Sunday, 22 May 2011

Why Yes, a Fully Charged Nissan Leaf Can Go 87 Miles with Range to Spare

“Your mileage may vary” or some variant of this phrase is the most common utterance heard around our long-term Nissan Leaf these days. Inquisitive passersby have had loads of questions regarding the cutesy electric car and, not surprisingly, the most frequent topic concerns range. “How far can it go?” “How far have you driven?” “Have you ever run out of power?” (It would have been more proper to say “energy”).

Why Yes, a Fully Charged Nissan Leaf Can Go 87 Miles with Range to Spare imageWhen the Leaf first arrived, testing director Kim Reynolds and I knew someone would eventually need to do an extended driving run. Someone would start with a fully charged Leaf and put as many miles on it in a single trip as he or she dared. Although it wasn’t explicitly stated, there were some guidelines for the run. First, no battery recharging. Second, drive safely, because nobody wants to see us driving down the freeway at 40 mph. Third, no “perfect scenario” types of driving. No points would be awarded to the individual who drives on a closed-off, low-speed loop for hours on end to wring out the most miles.

That someone turned out to be me. Reynolds had left town – something about driving the long-term Chevy Volt back from Michigan. With a free evening and a juiced battery, it was time to go home. I took a deep breath as I unplugged the MT garage’s Level 2 charger from the nose-mounted receptacle. I snapped the front cover that conceals the recharging ports back into place, knowing it wouldn’t be reopened until I returned in the morning (I hoped). Perhaps I’m being overly dramatic. What was the worst that could happen?

When I switched the Leaf on, I was greeted with a range estimate of 106 miles on the futuristically fancy gauge cluster. Ha, like I actually believed I was going to get that many miles. A week or two ago, I distinctly remember losing 20 miles of indicated range before I had even gone 2 miles. And for the record, I consider myself an easy-going driver. I realize auto journos have a not-entirely-undeserved reputation for generally aggressive driving, but we’re not all like that.

Why Yes, a Fully Charged Nissan Leaf Can Go 87 Miles with Range to Spare imageSo there I sat in the EV, knowing my round trip would easily breach the 80-mile mark. Up until now, the farthest any staffer had traveled between charges was a little over 58 miles, and my notes indicated there were still around 20 miles left in the battery. If we look at the Leaf’s Monroney, the EPA claims owners should average around 73 miles on a charge. Phooey to that, I said. Steady driving and much mental math, here I come.

I won’t bore you with the excruciating details of finding optimal “throttle” angle and keeping ideal following distances, but the first half of the round trip commute commanded 44.7 miles. After wishing for a traffic-clogged freeway, then getting my wish, I was able to cruise along, covering close to six miles per kilowatt-hour. The going was good until the freeway opened up and my energy economy began to slide. In a rush to preserve my hard-earned ‘mpkW-h,’ I abandoned the freeway as quickly as an exit showed up and took an all-new way back home that luckily never required driving faster than 50 mph. Between L.A.’s great moving parking lot and my insistence on driving at legal speeds, I was home in two hours.

What was I left with after 44.7 miles? I pulled into my garage with the average energy use pegged at 5.2 miles per kW-h and the indicated remaining range at 56 miles. To the immediate left of the high-mounted digital speedometer, I had accrued four “trees” in the Eco Indicator. The trees are intended to represent the amount of tailpipe carbon emissions saved by driving a Leaf. The forest of trees disappears with each shutdown, but every tree is stored over the long term in the standard navigation system. Prior to this trip, the most I had seen in a single drive was very close to three.

Why Yes, a Fully Charged Nissan Leaf Can Go 87 Miles with Range to Spare imageUnfortunately, there doesn’t seem to be any set CO2 standard for the virtual trees. At time of writing, Nissan’s telematics service Carwings reports that 30,269 of these trees have combined to save 130 tons of tailpipe-emitted CO2 here in the U.S. (around 8.59 pounds per tree). Throw in the Leaves from Europe and Japan, and 202,535 trees have saved 407 tons, which equates to 4.02 pounds per tree. Statistical rounding surely doesn’t help these figures, but those are some pretty big gaps. We’ll be sure to follow up on the digital arboretum.

The commute back to the office the next morning was a little shorter because I took my usual route: 42.6 miles. With 56 miles on the dash at start up, I was expecting to be left with 5 miles at the worst, but was pleasantly surprised to finish the job with 13 miles remaining (battery charge level warnings came on with 20 miles left). This time around, just an hour’s worth of driving completed the final 42.6-mile leg. Here are my trip details:

-    Final trip distance: 87.3 miles
-    Indicated range left: 13 miles
-    Average energy use, according to the Leaf: 4.9 miles per kW-h
-    Total energy appropriated for full recharge from 208-volt, 30-ampere supply: 21.45 kW-h
-    Total time needed for full recharge: 6 hours, 4 minutes
-    Total actual driving time: Around 3 hours
-    Driving style: Careful but not hypermiling
-    Transmission drive mode: Normal Drive
-    Climate control use: What’s that?

Why Yes, a Fully Charged Nissan Leaf Can Go 87 Miles with Range to Spare imageWe’ll be exploring recharging rates and charge times in a future blog, but the 21.45 kW-hrs doesn’t wholly represent chemical energy in the battery.

But now I’m not satisfied with my total miles. Next go-around, I’m shooting for 90 miles. Then 100 miles, maybe…or maybe not. I’m hoping the greater regeneration from driving in Eco will yield an even higher final trip.

Also during my next extended run, I’ll try and let it sit outside for a night and see how the battery performs on the 100-mile trip. Anybody from the bookie trade want to take bets as to whether I’ll make it back then?


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