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Monday, May 30, 2016

5 Years of Nissan Leaf Driving

In 2011, I received one of only 9,655 Nissan Leafs delivered to the U.S.  My car left Japan less than a day before the Tōhoku earthquake and tsunami devastated the island nation.

When the car arrived, I was in love. It was peppy, smooth, and quiet. It had enough range for nearly all of my driving.

May 18th 2011 - The day I picked up my Nissan Leaf

The five years we've had have been such good times.

I was lucky that Oregon was aggressively installing EV charging infrastructure. This let me take my car on adventures all around the state. A charging station in my garage filled it up every night and I could charge at work too. This made EV ownership a breeze. Most days, I only charged in my own garage, but knowing that all those stations were there if I needed them, made it comfortable to drive around and take detours as I like.

I was an active reader of the EV forums and news. There were people reporting various types of problems. Range degradation, 12V battery problems, paint issues... I was lucky that none of these problems were impacting me.

4100 Plug Ins

Here are the stats for these five years of Leaf driving: 44,000 miles, 4100 charging events, 44 quick charges. There are Leafs out there with over 100,000 miles on them. Mine is not one of them, it was/is primarily a commuter car.

5 Years of Battery/Range Degradation

After a couple years of ownership, people in Arizona and southern California started complaining of excessive battery degradation. The weather here in Oregon is much more battery-friendly (reason #6), but I was interested to see how the batteries performed as they aged.

How have the batteries of the Nissan Leaf held up after 5 years?
There are two simple ways and to gauge the battery health and one more difficult (but more accurate) method.

The first method is the Capacity Bars. There are 12 small marks just to the right of the "fuel gauge". These are the battery health indicators. The top bar (or 12th bar) turns off when the battery has lost 15% capacity. Bars 11 - 4 each represents 6.25% of capacity. This is an easy way to see the battery health, but it is a course measure. Currently, my car is at 80% capacity and it still has 11 bars.

The second method of determining range is to charge the car fully and to look at the range meter (referred to as the guess-o-meter (GOM) by many Leaf drivers). This is not a very accurate method since the value depends on how you have been driving the car recently. This means the results are not consistent or reproducible. Here are three snapshots of the range meter starting with the car when it was new, to one that I snapped just after the 5 year mark.

2011 Nissan Leaf Fuel Gauge, Fully Charged: New (left), 3 years old (center), and 5 years old (right) 
I should point out that even though you see 118 miles reported when the car was new, I was never have been able to achieve such a range. Even the 69 miles that the GOM reports today is optimistic; as you'll see with the final method below, the range is less than 60 miles.

The 3rd and most accurate method is to use Leaf Spy. I found this tool just after having the car for 2 years. Since then I have been logging readings and made the chart below of the battery pack's performance. 

Let's unpack this graph. The blue line is measured range. You can see how there are seasonal changes with the weather. The red line is just a normalized version of the blue line. Removing the seasonal noise gives you a clear view that the capacity degradation is slowing. In the first year, the range dropped by about 4 miles. In the last year (4 to 5), however, there was less than 2 miles of range lost.

The yellow line is the average of all the vehicles that have been self-reporting on MyNissanLeaf. My car is doing much better than this average. This is most likely due to the lowish miles and the mild climate.

It's nice to see the degradation slowing, but it is accumulating. This has meant that we are now using the fast chargers more than we were previously. I am concerned that this could accelerate the degradation. We'll see.

I should note that this is just one example. Additionally, Nissan improved the Leaf battery chemistry in 2015 (known as the Lizard Battery). This new battery could have a different degradation curve.

Looking To Year 6

The Nissan Leaf has a telematics system called NissanConnectEV (formerly known as CarWings). The app lets you check the state-of-charge and turn on the HVAC. The status updates for this telematics app are over-the-air. The list of charging stations in the car's nav system is also updated over-the-air. The car uses the AT&T 2G network for these data transfers. The 2G network is scheduled to be shutdown. The 2G shutdown date has been delayed multiple times. It is currently scheduled for the end of 2016 and AT&T seems serious about keeping to the date this time. When the shutdown occurs, my car (and all the 2011 through 2015 Leafs) will need to be updated to a 3G or 4G modem.

I'm not sure how much this 3G/4G upgrade will cost. I rarely use CarWings, so I am not willing to pay much for the upgrade. Nissan has said that cost information will be available in "late summer of 2016." This is something that I'll have to deal with in year six.