Monthly Archives: October 2013

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Why the Skinny Tires?

One of the most-asked questions I get about my i-MiEV is what’s with the skinny tires on this car?

With EVs, we focus mostly on efficiency, since we don’t have capacity to burn. My wife’s new car, a Jeep Compass, has large, 235 section, 16″ tires. Those were the second-largest available on the car. Each one weighs around 40 pounds, mounted on the wheel.


Jeep Compass with 16″ wheels

Maybe we should be asking this another way: Why do gas-powered cars have such large tires? The answer? Because they look cool. There is no reason a 3,097 pound vehicle should need 235-55R16 tires. Tires that wide were the size of the rear tires on the ’82 Corvette.

The Vette needed wider tires to get the power to the road. Why does a Jeep need ’em? Because they look cool.

What are the penalties of having these heavier tires? The first is “unsprung weight”. This means a part of the car that doesn’t have a suspension component between it and the road. Since the tires touch the road, they are considered unsprung weight.

Colin Chapman, one of the founders of Lotus Engineering, Ltd., was meticulous about unnecessary weight, specifically unsprung weight. (Here is a great reference.) He knew that not only does a heavy car burn more gas, it’s slower. Lotus vehicles are well known for Colin’s penchant for “adding lightness”.

Gas-powered cars can get away with these wastes of energy because they have energy to burn — literally. EVs don’t have this luxury. Hence, the skinny tires. Tires used on EVs are lighter (for less unsprung weight), skinnier (for less aerodynamic drag), and have lower rolling resistance (for better range, but lower traction).

The BMW i3 has an interesting work-around: BMW uses skinny tires, but large diameter. This allows for a 16″ tire-sized contact patch (the part of the tire that actually touches the road at any one time) in a 19″ tire, but with the lower aerodynamic losses. I just don’t want to see how much they cost to replace.  🙂

To Lease or Not To Lease… That is the Question!

Leasing has a bad rap. Why would you ever pay month after month with nothing to show for it? And yet, more and more people are renting their apartments, doing just that.

What do they know that we don’t?

Well, renting an apartment has benefits: You can move when you want (if you have a month-to-month lease!), you don’t have to pay for maintenance, and you don’t have to mow the lawn. However, at the end of your lease, you have nothing to show for it.

Is it just as bad for leasing a car? Yes and no.

For a regular gas-powered vehicle, leasing may not be the best idea, unless you want to have a new car every 2-3 years and don’t mind a continual car payment. During the first few years of car ownership, there is typically very little maintenance past standard scheduled maintenance. You also get to have the latest new car with new technology. At the end of the lease, if you really like your car, you can buy it outright, making those lease payments more of a down payment over time.

For electric vehicles, leasing is ideal. Why? Today’s EVs typically go fewer than 100 miles per charge. This is continually improving though. With improvements in battery technology, 100 miles per charge will be laughable in just a few years from now. How do we avoid this accelerated obsolescence? Leasing.

Purchasing an EV when you drive very few miles per year and you don’t live in a hot climate isn’t such a bad idea. You typically make the price difference between a gas-powered car and an EV in 5-6 years. If you do drive many miles or live in a hot climate, battery life will decrease faster than expected, and your car’s usable range will be less than you may need.

Leasing helps avoid this by giving you not only a new car every few years, but a new battery. This is worth having a continual car payment, don’t you think?

Regenerative Braking vs. Coasting

Every topic must have some sort of polarized discussion. Mac vs. PC. Republican vs. Democrat. Solar vs. Nuclear. Well, regenerative braking vs. coasting is the electric vehicle discussion.

Earlier, we discussed what regenerative braking is, so I won’t cover that any further. Coasting? Well, that should be fairly clear. It is shifting the car into neutral while the car is moving.

Benefits of regenerative braking:

  • You get some of your inertial motion energy back as battery power — usually around 70%.
  • Saves wear and tear on brakes. In truth, with high levels of regenerative braking, your brakes should last the life of the car.
  • Allows for one-foot driving. You can accelerate and decelerate using just your accelerator pedal.

Benefits of coasting:

  • 100% of your forward momentum is left alone. Only aerodynamic and frictional losses reduce your forward momentum.

Disadvantage of regenerative braking:

  • Unless you’re very careful with your accelerator, it’s easy to be continually using energy then gathering energy back and forth. This isn’t as efficient as coasting.
  • Getting used to one-foot driving takes some time and practice.

Disadvantage of coasting:

  • You have to shift the vehicle into neutral. In emergency situations, you could not accelerate out of harm’s way without shifting back into a driving mode.
  • Doesn’t work well in stop-and-go traffic situations.

There you have it. Arguments for and against both sides. As for me, since I drive in traffic a lot here in Dallas, I use regenerative braking exclusively. In fact, I use the highest setting of regenerative braking and, as a side effect, get city mileage range well beyond the EPA ratings. As always, your mileage may vary.

A LEAF With Double Range?

Recently, at ECOSeries in Spain, Nissan brought three LEAFs to race. Two of them were standard, off-the-lot LEAF models. The third, interestingly enough, was a LEAF with twice the battery capacity — 48kWh instead of 24kWh. While there were no photographs of the interior of the range-doubled LEAF, one must speculate a few things:

  1. Did Nissan just take two full-sized battery packs and stuff them into every nook, cranny, and crevice of the LEAF?
  2. Is Nissan testing a new, higher-capacity battery that is the same volume as the existing pack?
  3. When can I buy it?  😉

A Nissan LEAF with a 48kWh battery makes for some interesting possibilities. Currently, the regular 24kWh LEAF has an EPA estimated range of 75 miles (blended between 80% charging and 100% charging). Doubling that brings us 150 miles. Now, if we consider only 80% charging (for longevity of the battery), the EPA range is 66 miles, putting the doubled pack at 132 miles.

Would this make a difference for most people? Possibly. “100” is a magic number, and if we can get an EV with greater than 100 miles of range, I believe much of people’s range anxiety would be greatly reduced, even if the average trip in a LEAF is still far less than 25 miles.

With the non-range-doubled LEAF, I could make it to and from the airport if I was careful. With the range-doubled LEAF, I could make it with range to spare.

The final question is: When can we buy it?

Are Electric Cars Safe?

Recently, a Tesla Model S caught fire. Some media outlets went crazy, talking about how this is the bellwether that electric cars just aren’t ready yet.

Huh? There are over 150,000 car fires in the US every year and the one Tesla that catches fire is newsworthy?

Tesla, and Elon Musk, responded quickly to this Model S fire, as they should have. Keeping people in the dark is how rumors get started. Elon explained that a piece of metal debris punctured the front of the battery pack with the force of 25 tons.

With that level of force, what would happen to a typical internal combustion engine (ICE) vehicle? Well, what’s in the front of the Model S? A “frunk” and the front of the battery pack. In an ICE vehicle? The engine.


Some family resemblance?

On the left is the Tesla Model S. On the right is the Jaguar XKR. Between the front wheels of the Tesla is where the battery starts. Between the front wheels of the Jaguar is where the ICE resides.

Batteries make power by a chemical reaction. If you’ve ever opened a battery, it’s a black, gooey mess inside. Short-circuiting a battery can make the chemical reaction go crazy, starting a fire. That’s what the metal object did on the Tesla.

Internal combustion engines make power by compressing gas and air together at high pressure, then igniting it with a spark. If you were to open a working engine (don’t try that at home!), you would be sprayed with flaming, high-pressure gasoline.

If the ICE were to be punctured with the same metal object at the same point, the car would be up in flames in seconds. The Tesla? It alerted the driver to a catastrophic failure, and told him to pull over. Only minutes later after the car stopped and the driver exited the vehicle did the Tesla’s battery catch fire.

For me, I would rather have minutes to exit my vehicle than be instantly consumed by pressurized, flaming gasoline.


I believe I’ve been bitten by the “silent” bug. Let me explain:

Ever since I can remember, I have a ringing in my ears. It’s constant — there is no escaping it. Unless I’m paying attention to it, I many times don’t notice. When drowned out by loud noises, it’s imperceptible. Loud noises being a loud TV, radio, or even driving at highway speeds with tire noise.

Now that I have an electric car, however, I’m enjoying the silence of it, even if it means I hear the ringing in my ears a bit more.

When my wife came to live with me, she was astounded how quiet my house was. I live in the city with a highway about 1/2 mile away, a school across the street, and houses within jumping distance of each other. Double-paned windows, brick walls, and carpet throughout the house make mine a very quiet house.

This weekend, my garage door opener finally failed after 30+ years of service. Over the years, I put a lot of “hacks” into place to keep it going. This weekend, however, an irreplaceable part failed. (Try getting parts for a 30-year-old garage door opener!)

I went to the neighborhood home repair superstore and purchased a new garage door opener. Not just any opener, but a very quiet, belt-driven one.

What a difference! I can’t wait to try it tonight — opening the garage door quietly, pulling my silent electric car into the garage, and scaring the you-know-what out of my wife.

I’ll let you know tomorrow if I’m still married.  😉

PS: Yes, I’m still married.

Infinity Miles Per Gallon

Sorry, a bit of a rant here. Chevy Volt owners love to post that their car gets “150 MPG”, “250 MPG”, etc. What they’re failing to account for is the electric element in this equation.

If I carry 1 gallon of gasoline in the back of my i-MiEV (as I did a few days ago to fill up the lawnmower), I am getting infinity miles per gallon!

Are we understanding the silliness? Additionally, if you’re getting 250 MPG in your Volt, are you better off with a 100% electric vehicle instead?

Thank you. I now return you to your previously scheduled program, already in progress.  🙂

100 MPH Standing Still

Most of us agree that the Tesla Model S looks great. It might even look like it’s moving at 100 MPH standing still. Is this just hyperbole? Not if we’re talking about charging!

Here is an interesting calculation you can do to see how fast your car is charging, in miles per hour!

MPH = Range / ((battery capacity in kWh * 1000) / (input voltage * charger output current))

Let’s populate some of these figures and see how “fast” your car can charge:

The OEM EVSE that comes with the Mitsubishi i-MiEV (62 mile EPA range rating) is an 120V, 8A charger. The battery has a 16kWh capacity.

MPH = 62 / ((16 * 1000) / (120 * 8))
MPH = 3.72

Pretty darn slow. For every hour of charging on the L1 EVSE, I get less than 4 miles of range. 4 MPH is walking speed.

Let’s try the L2 charger I have. This is a little trickier since my Clipper Creek charger is rated at 20A, but my car can only charge at 13.75A (3300W).

MPH = 62 / ((16 * 1000) / (240 * 13.75))
MPH = 12.7875

Getting better. We’re up to jogging/running speed.

For you LEAF owners with the new 6.6kW charger:

MPH = 75 / ((24 * 1000) / (240 * 27.5))
MPH = 20.625

Still better. We’re up to sprinting speed.

Even though my i-MiEV doesn’t have an L3 (DC/CHAdeMO) charger, let’s see how fast that will go (assuming the i-MiEV can charge at full CHAdeMO speed).

MPH = 62 / ((16 * 1000) / (440 * 62.5))
MPH = 106.56

Nice. However, CHAdeMO will only allow you to charge to 80% capacity. This should be the same speed as the LEAF’s L3 charger.

Let’s go for broke with the new 120kW Tesla SuperCharger!

MPH = 265 / ((85 * 1000) / (730 * 120))
MPH = 273.11

Granted, there are some educated guesses made, but wow! The SuperCharger actually may be faster than my calculations, but that sure makes a difference.

As always, your mileage may vary. If you’re soft on the accelerator, your charging MPH will increase.

Security Blanket

Although my daughter is too young to utter the words, “I want my bwankee”, let alone talk, I found a study from Germany that shows how much of a security blanket EV drivers want in their cars.

The study asked the subjects how much range they felt they needed in their electric vehicles. For people who drove on average 36 miles per day, they said the minimum range their EV should have is 84 miles. That’s more than double what they really needed.

The subjects were then asked again 3 months later, and their minimum acceptable range dropped to 77 miles. Still more than double what they needed.


I’ve noticed the range anxiety of my car fading away over time as well.

  • Day 1: Had to leave the dealership with about 2/3rds of a charge, due to (my) time constraints. I knew I had some highway miles to drive on the way home, and that highway miles took far more power than city miles. I was constantly looking at my power and charge gauges.
  • Day 30 (approximately): Still using L1 charging because I’m too cheap to buy a L2 charger. As long as I don’t drop below 1/2 charge, I can fully charge my car overnight. I occasionally look at the charge meter but still carefully watch the power gauge.
  • Day 90 (approximately): Got an L2 charger. I make a mental note about where I’m driving, compared to my power gauge, but think little of it anymore. When driving, I don’t watch my power gauge very often.

For me, it took around 3 months to really get over range anxiety. Even then, my anxiety level was quite low, except when I needed to take an emergency 65 highway mile round trip. I did some L1 charging at the mid-point, which ended up being just fine for my trip, returning with 1 bar left on the power gauge. Drafting large trucks also helped. 😉

Autonomous Vehicles

There are several car companies with cars with driving aids. Automatic lane departure warnings. Blind spot warnings*. Automatic braking. My favorite though is the technology that Infinity has available to detect pending crashes 2 cars ahead of you. Impressive!

"Hope you enjoyed your ride!"

“Hope you enjoyed the ride!”

The next step? Fully autonomous vehicles. The movie “Total Recall” (the original one) had an autonomous vehicle called the “Johnny Cab”. Inside this car was the bust of a cab driver, complete with speech recognition and semi-artificial intelligence.

While we don’t have self-driving taxis yet, several auto manufacturers and software companies are working on self-driving personal vehicles. Personally, I think this is a great idea. My wife? Not so much.

Google was one of the first out of the gate with self-driving vehicles. They have a fleet of Toyota Priuses that can go from one location to the next, even on public roads. These cars have driven hundreds of thousands of miles with only two accidents: Both accidents were caused by human drivers crashing into the self-driving vehicles.

Nissan has been making waves recently with demonstrations of a fully autonomous LEAF. The difference here is that Nissan builds the cars, while Google is still just a software company (Motorola acquisition not withstanding). Nissan plans to bring their autonomous technology to the market by the year 2020.

Self-Driving LEAF

Self-Driving LEAF


You can imagine the positives quite easily: Fewer — or no — accidents. Fewer traffic problems. Less fuel used (because the computers will automatically determine the best route). Being able to do other things than driving.

What about the negatives? Now, I’m not concerned about the Terminator-style “robots taking over the world”. I’m wondering about car manufacturers. With fewer accidents, fewer cars will need to be replaced. Will car sharing become widespread? Will the act of driving become extinct?

Either way, I’m looking forward to my first autonomous vehicle. These are exciting times!

* Didn’t stop a Lexus driver from nearly side-swiping me, even though I saw the yellow blind spot alert light in her side mirror. Humans continue to be the weakest link.