Stories from the cold snap

Winter in CanadaLast month, parts of the US and Canada braced for record-breaking low temperatures as a blast of arctic air blew across North America. Here in Ottawa, the thermometer stayed below -20C for three days in a row, plunging to as low as -28C.

A temperature of -25C is an important threshold for the LEAF batteries because the chemical process that produces electricity will basically freeze at that temperature. To prevent that from happening, the battery pack is surrounded by thermal blankets and electrical heaters to keep it warm. According to the Owner’s Manual, the heaters kick in at -17C, heat up the batteries to -10C, and then turn themselves off until the battery temperature hits -17C again.

The heaters consume about 300 Watts when running, which is not a lot energy compared to what the motor uses (up to 80 kW). If the car is plugged in, the heating energy comes from the grid, but if the car is unplugged, the heaters will use electricity from the battery itself, creating yet another impact on total range if you park outside for long periods of time.

Another important point to keep in mind is that the heaters will only turn themselves on if the batteries are at least 30% charged. What happens if there’s not enough charge? Well, if the battery temperature drops below -25C, a safety mechanism will prevent the car from operating. You will either have to wait for the air temperature to rise again or plug the car in so that it can warm itself up using energy from the grid.

That’s all the theory but how often do the battery heaters run in practice, and how much energy do they use?

I ran a little experiment during the cold snap by leaving the car unplugged during the night and also during the day, and used the data logger from FleetCarma to verify how much energy was effectively used. I also measured the impact on my daily range, simulating the case where I would not able to trickle charge at work.

Parking overnight outside unplugged

Outside Temperature

With the weather forecast calling for very cold temperatures overnight,  I charged the LEAF to 80% (10 bars) and left it parked outside for the night, to see how the battery heaters would work. I also wanted to measure the effect of driving to work in the morning without any pre-heating from the grid, basically the opposite of what I would normally do — a worst case scenario we all try to avoid. The result was quite interesting.

IMG_8910-1Early in the morning, with the temperature just a notch from -28C, I actually caught the LEAF in the act. From inside the house, I could see the bright blue charging status indicator lights blink in a specific pattern, showing that the battery warmer was busy doing its work.

Carwings CarWings indicated that the battery charge had dropped from 10 to 8 bars overnight. More precise data from Fleetcarma showed that the battery warmer ran for 2 hours and 42 minutes, bringing the battery charge from 79.6% down to 67.4% (a 12.2% loss).

Once inside the car, the Dashboarddashboard confirmed the 8 bars of charge. It also showed a single bar of battery temperature. For some reason, the car thermometer showed -23C, almost 5 degrees warmer than the outside temperature. Notice the estimated range of 64 km. That is very optimistic.

Arrived at workIt usually takes me 2 to 3 bars to get to work without any climate control, but at this temperature, with no pre-heating and with the cabin heater on, it took me 5 bars instead. As you can see on the left, I arrived at work with only 3 bars left and estimated range of 21 km. Fleetcarma data showed that the 37 min, 17.15 km trip reduced the battery charge from 67.3% to 39.8%, arriving at half of the original 80% charge I had in the morning. As for that optimistic range of 64 km, in reality it was more like 38 km (with an 80% charge).

Arrived at workWith -25C on the dashboard thermometer, the remaining 21 km of range would be enough to take me back home. However, if I had to spend 8 to 9 hours at work with the car unplugged, the battery warmer would probably kick in during the day again causing the estimated range to drop. Fortunately, I have access to a 120 V outlet at work, which makes a big big difference in winter, so that wasn’t a concern.

So, parking outside unplugged overnight: definitely not a good idea!

Parking outside at work, unplugged

On a different day, I did the exact opposite: parked overnight plugged-in as usual inside the garage, and parked outside the whole day at work unplugged. The battery warmer did not kick in at any time during the night, even though my garage is not heated. Temperatures during the day were not as harsh as during the night, going from -27C at 8am to a high of -22.5C  at 4pm.

Arrived at workI left to work with a full charge (88.7% SOC), drove the same 17 km, arrived with 67% left, or 77 km of estimated range. I parked outside as planned. The battery warmer kicked in 4 hours later and ran for 3 hours and 7 minutes, causing the battery charge to drop from 66.3% to 57.5%, an 8.8% loss.

photoBefore I left work, I pre-heated the cabin remotely, while still unplugged, which took another 1.7% of the charge, down to 55.8% SOC. I arrived home with 37.7% charge, or 26 km of estimated range left.

Total range for the day (with a full charge, without charging at work): 34km driven + 26 km left = 60km.

Conclusion: Parking outside at work is not as bad as parking outside overnight, mainly because hours are shorter and temperatures are usually higher so impact on range is not as critical.

So how much energy does the battery warmer consume?

During the experiment, I was able to measure three battery warming events in total. While that is not enough data to extrapolate a pattern or a formula, this is the summary of what I was able to observe:

  • For temperatures varying between -22C and -28C.
  • Time it took for the battery warmer to kick in: 3.5h to 7.5h
  • Warming time: 2.7h to 5.2h
  • SOC% drop: 8.8% to 16.4%
  • Power consumption: 287W to 421W

LEAF Range vs. Temperature, After Two Winters

leaf-ice-riverLast year, I posted my first Range vs. Temperature report after the first winter with our Leaf. As the temperature dropped, you could clearly see a trend going down in terms of range, from about 140 Km in the summer, to 80 Km in the winter. We had a fairly mild winter for Canadian standards that year, and I happened to be away on vacation during the coldest days. As a result, I only had a few trips under very low temperatures and the lowest I was able to record was “only” -22C (-8F), and without enough trips to create a good average.

The second issue was that I didn’t know the car very well and I used the cabin heater a lot. As a result, I ended up not having enough data to show how much effect cabin heating would have on range. So the drop in estimated range was fairly significant as you can see below.

Range vs Temperature covering first winter

Range vs Temperature covering first winter

Last winter, I decided to make an experiment to test my hypothesis that cabin heating, not outside temperature, is the main factor affecting range in the winter. As the temperature dropped in January, I decided to take one for the team and drive with minimal cabin heating as much as possible, relying mostly on the heated seats, heated steering wheel and a good winter jacket. I also pre-heated the car before each trip, trying to simulate what I would normally do on a long trip. Pre-heating the car means charging for 20 to 30 mins before each trip and also pre-heating the cabin for at least 15 minutes while still plugged in. This procedure heats up the coolant used by the heating system, using grid power instead of battery power.

The estimated range is based on 120 V charging times. I didn’t use the FleetCarma data because I wanted to compare the results with the original baseline from the first winter, which I created before having the data logger.

With all that in place, I got the following results:

Range vs Temp, before and after

Range vs Temp, before and after

By comparing the two charts side-by-side, you can clearly see that I was able to consistently get at least 100 Km of an estimated range and bring the trend line to a flat line, regardless of the outside temperature.

These results confirmed my expectations but I still find it quite impressive. It is as if the battery didn’t care about the outside temperature as long as its own internal temperature was fine. The fact that you’re either charging or driving the car maintains a flow of electrons in and out of the battery which is enough to generate enough heat to keep the battery chemistry warm. The real challenge is how to keep yourself warm, and any passengers you might have.

I only had two trips recorded with temperatures below -23C, but I had to use the cabin heater in both occasions (freezing to death has its limit). One trip was at -25C (94 km range) and the other at -27C (74 km range). For the latter, the thermometer outside the house actually said -29C but I used the car thermometer as a more consistent reference. I added these two data points to the graph below to illustrate that the flatness of the curve breaks down, closer to last year’s trend, the moment you turn on the heater.

Performance after two winters

One thing these results show is that the cabin heater in the 2011 model is very inefficient. There is hope the 2013 will perform better but it is yet to be tested under the deep freeze (some people expect the performance to be the same when the temperature falls below -10 C).

Some LEAF owners have been successful in installing an internal ceramic heater in the cabin that performs much better than the regular heater. It is also possible to carry a separate 12 V to power that ceramic heater. With such auxiliary heating system in place, I would be very confident that the Leaf could drive 100 km in one charge in the winter regardless of the outside temperature.

Final Thoughts

With winter quickly approaching, we’ve been getting a lot of questions about how the Leaf performs under deep freezing temperatures. Our Leaf already has two Ottawa winters under its belt and we’re getting ready for its third one without a lot of concerns since we pretty much know exactly what the car can and cannot do. So this is how I can summarize our experience with Leaf in the winter so far.

  • Range definitely drops but how much it drops mainly depends on how much you use the cabin heater, not necessarily on the outside temperature.
  • If you heat up the cabin like a furnace and drive like there is no tomorrow, your typical 140 km range can easily drop all the way down to 60 km or even less. But if you manage to keep your cabin cool, drive conservatively, and use some of the techniques described below, you can still drive 100 km under fairly low temperatures.
  • With a short commute like mine (17 to 29 km each way), winter range is rarely a concern. However, if I need to run some errands in the evening, I do need to top off the charge during supper. To me, that’s main difference between summer and winter. In the summer, I rarely need to charge during the day.
  • During the weekends, most of our driving is spread out during the course of the day, with many opportunities to recharge at home. For longer than usual winter drives, we take our range extender (my wife’s car).
  • Heavy snow fall increases rolling resistance, and heavy freezing rain requires you to run the windshield defrost most of the time. I find these two conditions actually worse than a bone chilling but sunny day.
  • There are several techniques you can use to minimize the use of the cabin heater. It is essential to pre-heat the car before you leave, using grid power, and take advantage of the heated seats and heated steering wheels, and keep your winter jacket on.
  • The 2013 model has a more efficient cabin heater that is expected to perform better than the one that I have, but its performance is yet to be tested under very low temperatures.
  • Range concerns aside, the Leaf is the most comfortable car I’ve ever had in the winter. The extra weight from the batteries and the traction control system make it very safe to drive under heavy snow and slush conditions. It doesn’t have any problem “starting” in the cold, or that heavy and sluggish feeling of a gas car in the winter.
  • Finally, being able to charge at work, even from a regular 120 V outlet, makes a huge difference during the winter, for three main reasons:
    • All the energy I spend driving to work is easily recovered during the work hours, so any concern about range only starts after 5 PM.
    • Charging at work keeps the battery warm during the day, improving the car performance during the drive back home.
    • I’m able to continue to charge to 80%, at home and at work, which increases the longevity of the battery pack. Without it, I would probably need to charge to 100% at home every night.

    I hope this helps anyone considering buying a Leaf but is still concerned about driving it in the winter.

You’re buying gas to warm up the hood of your car

Electric vehicles convert up to 62% of the electrical energy from the grid to power at the wheels. Very little is wasted as heat. I took this picture after a one hour drive during a snow storm here in Ottawa. The snow that fell on the hood didn’t melt. It looks like I was just park outside.

Most people don’t realize this but about 80% of the money you spend on gas is actually lost/wasted by your car engine. Internal combustion engines are very inefficient at converting the fuel’s chemical energy to mechanical energy, losing most of it to engine friction, pumping air into and out of the engine, and wasted heat. You’re basically buying gas to warm up the hood of your car.

Source: http://www.fueleconomy.gov/feg/evtech.shtml

Two very cold nights parked at the airport

ImageI left the LEAF at the airport Park and Fly for two nights without realizing it was going to get really cold! If you haven’t heard, the Leaf battery will freeze solid if the temperature hits -25C, and no electrons will pass through the frozen electrolyte. To prevent this from happening, the Leaf has a 300 W battery heater that kicks in when the internal battery temperature hits -20C, stopping when it reaches a more comfortable -10C. The energy to power the heater comes from the battery itself, so in theory, you can lose a significant portion of your charge simply by parking the car during a long cold spell. That’s why you should leave it plugged in when parked in the winter, which clearly wasn’t my case as the Park and Fly doesn’t have any charging points.

The first night hit -23.2C and stayed very low for several hours, while the second night wasn’t so bad as the temperature stayed above -20C. I kept monitoring the charge using the GreenCharge app on the iPhone, but it didn’t change at all. I was curious to see if there was any change in the SOC% so I uploaded the data from the C5 logger to the FleetCarma portal and checked. For the two nights, the state of charge only dropped 1.2%, from 57.4% to 56.2%, which proves that a few degrees below the -20C threshold is still not enough to make a dent.

Phew!

By canadianleaf Posted in Winter

First scheduled maintenance service (6 months)

We took our LEAF for its first check-up last Friday, exactly 6 months after delivery and two weeks after hitting 10,000 Km. Normally, the first mandatory service is after one year, or 24,000 Km. After six months, the only service required is a tire rotation, which I would have to do it anyway as we moved from winter to all-season tires. However, with all the snow, sand and salt we get during the winter in Ottawa, I decided to go with a more comprehensive check-up.

Service was $85 + taxes (+ $1.99 of lubricants). It included road test, checking lights, wipers, coolant system, brakes, tires, charge port, seals, suspension, lube locks, latches and hinges, and swapping winter tires to all-season (the low tire pressure warning light is gone now). I found the cost reasonable. It was equivalent of servicing a Versa, minus the oil change. A similar service on the Corolla cost us $115 + taxes last time.

The dealer (Hunt Club Nissan) also  measured the current thickness of the brake pads: 9 mm at the front, 7 mm at the back. Brand new pads are 10 mm thick. At this rate, due to the wonders of regenerative braking, the front brake pads should last about 100,000 Km, which is excellent! But the rear brakes, only 33,000 Km. They told me the rear brake pads should wear down faster because of the parking brake, which was news to me… I’m curious to see how thick they progress six months from now.

The latest software upgrade was installed. I noticed the audible alarm if you put the car in drive or reverse while one of the doors is still open (I actually did that accidentally!) A few counters got reset, but everything else was preserved, including the performance history and charging stations on the map. I’ll keep monitoring the state of charge and range to see if there’s any difference. So far I haven’t noticed anything out of the ordinary.

We received a new owner’s manual, revised in Jan 2012. Recycled the old one.

They installed the lower-apron bracket, which is a minor recall “added for vehicles used in cold weather areas to prevent the possibility of snow and ice entering and accumulating in the motor compartment.”

We also got the windows tinted, as dark as legally allowed. Finally some privacy! 🙂 Good thing I didn’t do it before the heat wave because we’re not supposed to lower the windows for 3-5 days, until the film is cured. Cost was $300 + taxes.

The LEAF was charging at the dealer when I arrived. They also drove me to and back from work, which was nice. Never had this kind of service from Toyota!

Range vs. Temperature

I’ve been gathering performance data from the LEAF since day one, but it took me a while to figure out the best way to compile and analyze the data. The main reason is that the LEAF does not display an exact state of charge for the batteries, but only a rough one-out-of-twelve bars charge level, which is not very precise.

It is possible to purchase an SOC-meter (state of charge meter) that plugs into the LEAF’s internal data port and displays a more accurate read of the battery’s state of charge. But more recently, users at the My Nissan Leaf Forum realized there’s a strong correlation between the charging time display, particularly the one displayed for 120V charging, and the actual SOC values, with the relationship published in this chart. The charging times give you about 50 levels of resolution (from 0:00 to 25:00 in 0:30, or 2%, increments) compared to the 12 bars in the regular battery level gauge. You could also use the 240 V charging time (7 hours from zero to full) but that would provide only 14 levels of resolution.

As an example, if the charging time display says it will take 3.5 hours to charge to 80% using a 120 V charger, it means you have 70% usable energy in the batteries. A 4-hour estimate means 68% charge level, and so on so forth.

So I went through my logs and found 148 trips where I had saved the 120 V charging times before and after each trip, as well as the outside temperature and traveled distance.  Most of the trips were from my commute to work (17.1 Km each way), but the average trips were 28 Km each.

For each trip, I calculated the total energy used and estimated how long I could have gone on that trip on a 100% charge. Then I sorted all the estimates by outside temperature and averaged the results for each temperature level. It’s a fairly simplistic method but, given enough samples, it should give us a good picture of the LEAF performance under my driving profile.

Here are the results:

Nissan LEAF -- Estimated Range vs. Outside Temperature

The vertical bars show the estimated range for each temperature. The black line is a linear trendline. Precision is higher between -12C and +12C where 90% of the measurements were made.

Some interesting points to draw from this chart:

  • The absolute worst case is 80 Km range on a full charge. This has more to do with use of climate control than with the outside temperature per se.
  • The chart shows it is possible to hit the advertised 160 Km of range even on temperatures as low as 5C. This has a lot to do on how efficiently you’re able to drive, even at low outside temperature.
  • The linear trend shows a 20 Km loss in range for each 10 degree drop in temperature. In overall terms, a rule of thumb estimate would be:
    •  160 Km @ 20C
    • 140 Km @ 10C
    • 120 Km @ 0C
    • 100 Km @ -10C
    • 80 Km @ -20C.
  • Notice that these results are mostly based on short 28 Km trips, where range is usually not a big concern to the driver. On longer trips, you’re more likely to drive more efficiently and go easy on climate control use in order to conserve energy. For example, early this month I was able to drive 125 Km @ -10C on a full charge.

Finally, these results are fairly similar to the ones provided by Ross Redman, who bought the first i-MiEV in Canada. His results were published on a recent article by CBC, and shamelessly reproduced below.

Range of Ross Redman's Mitsubishi i-MiEV

So what’s the practical impact of this drop in range?

In my particular case, it’s very minimal. My regular commute to work is a 35 Km round trip. The longest regular trip I have to make during the week is 70 Km. The only real difference is that I have to plan a bit more, and eventually “top off ” the charge during the day, in the coldest days, instead of just overnight. For me, that’s a very small adjustment to make, and I’m still able to drive the same 2,000 Km a month at a much lower cost to me and to the environment.


“Extreme Cold” Range Data

Last month, I ran a range performance test to help Tony Williams validate extreme weather range data. He basically needed someone to drive the Leaf from fully charged to zero under an outside temperature of at least -10C. The car had to be charged at 100% and left outside (“cold soaked”) for at least 4 hours before the driving test. Terrain should be mostly leveled, with a mostly stable temperature and no extreme power used. He also provided a list of performance data required to be collected during and at the end of the test.

I drove the LEAF around the neighborhood (40 Km/h speed limit) and through quiet roads (70 Km/h). I thought I would run out of juice after two hours or so but the test actually lasted 3 hours and I drove 125 Km at the end, which is quite impressive given the low temperature (-13C at the start, -10C at the end).

I kept climate control at minimal though. The heated seat and steering wheel was on all the time, keeping the driver warm, but I kept the air temperature in the cabin at minimal, with the fan at low speed, mostly to avoid fogging the windows.

I drove all the way down to “turtle mode”, which basically means one kilometer left of range. I reached that point very close to my house, just in time to pull over the driveway and into the garage for a good recharge.

As a reward (yes, there was a carrot to this :)), Tony sent me a nice “Love My Leaf” t-shirt, available for purchasing at his web site, lovemyleaf.com.

So here are the full results.

Fully charged at start: –:–
Assumed battery temperature: -13C (soaked for 4 hours)
Final Dash Km/kWh: 7.0
Total distance traveled: 125.1 Km

Distance traveled at Low Battery: 15.8 Km
How many fuel bars showing: 1
120V to 100% Charge: 21:00
Temp: -10 C

Distance driven at Very Low Battery: 4.4 Km
How many fuel bars showing: 0
120V to 100% Charge: n/a (The “low level” warning covered the charge estimate, should’ve closed it…)
Temp: -10 C

Km driven at Turtle, if applicable: 50 meters, before pulling over my driveway.

Heater power use:
– Climate control = 0.5 KW average (windshield only, minimal temp, minimal air flow)
– Other systems = 200 W (incl. heated seat, heated steering wheel)

Raw data:

      Outside Battery         Charge  To 100% Charge
Time    Temp(C) Temp    Km      Bars    240 V   120 V   CC (KW)
12:28   -13     3 bars  0(6657) 12      --:--   --:--
12:29                                                   3
12:29                                                   3.7
12:30                                                   4.6
                        1.1
12:31                                                   4.5
12:32   -12                                             0.75
12:33                                                   0.7
                        4.7
12:35                                                   0.5
                        5.9     11      0:50    2:00
                        6.3     11      1:00
                        7.0                     2:30
                        8.0             1:30    3:00
12:50                                                   0.2
                        9.9                     3:30
                        11.3                    4:00
                        11.4    10      2:00
12:58                                                   0.75
                        13.7                    4:30
12:59   -11
                        16.1                    5:00
                        18.1                    5:30
                        19.8    9
                        21.5            2:30    6:00
                        24.0                    6:30
                        26.9                    7:00
                4 bars  27.1
                        28.9    8
                        29.1                    7:30
                        31.3            3:00   
                        32.4                    8:00
1:26    -10
1:27    -11
                        36.0                    8:30
1:31    -10
                        38.3                    9:00
                        39.2    7
1:34                                                    0.5
                        41.7                    9:30
                        42.4            3:30
                        44.6                    10:00
                        47.1                    11:00
                        49.3    6
                        52.7                    12:00
                        53.3            4:00
1:51                                                    0.75
                        58.7    5
                        59.0                    13:00
                        63.4            4:30
                        64.9                    14:00
                        67.2    4
2:09                                                    0.5
                        70.4                    15:00
                        73.8            5:00
                        75.8    3               16:00
                        81.9                    17:00
                        84.9            5:30
                        86.9    2               18:00
                        92.5                    19:00
                        95.5            6:00
                        98.4                    20:00
                        100.8   1
                        104.2                   21:00
                        104.9   1 Low
3:00                                                    0.75
3:04                                                    0.5
                        120.7   0 ---
                        125.1   Turtle
3:30    -10     4       125.1   Turtle  n/a     n/a     0.5

Getting the hang of winter range calculations

I’d like to share two examples of range estimate calculations under winter conditions that were verified by actual trips. I used the same method to estimate the range at the beginning of the trip, and compared with the actual remaining range on the dashboard at the end of the trip. In both cases, the estimate was very close to the final dashboard range.

First example was a 57 Km trip. Initial state of charge was 10 bars. Range chart estimates for 10 bars @ 80 Km/h were 137 Km. Temperature was -2C, meaning 22% drop in range. We planned to use climate control throughout the trip to avoid fogged windows, which I estimated would take another 15%. So The initial 137 Km range minus 37% quickly became an 86 Km range. If the estimates were correct, that would still leave us with 29 Km to spare.

At the end of the trip, we made it home with 28 Km of range on the dashboard.

Second example:

– Round trip: 37 Km
– Starting charge: 10 bars
– Range chart estimate at 20C and 80 Km/h: 137 Km
– Outside temperature: 2C (-18% drop in range)
– Climate control on: -15% drop in range
– Final range estimate: 137 – 33% = 92 Km
– Estimate range to spare: 92 – 37 = 55 Km
– Actual dashboard range at the end of the trip: 55 Km (no kidding)

A couple of notes:

  • I used the final dashboard range measured after putting the car in park. Estimated range in Eco mode would be a bit higher, but you have to consider the fact that the last kilometer of the trip was done at low speeds, so things kind of balance out at the end.
  • The range chart estimate is based on constant speed, which was obviously not the case of either trip.
  • Outside temperature was not necessarily constant.
  • The method is clearly not very scientific but it gives me a fairly good estimate of what to expect. The formula will probably change once outside temperature dips below -20C, because that’s when the internal battery heaters kick in.

5,000 clicks and counting

5,000 Km driven on the Nissan LEAF

Our LEAF has crossed the 5,000 Km mark today. The car is doing great after 2.5 months since delivery. At this rate, we’ll probably hit 24,000 Km in a year, 20% more than we first predicted. No problems with the car so far, and I haven’t got stranded yet. 🙂 The range has been more than enough for the kind of drive we do in the city, and we’ve been getting plenty of chances to recharge both at home and at work.

Cost of ownership has been really low and impressive. We spent about $30 in electricity with the LEAF in October, and $35 more in November, and drove almost 2,000 Km in each month. Charging at IBM helps, but the trickle-charging at mid-peak hours is just enough to cover the 34 Km round trip to work so most of the charging still happens at home, which is much faster, more efficient and can be done at off-peak hours, when all the coal fire burning power plants are safe at sleep (Ontario still has 18% of its electricity coming from coal but mostly to respond to peak demand).

These days, I’ve been getting a lot of questions about the winter, though we haven’t got much of a winter yet — barely crossed the freezing mark, but it’s been enough to give us a feeling of things to come. I’ll try to summarize it below.

How does it drive in the snow?

Not much different than any other car. Winter tires have been working as expected, with ABS and traction control doing their job, so nothing new really.

LEAF after a snowfall in Ottawa

How does it drive below freezing?

Response and acceleration are about the same. The *power* (KW) is there when you need it. The difference is in how much *energy* (KWh) you’re able to draw from the batteries at lower temperatures. It basically means the lower the temperature, the lower the range.

How far can you go in the winter?

The estimates provided by Tony Williams’ Range Chart at the My Nissan LEAF Forum have been fairly precise so far. The chart predicts a 1% drop in range for each 1C drop in temperature below 20C. This is very in line with what I have observed since the temperature started to fall.

As an example, I’ve monitored a 76 Km round trip we did last week, mostly on highways. We started with an 80% charge, with the guess-o-meter telling us we had 138 Km of range, which basically meant: if we continued to drive around *our neighborhood*, at 40-60 Km/h, we could drive 138 Km. Not very helpful of course. The Range Chart told me this instead: 10 bars @ 100 Km/h = 116 Km. Temperature was hovering around 5C, so 116 Km minus 15% = 98 Km range. This estimate did not include the use of climate control, which I knew we were going to need in order to avoid condensation. So 22 Km of extra room sounded good enough, so off we went. At the end of the trip, we arrived at home with one bar left, and it had just started flashing. That meant 16 Km of range according to the Range Chart (19 Km – 15%). So in summary, we drove 76 Km out of an estimated 82 Km range (98 total – 16 left), which was a very good approximation considering we used climate control during most of the trip.

Condensation forces you to use Climate Control

With heated seats and heated steering wheel, I haven’t felt any need to heat up the cabin so far, even when it’s 0C outside. The energy to heat up the seats and the steering wheel is fairly low, about 40W each, and have virtually no impact in your range. However, once you have passengers in the car, condensation starts to build very quickly and things get complicated. The A/C alone is not strong enough to keep the air inside dry, so you are forced to bring fresh air from the outside, and because this air is very cold, you have to use the climate control to warm it up. That’s takes a lot of energy compared to the heated seats: 4.5 KW initially, and then 1.5 KW once the target temperature is reached (minimum is 18C).

Expect 15% drop in range from Climate Control

Even at the minimal setting, Climate control draws a steady 1.5 KW from the main batteries. It’s a bit hard to estimate how much that will translate into range, but assuming an average 10 KW draw from the motor, that would mean an extra 15% being used. That’s the number I’m using right now to plan my trips, as a worst case scenario, but I still need more hard data to confirm it.

What’s going to happen when the temperature goes down to -25C?

No much data on that yet, but I suspect the decrease in range will not be linear. According to Nissan, the battery heaters will kick in at -20C and heat up the batteries to -10C. They will then shut off until the battery temperature falls again and hits -20C. The heaters do not take a lot of power — only 300W, and they work based on the internal temperature of the battery, which is typically higher than the outside temperature. You also have the thermal blankets, and the car itself, to help maintain the internal temperature. You can also help by starting the charger in the morning before you leave. Charging causes the batteries to warm up and that will boost your range a bit.

So overall, what do you think the impact of a harsh winter will be?

I “guesstimate” a worst case scenario of 40% decrease in range for the coldest days of the year. That will still put us within a 100 Km range on a full charge, which is still well within what we usually drive. No long trips to Ogdensburg for sure, but not a significant impact to what we currently do.

I foresee some changes in habit though:

– We normally charge to 80% at night. That helps prolong the lifetime of the battery and also saves energy. However, during the coldest weeks of the winter, we will probably have to push the charger to 100% overnight.

– We will probably need a boost during the day. In between arriving from work and doing errands in the evening, we will probably need to plug in during supper (yes, on-peak hours…) in order to get the extra range if we really need to or just to be on the safe side.

– We’ll have to get used to keeping the cabin cool rather than running a furnace inside the car. We’ve been used to hot cabins all these years driving gas-powered cars, to a point of discomfort sometimes. We’ll need to change that habit in order to use energy more efficiently.

So there you have it. How have all these changes affected our daily drive so far? Not very much, really. I just have to plan a bit more, and I confess I’ve been fairly conservative and ended up with lots of left-over range at the end of day. At least, that’s a good way not to get stranded! 🙂

First road trip on our LEAF


Driving the Nissan LEAF in the city is a no-brainer in terms of range. We rarely need to drive more than what the LEAF can go on a full charge, and we’re always relatively close to places where we can recharge during the day (home, work, even the dealer). But on road trips, this scenario changes significantly.

I recently had to drive to Ogdensburg, NY in order to pick up a set of snow tires. Not that we can’t find snow tires in Canada — we certainly can, but for some strange reason, tire manufacturers impose much higher prices north of the border so buying the same tires in the US can save us several hundred dollars (about $300 in my case).

A round trip from Ottawa to Ogdensburg is about 165 Km, which is right at the limit of the advertised range of the LEAF, so the trip would have to be very well planned.

On a side note, I did have the option to drive our “range extender” (my wife’s car) instead of the LEAF on this trip, but that would take away all the fun, wouldn’t it?

Dry runs

The Ottawa-Ogdensburg route

There’s a 75 Km highway connecting Ottawa to the US border called the 416. That would be the obvious choice if I was driving a gas-powered car, but driving an electric car at highway speeds significantly reduces the total range. I decided to take LEAF for a spin at the 416 to see how much that would be, and these were the results:

Highway Test:
– Cruise control set to 90 km/h
– 14C, dry road, windy
– Climate control off
– 100.3 Km driven (11 Km/bar)
– Ended with 3 bars left (31/35 Km)
– Estimated total range: 133 Km

Obviously, that wouldn’t be enough for a round trip to Ogdensburg, but the result falls very closely to what the Nissan LEAF Range Chart predicts.

According to the range chart, I would need to lower the target speed down to 70 Km/h in order to achieve a safe 177 Km range. However, this range estimate assumes an outside temperature of 20C, which is quite rare around here in November! Lower temperature means I would have to lower the speed even more, so it became clear that taking the highway would not be a practical option.

The Spencerville Mill, in Spencerville, ON, was my 62 Km checkpoint

With the highway out of the picture, the next step was to find a good route over country roads. Luckily, there are a lot of quiet and well paved roads that can take me to the same destination. These roads are quite pleasant actually, going through small towns like Spencerville, ON and beautiful farms.

Country road test:
– Max speed 65 Km/h, down to 40-50 Km/h in city areas
– 9C, dry road, no wind
– Climate control off
– 124.5 Km driven (13.8 Km/bar)
– Ended with 3 bars left (44 Km)
– Estimated total range: 168 Km

At this pace, I would be able to go all the way to my destination and back on a single charge. In addition, the place where I was buying the tires from (Bill’s Tire) would let me trickle charge while in there, and even a bit longer if I needed to. This would give me some comfort room. I also contacted a friend who lives in Kemptville, right on the route and 40 Km from my house, in case things didn’t work as planned and I needed to make an emergency stop for a recharge at his house.

One final factor to consider was the extra weight of the tires I would be bringing home. I would also be riding on snow tires, which have more rolling resistance than the original Ecopia tires. I didn’t have any data to estimate the impact on performance. The extra weight would add 2.5% to the weight of the car, but the snow tires I would be buying were also low rolling resistance tires. I assumed the drop in performance to be within the margin of error of my estimates, and that I could compensate by monitoring performance and adjusting my speed accordingly on my way back home.

First attempt


I started the drive to Ogdensburg on a Saturday morning. I woke up early and started on the same route I had done previously. Only that this time, conditions were quite different. Early in the morning, the temperature was -7C. Yes, negative 7. I lost the first bar very quickly, with less than 10 Km. Reducing the speed didn’t help as the second bar went out fast too. After 50 Km, my average was 10 Km /bar. I figured at that pace, I would get to my destination with only 4 bars left, and require at least 4 hours of trickle charging to get me back home. So, it was tough decision to make, but I had to turn back and try another day.

Failed attempt:
– Max speed 60 Km/h, lowered to 40-50 Km/h
– -7C, dry road, no wind
– Climate control off
– 99.5 Km driven (10 Km/bar)
– Ended with 2 bars left (38 Km)
– Estimated total range: 138 Km

Second attempt

The weather forecast was calling for much better weather during the week. Wednesday was promising a high of 15C so I planned to leave work early and head to Ogdensburg, taking advantage of the higher temperature. Leaving from work would only add 4-5 Km to the round trip, and thanks to IBM, I was able to top off the batteries back to fully charged at the parking garage before I left.

Charging while changing tires

The trip to Ogdensburg took 86.3 Km and arrived there with 6 bars left. That was about 14 Km/bar, which was really really good. The estimated range left was 95 Km, and I needed only 82 Km to get home. To be extra-safe, I asked the guys at Bill’s Tire to plug in my Level One charger as soon as they parked the LEAF in one of their service bays. They had absolute no problem with that. The service only took 30 minutes — the tires were already mounted on the rims when I arrived, but they let me continue the charge until I got at least 10 Km of extra range for safety. I ended up plugging in for 70 minutes which raised my estimated range from 95 to 106 Km.

With the snow tires on and the original tires tucked away in plastic bags over the folded back seats, I was ready to head back home. Over the border, I had to stop at customs to declare the purchase and pay the Canadian sales tax (13% HST). Tires made in North America are duty free.

Once on Canadian roads, I started to monitor the car performance. Driving at 65 Km/h, I was averaging 13 Km/bar, which was good. I drove through Kemptville, where my friend lives, with about 60 Km of estimated range, and I needed 40 Km to get home. I didn’t see the need to stop for an emergency charge so I stayed on course.

At this point, range anxiety turned into temperature anxiety. With the sun about to set, the temperature outside started to drop quickly. First 14C, then 13C, now it was 12C. For safety, I changed to a quieter back road that allowed me to reduce the speed to 40 Km/h for about 17 Km, while also shortening the distance that I still had to get through.

The final 12 Km were fairly easy, even though I had to go on regular 80 Km/h roads with only one bar left. The “guessometer” was estimating a range of 29 Km so I could safely raise the speed to 65-70 Km/h without any problems. When the estimated range dropped to 20 Km, the last bar started to blink and the center display changed to “battery level is low”. Fortunately, I was only 5 Km from home. I arrived there safely with 15 Km of range to spare.

Back at home with 15 Km to spare.


Final report:
– Max speed 65 Km/h, down to 40-50 Km/h in city areas, 40 Km/h for 17 Km.
– 15C, dry road, no wind
– Climate control off
– 166 Km driven
– 1:10h level-one charge (extra ~10 Km)
– Ended with 1 bar left, low battery alarm, 15 Km range
– Estimated total range, without the level one charge: 171 Km

LEAF on snow tires


Additional notes:
– Back at home, recharging from less than 10% to 80% took exactly 4 hours. I know for a fact that charging from 80 to 100% takes 1.5 hours, which brings the total to 5.5 hours. I really don’t know where the advertised 7 hours recharge time comes from.
– The tires I got were the Michelin X-ICE XI2 205/55R16.
– The name of the tire store is Bill’s Tire Center, 1000 Patterson St, Ogdensburg, NY (315) 393-7660. Great people and great service. Cost per tire was $133, $50 rims, $10 installation, plus a $2.50 waste tire mgmt fee. Total with taxes: US$836.04. Same service in Ottawa would cost C$1150 + HST.
– I didn’t install tire pressure sensors inside the snow tires so now I get this yellow alarm on the display. Not sure if there’s a way to disable the alarm. A set of pressure sensors costs $290 at the dealer. Maybe I’ll get some next winter.
– Crossing into the US, I got a *lot* of questions. Not about me, but about the car!