Saturday, November 29, 2014

Level-2 chargers arrive at work

When my company moved me to its consolidated location, I was no longer one of the only electric cars on site.  It would seem that there were nearly a dozen of us.  To accommodate the need to recharge our electric vehicles, the company allowed the electric cars to make use of the various landscaping outlets that could be found around the campus.  These few 110-volt plugs were in high demand and provided very little distance to anyone who connected late in the day.  In my case, six hours of charging would give me about fifteen miles of range, so most of the time it was not worth the effort to hunt down an open outlet.  My employer even made an effort to install three new 110-volt outlets by the main entrance to the facility (which was over ½ mile from my desk), and these three outlets quickly became the most popular on campus.

Then, Tesla released its Model-S sedan and electric cars became fashionable accessories for the executive set.  Two level-2 (220-volt) charges were installed in close proximity to the executive offices, allowing four cars to get a reasonable charge.  One was installed in the small parking lot just outside the executive offices, and the other was installed in the guest parking outside of the new executive reception center.  Neither of these level-2 chargers was convenient for the rest of the workers.  Still, I was able to walk the ten minutes and climb the four levels of terraced buildings to be able to plug in my car.  Even after 4:00 (when the early chargers would rush home), I could still get in about 2.5 hours of charging giving me an extra 25 miles of range.

Luckily for the environment, electric car popularity in Silicon Valley boomed and more electric cars were showing up at work.  Unfortunately for me, that meant fewer opportunities to charge.  At about the same time that my office was moved closer to the original level-2 charges, four new level-2 charge points were added to the campus, bringing the capacity to twelve electric cars charging at the same time.  They also installed solar panels on all the roofs to generate clean electricity.  And, to ensure greater access to all EV drivers, they imposed a limit of four free hours of charging, with subsequent hours being charged a fee (fine?) of $10.00 per hour.  The idea is that the company would help you complete your trip, not provide all of your driving electricity.  Now there are more access points on campus, two of which are fairly convenient, and I am usually able to find a vacant spot after 4:00 for when I could use the extra comfort-zone for my drive home.

Friday, November 21, 2014

Eco versus Drive

Although the electric car comes with a transmission (and a shifter), this is not your traditional transmission.  A gasoline engine cannot stop turning, and its range of efficient operation is more limited than an electric motor.  To work around this, gasoline cars had 2-speed transmissions in the 1950’s, 3-speed transmissions in the 1960’s, 4-speed transmissions in the 1980’s, and so on to the point that Chrysler has released a 9-speed automatic transmission.  All of these transmission speeds (or gears) are designed to improve how a smaller gasoline engine can work harder when needed and slack off while cruising.  To back up, the transmission includes a gears with reverse threading to turn the wheels backwards.  The automatic transmission also includes a slippage mechanism that allows the vehicle to remain at rest while the engine continues to run, costing it low-speed efficiency. 

By contrast, the electric vehicle has just one speed that is always engaged.  This is possible because of several factors.  The electric motor can start turning from a standstill (without a slippage mechanism), and it requires no complicated change of gears to get up to speed.  Also, direction can be controlled by changing electric polarity to the motor, so there is no need for a separate gear for backing up.  So, in an electric car, most of the transmission functionality is handled virtually via an electronic controller.

The "shifter" on my Mistubisih I-MiEV in its usual position (Eco)
Of course, maintaining a familiar set of levers and knobs to operate the electric car makes it easier for most people to adopt.  The Mitsubishi i-MiEV includes a traditional shift lever for selecting the different operating modes (just like a conventional transmission selector) and includes positions for drive (D), economy (E), and brake (B).  These three modes affect the programming of the electric motor controller and how much electricity flows between the motor and battery.  In drive (D), the motor is delivered maximum electric current, but regeneration when not braking is minimized.  In economy (E), the power delivery is slowed, smoothing out accelerator pedal response and reducing energy consumption while increasing the regenerative effect when not braking.  Finally, brake (B) combines the drive (D) mode responsiveness with stronger regeneration than economy (E) and is most useful when driving on long hills.  Note that regeneration is the same in all modes when using the brake pedal.

I usually drive using economy (E) because my route is mostly level and this mode results in a smooth delivery of power.  In addition to increasing my driving range slightly, it makes for very comfortable acceleration and makes it easier to maintain a steady pace on the freeway.  In drive (D) mode, the motor response is more punchy, with more immediate response at slower speeds and making it harder to maintain a steady pace on the freeway.  For nearly all driving situations, economy (E) is the more comfortable, predictable, and economical mode for driving.  This changes the moment I get into stop-and-start traffic on the freeway.  Because regenerative slowing does not light the brake lights, I do not feel safe relying on regenerative slowing in heavy traffic, so I switch to drive (D) whenever traffic gets slow on the freeway.  This way, I communicate my slowing clearly to the drivers behind me.

Saturday, November 8, 2014

Now that’s quiet!

I remember buying my 1982 Mercury Capri RS 5.0 with its V-8 engine and sport-tuned exhaust.  I went to a lot of trouble to select a top-end Yamaha car stereo unit, Alpine speakers, and thick cabling and spent a long weekend wiring it up.  It sounded great in my parking space as I turned on the unit for the first time.  Then I started the engine … and I learned my first important lesson about car audio.  It doesn’t much matter how good the car stereo sounds if you cannot hear the music with the engine running.  I rationalized that the music did sound better than the factory system and I would be driving the car a lot on long-distance trips.  And the amazing sound of the V-8 engine rumbling through the sport-tuned exhaust had me forgetting at times about the stereo system I had just installed.  If I wanted to really enjoy music in this car, I would have to park and shut off the engine.  (I did that a few times.)  I learned my lesson well and never again replaced the factory car stereo unit.
My 1982 Mercury Capri with its sport-tuned exhaust

When I bought the Mitsubishi i-MiEV, I was happy that my model came with a CD & MP-3 player.  It’s hard to make a bad sounding CD player, and with the MP-3 setup, I simply stick in a disc with 10 hours of my favorite tunes and leave it in there for when I tire of commercials on the radio.  I still run the factory stereo, but that has more to do with cosmetics than acoustics.  For the first time, I can hear many of the details and nuances of classical performances while driving (as opposed to filling in the drowned-out parts from memory).  Sitting at a traffic signal, there is no noise from the car (beyond the ventilation fan) and you can hear every detail.  This holds nearly true while driving around town.  It is only at highway-speed that the road noise starts to drown out the music, nearly as much as with a gasoline powered car (without the sport-tuned exhaust).

The car is so quiet, correction … peaceful when stopped that traffic lights do not annoy me the way they once did.  I used to hate to sit idling at a traffic signal for three or four minutes during commute hours waiting for my brief green light.  I would worry about the gasoline being wasted, the extra pollutants, and the build-up of heat during the summer months.  (I started turning off the engine at these prolonged intersections.)  But eventually, it was the noise that got to me.  Now, when waiting at a red light in my electric car, there is no noise, no exhaust, and no waste while I am stopped.  I can hear every detail in my music and I feel more relaxed.  Of course, without my engine running, I can hear other people’s conversations too that were once more private.  So, now days, you really need to look around you before you start yammering about anything embarrassing.

Creeping along in very slow traffic can also be a major source of noise, both for the drivers and the neighbors living within earshot of the congested roadway.  But, I was able to experience the congestion of the future at a recent electric vehicle rally and parade nearby me.  Some 500 electric vehicles were to assemble at 7:00 am on a Saturday morning, the logistics of which resulted in a traffic jam extending ½ mile on the main road to the campus hosting the event.  In this particular traffic jam, with the windows down, there was no engine roar from surrounding cars, and better still, there were no choking exhaust fumes.  It was by far the best traffic jam I have yet to have the opportunity to get trapped in.  I now look forward to traffic congestion of the future.