Electric cars

[metspitzer]

Every time the price of gasoline goes up a penny it costs the US
Postal Service $8 million

http://www.foxnews.com/story/0,2933,367187,00.html

}

It is my understanding that stop and go driving is what electric cars
do best. I would think the post office would be the best candidate
for electric cars, at least in heavy populated areas.

 

[bud--]

But with an electric car you can use the motor as a generator and do
regenerative braking converting most of the kinetic energy back to
electrical energy in the battery. In a conventional car the kinetic
energy is lost as heat in the brakes.

 

[James Sweet]

high volume stop starts are energy wasteful, overall efficiency drops
rapidly the more an electric vehicle has to stop and start.....electric is
best on long straight runs even more so if this includes batteries.

That's true of any vehicle, if you have a lot of stops, an electric
vehicle should have advantages in that the engine doesn't need to idle
while the vehicle is stopped.

 

[[email protected]]

|
| pat wrote:
|> high volume stop starts are energy wasteful, overall efficiency drops
|> rapidly the more an electric vehicle has to stop and start.....electric is
|> best on long straight runs even more so if this includes batteries.
|>
|
|
| That's true of any vehicle, if you have a lot of stops, an electric
| vehicle should have advantages in that the engine doesn't need to idle
| while the vehicle is stopped.

That and the brakes can return most of that energy back to the batteries.

 

[James Sweet]

|
| pat wrote:
|> high volume stop starts are energy wasteful, overall efficiency drops
|> rapidly the more an electric vehicle has to stop and start.....electric is
|> best on long straight runs even more so if this includes batteries.
|>
|
|
| That's true of any vehicle, if you have a lot of stops, an electric
| vehicle should have advantages in that the engine doesn't need to idle
| while the vehicle is stopped.

That and the brakes can return most of that energy back to the batteries.

In theory, yes, in practice, I don't know how much actually makes it
back into the batteries. I suspect dynamic braking is much more
effective in long steady braking such as descent down a long hill than
in small, low speed stops. I have no data to back this up though and
would be curious to see real world measurements.

 

[James Sweet]

Don't use them at those temperatures.

Where does it get to 50 below?

Certainly in most of the populated areas of North America the
temperature range would not be an issue.

 

[metspitzer]

What happens when it goes to 50 Degrees F below zero? I suppose the
batteries will have to be heated, and that will cost more than they
save.

Don't use them at those temperatures.

 

[Don Kelly]

----------------------------

Where does it get to 50 below?

Certainly in most of the populated areas of North America the
temperature range would not be an issue.- Hide quoted text -

- Show quoted text -

Fairbanks, Alaska it gets 50 below in the winter and has freezing
temperatures for six months out of the year. We use electric battery
blankets, head bolt and transmission heaters in the winter. It used
to cost about $100 a month to plug in a car from October to March, but
that cost has risen by about 50 percent. Battery powered cars are out
of the question here. The same applies to solar power and wind
power. There are about 100,000 people living noth of the 63 meridian
that have this problem in Alaska.


----------------

Do you use in hose water heaters? - I have found these to be more effective
than the typical block heater in that they set up a natural convection of
"hot" water. While having only occasional experience of -50, I remember
many -40 days in Alberta, Manitoba and Quebec. Now, on Vancouver Island, it
is much balmier so these memories do fade. Through places like Juneau and
Ketchican, electric cars would work and as there isn't far that you can
drive there-they might do quite well.

 

[James Sweet]

Fairbanks, Alaska it gets 50 below in the winter and has freezing
temperatures for six months out of the year. We use electric battery
blankets, head bolt and transmission heaters in the winter. It used
to cost about $100 a month to plug in a car from October to March, but
that cost has risen by about 50 percent. Battery powered cars are out
of the question here. The same applies to solar power and wind
power. There are about 100,000 people living noth of the 63 meridian
that have this problem in Alaska.

That's a pretty tiny minority of the population really, and a special
case for sure. With a population of over 300 million, 100k is but a drop
in the bucket, and I'll stand by my assertion that for the vast majority
of the population, the temperature is not an issue. Obviously not
everyone everywhere could get by with an electric vehicle, but the same
can be said of any type of vehicle.

 

[bud--]

In theory, yes, in practice, I don't know how much actually makes it
back into the batteries. I suspect dynamic braking is much more
effective in long steady braking such as descent down a long hill than
in small, low speed stops. I have no data to back this up though and
would be curious to see real world measurements.

The only hybrid I have looked at is a Prius. It is rated 48 mpg city, 45
highway - the regenerative braking must be pretty good. The brakes are
smaller than they would be on a 'normal' car. If you stop too fast, less
energy is captured. (Driving stupidly in a 'normal' car lowers gas
mileage too.) On very long descents you can capture more energy than the
battery capacity. For that there is a mode that runs the engine for
compression braking.

 

[James Sweet]

The only hybrid I have looked at is a Prius. It is rated 48 mpg city, 45
highway - the regenerative braking must be pretty good. The brakes are
smaller than they would be on a 'normal' car. If you stop too fast, less
energy is captured. (Driving stupidly in a 'normal' car lowers gas
mileage too.) On very long descents you can capture more energy than the
battery capacity. For that there is a mode that runs the engine for
compression braking.

For all the cool technology it contains, I'm afraid I'm just not
impressed by the Prius. When I was a kid, my parents had a Mercury Topaz
diesel that got 55-60 mpg, and that was 25 years ago. 100 mpg would
pique my interest, but 45-50 is old hat, even with current fuel prices
it's more economical to drive a conventional car and not have the
complexity of two powerplants, batteries, computers, etc. I suspect
these things will be a nightmare when they reach 10 or so years old and
the batteries are failing.

 

[daestrom]

Where does it get to 50 below?

Certainly in most of the populated areas of North America the
temperature range would not be an issue.

While not Fairbanks, we often get temperatures in the mornings that
are -10F. New York isn't known for its cold weather, like some other
states, but I wonder how the batteries would fair at -10F in the morning.

daestrom

 

[daestrom]

I think there are other northern states where batteries would be a
problem including Montana, Minnesota, North Dakota, Michigan and
Wisconsin.
For these new hybrid cars to be accepted they will have to operate in
freezing temperaures of at least 20 degrees F below zero.

Growing up in Michigan, I can attest that it gets colder here in NY.
Michigan has the Great Lakes to help moderate the temperatures of any artic
air coming down from Canada. International Falls, Minnesota is often in the
news as a cold place. And here in New York we see -10F to -20F a few times
each winter.

daestrom

 

[krw]

While not Fairbanks, we often get temperatures in the mornings that
are -10F. New York isn't known for its cold weather, like some other
states, but I wonder how the batteries would fair at -10F in the morning.

Something like C/2 for every -10C, no? So range gets to be a
serious problem in the winter for much of the US. BTW, I lived in
NW VT for 15 years. Most years there are a couple of weeks were the
lows are in the -20F range and the highs 0F, or below. Not a good
place for batteries, though never froze one like my brother in
Minneapolis did.

 

[James Sweet]

Something like C/2 for every -10C, no? So range gets to be a
serious problem in the winter for much of the US. BTW, I lived in
NW VT for 15 years. Most years there are a couple of weeks were the
lows are in the -20F range and the highs 0F, or below. Not a good
place for batteries, though never froze one like my brother in
Minneapolis did.

How about the numbers for NiMH? I don't think lead-acid is a serious
contender for electric cars anymore. If the prices of Li-Ion would drop,
performance and range could approach that of gasoline cars.

 

[[email protected]]

| Gerald Newton wrote:
|>>> Fairbanks, Alaska it gets 50 below in the winter and has freezing
|>>> temperatures for six months out of the year. We use electric battery
|>>> blankets, head bolt and transmission heaters in the winter. It used
|>>> to cost about $100 a month to plug in a car from October to March,
|>>> but that cost has risen by about 50 percent. Battery powered cars
|>>> are out of the question here. The same applies to solar power and
|>>> wind
|>>> power. There are about 100,000 people living noth of the 63 meridian
|>>> that have this problem in Alaska.
|>>
|>>> ----------------
|>>
|>> That's a pretty tiny minority of the population really, and a special
|>> case for sure. With a population of over 300 million, 100k is but a
|>> drop in the bucket, and I'll stand by my assertion that for the vast
|>> majority of the population, the temperature is not an issue.
|>> Obviously not everyone everywhere could get by with an electric
|>> vehicle, but the same can be said of any type of vehicle.
|>
|> I think there are other northern states where batteries would be a
|> problem including Montana, Minnesota, North Dakota, Michigan and
|> Wisconsin.
|> For these new hybrid cars to be accepted they will have to operate in
|> freezing temperaures of at least 20 degrees F below zero.
|
| Growing up in Michigan, I can attest that it gets colder here in NY.
| Michigan has the Great Lakes to help moderate the temperatures of any artic
| air coming down from Canada. International Falls, Minnesota is often in the
| news as a cold place. And here in New York we see -10F to -20F a few times
| each winter.

I understand that they are doing a lot of alternative electric cars in
Iceland these days, due to the cheaper hydrothermal energy sources.

 

[krw]

How about the numbers for NiMH? I don't think lead-acid is a serious
contender for electric cars anymore. If the prices of Li-Ion would drop,
performance and range could approach that of gasoline cars.

I'm sure someone has better numbers, but chemical activity is
temperature dependent. IIRC it doesn't matter much what the
reaction is.

 

[bud--]

True. But the energy gained is, IMO, somewhat exagerated. In true "stop &
go" driving when you want to "stop" you want to STOP and you don't want to
screw around with "slowing down" with regenerative braking first.
Regeneration would work best on a long downhill stretch (without STOPPING)
after a long uphill stretch.

In my normal driving I don't make many fast stops. Prius has smaller
than normal brakes because of regenerative braking. And the city mpg
(stop and go)is better than highway. Regeneration must be quite effective.

A hybrid has many of the same advantages although unless the power
management is somewhat predictive the cells might already be at 100% charge
when the regenerative braking is call upon.

I read Prius wants to keep battery charge between 40 and 60% of capacity
because it gives longer battery life (NiMH). I suspect on a long descent
they would run it up to 100%.

 

[krw]

In my normal driving I don't make many fast stops. Prius has smaller
than normal brakes because of regenerative braking. And the city mpg
(stop and go)is better than highway. Regeneration must be quite effective.

There is no benefit to a hybrid at highway speeds because the engine
has to run anyway. .,..and you're lugging the weight of the
batteries along for no benefit.

I read Prius wants to keep battery charge between 40 and 60% of capacity
because it gives longer battery life (NiMH). I suspect on a long descent
they would run it up to 100%.

I would seem to be a *LONG* descent charge .4C or the batteries are
too small to be of much use.

 

[bud--]

There is no benefit to a hybrid at highway speeds because the engine
has to run anyway. .,..and you're lugging the weight of the
batteries along for no benefit.

..
You can use a smaller engine, with battery/electric motor added for when
you need more power - acceleration, ascent. (For a very long fast ascent
where battery assistance is required you can run out of battery.) The
smaller engine operates at a more efficient point. The benefit - around
44 mpg highway for a Prius.

And with a conventional car you are lugging the weight of the higher
horsepower of the engine that is not being used most of the time.

In a Prius, at higher speeds the engine - through the transmission -
does not turn the wheels fast enough. One of the 2 electric motors is
used as a generator feeding the 2nd motor. That operates through a
planetary drive to increase the wheel speed. [See Hybrid Synergy Drive
in Wikipedia.]

The engine, by the way, is a variation that uses an Atkinson cycle
(which I had never heard of).
..

I would seem to be a *LONG* descent charge .4C or the batteries are
too small to be of much use.

..
Design of anything is a series of trade-offs.