Monday was meter reader day for us.
We may not have been totally dedicated to the “fuel” consumption of our LEAF initially, but we became more attuned to its impact as each day passed. We brought home our LEAF on March 25 and first charged it using the 120-volt brick charging unit, as our 240-volt Blink electric vehicle supply equipment (EVSE or wall charging station or charging dock) had not yet been installed. In reviewing our old posts, it seems that with the 120-volt brick, we achieved roughly 3.4 miles per kilowatt hour. As it happens, we’ve run the math since we received our LEAF and calculated a total miles per kilowatt hour of 3.3 using our 240-volt Blink charging dock to date. We mention this not because the range will vary depending on charging method, but because the 120-volt EVSE was not metered in the second meter mentioned below. Let’s take a closer look.
On Monday, our accumulated mileage to date (since March 25 delivery) is 3,833. The kilowatt hour usage reading on our second SDG&E meter is 1,161 kilowatt hours. This includes all electricity provided through the 240-volt Blink EVSE, but none provided through the 120-volt EVSE. Pretty simple math – 3,833 divided by 1,161 provides 3.3 miles per kilowatt hour from the wall. We have never reset the energy setting on our car since new, and it reads 3.5 miles per kilowatt hour. So there is some discrepancy between the two. We don’t really know the reasons why. (Edit: 100% of electricity taken from the wall is not converted to power in the battery just as not all gasoline is converted to power in a gasoline engine. This accounts for at least a portion of this descrepancy.) This difference amounts to about 6%.
We are part of a San Diego Gas & Electric (SDG&E) electric vehicle (EV) experimental rate plan. As such, our super off peak rate (from midnight to 5:00 AM) is roughly $0.075 per kilowatt hour. We generally charge our car during this time frame, using the Blink’s built-in timer. We plug in our car after the last drive of the day and it starts charging at midnight. As our usage varies from day to day, it generally takes two to three hours to bring our LEAF back up to an 80% charge. We generally charge to 80% vs. 100% as we have no need to travel more than an 80% charge will allow, and according to Nissan, battery life is extended with an 80% charge cycle. Currently, these are the only two choices offered by Nissan with the LEAF – 100% or 80%. We have charged (rarely) at the highest rate of $0.35 per kilowatt hour, although we try to minimize that. Also, we have never charged at a publicly available charging station, although we did charge at a friends house on their Blink for an hour or so once.
Getting back to the math – 3.3 miles per kilowatt hour (@ $0.08 – we rounded up to account for the infrequent higher rate charging) equals 41 miles per dollar. In San Diego currently, regular gasoline is $3.80 per gallon. That equates to a cost factor equivalence 156 miles per gallon. But let’s say you were paying the national average rate of $0.11 per kilowatt hour. That would still equate to 30 miles per dollar. Not as impressive perhaps, but that still equates to roughly 114 mpg in San Diego at current gasoline prices.
We stand by our initial assessment – The LEAF is a situationally specific vehicle. It is not right for everyone, but if it is right for your situation, it offers an extremely low cost of operation compared to even an extremely efficient hybrid gasoline-electric vehicle. (Disclaimer – others may get greater or lesser miles per kilowatt range. Our 3.3 miles per kilowatt usage equates to a 100% charged range of (3.3 miles X 24 kilowatt hour battery) 79.2 miles.)
UPDATE (Nov. 18, 2011): In the comments below, indyflick correctly points out our incorrect usage of the term MPGe in our original article (which we have since edited out). Miles Per Gallon Equivalent (MPGe) is an EPA formula that compares the energy equivalence of electricity vs. gasoline. indyflick provides the formula in the comment so I will not repeat it here. Our intent was to show an economic equivalence, versus an energy equivalence. There is an important reason for this distinction. MPGe will not vary. Energy is energy so MPGe will remain constant. In our illustration, we are interested in actual cost of operation, which will vary based on the cost of energy. MPG in a gasoline powered car will vary based on vehicle and driving style, so your fuel costs vary accordingly. Similarly, the cost of operation of an EV will change based on the cost of electricity as well as maintenance costs. Ignoring maintenance costs (which have been nil to date), we meant to focus on our cost to move our LEAF down the road, but especially to compare that cost to that of someone driving a gasoline powered car. We, in error, referred to that as MPGe. We apologize for the confusion.