solve local problems unrelated to efficiency.
GOT IT? Thank you. That ends this party political broadcast.
" Did you actually READ all the responses, to your questions and
the others you no doubt found when you no doubt Googled on the
recent traffic in this NG, and THINK about them?"
YES I DID. I have googled, I have read; that's why I included the reference
to coal powered electric plants. (Of course, being an old fart, I may have
missed "IT".) What I concluded is that in other countries the EV switch is
provided by Toyota. Why? Is it because using it will improve gas mileage?
I have noticed that the ICV in my Prius runs way more often than I expected,
and for more than just recharging the batteries. The cute animation in the
LCD display clearly shows that most of the time the ICV is powering the
wheels, i.e., providing more power than the electric motor by itself can
provide. I am suspicious that this is done so as to improve the Prius's
"drivability" in the US; i.e., greater acceleration. Us Americans are
accustomed to "tearing" away from the traffic light. While in other
countries slower accelerating vehicles are more the norm. I have also
noticed that when I take my foot off the gas after a stop the Prius 'creeps'
just like a normal automatic transmission ICV only vehicle (something that a
manual transmission driver does not need). Again, a feature to improve
drivability at the expense of mileage.
Given that it is well known that jack-rabbit starts result in significantly
lower gas mileage vs a more constant power curve, I would be willing to
accept slower starts for more gas mileage. Ergo, my interest in an EV
switch. It is also well known that an ICV engine runs much more
efficiently at a specific RPM where it generates maximum torque per gallon
of gas; so it would make sense to operate the ICV at that speed exclusively
for recharging the batteries and never for pulling the vehicle. That is why
railroads use diesel-electric engines as opposed to diesel only engines.
(Why tractor trailers don't also do this is a mystery to me.) (Yes there is
a point where the diesel engine generates electricity as fast as the
electric drive wheels consume it and that point varies with each engine
based upon its expected use.)
So back to my original question: Has anyone installed an EV switch and used
it long enough (a year or more) and noticed a marked improvement in gas
mileage (10% or more).
(Why 10%? Because that show much I improved my Bonneville's mileage simply
by using my cruise control as much as possible to accelerate the vehicle and
maintain a more constant speed than I myself could do on the highway.)
BTW; I am a Physicist by training. I am not interested in "Implications" I
"R PRINCETON" writes:
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