The Drive-a-Toyota Act

I think the car has other things for fuel efficiency, like harder tires
for less rolling resistance, better aerodynamic shape, and, I guess, no
alternator, all of which save energy. Plus it has a continuously
variable transmission, which is more efficient that automatic and manual
transmissions. And it has aluminum hood (bonnet for those of you in the
UK) and hatch instead of steel, to save weight.

Cars can also have electrically powered water pumps, power steering
pumps, valves, and compressors for the air conditioners, although I
don't know if any do, yet.

Plus, the Prius uses an Atkinson cycle engine than a regular (Otto) gas
engine, which is more efficient.

Jeff

 

"Elmo ...

The electric motor really helps out the mileage upon speed up with its
assist to the gas engine, and has much less of an effect in the more
steady state of a flat 50 MPH cruise. Actually, if flat, one can use the
electric a bit with a bit of foot tricks, and not lose speed.
Tomes

 

"Jeff" ...

The Prius uses the electrically driven AC. When sitting in traffic on a
hot day and using the AC, it makes the engine run a lot to keep the
battery at a relatively even charge. When 'normally' driven (meaning on
roads without jams), the normal electric generation that the car does from
engine waste and slowing makes AC usage close to 'free' as far as I can
tell.
Tomes

 

Well, you provided an assertion that batteries wear out. While that
may be valid, it's pretty much useless and not terribly persuasive.
Everything wears out, the question is how fast under what use.
Since you claim to be an authority on the subject, perhaps you could
describe to us how to estimate the life expectancy of a battery pack
given a few factors like cycle time, discharge percentage, ambient
temperature, etc.
Maybe a word or two on various charging schemes to extend battery
life?

 

You're welcome!

 

Oh.

Well, then, I'm an authoritative source on Toyota's HSD, and I know for
a fact--based on authoritative sources--that you're full of shit.[/QUOTE]

Care to give a specific example?

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

WTF are you talking about?

I asked you an honest question. Do you have an honest answer?[/QUOTE]

I don't see where you said you didn't see my post with the info. I gave.
If that's what you were implying, sorry - I missed your point. I took
you to be saying you didn't accept the facts I gave as being in the
categroy of authoritative information. Looks like you and I had a
genuine miscommunication there. So maybe we can back the truck up a little.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

Dude, read what I said: I wasn't paying attention, and I asked you what
authoritative information did you give? You have at least partially
answered the question. You so far having fulfilled the "authoritative"
part of it, though.[/QUOTE]

Sorry - I didn't understand that you literally meant you didn't see the
info. I posted - I thought you meant you refused to accept the info.

Again - I didn't know you meant you had not seen what I posted.
Miscommunication there.

Not really. I misunderstood your meaning about not having seen the info.

Toyota's own article contradicts that. But they could have understated
it to take into account a little aging of the batteries, i.e. not brand
new as you stated. But still - two miles ain't much.

You are correct.

So the a.c. is all electric?

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

Great! Can you point to references? Web sites, books, articles?

If you can't, or if you won't...well, leave that as an exercise for the
reader to determine the validity of your statements.[/QUOTE]

Here's one that I have found to be more in depth than a lot of others -
gets more into the nitty gritty of charging and discharging - this page
is one of three parts: http://www.batteryuniversity.com/partone-11.htm

I like this one: http://www.batteryuniversity.com/partone-11.htm
because for years, the manufacturers have been saying on their packaging
(probably still do) that NiMH batteries do not have a memory effect,
which I knew to be a false claim. It's appalling how many supposedly
techincal and "expert" sites on battery technology have swallowed the
"no memory" lie about NiMH. The chemical mechansim for the memory
effect in NiMH is totally different in NiCad's, and it is certainly a
much smaller phenomenon in the NiMH's, but it is a stretch to say that
NiMH has no memory effect.

www.thomasdistriuting has some good technical info. on batteries and
their proper charging, but as a rep. for a manufacturer, they do tend to
leave out certain facts in a marketing kind of way. IIRC, they say that
NiMH do not have memory effect even though they say they have to be
periodically "reconditioned" (which is contradictory to claim both - if
they did not have memory effect, they would not need to be
reconditioned), but other than that they are a good company to deal with
(great source for digicam batteries and chargers - their chargers are
designed to *properly* charge and condition the batteries unlike a lot
of other consumer small battery chargers).

Well constucted Google searches will come up with those and many more
sources of info. on batteries - some of them even have accurate
information.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

An honest question: All those things suck energy whether mechanically or
electricaly powered (and the power has to ultimately come from the IC
engine). For each one, is the electrical version inherently more
efficient than a mechanically powered (belt or gear driven) one?

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

The optimaization that they have done in the charge and discharge limits
for battery life is smart on their part. There's really a lot more to
say on that. But yes - as a circuit designer who has designed battery
chargers inot commmercial equipment and who has tested batteries for
miliatry applications, it is important to play whatever games you can
with the charging algorithms to optimize the parameters that are
important to the application - in this case - battery life.

That's one reason I never just run to WalMart to buy the cheapest
battery charger for my digicams. I get them from Thomas Distributing
because they have done some really good tricks to charge and condition
during the charge cycle without a separate discharge/recondition cycle.

There - ther's "a word or two".

Let's see - oh - with valve-regulated lead-acid (VRLA - absorbed glass
mat) batteries - you have to be careful with traditional lead acid
chargers and alternators - if your charging voltage goes above a certain
level (2.53 volts per cell), you drive it into a dangerous and
potentially damaging hydrogen-oxygen dissociation.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

I think the electrically powered ones of these are usually more
efficient, because they can be more efficiently shot off (even if you
shut off the A/C, there still is loss from friction in the pulleys) and
they operate at the proper speed (the A/C compressor in my car would run
a lot fast if I drive in 3rd gear on the highway instead of 5th).

Plus, I think the generating mechanism on a hybrid means less wasted energy.

Jeff

 

Done.

 

http://www.thomas-distributing.com/index.htm

 

Toyota's own article contradicts that. But they could have understated
it to take into account a little aging of the batteries, i.e. not brand
new as you stated. But still - two miles ain't much.[/QUOTE]

shoot, I was thrilled.

Yes.

The overall engineering of the Prius, once you get into it *and* live
with it for a couple of months, is pretty amazing. They've taken the
gross inefficiencies and managed those out of the system; driving the AC
electrically is one good example.

 

It's not even what I call a transmission, although obviously it performs
the task of one.

The Toyota Power Split Device is so ingenious partially because of its
utter simplicity. It has nothing at all in common with a modern
automatic transmission of any kind.

In fact, changing out from a traditional auto transmission to the PSD is
enough reason to put the batteries in the middle. From a maintenance
standpoint, they've taken out a hugely complex and frail component of
the modern drivetrain and replaced it with something much simpler,
requiring no maintenance, and incredibly less likely to break.

 

An honest question: All those things suck energy whether mechanically or
electricaly powered (and the power has to ultimately come from the IC
engine). For each one, is the electrical version inherently more
efficient than a mechanically powered (belt or gear driven) one?[/QUOTE]

The issue is really the efficiency *at the time the piece is being used*.

It is INCREDIBLY wasteful and noxious-smelling to run the ICE just to
provide idle speed crawling and AC in downtown rush-hour traffic.

If you run the engine at its peak efficiency solely in order to charge
the battery, then shut it down and let the battery crawl the car along
and run the AC, you've dramatically increased the efficiency of and
reduced the waste from the gasoline that went into the system.

An idling engine is very wasteful. Decouple the engine from the things
that are required during "idle" time, and shut it down. Voila.

Whenever I'm downtown and end up sitting there in rush hour, I
experience this very situation. I crawl through the traffic at "idle"
speeds, with AC on, even on hot days, without the internal combustion
engine running at all.

 

CVTs are transmissions.

The PSD is different enough that I would say that it is far more than a CVT.

A far analogy between a PSD and CVT is PSD:CVT::My laptopVD player. My
laptop has a DVD (and I do watch movies on it), but my laptop does far more.

The analogy is also good, because the laptop eliminates redundant
devices, like separate screens for the laptop and DVD and seperate power
supplies.

That's true. But neither do CVTs and automatic or manual transmission,
except power goes into and power comes out at a different ratio (or the
same ratio).

You can also switch to a CVT, which is a really simple device, more
simple than a automatic transmission.

Thanks. Your message prompted me to learn more about how the synergy
drive works.

Jeff

 

CVTs are transmissions.[/QUOTE]

I put the traditional CVT on par with the traditional fluid drive
automatic transmission with respect to complexity and number of failure
points, as well as its proclivity to fail.

The Toyota PSD is way, way, way, WAY different.

 

I don't know what you mean. I've driven the car in 25-30 MPH traffic
where the car didn't start for a good amount of time.