Electric Vehicle Charging

If you read this blog, you will know that the company's operation in Derby, CT has a solar array that provides all our electricity needs, and then some (114% of our consumption since the installation went live in 2009Mar).

Rather than sell that electricity to the utility (in March the electric company sweeps out any kwh we have "banked" and pays us based on the average rate of the New England Regional market, which is about 5cents per kwh), the value is in deferring buying electricity from the utility (which in total of all the line items on your electric bill is about 21cents per kwh).

As mentioned earlier, we have a diesel powered delivery fleet of light-duty trucks. With a round-trip delivery of apx 150 miles, they might one day be served by electric power. We are testing the viability of this with the only pure electric vehicle available to non-fleet owners as a purchased vehicle, the Tesla Roadster. While not a "delivery" vehicle, it is a real-world case study in how electric vehicles perform in hot or cold weather, and the reality of their charge time that yields miles driven. Our methods and purpose is not unlike Google's fleet of vehicles.

An issue often raised is that there needs to be a charging station infrastructure for people to adopt to such vehicles over internal combustion engine power. While there are outlets most everywhere (the Tesla can charge on 110v 15a), a quick charge requires power and that comes in 220v 40a or higher.

The defining characteristic is power (kilowatts) input into the batteries. Returning to your basic science: Watts = Volts x Amps. Thus, 110v x 15a = 1650w, or 1.65kw. Plug in for an hour and you have 1.65kwh. Go with a 220v x 40a for an hour and it = 8.8kwh, which equates to substantially more miles from the contribution to the battery's storage of power.

To put this in real world terms from our actual experience and data, charging a Tesla for 1hr at 110v = 5 miles of driving. 1hr at 220v = 25 miles of driving.