Range going uphill in subfreezing temperature

Today was our first full day driving our newly leased Leaf S. It was mostly in-town driving. We have some range-anxiety about taking the car up the mountain.

does anyone have real-world range on a fully charged Leaf going constantly uphill for 26 miles in subfreezing temperatures? how about going 36 miles, constant uphill in warm or temperate temperature? would we be able to make it to our local ski resort (26 miles away)/local lakes (farthest is 40 miles away) and back?

of course, coming home would be all downhill.

and, how about if we loaded up the roof with two kayaks...what is the decrease % in range?

thank you.

I can't give you any "real world range experience" on your questions, but when did that ever keep me from expressing my opinion?

Tony's excellent LEAF Range Chart addresses elevation changes in a footnote. He says to assume an extra 1.5kWh for each 1000 foot gain in elevation, and that you may recover 0.75kW per 1000 feet coming back down. By the way, you should consider total gain and loss, not net gain and loss. If there is a valley in the middle of the climb that can be significantly different.

But 52 miles round trip in sub-freezing temperatures sounds like enough of a problem in itself, especially if there is snow or ice on the road, without considering elevation changes.

I assume you wouldn't be taking the kayaks to a ski resort :? but they will add a lot of drag to the car, and air resistance loss goes up as the square (or is it the cube?) of the speed. So the "decrease %" would be highly dependent on how fast you are traveling.

Ray

Well, I just have to add that no EV, Temperature management system or not, likes sub freezing temperatures.

Please report your experiences.

Keep in mind that the slower you climb, the less power you use. Allow extra time to get there and climb at a leisurely pace. Use the heated seats and wheel, not the cabin heater - at least not any more than you absolutely have to.

Here are some great descriptions of hills and cold driving:
http://www.mynissanleaf.com/viewtopic.php?f=31&t=4952&hilit=exeter
http://www.mynissanleaf.com/viewtopic.php?f=31&t=3512&p=259299&hilit=cold#p255944
http://www.mynissanleaf.com/viewtopic.php?f=4&t=11505&p=265886&hilit=cold#p265886
http://www.mynissanleaf.com/viewtopic.php?f=50&t=11123&p=255938#p255938

Here is my 1/22/12 experience. Mt. Hood, Oregon hill climb today, 3736' up. I did 100% charge with preheat ending with to 1.5-2 bars left (19 on the GOM) from 30-24 degree temperatures, all on snow, total miles was 52.2. I started in Odell, OR, 725' elevation and went up to Teacup Lake Nordic ski area to cross country ski, 4461'. I drove between 35-50 mph going up and got there with four bars remaining and 13 miles on the GOM. I have 17 lb. wheels, with General Altimax Artic, siped and studded tires filled to recommended psi. I coasted back down the mountain, reaching up to 53 mph at times, but mainly was going about 40-45 mph. I used my heated seats, and only used the defrost at 60 degrees when the windshield needed it, both ways. Fun experiment. We have had snow and ice since last Wednesday and this car performs very well with the low center of gravity, traction motor, and studs. I could not be happier with the handling of the LEAF in this winter weather.

I have a Yakima roof rack that I put bikes & stand up paddle boards on. The rack probably penalizes me .3-.4 m/kWh @ 65 mph. I only drive 55 mph max with bikes &/or paddle board due to the significant range penalty above 55 mph. The Yakima rack usually only stays on top a few days every month.

I've done it at 5º to 12ºF. 42 miles to the top of the pass, 4400+ feet net, about 5200 feet overall, since I had to get over two passes:
http://www.mynissanleaf.com/viewtopic.php?f=6&t=6330&start=52" onclick="window.open(this.href);return false;

I mostly did it at 30 mph, no heat (until the end, when I was sure I would make it); I was dressed in downhill ski gear for warmth. Tire pressure matters, I use 38-42 psi (cold drops pressure, so you might want to start out in the 40+ psi range).

I started with Tony's range chart and did the calculations for distance, speed, temperature. I then dropped my speed a bit to 30 mph for an extra margin of safety and made the top of the second pass (10,910 feet) with two fuel bars, a very comfortable reserve.

I have an advantage in that I am at higher altitude than the Bend area, so I have somewhat reduced air resistance due to lower air density, but that can and should be factored in, as well as temperature and speed (and is one of the important footnotes on Tony's chart).

I will be making the same trip this coming January for my second warranty battery check. Even with a more degraded battery I don't expect any problems.

So, depending on speed and total altitude gained it should be possible to do 26 miles uphill in subfreezing weather, assuming you aren't driving on snow very much. I'd suggest making a practice run in warmer fall weather to get an idea of how it goes.

BendLeaf,

I have been driving the between 27 to 29 miles each way to Mt. Hood Meadows the last two winters. This winter, I think they are going to let me plug in to at least 120v while I am there, which should help. I am penalized by a two bar loss at the start because I have to climb from 725' to 1900', then back down to 1300' before climbing back to around 4500' to the lower lot and 5500' to the upper lot. I drive 45 mph pretty much the whole way up to the resort and only use defrost. My 2011 heater sucks energy, whereas yours should be much better and my studs penalize my range to. Hopefully, Mt. Bachelor will let you use an outlet up there.

LeftieBiker said:

Keep in mind that the slower you climb, the less power you use. Allow extra time to get there and climb at a leisurely pace. Use the heated seats and wheel, not the cabin heater - at least not any more than you absolutely have to.

Click to expand...

It's only true because you're going slow, the same as it works on level terrain. The energy to lift the vehicle is still 1.5kWh per 1000 feet.

1 kilowatt (kW) = 2,655,223.74 foot pounds per hour (ft-lb/h)

3350 pound LEAF
650 of crew / cargo / pax

4000 pounds * 1000 feet = 4,000,000 foot pounds

= 1.5kWh

TonyWilliams said:

LeftieBiker said:

Keep in mind that the slower you climb, the less power you use. Allow extra time to get there and climb at a leisurely pace. Use the heated seats and wheel, not the cabin heater - at least not any more than you absolutely have to.

Click to expand...

It's only true because you're going slow, the same as it works on level terrain. The energy to lift the vehicle is still 1.5kWh per 1000 feet.

1 kilowatt (kW) = 2,655,223.74 foot pounds per hour (ft-lb/h)

3350 pound LEAF
650 of crew / cargo / pax

4000 pounds * 1000 feet = 4,000,000 foot pounds

= 1.5kWh

Click to expand...

You aren't taking drag at higher speeds into account, or the extra energy needed to accelerate to higher speeds. It's about more than just maintaining speed...

LeftieBiker said:

TonyWilliams said:

LeftieBiker said:

Keep in mind that the slower you climb, the less power you use. Allow extra time to get there and climb at a leisurely pace. Use the heated seats and wheel, not the cabin heater - at least not any more than you absolutely have to.

Click to expand...

It's only true because you're going slow, the same as it works on level terrain. The energy to lift the vehicle is still 1.5kWh per 1000 feet.

Click to expand...

You aren't taking drag at higher speeds into account, or the extra energy needed to accelerate to higher speeds. It's about more than just maintaining speed...

Click to expand...

What Tony means is that 1.5 kWh / 1000 feet is the approximate additional energy required to climb, on top of the energy required to travel the same road if it were flat. Of course, you can reduce the latter by driving more slowly and not blasting the heater. The 1.5 kWh / 1000 feet isn't quite so negotiable; that's the "potential energy" (a basic physics term) that needs to be gained.

In addition, the battery's energy will be used less efficiently (more will be turned to heat) if a high power level is maintained. That's on top of the drag losses. To account for the higher power level typically required to climb a mountain, maybe it's not a bad idea to figure on perhaps an additional 1.7 kWh / 1000 feet climbed, instead of 1.5 kWh.

Personally, I live on a mountain and regularly do a 5000' climb to return home from the valley below. So this isn't just theory for me.

LeftieBiker said:

TonyWilliams said:

LeftieBiker said:

Keep in mind that the slower you climb, the less power you use. Allow extra time to get there and climb at a leisurely pace. Use the heated seats and wheel, not the cabin heater - at least not any more than you absolutely have to.

Click to expand...

It's only true because you're going slow, the same as it works on level terrain. The energy to lift the vehicle is still 1.5kWh per 1000 feet.

1 kilowatt (kW) = 2,655,223.74 foot pounds per hour (ft-lb/h)

3350 pound LEAF
650 of crew / cargo / pax

4000 pounds * 1000 feet = 4,000,000 foot pounds

= 1.5kWh

Click to expand...

You aren't taking drag at higher speeds into account, or the extra energy needed to accelerate to higher speeds. It's about more than just maintaining speed...

Click to expand...

You're right, I'm not with this calculation. This is the power to lift the car.

The power in drag is considered in the speed of the vehicle in the range chart. It doesn't matter what your speed is, the ADDITIONAL energy to lift the vehicle is 1.5kWh per 1000 feet of elevation gained.

dgpcolorado said:

I've done it at 5º to 12ºF. 42 miles to the top of the pass, 4400+ feet net, about 5200 feet overall, since I had to get over two passes:
http://www.mynissanleaf.com/viewtopic.php?f=6&t=6330&start=52" onclick="window.open(this.href);return false;

I mostly did it at 30 mph, no heat (until the end, when I was sure I would make it); I was dressed in downhill ski gear for warmth. Tire pressure matters, I use 38-42 psi (cold drops pressure, so you might want to start out in the 40+ psi range).

I started with Tony's range chart and did the calculations for distance, speed, temperature. I then dropped my speed a bit to 30 mph for an extra margin of safety and made the top of the second pass (10,910 feet) with two fuel bars, a very comfortable reserve.

I have an advantage in that I am at higher altitude than the Bend area, so I have somewhat reduced air resistance due to lower air density, but that can and should be factored in, as well as temperature and speed (and is one of the important footnotes on Tony's chart).

I will be making the same trip this coming January for my second warranty battery check. Even with a more degraded battery I don't expect any problems.

So, depending on speed and total altitude gained it should be possible to do 26 miles uphill in subfreezing weather, assuming you aren't driving on snow very much. I'd suggest making a practice run in warmer fall weather to get an idea of how it goes.

Click to expand...

We did a test drive today going from 3500' to 5700' under 60mph on a 100% charge, in 94 degree weather (88 at destination). Reading at the parking lot of Mt. Bachelor was 52% battery remaining. By the time we arrived home, battery reading was 45% remaining.

During the winter, there will be studded tires, a roof rack and skis strapped on the roof. Is it safe to estimate that we can make it back down the mountain even with all the extra drag, driving in occasional snow, battery not liking freezing temp.?

BTW, Mt. Bachelor indicated there are no plans to put in a charging station in the parking lot. And, I doubt if the suits will allow us to plug-in.

Thank you everyone for all the feedback.

bendleaf said:

Is it safe to estimate that we can make it back down the mountain even with all the extra drag, driving in occasional snow, battery not liking freezing temp.?

Click to expand...

A key point in what you call "not liking freezing temp" is that the colder the battery is the less energy it can hold, even well above freezing temperatures. Tony's rule is that for every 4°F below 70°F you should subtract 1% from the range. You can see that means you will have lost 10% even at 30°F. Your nominally 21kWh (usable) battery is now temporarily a 19kWh battery.

Ray

bendleaf said:

We did a test drive today going from 3500' to 5700' under 60mph on a 100% charge, in 94 degree weather (88 at destination). Reading at the parking lot of Mt. Bachelor was 52% battery remaining. By the time we arrived home, battery reading was 45% remaining.

During the winter, there will be studded tires, a roof rack and skis strapped on the roof. Is it safe to estimate that we can make it back down the mountain even with all the extra drag, driving in occasional snow, battery not liking freezing temp.?

BTW, Mt. Bachelor indicated there are no plans to put in a charging station in the parking lot. And, I doubt if the suits will allow us to plug-in.

Thank you everyone for all the feedback.

Click to expand...

2200 feet of gain over 26 miles ought to be fairly easy even in subfreezing temperatures, assuming that you are willing to slow down. At 60 mph it might be harder. Slowing down will also lower the drag from all the gear on the roof. [Please be aware that aerodynamic drag increases as the square of velocity, so the energy lost to drag is four times greater at 60 mph than at 30 mph.]

How much the cold affects the battery depends on the temperature at your home; I charge in a garage that doesn't drop below freezing so I am not affected as much as if I parked outside. Charging warms the battery significantly, so arranging charging to end when you plan to leave ought to warm the battery and increase the charge it holds.

Driving with studded snow tires will lower your mileage efficiency somewhat as will all the gear on the roof. Driving on snow could lower it a lot. There is no way to know how much until you give it a try.

Please be aware that very cold weather will reduce regen braking significantly. Freezing weather is no big deal but regen at 0ºF will be quite poor compared to warmer weather. So you would gain less charge on the downhill part of the trip when using regen to slow than in warmer weather but, of course, it doesn't take much energy to go downhill so it may not matter.

When the weather gets cold put some gear on the roof and see how far you can go before you get to ~35% or so. I think that you will make it. Do you have passing lanes or are you limited to one lane in each direction? If you have passing lanes you ought to be able to choose your own speed. That's much more difficult if you are dealing with just one lane and a lot of impatient skiers behind you. Expecting to do the trip at 60 mph in subfreezing temperatures may be unrealistic.

This is the first time ever that I did not buy studded snow tires, not just because of range but because of the noise. The leaf is so quiet that I figure it would be annoying.

I have yet to drive it in the winter but I think it will be "interesting" to say the least.

Lots of preheating on the level 2!

Work to home for me is about 12.5 miles and a climb of ~1800 feet. It takes about 27% of a charge with the AC blasting at like 68F & stereo on at 61 or 62 mph. I think you could do what you're asking about fairly safely if you were conservative with your heater usage and went a little slower (even the difference between 55 and 60 mph is noticeable).

I've gone from Roseville to my house before without a problem. That's a little over 50 miles, mostly freeway at 61ish mph at night with radio, ac and headlights - a climb of about 3800 feet - and got home right after the lady yelled at me the first time (maybe 15% soc remaining).