Sunday, July 31, 2011

Range Anxiety

On a long and lonesome highway.....(well not east of omaha!)
Photo by: Chandra Ramkumar
Another uneventful month of EV driving. Total mileage was down slightly to 650. Electric consumption was also down, to 173 Kwh, for an average of 3.8 miles per Kwh. I think we crossed the line from heating to cooling, and running the A/C a few times has increased our e- consumption slightly.

Did have one episode of range anxiety this month. No, not in the Leaf. It was in my daughter's Toyota, driving back from Arizona. Getting on towards nightfall, running low on fuel. That's when I realized we were on a stretch of freeway without any services. How many miles of range did I have left? How far to the nearest gas station? Oh, if only I had a telematics system that could tell me these things. Then maybe I wouldn't feel so anxious.

The story has a happy ending, but just barely. We found the only gas station in a 110-mile stretch. It was still open. We filled the tank, and they promptly shut down for the night.

Saturday, July 02, 2011

June recap

Odometer Miles Kwh Mi/KWh Cost Per mile MPGe Temp(F)
March 2011 2118 650 208 3.1 $24.13 $0.037 105.3 45.1
April 2011 2958 840 272 3.1 $31.55 $0.038 104.1 45.5
May 2011 3570 612 185 3.3 $21.46 $0.035 111.5 52.3
June 2011 4259 689 177 3.9 $20.53 $0.030 131.2 59.4

Well, it's definitely heating up around here. Average temperatures have nearly broken the 60-degree barrier. Time to break out the cargo shorts. Just over 4000 miles on the Leaf and no issues to report. Deliveries of the Leaf are starting to heat up as well.

So why have I made three references to temperature? Look at the right-hand column in the table. I started tracking mean monthly temperature. With only four data points, it's not statistically rigorous, but there appears to be an linear relationship between MPGe and temperature, with a coefficient of 2.25 (ie Multiply temperature by 2.25 to get MPGe). Check back here in July and August to see if it holds.