Winter Driving

[BillThompsonMIEV]

Hello to all. Although I live in the San Antonio, TX, some of my friends and I are curious about performance in the harsh winter climates of our northern states and Canada. Specifically, I am curious on the RR after a full charge to 16 bars. Could you respond in this manner: typical RR in spring/summer compared to typical RR in the winter. This might give all of us a more specific feel as to cold weather effects on our MiEV's. Thanks. Bill.

 

[tonymil]

I'm in upstate NY and so far there hasn't been a single day that I would call "harsh winter". However, during our mild winter days I have been very liberal running the heater and the seat warmer and so far I'd say the RR has dropped from 70-75 miles during the spring/summer to about 50-55. I have no idea how much more that will drop when we finally get some really cold days and nights - and some slippery stuff on the ground. I think just like summer driving where some of us were getting ranges in the 70's, some in the 80's and some in the 90's we're going to see a lot of variability based on driving habits, heat usage and outdoor conditions. I don't know that we'll end up with a "typical" number.

 

[fjpod]

In the summer, with almost no A/C use, I was averaging low 90s RR on a full charge. Although we have not yet hit the heart of winter here in NYC, I am using heater/defroster and my RRs have dropped to 75-85. Probably going to get a little worse with lower temperatures. My car is outdoors overnight where I charge it in the driveway.

 

[leec]

The RR is highly dependent on recent driving patterns: I live on a hill so my RR is always skewed by the climb which takes about 1kWh. When I head out, my RR estimate shoots up at least a few miles as I descend the hill. Furthermore, I usually don't charge to 100% unless I'm planning to use it for the sake of allowing maximum regenerative braking on the way down the hill. This saves on the brake wear and keeping the battery charge away from maximum voltage extends it's life, too.

Winter range is interesting: lower temperatures will reduce battery efficiency but quick charging will increase battery temperature and keep it closer to the optimal range. On the other hand, driving with traction tires will reduce range.

I recently did some mountain driving in my i-MiEV. You can see the trip report for further details.

 

[Brian]

I've been keeping track of my mileage per kWh pretty meticulously so far.
Since August, the average has been around 4.0 miles per kWh. Typical driving conditions are speeds below 45 MPH, no A/C use, and using Eco mode for accelerating and B mode to slow down for maximum regen (and some coasting in Neutral). And also an average of 10 miles driven per day.

We just got our first snow storm of the year. 2 inches at my location, but the surrounding areas had up to 12 inches. Luckily it was warmer that morning because we had 1.2 inches of rain before it got cold enough to turn to snow on the way down.

So, no true "winter" driving on unplowed streets yet. But in using the defroster (on the two lowest fan speeds) the early indications are miles per kWh dropping to 3.6. There have been a couple weeks of morning commutes where the "outside air temperature warning indicator" has come on. This is the 'snowflake' that appears in the same window as the odometer display. In reviewing the owners manual, it does not appear to change any functions in the behavior of the car that would effect range, it only serves to warn that the roads may be icy. (page 3-67)

As it gets colder, I suspect I'll be using the heater for comfort and not just keeping the window clear. I really need to keep the seat warmer option in mind since that hasn't been considered yet. But there will be updates to my range as the season progresses.

 

[DonDakin]

Hi All,

Winter range is one of the things that I was most worried about for an EV up here in Montreal. Winter is starting to really kick in and things have been good so far. One thing that I do is keep the car in the home garage and this makes a big difference in the morning drive in. With my other ICE cars I would leave them outside all winter and of course they would pile up with snow and cold soak but since it'a an ICE that's no problem. I would use a remote starter and warm the car up for 10 minutes to get the defrost going as usual. For the imiev I wanted to keep it inside mainly to spare the battery the cold soak overnight. But what I am noting is that keeping the car in the garage just makes getting out in the winter so much more pleasent. No cleaning off the car, no defrosting. Preheating in the garage makes it warm and toasty for the ride in. It's actually nicer driving the EV to work in the morning after a snowfall then going out and cleaning the ICE off and driving that one in.

As for range at about 1-2 Deg C keeping the fan on 1 click and the heat on one click with an already warm car is fine and produces about 70-80 KM of range no problem.

When it's -5 Deg C heat has to be up a knotch and Range seem to drop down to 50-70 KM area.

It gets more complicated to think about range in winter because so many things affect it.

I have noted that driving to work with several inchs of snow fall and unplowed streets seems to take about 50% more energy. Thats including heat at a temp of 1-2 deg C.

Of course you can always do a worst case scenario and come up with a really low range number somewhere around 50 KM or less. But I think that's a little unrealistic.

Generally when it's cloudy and it snows temps tend to rise so there is a little give and take with temp vs snowy conditions. Also when it gets colder on very clear days there tends to be more sunlight and the sun heats the interior really well even when it's cold so again a little give and take.

To have a little backup I also bought a 1500 BTU catalytic propane heater that I keep in a utility box behind the back seat. That's my winter range extender. I've never really had to use it up to now other then testing but I may use it in Jan and Feb on really cold days. My real secret weapon are heated insoles for my boots. They really help keep the chill away and use very very little electric energy.

All in all Up to now I have not had any issues with the winter weather and the iMiev. The traction computer in the car makes winter driving completely simple and safe. It's really impressive. I use the heat and defrost with A/C as i normally would and things are fine for my short daily driving which is about 30-50 KM.

Don....

 

[peterdambier]

We did have -15C = 5F one night. Not too much snow but uncomfortable. I have just begun learning how to operate A/C and heater to defrost and defog and getting it warm inside. Putting everything on automatic does not help.

RR got down from 164 / 107 kilometers (100 / 66 miles) to 80 / 50 kilometers (50 / 30 miles). We have actually been driving a little more than 100 kilometers with the turtle giving us a fit. Reading the charge gauge indicates not so much change. The cold did get us a little more careful but I guess I still could travel more than 80 km or 50 miles.

 

[MLucas]

I'm seeing the same results as DonDakin. We haven't hit the really cold temperatures yet in the Niagara Region. The lowest I've seen the temperature go according to the instruments, is -3C. With careful drivinig and heat on notch 1, I'm seeing a loss of 1 or 2 bars off my daily 43km commute. In the summer, I can make it to Buffalo on 5-6 bars off the power meter in the winter its between 7-8 at 0C. I'm going to get a heated autoblanket and see how that goes. Because, anything above 2 notches on the heater causes my power meter to drain quickly.

 

[Don]

We haven't had much cold weather here either - One overnight got us down to about the freezing point . . . . it's 70 degrees here today

So far, my experience with the heater is that it consumes more energy and range than the A/C does, and this surprised me a bit, but I guess it shouldn't have. When you're air conditioning, you're trying to change the temp in the car by 20 or 25 degrees - it's 95 outside and you'd like it to be 75 inside, but we ask much more of the heater than that - It's 30 outside and you'd like it to be 75 inside

As to what cold weather does to the battery pack with regard to energy/range loss - That will be a harder thing to figure out. Someone will have to make several 50 mile trips in 30 degree temps using no heat of any kind so they can compare that with what they were getting in the summertime when they were making the same trips with no A/C at all

Don

 

[sandange]

We've been on the road for the holidays visiting family

24 Dec - 134 km , no heat , only heated seats, and car blanket on our lap and legs , dressed with gloves, hats and warm boots. Charged at several location while visiting family and shopping, modified level 1, & level 2.

24-25 Dec - car outside, had charged with modified level 1 for more than 12 hours in temps -13. Day time temps warmed up to -8c.
Left with full charge for 92 km trip. Had to stop and charge level 2 for 45 minutes to make it home , 4 km left on the RR guage - again no heating other than seats and lap blanket.

Conclusion so far, we added heated cushion for passenger and a electric car blanket for the legs.
For temps down to -10c, this is just enough not to run the main heating system. at the lower temps the RR does suffer 10-15 %

Waiting on colder temps to further evaluate., Last night Dec 25-26 temps were down to -18 C, car was garaged,
Propane heater is on standby for further testing, and will start plugging in the electric car blanket.

 

[JoeS]

sandange, you and your family are real troopers! Thanks for the updates describing conditions we (thankfully?) never see here on the coast in California. I notice that the electric blanket draws 3.5A-5A at 12v, which really makes it trivial compared to the power draw by the car. For example, the blanket at 5A*12v=60W. The iMiEV, in the middle of Eco region on the power gauge is IIRC 22.5A at 330V = 7,400 watts! No problem. All the best for your upcoming 'adventures'.

 

[MLucas]

Drove through my first real snowstorm of the season last night here in Buffalo, NY. I really got to see what the i MiEV can do in the snow. Very impressed with the little car that can. At first the car seemed a bit squirrley but then I realized it was just 'pilot induced turbulence'. Once I relaxed and let the car manage the terrain, it straightened out nicely. The ASC kicked in several times throughout the drive, keeping the car in line on the road. The QEW wasn't plowed, so the right lane was not exactly cleared and the left lane was full of snow. Getting around the white knuckled ninnies was always a bit shaky in my 08 Versa, but much better with my 12 i MiEV. The 600 lbs of batteries keep the car well planted and the ASC sorts out the rest. I felt very confident passing cars in the snow laden left lane, I don't like being around other drivers in these conditions - if I lose it or they lose it, I want it to be a solo performance only. Braking/slowing is excellent in these EV's, its much like a manual transmission - instead of slowing just downshift or in our case REGEN. The only time the ABS went off was after I entered my subdivision, I nailed the brakes to see what would happen. Not much, the car stayed where I intended and I just heard the crunch-crunch of the ABS going off. I am running with the OEM all-season tires, no snow tires.

 

[PV1]

Yet another EV that goes pretty well in the snow. I heard the Tesla Roadster does pretty good, too, considering its low ground clearance and sports car chassis. When the big snow hit the midwest a couple of years ago, two guys were driving a Roadster from California to the Detroit Auto Show, and they reported the car went through the snow without a problem.

After hearing reports like yours about the i's winter performance, I've been thinking I could buy the car earlier since I can afford it, but I wouldn't want to put a brand new car through the salt and cinders. How's the range looking in these conditions?

 

[dsmall24us]

After hearing reports like yours about the i's winter performance, I've been thinking I could buy the car earlier since I can afford it, but I wouldn't want to put a brand new car through the salt and cinders. How's the range looking in these conditions?

I am doing my winter driving in Rochester NY. We average 100 inches of snow a year. So far I am very satisfied with the handling. Drives even more smoothly and quiet on snowy roads and feels stable changing lanes and going up and down grades. The car seems better than the 1st generation prius I had. I also had a rear wheel drive Smart car and the Imiev is much better in the snow due to its extra weight and driving in Eco mode which seems well suited to snow covered roads. My RR is now showing about 60 after a full charge versus approx 78 during the warmer time of the year. The RR drops into the high 40's when I turn the heater on. Most of the time I preheat or defrost before going out and use the heater on a low setting. I would be content most of the time to drive with just the seat heater. I really wish the front passenger had a seat heater too. In very poor conditions where I need to run the defroster and heater like in the last storm we had I would not try to plan on going more than about 35-40 miles. One of the reasons as traffic moves quite slow which ordinarily would increase the range during normal conditions, during the winter that just increases the time that you are drawing on the battery for the heater/defrosters. Overall I still give high marks to my imiev in the snow/winter.

Dan

 

[JoeS]

Thank you all for your detailed updates about winter driving in the iMiEV. Fascinating reading.

A question about our Active Stability Control (ASC), consisting of the three different, yet complementary, functions: ABS, Traction Control, and Skid Control. Whereas I can see that having ASC ON would be especially beneficial when driving in loose snow/ice-covered conditions, the owner's manual suggests that if one is having trouble starting out from a particularly slippery spot then one might turn off ASC. Specifically, on Page 3-48, "When moving out of mud, sand, or fresh snow, pressing the accelerator pedal may not allow the electric motor speed to increase. In such conditions, temporarily deactivate the ASC, using the ASC OFF switch." Presumably they're talking about the Traction Control feature keeping the wheels from spinning or even turning, but, on the other hand, here's their Traction Control description (Page 3-46) "On slippery surfaces, the traction control function prevents the drive wheels from spinning excessively, thus helping the vehicle to start moving from a stopped condition..." Looks to me as though we have two nice alternatives to help us get out of a slippery spot.
Have any of you snow-bunnies experimented with this or found a need to disable ASC for this scenario?

 

[DonDakin]

Hi All,

I Finally had my first winter problem with my imiev.....

For some unexplained reason the car would no longer move forward.....

I guess Ev's are bad winter cars......

See pic below:

http://imgur.com/n1J0P

Don...

 

[nt2w]

We got hit with the same storm as the rest in the Northeast late last week--- 17 inches of new snow fell from 9pm 12/26 to the afternoon of 12/27, with several hours of 2"+ per hour. Since my i doesn't have snow tires, it stayed in the garage (my VW TDI with new snows made it into work, plowing snow over the headlights in the morning).

Taking the i out later on the (mostly) plowed roads, it's pretty stable and predictable, and the stability control is clearly up to the task. The skinny tires are a major plus in snow, biting down for a better grip.

Couple notes- JoeS asked about turning off the ASC- this is usually done on other cars to "rock" your way out of snow or mud. It's hard to explain, but when you're already stuck, you don't want the ASC to be working against you as you try and rock the car back and forth, using the momentum of the car to give you traction... I got my MiEV stuck in the mud on the lawn washing it this fall (pretty easy with those skinny tires, which are a negative in mud) and tried the ASC off, but had to get my wife to steer while I pushed.

I had wondered about how the ASC handles lift-throttle oversteer situations (think old VW's and Porsches) in snow. Given that lift-throttle situations kick in the regen at various levels, this could be potentially dangerous when entering a curve on slippery roads and letting off the "gas."

My curiosity was whether the controller would reduce regen in this situation, or just use the brakes. I found out today, when on purpose, I put the car in "B" and let off the throttle while steering tightly into a curve. The ABS kicked in and held the car's attitude facing forward, regen remained the same. Question answered!

Finally, there have been questions regarding range versus temperature versus heat. I've been tracking this for my i since September as the temperatures have fallen. Coldest temperature so far has been about 0F, -18C. Subzero weather is forecast for later this week. Range definitely takes a hit both from the cold and from the heater. I am not as dedicated about putting heated shoes and vests or blankets on to save the battery as others (Sandange is the champ for that one!), so I just go ahead and use the heat/defrost and drive as normal, since the reduced range is no problem in my circumstances... I just charge more often.

Since I'm no good at posting pics here, here is a URL to the PDF of the chart: https://docs.google.com/open?id=0B0RqdvINrwPlVWlRbkZzSHVjUUk

I apologize for the mixed units- I monitor weather using SI units and the car's RR is in miles... if I weren't so lazy, I would change it... maybe I will later.

Cheers-

Rich

 

[nt2w]

Just a bump- edited my last post to add some additional comments- still haven't edited the range units graph.

Another winter thought- yesterday while driving in light snow I was annoyed by the rear window defogger grid- it leaves about 4 inches of unheated space at the top of the rear window, where snow blowing off the roof accumulates and doesn't melt. Over time, the wiper can't clear it. The grid should extend a little farther up to help with that...

Rich

 

[jray3]

During the first snowfall of the year here near Seattle, I threw on an old pair of studded 13" tires on Honda Civic rims. Easy fit on the rear, and very similar circumference to our 15" low profile stockers. I remember that studs were noisy on the gasser, but OMG- they're nigh intolerable in an EV! Am not noticing a huge RR redux. Anyway, they're annoying to the point that I'll change back to stock asap and tread lightly in the next snowfall.

The tire pressure sensor warning light is the only other annoyance- much to my wife's amusement. She 'captions' for all her cars. In this case it was "Doc- help.. I can't feel my legs! But why am I still walking?". :lol:

 

[nt2w]

Thermometer on the i got down to -14F/-26C this morning on the way in to work. It was 31F when I pulled out of the garage!

No real noticeable difference- car was fully charged- range showed 68 miles with heat off, 53 miles with heat on. Pre-heated for about 20 minutes and it was toasty all the way to work.

The office is a 5.5 mile drive- RR went from 53 miles to 41 at the end of the drive into work, even though the gauge only dropped one bar, which is typical for me.

Opportunity charged when I came home for lunch, then back to work- some errands after work and back home- I think RR was down in the 20's. Recharging seemed to take a bit longer at the lower temperature.

Rich