Tuesday, October 9, 2012

Seventeen Months in Our Nissan LEAF

Three LEAFs and a Fisker Karma at the solar canopy charging station at Mistubishi HQ in Cypress CA on National Plug In Day, Sept 23, 2012

I'm very late in posting this August update in October.  I apologize.  Part of the reason for the delay is that I always include an update from my monthly utility bill so that I can update my driving costs, but as explained below, SCE has improved my meter, and so now they can't find a way to bill me (irony).  Another reason that I've taken extra time this month is that events on the LEAF scene have been changing rapidly with regard to heat-related battery capacity loss, especially in Arizona, and I wanted to include the most recent information.  And lastly, I've been busy researching a new hobby, electric bikes.  I'll report more on this next month.

August was our seventeenth month of driving electric in our Nissan LEAF.  Another 1,000 miles, bringing us to almost 16,000 miles and our LEAF continues to perform flawlessly. It has never given us a single problem.  It is still as pleasant and comfortable as the first day we drove it, and we love the quiet and smoothness of the driving experience.  Our LEAF continues to cost us nothing in operating costs to drive, as the combination of our solar "power plant" on our home's roof and the Time of Use rates from our utility, SCE, add up to an annual bill of zero.  Even if we didn't have solar power, we would have paid only about $37 for electricity to drive the LEAF this month, around 3.7 cents per mile.  That is much less than half the cost of driving a Prius for the same number of miles.  And we still haven't spent a penny on maintenance in 16,000 miles of driving.

New SCE Smart Meter and Billing
I don't have any up-to-date billing figures from our utility because, ironically, we now have a "smart" electric meter.  Yes, SCE finally came up with a smart meter and software that should be able to handle solar net metering and time of use billing for EV charging at the same time.  I'm told that at some point in time, I'll be able to go to SCE's web site and see hourly power usage and solar net generation graphs.  At this point, after more than a month of having a smart meter, I can't even get a monthly bill.  Which is a shame, since we are in prime summer "over-generation" season, when I like to gloat about the size of my SCE credit balance.  Our daily power usage has dropped, as well, since our son and his family have moved into their new home and out of ours. As I've said many times before, the combination of solar PV power and EV charging is a perfect match.  We're so happy with the performance of our solar power that we are going to look into adding air conditioning to our home this year.  Used carefully, we don't think that air conditioning will cost us much at all, due to the offset of our solar cells.

UPDATE: A special SCE meter reader showed up a week ago, about 45 days after the smart meter was installed, saying that SCE hadn't been able to get any readings from my meter and that he needed to take a manual reading.  He also said that they might have to replace our meter in the future if the situation persists.  A week later, there is still no bill available on SCE's web site.

FURTHER UPDATE: On Oct 6, I noticed on the SCE web site that some of my September usage data is displayed and that my credit balance of -$72.83 has now grown to -$137.13.  I still don't see a bill on the SCE site, and the date range of the current account summary isn't clear, but SCE has at least been able to use the data from the manual meter read of 10 days ago to get some usable data.  I'm going to keep the previous credit balance in my figures below, since the dates for the new SCE figures aren't clear and they don't match the August month end date of this update, but Ill update my kWh usage total for the net metering year using my own figures.

FINAL UPDATE: On Oct 10, about a month late, our August SCE bill appeared on SCE's web site, and I am now able to identify the date range of the bill and assign the billing to the month of August.  SCE handled the transition between the two meters in mid-August by creating two different bills in one, and the total amounted to a credit of $64.30 that will be added to our previous credit balance to produce a running total "bill" of -$137.13.  I've adjusted the numbers at the bottom of the page to reflect this latest bill.   I expect to see an additional credit for the final summer month of September, and I still expect to see a final actual bill due at the end of February, our twelfth net metering month of the year, of zero, for all of our electricity usage, including charging our LEAF for 11,000 miles of driving in the year.

Tony Williams' Baja to BC LEAF

Battery Capacity and Range
Issues with battery capacity loss from LEAF owners in hot desert climates have continued to be reported.  Though the actual number of LEAFs with capacity bar loss is unknown because the MyNissanLEAF forum only represents a subset of owners, according to the wiki here, about 52 LEAFs in Arizona, 29 in California, and 23 in Texas have reported having lost at least one of twelve battery capacity bars, with 11 of these cars having lost three or more bars.  Details of the testing that Nissan did on some of the affected cars, and an ensuing test on a dozen cars in Arizona by a group of MyNissanLeaf.com members can be read on the wiki page.

At this time, Nissan has bought back at least two of the affected Arizona cars under terms similar to those laid out in the Arizona lemon law.  Nissan has asked Chelsea Sexton, a well known and respected figure in the EV world, to convene a global advisory board to advise Nissan on communication with LEAF owners and on strategy.

Our own LEAF continues to operate perfectly, shows all twelve battery capacity bars and appears to still be able to drive just over 70 miles on a full charge at our usual driving efficiency, about 85% of its original driving range.  Our average daily mileage driven is under 35 miles and we rarely need to drive the LEAF more than 55 miles.  We now charge the LEAF to 80%, Nissan's recommended long life charging mode, which gives us about 60 miles of range to empty.  It appears that our 2011 LEAF will able to handle our driving needs at least through the end of our 39 month lease, 22 months from now, even if the battery capacity has declined below the 80% that Nissan suggests that we should expect.

My take after watching this story unfold is that the LEAF is a great car that can fulfill the needs of a large number of buyers, especially those living in temperate regions with cool summer temperatures and daily commutes of around 50 miles.  The shorter the owner's daily commuting needs, the more likely the current LEAF will work well for the owner for several years. These owners can expect a very reliable family car with ownership costs and CO2 and other emissions well below those of the average car, and they'll never need to take it to a gas station for fuel.  If summer temperatures are hot, I recommend leasing the car to minimize risk due to capacity loss.  For those who live in regions where summer temperatures regularly reach three digits, who have longer commutes and who drive the US average number of annual miles or more, I recommend careful research into the LEAF's range capabilities, potential battery capacity loss over time, and consideration of the buyer's required commute range needs over the time period that they expect to own or lease the car.

Capacity loss is a given with any battery.  The rate and degree of loss is dependent on the battery's chemistry, temperatures, mileage driven (which is related to the number of charging cycles), depth of discharge, charging wattage and frequency and other factors.  In my opinion, it is incumbent on EV manufacturers to either warranty battery capacity, or to be very transparent with potential buyers about the car's expected driving range capabilities over time and in the region where the car is being sold.  In public statements and in the video in this thread on MyNissanLeaf.com here, Nissan has admitted to "being a little behind in engaging with our customers and giving credibility to their questions".  In my opinion, improvement in that area is the first step in the direction of correcting an issue that has hinged on customer communication.

Corbin Sparrow EV at Mitsubishi HQ in Cypress, Ca for National Plug-In Day, Sept 23, 2012

The Numbers:
2011 Nissan LEAF SL Placed in Service: March 30, 2011
All Home Charging Done Using: 240 Volt Aerovironment/Nissan Level 2 EVSE
Home Solar PV System: 24 Sunpower 215W panels totaling 5.16 kW DC mounted on a 20 degree South facing roof.
Total Solar PV Power Generated for Net Metering Year Ended February 2012:  8,568 kWh
Our LEAF's Longest Range Full Charge to Empty ("Turtle"): 86.5 miles (at 4.0 mi/kWh on dash), April 2011.
Our LEAF's Most Recent Range, Full Charge to Turtle: 75 miles (at 4.1 mi/kWh on dash), July 2012
NOTE: Longer maximum range is possible if the LEAF is driven more conservatively. Many LEAF owners have achieved range of well over 100 miles.

Month:  August 2012
Total Miles at Month End: 15,879 
Miles Driven in Month:  1,009 miles
Electric Power Used for Charging in Month: 294.7 kWh (measured at wall power source, includes public charging)
Public Charging in Month, Power Use:
 7.6 kWh 

Charging at Home in Month, Power Use: 287.1 kWh
Energy Efficiency, Month of August 3.42 miles/kWh (wall to wheels)

Energy Efficiency, Month of August:   4.29 miles/kWh (in car main dash display, battery to wheels)
Efficiency Wall to Wheels in Month at 240 Volts: (3.42/4.29) = 80%
Total Charging Energy Used, Lifetime:  4,874.9 kWh (Includes public charging)
Energy Efficiency, Lifetime:  3.26 miles/kWh (wall to wheels)
Energy Efficiency, Lifetime:  30.7 kWh/100 mi (wall to wheels)
Number of Home Charging Days in Month: 28
Most Electric Energy Used for Charging in a Day in August:  19.5 kWh  (5.1 charging hours)
Most Electric Energy Used for Charging AT HOME in a Day in August: 18.5 kWh (4.87 charging hours)
Least Electric Energy Used at Home for Charging in a Charging Day in August  1.9 kWh (0.5 charging hours)
Average Electric Energy Used for Home Charging in a Charging Day in August
10.25 kWh  (2.9 charging hours)
Household Power Used for Month:  726 kWh (without car charging)
Total Power Used for Month:  1,013 kWh (includes car charging)
Solar PV Power Generated for Month:  848 kWh
Net Power Used or Sent to Grid for Month:  165 kWh net used
August Electric Bill, So Cal Edison, Schedule TOU-D-TEV:  $-64.30 

Solar Net Metering Year Total Cumulative kWh Used at Month #6:  1,120 kWh (estimated Total kWh net used for the net metering year. This is total household and EV charging usage minus solar PV generation.  Figures are from my tracking, SCE's tracking is messed up at this time.)

Solar Net Metering Year Total Cumulative Cost at Month #6 -$137.13 (Total energy and delivery costs for all power usage for the net metering year.)
Cost for Charging Car in August:  $0.00
Cost per Mile:  $0.00
Cost for Charging Car, Lifetime: $0.00
Cost per Mile, Lifetime: $0.00  

(If We Didn't Have Solar Power, Est Cost for Charging Car in August: $37.32)
(If We Didn't Have Solar Power, Est Cost per Mile in August: $0.037) 
Average (Mean) Miles per Driving Day in August:  34.8 miles

Average (Median) Miles per Driving Day in August:  30 miles
Longest Day's Driving in August:  62 miles
Longest Day's Driving in August Without Mid-Trip Charging: 62 miles
Shortest Day's Driving in August:  4 miles
Number of Times we Took the Prius Instead of the LEAF Due to Low Charge: 5
Unexpected Low Charge and Unable to Reach Destination:  Never