Separating out range factors

[LindsayNB]

Has anyone made an effort to separate out speed, AC and heating, temperature and age as factors in range? I find it a little frustrating that people seem to want to produce a single number (73, 100, etc.) when range clearly depends on several factors. Ideally it would be nice to have a series of ranges or distance per kW for a number of common speeds with AC and heating off, and then some kW/hour at various AC/heating settings.

My commute is 48km/30miles each way, which is well short of even the 73mile range from the EPA, but 41km/25miles of it, each way, is highway driving at 100kph/62mph. The "70 miles at a steady 55 mph on the highway on a hot 95-degree day with the air conditioning on" example from Nissan says I would probably be ok in spring, summer, and fall, although not with a very large margin. On a cold day in winter (say 20 degrees below freezing) it seems I might not make it without a recharge at work.

It's hard to know from the various figures I've seen whether I'll be able to commute that comfortably or whether I need to arrange charging at work, or, failing the "double the range you think you need" rule I should wait for the next generation of EV. Any thoughts?

Has anyone figured out the relative energy costs of the various factors, even roughly?

 

[mwalsh]

Has anyone made an effort to separate out speed, AC and heating, temperature and age as factors in range? I find it a little frustrating that people seem to want to produce a single number (73, 100, etc.) when range clearly depends on several factors. Ideally it would be nice to have a series of ranges or distance per kW for a number of common speeds with AC and heating off, and then some kW/hour at various AC/heating settings.

I've done 30 miles at freeway speeds with the AC on low. There is a slight overhead for either the speed and/or the AC, but it's not massive. With the two of us in the car (both ~200lbs), we were averaging between 3.9 and 4.6 miles per kWh.

 

[kmp647]

so your commute would use 15 plus kwh

leaving 5 kwh till the low fuel lamp appx

my commute is identical to your description and i have the same reservations. i will generally be able to trickle at work

but i would rather not have to

I think we will both make it!

 

[evnow]

Has anyone figured out the relative energy costs of the various factors, even roughly?

Various efforts have been made. Including fairly complicated mathematical models ... nothing conclusive. Only Nissan can give accurate simulated figues ...

Except under extreme conditions you should be able to comfortably make your 60 miles. Extreme conditions would include things like crawling in a jam for 10 hours with heater on.

The 73 miles EPA gives will prove to be pessimistic. They use a 30% fudge factor after actual tests that they have found to be useful for gas cars ...

 

[mwalsh]

The commute is identical to mine too. We can totally make it...no worries - think positive. Well, OK, I haven't tried the heater, and we may run into some problems as the battery starts to degrade. But hopefully the latter is a good few years down the road.

 

[LEAFer]

This is not for the LEAF ... it is for the Tesla Roadster. Nevertheless, it is very informative, and gets you a rough overview.

http://www.teslamotors.com/goelectric/efficiency

http://www.teslamotors.com/blog/roadster-efficiency-and-range

 

[DaveinOlyWA]

Lindsey; post your location. we dont know if you have extremely hot summers or frigid winters to contend with.

my Leaf will also be doing a commute of RT of 58 miles with about 42 miles of it being freeway (speed limit is 70 will be driving 60 though and no that is not slow. trucks are limited to 60 mph so there is a lot of traffic at that speed)

some people think its inconvenient to drive a mile per hour below the speed limit for any reason. i am not one of them, that is why i am buying the Leaf and i have no issues whatsoever with range. i know the car's limitations and will drive accordingly.

i currently drive a 2010 Prius that has a range of 600+ miles in the summer and i drive it at 60 mph also.

the way i look at it, i can slow down a few mph, take an additional 5 minutes to get where i am going or i can run out of charge from driving too fast and get to my destination 2 hours later after i get ane emergency jump from roadside assistance.

 

[LindsayNB]

Hi Dave,

I'm on the east coast of Canada. We have a few weeks of pretty hot weather in the summer, the rest of the summer is warm but not that hot. The AC on my car broke down this summer and there were only a couple weeks where I really missed it. We have three or four months of below freezing in winter, usually a week or two of -30C.

On the highway I drive 100kph/62mph, half of my commute is the limit is 100, the other it is 110. I drive the limit on the first half because it's single lane and hard to pass and I don't want to hold other people up. I stay at 100 on the second half because it is two lane. A few years ago almost everyone drove 119 in the 110 zone, these days a lot of people are doing 100.

There is a second route I can take on slower roads, but there you have to change speed a lot and a few stop signs and lights. On the main highway I usually set the cruise control for 100km and rarely have to brake or accelerate.

It will be another year at least before I can get a Leaf here, I'm just trying to figure out if I should wait, because my current car is in the expensive phase at the end of it's life and I'm wondering whether to stick it out till I can get a Leaf, or whether a Leaf will be impractical. If it's impractical I can also stop spending my evenings on Google News doing "Nissan Leaf" searches!

Lindsay; post your location. we dont know if you have extremely hot summers or frigid winters to contend with.

my Leaf will also be doing a commute of RT of 58 miles with about 42 miles of it being freeway (speed limit is 70 will be driving 60 though and no that is not slow. trucks are limited to 60 mph so there is a lot of traffic at that speed)

some people think its inconvenient to drive a mile per hour below the speed limit for any reason. i am not one of them, that is why i am buying the Leaf and i have no issues whatsoever with range. i know the car's limitations and will drive accordingly.

 

[LEAFfan]

Has anyone made an effort to separate out speed, AC and heating, temperature and age as factors in range? I find it a little frustrating that people seem to want to produce a single number (73, 100, etc.) when range clearly depends on several factors. Ideally it would be nice to have a series of ranges or distance per kW for a number of common speeds with AC and heating off, and then some kW/hour at various AC/heating settings.

My commute is 48km/30miles each way, which is well short of even the 73mile range from the EPA, but 41km/25miles of it, each way, is highway driving at 100kph/62mph. The "70 miles at a steady 55 mph on the highway on a hot 95-degree day with the air conditioning on" example from Nissan says I would probably be ok in spring, summer, and fall, although not with a very large margin. On a cold day in winter (say 20 degrees below freezing) it seems I might not make it without a recharge at work.

It's hard to know from the various figures I've seen whether I'll be able to commute that comfortably or whether I need to arrange charging at work, or, failing the "double the range you think you need" rule I should wait for the next generation of EV. Any thoughts?

Has anyone figured out the relative energy costs of the various factors, even roughly?

Hi Lindsey...welcome to the forum! I have no doubts whatsoever that you will comfortably be able to make that commute. Mark Perry told me at the Tour that at 65mph, it is well within range for your distance, and for winter you will have the cold-weather package that includes heated seats, steering wheel, and a heated battery pack. When you drive this LEAF, you will absolutely want it. This is only the second car I've ordered without seeing it in person and test driving it.

 

[DaveinOlyWA]

hey thanks for the info Lindsey. well you will have the advantage of the real life experiences of people on this site. now because of the extremes, it wont be a perfect correlation, but it will give you an idea as to what to expect.

now on my test drive, i played with the climate controls and saw how it gave instant feedback on the expected ranges and the one thing i realized its time based. so if you are in a situation where significant delays in travel time due to heavy traffic is an issue, then that should weigh heavily on your decision.

climate control works on how long its running and not how far you are going. so if traveling 60 mph with the heat blasting on a below zero day, it will take say 5% off your range. but if traveling 30 mph, it may take 15% off your range despite the more efficient speed.

 

[LindsayNB]

Thanks for the Tesla links, the various figures and the encouragement. Sounds like I can continue with my leaf news obsession and I guess that starting today we'll be getting more and more data from owners. Hopefully the early owners will be generous with mileage data and we can start putting together a model like the Tesla's. From the thread about delays it sounds like we'll have lots of time to put such a model together.

Thanks again!

 

[wsbca]

Extreme conditions would include things like crawling in a jam for 10 hours with heater on.

(this is a slight hijack of the original thread theme of range impacts in the context of a regular commute - sorry)

It seems to me in situations like this the prudent behavior would be to get off the road and relax with a cup of coffee and a newspaper for some period of time until the jam clears, optionally getting some L2 charge somewhere while you wait. You might even end up getting to your destination at close to the same time if speeds pick up as the jam clears. This presupposes there's somewhere suitable to stop, and that the charging infrastructure is comprehensively deployed, and that the jam is not some sort of perpetual bottleneck that can't be waited out, and that you have at least a little flexibility in your arrival time....that's a lot of assumptions, but in a lot of cases they could hold.

A simplification would be just to say that if you ever get caught in traffic that was putting you at risk of a range deficiency incident (RDI - I just made that up), then your fallback is to simply stop along the way and top up as needed, even though you don't normally need to on that particular route. I guess that's an argument for having an L3 port, if the possibility of a modest time delay from an L2 topup is a major issue.

What I mean is...any trip you embark on where the range reducing effect of unforeseen traffic and/or climate control load could possibly cause an issue is likely to be salvageable by a relatively brief stint of en-route L2 charging...otherwise you wouldn't have made it anyway (without the traffic or the climate issues)...at least I think that makes sense.

 

[Smidge204]

I think we can get a pretty good guestimate on the impact of climate control and accessory use on range by making a few careful assumptions.

Going by this video at around 2:05 and 2:06 we see that with the heat blasting total non-drive power is ~5kW. Total usable battery pack is 22.8kWh (25kWh and Nissan claims maximum battery utilization is 95%). So sitting still you can blast the heat for roughly 4.5 hours.

I'll save you the math (if you want to see it I'll post the spreadsheet) but the final range curves look like this:

This is some very crude approximation. As real-world data begins to pile up we can start to get an idea of how well the car really performs. But at least this gives you an idea of the way climate control will impact range. (Hint: Using full heat in stop&go traffic is bad.)

Assumptions this graph makes:
-Steady speed on level concrete, no wind, no regen
-Rolling resistance factor of 0.01
-Aerodynamic drag coefficient*area = 7
-Total battery power used: 22.8kWh (95% total capacity as per Nissan claims)
-83.5% overall efficiency (fits upper curve of MAX WEIGHT to 138 miles at 38MPH per Nissan claims)
-5kW Accessory + Climate Control power
-Probably a few other things
=Smidge=

 

[SanDust]

On a cold day in winter (say 20 degrees below freezing) it seems I might not make it without a recharge at work.

It's hard to know from the various figures I've seen whether I'll be able to commute that comfortably or whether I need to arrange charging at work, or, failing the "double the range you think you need" rule I should wait for the next generation of EV. Any thoughts?

Has anyone figured out the relative energy costs of the various factors, even roughly?

The big issue for you will be winter temperatures. Cold weather kills range. Cold air is denser so your aerodynamic losses go up. Cold tires stick to the pavement more so your rolling resistance goes up. Cold parts don't move as freely so your drive train losses go up. Plus the cold weather may degrade battery performance. And of course you have to run the heater, which uses far more energy than AC (think heat pump).

Even with the cold weather package, which you have to have, at twenty below freezing my guess would be you'd have a 50 mile range. That would be for a new battery pack. As the pack ages that range would go down.

Whether you can get a few miles charge at work and have this work for you is personal. If thinking about the possibility of having the battery go flat gives you the willies then probably not. If you get stoked by the challenge then probably yes.

 

[LakeLeaf]

Has anyone figured out the relative energy costs of the various factors, even roughly?

Various efforts have been made. Including fairly complicated mathematical models ... nothing conclusive. Only Nissan can give accurate simulated figues ...

I think that only early Leafers will give us real world driving information. Hopefully we will get quite a bit of this type of information from the first 50 or 100 owners. I'm not sure that Nissan actually tested much in "normal" conditions, although it would be fascinating to see what their simulations are! I think one number that will be of great interest is - how far can the Leaf go on a full charge up a 6% grade at 55/65MPH. (My guess is right around 25-30 miles) Someone who is able to turn around and come back down the hill to recharge is eventually going to do that test. For me - that number will be quite key - it's basically the maximum battery burn rate if you turn off everything you can turn off, so it's kind of a high water (or is that low water) mark.

If Nissan has all of this data, they sure have not been anxious to date to share it.

 

[SanDust]

If Nissan has all of this data, they sure have not been anxious to date to share it.

It would probably freak people out. What Nissan is doing is making sure the initial roll out is in areas with milder climates. Seattle, Portland, San Francisco, Los Angeles, San Diego, Phoenix, and Tucson are places where you expect the thermometer to drop below 0F rarely if at all.

We have a pretty good idea of what the Leaf's range will be in cold weather because GM has been more forthcoming about cold weather range. The Volt's EPA range is 35 miles. The Leaf's EPA range is 73 miles. So roughly half. GM has said that the worst range someone will get is 25 miles, except in really cold weather when it will be less. That moves the Volt's lowest range to 20-25 miles and the Leaf's to 40-50 miles. Note however that, if the battery is below 0F, the Volt will turn on the ICE and heat the battery pack to that temperature so as to increase battery performance. The Leaf doesn't have that option and I haven't seen anything describing how Nissan will deal with the problem of cold temperatures degrading pack performance.

 

[garygid]

Largest Range Factor?

If the Range is 75 miles in your real-life usage, and then the battery capacity goes down to 60% of original in the first year or two, will the resulting Range still be sufficient for you?

If the Range goes down 9% (of original) per year, is it still useful after 4 years (64% remains)?

 

[evnow]

... GM has been more forthcoming about cold weather range.

That is a laughable statement - given the wide range of ranges under various circumstances that Nissan has outlined for quite some time.

BTW, what is your "handle" in gm-volt.com ?