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Re: [OM] Jeepless in Seattle

Subject: Re: [OM] Jeepless in Seattle
From: Ken Norton <ken@xxxxxxxxxxx>
Date: Fri, 1 Jul 2016 15:01:39 -0500
> I’m pleased for you and your family, Ken; it sounds like a very satisfying 
> purchase.

Obviously, there could be unknown unknowns that scream "lemon", but
the miles are good and it as an older couple that had it. Fortunately,
PP (Problem Prius) are extremely rare.


> In addition, I find the longevity of the batteries really interesting, 
> considering the various arrangements that different manufacturers have 
> adopted for the batteries; leasing them, providing guaranteed replacements 
> etc . .. (as I understand it).  But you have mentioned a couple of times how 
> well the Prius batteries last.

The Prius is somewhat unique in that it still uses NiMH type batteries
that don't age out like the Lithium type batteries do. And Toyota
adopted a VERY conservative approach to battery usage that doesn't
deep-cycle them as much uses a narrower usable band. Obviously, the
plug-in hybrid is an exception to this and the new 4th gen Prius
builds upon that and only uses the NiMH for the lesser models and
fleet vehicles.


> But I’ve recently discovered that there is a problem of pollution with 
> electric cars, even pure electric...

So, let's address a few of the points here--specific to the Prius,
applicable in various forms to others:

1. Weight. The Traction Battery in the 3rd generation Prius weighs
about 93 pounds. Not much more than the standard car battery. The
standard car battery in the Prius is a fraction of the size/weight of
a normal car battery. The fuel tank of the Prius is half the size of
comparable cars. You are carrying around about 10 gallons less, on
average, than the comparable car. That's about 60 pounds. So, just
looking at the weight delta between the standard car batteries and
fuel carriage, the cars are actually weighing the same. In fact, our
fully loaded Prius comes in at under 3100 pounds. Hardly porky. The
smaller Toyota Corolla, similarily equipped is over 2800 pounds and
significantly more cramped. Besides, the "weight penalty" for gas
mileage is almost wiped out because of the charging of the traction
battery as a result of slowing down and braking. So, while you use a
tiny fraction more energy to get the car up to speed, you recover some
of that slowing back down. A non-hybrid vehicle recovers none so the
weight penalty is effectively 100%. And weight has no bearing on speed
maintenance and depending on wind conditions can actually improve gas
mileage when maintaining speed. We experience such minor gas mileage
differences in our vehicles based on loading that I think that the
weight penalty calculation is pretty much a farce. Seriously, the
difference between one person in the car and four people in the car is
about one mile per gallon. That's a 2% hit. And that's really been
worse case. If the wind is blowing us around, the gas mileage is
better if there is a car load of people.

2. Speaking of regeneration. So, as you approach an intersection where
you have to stop, if you don't jam on the brakes like a teenage boy
who just spotted a pretty girl, the electric motors (which are
dual-mode) will go into generator mode and will produce drag through
the generation of electricity which goes right to the battery. If you
are a light touch on the brakes, the brake pads will never actually
engage. If you are really good with the brakes and coast, you can
generate 50Wh from a single stop from highway speed. However, the
vehicle is also smart enough to recognize icy conditions and will
balance the rear brakes with the front engine-drag braking to keep
from skidding wheels. Beyond a certain point, the brake pads will
start to engage, and under heavy braking, it's pretty much all brakes.

3. The BMW system for non-hybrid vehicles is pretty slick. My 2004 X5
4.4i has an earlier generation of this technology that BMW didn't
market yet, but the later versions are quite slick. It basically is
selective in how it engages the alternator and the air conditioner.
When accelerating, they shut off, providing no engine drag, but will
reengage when there is surplus energy coming from the engine itself.
While not "officially" having this technology, my 4700 pound 4 wheel
drive SUV with a 315hp V8 gets 28 mph if I'm being a good doobie. 0-60
in a hurry if I'm not being a good doobie with a top speed somewhere
north of insane.

4. Tire wear. Not sure I buy this one. Tires meant for hybrids and EV
vehicles tend to be of a very hard compound, are pumped up to scary
air-pressures and provide as much tire life as anything else out
there. Sorry, but this one doesn't pass the smell test.

5. Exhaust. Now, this can be a problem, but depends on the vehicle. In
the case of the Prius, the gas engine is meshed into the CVT
drivetrain in such a way that it is able to run at pretty much any
speed, regardless of what the final-drive shaft is. The gas engine
runs only at a couple different speeds and everything is specifically
tuned for maximum horsepower per energy input. No need to have a wide
power band, but instead build the motor so it only runs at a couple of
different RPMs. The engine has zilch torque--that's provided by the
electric motor. Anyway, what happens is that the engine is able to be
very efficient as it never just idles, nor does it need to handle much
stress. To keep the engine warm, the coolant is stored in a thermos
and cycled through the block to keep it up to temperature so it
doesn't temperature cycle while you are driving. When you shut the
engine off to park, it puts all the coolent in the thermos for keeping
it as warm as possible for as long as possible. When you start the car
back up, it moves back into the system and engine to get things back
into efficient operation as quickly as possible. All the mechanicals
are electric drive. Air conditioning, power steering, power brake
booster pump...

6. Recycled bits. If you view 100% of the vehicle as zero
recycle/reuse, they are HORRIBLE. The rare earth elements used in the
electric motors and magnets are criminal. But when you factor in that
these parts are totally recycled (quite the bounty on these parts, as
well as the batteries), reused and recovered, it's pretty much like
aluminum, where the energy required to create aluminum is offset by
the unending recycling of it where melting it for reuse is a fraction
of the energy used to create it.


> I really fancy the electric BMWs, although I could afford only the i3.  If 
> only the range were a little better.

I've got the hots for the i8. Drool.

The Prius is a rather unique vehicle among the hybrids, though. It is
a car that is actually very feature rich for the class of vehicle it
is. It is a platform where a lot of prototypical type of features or
technologies or engineering designs are implemented first before
pieces of them are made available in other vehicles. For example, the
engine shutoff and the thermos are now becoming standard on most
vehicles. The energy recovery, while used for the traction battery in
the Prius is now used for the house battery in the BMWs. The electric
steering and air conditioning compressor, and so forth...

AG
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