Honda Car Forum

hybrids don't just work by capturing braking energy.

They run a more fuel efficient cycle with a longer expansion stroke.
The Miller/Atkinson cycle. They can do this because acceleration is
supplemented by the battery. They also have a smaller engine b/c it
can use batteries to accelerate.

By using the Miller cycle they get a higher % of energy out of the gas
and into the drivetrain.

It's very ingenious.

Hydrogen is probably never going to "be here". You need a fuel source
to get hydrogen. Hydrogen is very hard to transport (harder than
natural gas which is difficult enough) and there are no cheap "fuel
cells". The advantages of a liquid fuel are great.

I think the next step is using a smaller gas engine and a
larger/cheaper battery that you can plug in. You could plug it in for
an hour a night and that would take you maybe 30-40 miles. On longer
trips and under acceleration the gas engine would turn on. That way
you'd be replacing gas with electricity, which can come from
nuclear/coal/wind whatever.

"Elmo P. Shagnasty" <elmop@nastydesigns.com> wrote in message
news:elmop-811E23.13304108112005@nntp2.usenetserver.com...
> But what problems do they solve, and what other solutions are there for
> the same problems?
>
> They solve exactly one problem: recapturing braking energy to re-use on
> acceleration. There's only one place where that works: city driving.
>
Regenerative braking is very far down on the list of values in
hybridization. The essential purpose is to use the primary power source more
efficiently. Putting a 240 hp engine in a passenger car to cruise around
town at 35 mph is extremely inefficient. Using a 50 hp engine to do that is
far more efficient, but responsiveness suffers badly. We are in the infancy
of hybridization now, but as the power technology advances a 50 hp hybrid
can be more efficient than a 50 hp conventional car and provide better
responsiveness than a 240 hp conventional car. The difference is made up by
stored electric power.

In actuality, a car would have to be pretty small to warrant only a 50 hp
engine. The design becomes straightforward, though. The power necessary to
climb a 6% grade at the prevailing maximum speed (75 mph in the US) at
maximum gross weight is exactly the engine power needed. For a mid-size car
that is in the 100 hp range, maybe slightly less.

The side effects of running the engine at higher power levels are valuable,
too. Hybridization increasingly separates the engine from the driver
control, so there are no issues with suddenly mashing the accelerator.
Emissions are much easier to control as the engine comes under computer
control.

I can understand why there isn't a lot of enthusiasm for the current
generation of hybrids. Not only do they have a limited track record, the
level of hybridization is not enough to knock anybody's socks off. (Well,
mostly not. See Honda's DualNote
http://world.honda.com/Tokyo2001/auto/DUALNOTE/ for a glimpse of what is
possible.)

Mike

"Mike Hunter" <mikehunt2@mailcity.com> wrote in message
news:n02dnUi0CLdClOzeUSdV9g@ptd.net...
> My satellite phone has the same type of battery as used in the Pruis. It
> is about the size of a thick postage stamp and it costs $52 to replace.
>
>
>
> mike hunt
>
Your battery has the same basic chemistry, but is a very different animal.
In portable electronics the most important design characteristics are power
density, light weight, barely affordable replacement cost, and short,
spectacular life. The last two are economic considerations. In the Prius
power density and light weight are not very important at all, the
replacement cost is what it is (since it is not designed to be replaced),
and the life is designed to match the life of the rest of the car. If you
were willing to have a much larger and heavier battery that used only a
third of its potential capacity, and a very sophisticated and expensive
charger that was always connected to a charging source when the battery was
in use, your battery could easily outlast your satellite phone. I doubt you
would like it, though.

Mike

"Mike Hunter" <mikehunt2@mailcity.com> wrote in message
news:ck2dnfJ60v3MluzeUSdV9g@ptd.net...
> Wanna bet the replacement cost is prorated, not fully covered by the
> warranty?
>
> mike hunt

Nope - 100% covered.

Mike

So you would like us to believe the useful life of a Pruis is 8yr 100K? A
Corolla that can be had for 5,000 less will easily last to 200k or more,
don't you think All the more reason one would be better off buying a
Corolla

mike


"Michael Pardee" <michaeltnull@cybertrails.com> wrote in message
news:cLGdnfHveeaTtOzeRVn-rw@sedona.net...
> "Mike Hunter" <mikehunt2@mailcity.com> wrote in message
> news:n02dnUi0CLdClOzeUSdV9g@ptd.net...
>> My satellite phone has the same type of battery as used in the Pruis. It
>> is about the size of a thick postage stamp and it costs $52 to replace.
>>
>>
>>
>> mike hunt
>>
> Your battery has the same basic chemistry, but is a very different animal.
> In portable electronics the most important design characteristics are
> power density, light weight, barely affordable replacement cost, and
> short, spectacular life. The last two are economic considerations. In the
> Prius power density and light weight are not very important at all, the
> replacement cost is what it is (since it is not designed to be replaced),
> and the life is designed to match the life of the rest of the car. If you
> were willing to have a much larger and heavier battery that used only a
> third of its potential capacity, and a very sophisticated and expensive
> charger that was always connected to a charging source when the battery
> was in use, your battery could easily outlast your satellite phone. I
> doubt you would like it, though.
>
> Mike
>

"Mike Hunter" <mikehunt2@mailcity.com> wrote in message
news:NHydnV8_052qrezeUSdV9g@ptd.net...
> So you would like us to believe the useful life of a Pruis is 8yr 100K?
> A Corolla that can be had for 5,000 less will easily last to 200k or more,
> don't you think All the more reason one would be better off buying a
> Corolla
>
> mike

No - the *warranty* is 8 yr/100K miles. Engine warranties (like the one in
the Corolla) are typically 3 yr/36K miles, but I'm sure you expect more.

Mike

C. E. White wrote:

>>See: http://www.directron.com/batteryterms.html
>>
> The Prius does not use NiCads. It uses nickel-metal hydride (NiMH)
> batteries. And the Prius system only discharges htem to about 80% of
> capacity. These batteries have very good life, and the limited dicharge
> enhances this further. I believe that in normal usage, you can expect the
> battery to last 150,000-200,000 miles.

We shall see. NiMH batteries typically have a reduced charge cycle
lifetime compared to NiCADs. That is one reason NiMH never caught on in
power tools where a contractor might cycle a battery several times per day.

Lifetime in cars is going to be highly variable depending upon usage
patterns and random manufacturing variations.

John

Michael Pardee wrote:
> "Elmo P. Shagnasty" <elmop@nastydesigns.com> wrote in message
> news:elmop-811E23.13304108112005@nntp2.usenetserver.com...
>
>>But what problems do they solve, and what other solutions are there for
>>the same problems?
>>
>>They solve exactly one problem: recapturing braking energy to re-use on
>>acceleration. There's only one place where that works: city driving.
>>
>
> Regenerative braking is very far down on the list of values in
> hybridization. The essential purpose is to use the primary power source more
> efficiently. Putting a 240 hp engine in a passenger car to cruise around
> town at 35 mph is extremely inefficient. Using a 50 hp engine to do that is
> far more efficient, but responsiveness suffers badly. We are in the infancy
> of hybridization now, but as the power technology advances a 50 hp hybrid
> can be more efficient than a 50 hp conventional car and provide better
> responsiveness than a 240 hp conventional car. The difference is made up by
> stored electric power.

One problem with that is the fact that the stored electric power
eventually runs down. It would not be fun to be in the passing lane on
a long uphill section of road going around a vehicle only to discover
that your battery storage has just been exhausted and that the available
torque is suddenly reduced 50%. Yikes!

One thing hybrids bring into the equation is a significant depenence on
near term prior history to a degree which conventional engines do not.

John

"John Horner" <jthorner@yahoo.com> wrote in message
news:Iedcf.54339$An6.619@trnddc08...
> Michael Pardee wrote:
>> "Elmo P. Shagnasty" <elmop@nastydesigns.com> wrote in message
>> news:elmop-811E23.13304108112005@nntp2.usenetserver.com...
>>
>>>But what problems do they solve, and what other solutions are there for
>>>the same problems?
>>>
>>>They solve exactly one problem: recapturing braking energy to re-use on
>>>acceleration. There's only one place where that works: city driving.
>>>
>>
>> Regenerative braking is very far down on the list of values in
>> hybridization. The essential purpose is to use the primary power source
>> more efficiently. Putting a 240 hp engine in a passenger car to cruise
>> around town at 35 mph is extremely inefficient. Using a 50 hp engine to
>> do that is far more efficient, but responsiveness suffers badly. We are
>> in the infancy of hybridization now, but as the power technology advances
>> a 50 hp hybrid can be more efficient than a 50 hp conventional car and
>> provide better responsiveness than a 240 hp conventional car. The
>> difference is made up by stored electric power.
>
> One problem with that is the fact that the stored electric power
> eventually runs down. It would not be fun to be in the passing lane on a
> long uphill section of road going around a vehicle only to discover that
> your battery storage has just been exhausted and that the available torque
> is suddenly reduced 50%. Yikes!
>
> One thing hybrids bring into the equation is a significant depenence on
> near term prior history to a degree which conventional engines do not.
>
> John

It's all a matter of design. In your example, a properly designed hybrid
will not run out of passing power because the engine power was enough to
maintain full legal speed, while passing power is available because it was
not needed to reach the cruising speed. A major reason multi-hundred
horsepower engines are used in passenger cars today is to provide that
margin, in spite of the economy penalty the vast majority of the time.

Even in the previous generation Prius - the one we have - our battery has
never dropped to "empty" (actually something like 50% charge) although we
live at 7000 feet and have made trips with ful load to Washington state and
the LA area. I've never heard anybody complain about that happening, either.
It just isn't a problem.

Mike

"John Horner" <jthorner@yahoo.com> wrote in message
news:m9dcf.54217$An6.8868@trnddc08...
> C. E. White wrote:
>
>>>See: http://www.directron.com/batteryterms.html
>>>
>> The Prius does not use NiCads. It uses nickel-metal hydride (NiMH)
>> batteries. And the Prius system only discharges htem to about 80% of
>> capacity. These batteries have very good life, and the limited dicharge
>> enhances this further. I believe that in normal usage, you can expect the
>> battery to last 150,000-200,000 miles.
>
> We shall see. NiMH batteries typically have a reduced charge cycle
> lifetime compared to NiCADs. That is one reason NiMH never caught on in
> power tools where a contractor might cycle a battery several times per
> day.
>
> Lifetime in cars is going to be highly variable depending upon usage
> patterns and random manufacturing variations.
>
> John

The Prius first went on sale in Japan in 1997, 8 years ago. I don't have
solid information, but AFAIK no reports have come out about failures of
those batteries.

As you say, we shall see.

Mike