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Tuesday, May 21, 2013

Take that, Exxon!: EV insights, Day 21

We've had our Mitsubishi MiEV electric auto for three weeks as of today.  Current mileage totals for our "fleet":

EV: 629
Prius: 240

Total: 869
Gallons of gasoline consumed: 4.8
Gallons of gasoline displaced through trade-in of Honda Insight hybrid for EV = 14.5
Fleet mileage: 869/4.8 = 181 miles per gallon
Fuel savings @ 4.5 cents per EV mile = 629*4.5 = $28.31

These numbers suggest annual gasoline displacement of roughly 250 gallons and fuel savings (counting the electricity consumed) of about $500.  As previously mentioned, that's based on trading in a 40-mpg auto, so for a 20-mpg auto, those numbers could be doubled.

- The EV is performing very nicely--it's now clear that we can consistently drive it twice to "town" (the "micropolitan" area consisting of Hanover, Lebanon, White River Junction, and Norwich) each day, with overnight fillups, even at the "slow" charging rate (using a regular 110 outlet), for at least several days without running low on battery charge.  We've used it exclusively, except when we have multiple commitments that conflict or overlap.

- As with the Honda we traded in, the range indicator is flighty--after the car is fully charged (the "charging" indicator light goes out), the range has so far read anywhere from 72 to 81 miles. It seems to go down faster when it's 81 than when it's 72, but that could just be my imagination--variables such as temperature, precipitation, cargo weight, headlight use, etc., all make it difficult to get precise, comparable measurements.  In any event, the lowest the range has gotten is about 40, except for the deliberate deep discharge described in my previous post.  While the EV takes 22 hours to charge from 0 to full, 10 hours of charging will take it from 40 miles on the range indicator to more than 70, so the charging fits well into a regular daily schedule.

I'll write a bit more about the MiEV's transmission settings in a future post.

Sunday, May 12, 2013

Take that, Exxon!: EV insights, Day 12

So, I've been out of town for most of the past week, but want to set down a few more thoughts while they are fresh. At this point, the mileage numbers since our EV arrived April 30 look like this:

EV: 367
Prius: 147

Not quite the 80 percent I was hoping for (71.4 percent), and I'm sure that was a little unrealistic. Still, the improvement over our previous transportation mix (two hybrids, one getting 50 mpg and the other 40 mpg) is obvious:

Previous: 514 miles, average 45 mpg = 11.4 gallons of gasoline
Current: 514 miles, 147 fueled by gasoline, average 50 mpg = 2.9 gallons

Another way to put it: we've gone from averaging 45 mpg to averaging almost 175 mpg (514 divided by 2.9), which I think is pretty cool. That in turn leads to the conclusion that the  mpge (miles per gallon of gasoline equivalent) rating doesn't tell the whole story. The mpge rating emphasizes that the EV is still consuming energy (certainly important to keep in mind), but doesn't communicate the full benefits in terms of gasoline use.  While the MiEV's mpge rating is 112, its actual mpg is, of course, infinity, and our average mpg is limited only by how many miles we can load onto it.

Yesterday, we fulfilled one of the basic MiEV battery requirements--a fairly deep discharge. The manufacturer advises driving it until the fuel gauge drops below two bars and then recharging it fully. After two trips Friday and charging overnight, its range indicator read 55 miles.  Two more trips yesterday took it down to 19, and then I drove it enough to take it to two bars (12 or 13 miles on the indicator) and then home.  It was exciting!  We live on the side of a hill, and the range indicator drops steadily when driving uphill.  The refuel warning was flashing steadily and I had visions of falling a few hundred yards short, which would have been a minor disaster. In the end, I eased it into the garage with 5 miles still on the indicator.  Whew.  Won't be doing THAT again anytime soon (the manufacturer says it needs doing every two years).

Some additional stats:

367 miles on the EV, fuel savings 4.5 cents/mile = total savings to date $16.51 (not too impressive, but we traded in a 40-mpg hybrid--if you replace a 20-mpg auto, the savings would be 9 cents/mile). For the fuel savings calculation, see this previous post.

Thursday, May 2, 2013

Take that, Exxon!

I posted here not long ago about taking a ride in a friend's electric vehicle, and how attractive it was. Well, after some dithering, we took the plunge and ordered one for ourselves. It arrived late Tuesday and we have just finished Day 2 of owning/driving.  It's great!

The perfect car for someone like me who likes to dig into the numbers.  So, here are a few early insights:

- This is a Mitsubishi i MiEV (we call it the mee-EHV) and it is rated by EPA to have a 62-mile range and fuel economy of 112 mpge (miles per gallon of gasoline equivalent).  What does that mean?  Well, EPA figures 33.7 kilowatt-hours (kWh) of electricity for the gallon of gasoline equivalent, so for that many kWh, the MiEV is supposed to travel 112 miles (as the saying goes, your mileage may vary).

- This means that the MiEV's battery "tank" only holds a bit over half a gallon of gasoline equivalent (62 divided by 112).  And it also means that the MiEV gets about 3.3 miles per kWh.  A kWh, in our neck of the woods, costs about 15 cents, so the cost per mile for fuel is 15/3.3 = 4.5 cents.  This compares with the cost of gas for the Honda Insight we traded in--$3.60 per gallon for 40 mpg, or 9 cents/mile.  And that's for a 40-mpg hybrid.

- The MiEV will also cost less to maintain, as it has a much less complicated motor (no oil changes). And I'm guessing that, as we focus on making it our main car for local driving, the wear and tear on our other auto, a Toyota Prius with just under 137,000 miles, will be drastically reduced.

As of Day 2, we've had five trips to town for meetings, work, etc.  We were able to take four of them with the EV, which has so far traveled 66 miles, leaving one for the Prius (18 miles).  I'm hopeful that over the long term, that ratio (close to 80% of local travel with the EV), can be maintained.

- 66 miles on the EV amounts to about 20 kWh, which is substantial--it's pretty clear that our total electricity bill is going to go up, perhaps nearly double, but that's because our previous usage was quite low.  At the same time, obviously, our gasoline spending is going to plummet.  Take that, Exxon!

OK, so enough geeky stuff.  

How does it look?  See above--you can be the judge.  I drove a VW Beetle for about 25 years, so a car's looks are not high on my list of required attributes.  

How does it handle?  Fine, drives like a normal car.  

What happens when you're merging onto a freeway and you need extra speed?  I think this is an interesting question, because I've been asked it a couple of times, in almost exactly the same words--evidently it is something that really preys on some drivers' minds.  Hasn't happened yet, but the pickup is quite good and ... I drove a Beetle for 25 years.

This post is already fairly long, so I'll leave it at that for now--I can provide more specifics about the transmission settings and gauges later.  We have a bare-bones version of the MiEV--to find out more about the deluxe version, see the excellent series of blog posts that begins here.

Other questions?  Ask away.