Tuesday, August 30, 2011

Living with Our LEAF after Four Months

Our LEAF is still going strong without a hiccup for over 3,000 miles now and four months of driving.  




We are really having fun with this revolutionary car.  It is big enough to comfortably fit all five members of our family, including a baby seat, for drives out to dinner and local fun outings.  And it is small enough to be fun to drive and responsive in all kinds of driving.  Even though I have been a lifelong car enthusiast, I am really happy to be driving the LEAF as my personal car for "fun driving".  I still don't miss my BMW 3 Series coupe at all.


We still haven't spent a penny on fuel for our LEAF because of the solar energy produced by the solar panels on our home's rooftop.  Even though household usage (not including LEAF charging) increased by over 230 kWh compared to last July because we've had a family of three living with us this month, and even though we drove more miles in the LEAF and charged if with more kWh than in any previous month, we still had an electric bill that showed a CREDIT of $55.82.  This was because of the Time of Use rate plan from our utility, SCE.  The solar power that we generated during Peak hours was credited at  between 19 cents and 55 cents/kWh, while our LEAF charging was billed at between ten cents and 16 cents/kWh.  This difference in Time of Use billing produced a CREDIT total, even though our net usage for the month was a positive 167 kWh.  For our net metering year, which is five months old, we have a credit balance of over $300, which will help to offset our electrical usage for the remaining months of the year, when our solar power generation will be lower.  I'm estimating that we'll end the net metering year next March with a total electrical power bill of zero! 


So we're truly driving at ZERO fuel cost because of our solar panels and Time of Use electrical rates.  Of course, we paid about $25,000 out of pocket for the solar installation in 2007.  Payback time for this outlay would have been more than 12 years if offset by only our savings in electrical bills.  But when adding in the savings in gasoline costs for driving up to 12,000 miles per year, the payback time drops to about 7 years.  And after the system is paid off by these savings, we will have free household electrical power and at least 12,000 miles of EV driving at no cost for as long as the life of the solar panels, projected at over 20 years.


Public Charging:
We publicly charged our LEAF four times in July, using public charging stations in Seal Beach, Newport Beach, in Diamond Bar at AQMD headquarters, and using the solar powered DC Quick Charge station at Mitsubishi Headquarters in Cypress.  All of this charging was free of cost.  Most public charging stations are offered free of cost at this time, to encourage EV adoption.  The DC Quick Charge station at Mitsubishi is the only such station operating in California at this time.  The management at Mitsubishi is being really progressive by allowing LEAF owners to use this station, even before their own Mitsubishi i EV comes on the market late this year.




Low Battery Charge Warning:
We've seen a low battery charge warning only once while driving in four months.  This was on the way back from a trip to the beach, with the whole family in the car.  We had a charge of about 13 miles and one bar of charge showing as we headed home.  But the route home was up a steep hill.  At the top of the hill, the last charge bar went dark and we got a Low Battery warning with the miles remaining showing 6 miles, and flashing.   My wife was concerned, since we had about 5 miles of driving to get home.  I reassured her that we'd make it and shifted into ECO mode to conserve power. Most of the trip home was downhill, and after driving conservatively, the miles remaining indicator still showed 6 miles when we pulled into the garage.  I decided to drive the car further until the second low battery warning appeared, and was able to drive another 4 to 5 miles.  This was a good educational experience, and it made me feel more comfortable with miles remaining readings at the low end of the range.  I recommend that all EV owners drive the car down to a low state of charge at least once, to better understand their car's behavior.


The Numbers:
Month:  July 2011
Total Miles at Month End:  3,139
 miles
Miles Driven in Month:  995 miles
Electric Power Used for Charging: 318.1 kWh (measured at wall power source, includes public charging)
Public Charging:
 24.5 kWh
Home Charging: 293.6 kWh
Energy Efficiency, Month of July 3.13 miles/kWh (wall to wheels)
Energy Efficiency, Lifetime:  3.14 miles/kWh (wall to wheels)
Most Electric Energy Used for Charging in a Day in July: 23.9 kWh  (6.3 charging hours)
Least Electric Energy Used for Charging in a Charging Day: 4.0 kWh  (1.1 charging hours)
Average Electric Energy Used for Charging in a Charging Day:  12.2 kWh  (3.2 charging hours)
Household Power Used:  764.4 kWh (without car charging)
Total Power Used:  1,060 kWh (includes car charging)
Solar PV Power Generated:  893 kWh
Net Power Used or Sent to Grid:  167 kWh net used
Electric Bill:  -$55.82 (A credit in this amount will be added to our net metering total credit for the year, offsetting future bills for months with lower solar output.)
Cost for Charging Car in July:  $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 July: $38.17)
(If We Didn't Have Solar Power, Est Cost per Mile in July: $0.038) 
Average Miles per Driving Day:  39.8miles
Longest Day's Driving:  77.2 miles
Shortest Day's Driving:  4.2 miles
Number of Times we Took the Prius Instead of the LEAF Due to Low Charge: None
Unexpected Low Charge and Unable to Reach Destination:  Never