Leaf Range in Colder Weather

I had exactly the same experience in Seattle (it was 32F). Only I did not get home, but was left without power 2 miles from home. Note that throughout the whole trip I had the heater off. So why is the range reduced in cold weather? Nissan says the capacity does not change much in cold weather. If heating is the only factor, why with heating off, is the range still lower? Or
is the battery capacity reduced? Carwings, which is notoriously unprecise, did give me a total use of 14 kWh for that day. The car started at 80% charged, so that would mean at cold temperatures, i.e. ~32-40 (The car is in a closed garage, which is slightly warmer than the outside) the battery would hold 17.5 kWH instead of 20 kWH. Still not clear why this reduced the range from 60 miles (beginning of my 40 mile roundtrip) to 38?

reduction in cold weather;

higher bearing friction; listed EVERYWhere, i personally think it to be nominal at best we say 1%

higher road resistance; rain, snow, etc. it all creates drag.

wind; not sure what day you were talking about, but we did have a few windy days. a 15 mph (which was wind speeds experienced in large percentage of Puget Sound area last week) headwind at speeds above 50 mph is a 25% increase in power needed to move along

cold air; cold air vibrates slower which means cold air molecules can snuggle better than wild hot ones which makes for more air to push when driving down the road. this is #1 factor lowering efficiency as much as 4-6%. now i dont know how the percentages are figured. there was a great discussion i glanced over on several websites. but you can get a start by examing "STP" which means standard temperature and pressure which says a "mole" of a gas which is about 22 liters give or take will weigh its approximate atomic # in grams.... or something along the lines of that. add to that the fact that all moles of all substances have the exact same # of molecules...

ok, now you know why i just glanced at it.

klapauzius said:

Still not clear why this reduced the range from 60 miles (beginning of my 40 mile roundtrip) to 38?

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Are you saying the range you got at 0C or 32F @ 80% charge was 38 miles? Which would mean 47.5miles for 100% charge... That's got to be wrong. How were you driving? Can you give us more details? Or have I miss-read something.

klapauzius said:

Still not clear why this reduced the range from 60 miles (beginning of my 40 mile roundtrip) to 38?

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After charging to 80% did the car show 60 mile range ? Is that with climate or without ?

As you know the range depends on the way you have been driving - not on the way you will drive. So, if the way you will drive is very different from the way you have been driving - the range estimate will be highly inaccurate.

Sorry about the confusion, so here are the facts:

Car was charged at 80% in the morning. It had been driven for ~ 12 miles before the ~40 mile round trip to the airport.
When going on that round trip, the range estimate was 60 miles. No heating was used.
After driving 38 miles to and fro the car went dead 2 miles from home.
Carwings reported ~ 14 kWH used for that whole day. I know the car was completely empty, ergo 14 kWh=80% charge at 0 C -> 17.5 kWH at 100%.

If the usable capacity would be 20 kWh at e.g. 25 C, I could believe this number and not assume something was wrong with the battery.
If the usable capacity would be 24 kWH at 25C, this would probably be a problem.

My SO did centralia yesterday at 100%. She did 70 mph and did 61 miles and was at ... for range estimate. Mpk was 3.1 miles per k... so would imply about 20 kwh used. Unlike u, she blasts the heat

klapauzius said:

Car was charged at 80% in the morning. It had been driven for ~ 12 miles before the ~40 mile round trip to the airport.
When going on that round trip, the range estimate was 60 miles. No heating was used.
After driving 38 miles to and fro the car went dead 2 miles from home.
Carwings reported ~ 14 kWH used for that whole day. I know the car was completely empty, ergo 14 kWh=80% charge at 0 C -> 17.5 kWH at 100%.

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So, on 80% charge you drove a total of 50 miles ?

I'd ignore both the estimate (since that was based on your 12 mile trip, probably local, compared to freeway trip to seatac). I'd also not give much credense to Cawings, it routinely inflates m/kwh - so the kwh reported is low.

Since you had done 12 miles already - you probably had about 65% charge. You only got 38 miles out of that using freeway, but no heat. I'd say there was some problem ...

What is Nissan's official response ? Are they still investigating ?

klapauzius said:

S
After driving 38 miles to and fro the car went dead 2 miles from home.

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Did you get the normal "Low Battery" and "Very Low Battery" warnings plus Turtle Mode before running out of juice, or did the car just die on you?

Also, how fast were you driving? Were you in D the entire time or ECO mode anywhere along the way??

I am not sure that I see an issue here. With elevation issues freeway speeds heating etc I can and do see ranges as low as 65 miles on a full charge. So at 80% and having driven 60 miles I would ha e to say that that would be near normal. The big thing is not relying on range estimate since it uses driving history instead of k.owing where u r going. I see this a lot cause I drive city steers which inflates the range then SO jumps on freeway and range goes from 109 to 75 in a few miles

I got all the warnings, yes. I got ~ 400 meters with turtle mode, before it died completely.

I am not sure that I see an issue here. With elevation issues freeway speeds heating etc I can and do see ranges as low as 65 miles on a full charge. So at 80% and having driven 60 miles I would ha e to say that that would be near normal.

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This was basically a round trip and the driving behavior did not change significantly between the trip to and from the airport. Same roads, same speeds (55 MPh on I5), same temperature and NO heater on. The total freeway driving part of the trip is ~ 14 miles (i.e. 28 total). And I have not driven 60 miles on 80% charge, more like 54. And about half of it at freeway speeds.
The problem is really that the last miles are the ones that count. Even the difference between e.g. 60 predicted and 58 until empty means you need a tow truck. In my case it was 60 predicted and 38 actual miles and that is not acceptable. I understand that one should not take the DTE to seriously, but overestimating range by 50% is bad. Given all the implications, Nissan should change the algorithm to underestimate by a 10% margin.
Another bad feature of the range estimation is this: If you switch to ECO mode, the DTE goes up, even if you are on the freeway and there is no difference between ECO and D at all.

Your "Eco to drive" on the freewway observation is an inoteresting point. Despite being low enough to not have a DTE at all a few times, I ha e only been in turtle mode one time. On the 9 power circles I did lose 6 of them in just over 2miles and that was at speeds of 30-40 mph. But at the same time we do know how the DTE is calculated and if we know that our trip in front of us is going to be faster or less efficient that does need to be taken into consideration.
e maybe a charge meter would be better. One that tells us how much kwh is left and we have to work the range out on our own

klapauzius said:

Another bad feature of the range estimation is this: If you switch to ECO mode, the DTE goes up, even if you are on the freeway and there is no difference between ECO and D at all.

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I disagree.

While you won't get ALL of the "10% increasewith ECO" on the highway, you do get a much improved boost. ECO on the highway makes it harder to goose-and-waste energy with the go-pedal....it makes you push harder for less energy output and it seems to me that it also smooths the peaks and valleys of the energy used in normal D mode to increase your range.

Don't believe me? Drive the same route in D and then the route at the same speeds (no cheating and using cruise control!) in ECO. I'll bet your range is at least 5-7% higher in ECO, and when you're pushing the limits of the stored energy in your pack, that's nothing to take lightly.

just got home, drove 89 miles on the Leaf and started with 9 of 10 white bars. granted, it was all city driving and a lot of cruising neighborhoods at 25 mph looking at houses and stuff, so the advertised range of 100 miles is a bit deceptive because only in the manner i drove today would i see that.

but i knew not to expect 100 miles in normal freeway driving. i expected 70 and it wintry conditions, it might appear to be only 60, but i already knew that and i was ok with that. it does do the longest normal driving we would do, has done it half a dozen times and it does not always have a lot left when it gets home, but its made it.

i think what we all need to do is get more feedback on what info the car does tell us when the charge is running low. like when do we lose the DTE (usually around 6-7 miles) and how far we can drive and at what conditions when the power circles start to disappear. unlike the range estimates, when the circles start to go, they go fast.

now there is still a discussion on the size of the battery pack but its apparent to me that its a 24 KWH pack and there is NOT 24 kwh to use. its probably more like 20-21 KWH. this is based on general info here and personal experiences based on what the car is telling me its performing at.

ECO on the highway makes it harder to goose-and-waste energy with the go-pedal....it makes you push harder for less energy output and it seems to me that it also smooths the peaks and valleys of the energy used in normal D mode to increase your range.

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If I use cruise control, which I always do, there should be no difference as I dont have a foot on the gas pedal. Still ECO gives you instantly more "Miles", which cannot be real.

klapauzius said:

ECO on the highway makes it harder to goose-and-waste energy with the go-pedal....it makes you push harder for less energy output and it seems to me that it also smooths the peaks and valleys of the energy used in normal D mode to increase your range.

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If I use cruise control, which I always do, there should be no difference as I dont have a foot on the gas pedal. Still ECO gives you instantly more "Miles", which cannot be real.

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There IS a difference but only if you quit using cruise control. Cruise control will jam the gas pedal if it has to to keep your speed at the set amount. If you're manually driving using ECO mode, I guarantee your speed will fluctuate and will always be lower than whatever speed you would normally have CC set for. And because you will be reacting to speed reductions 'through' ECO mode (driving 'though' that molasses feeling), your power usage will be less.

If you're in D and you press the gas enough to use 40 watts on the meter for 10 seconds, you'll go from zero to 40 watts in about 1/2 second and run at 40 watts for the next 9.5 seconds. If you do the same thing using ECO mode, it will take you about 2 seconds (maybe more) to reach 40 watts, so you're only there for 8 seconds or less. ECO mode slows the rate that the energy flows out of the battery every time you press the gas pedal....over a 60 mile trip, you'll see real, tangible range increase.

Try making your drive in ECO mode without cruise control....I'll bet you see at least 5+% increase in range.

Driving efficiently usually means not using CC unless u have a lead foot. Easing the speed up while down hills and slowly bleeding that extra speed while going uphills can increase your mileage.

Taking advantage of gravity can help but difficult to do while on the freeway especially around here where traffics usually does not allow much room for too much variance from the norm

Accurate range estimates require two things:
1. an accurate estimate of the usable energy left in the battery.
2. an accurate estimate of your future driving conditions and habits.

Of course #2 uses your "recent" past history, which might be a good, or terrible, estimate. For the moment, let's assume it is a good estimate, with near identical past and future driving conditions.

The remaining usable energy estimate can be good, or poor, depending upon how it is done. It appears that the LEAF has enough information (the cell voltages, etc.) to make some reasonable ESTIMATES, but that it might not use all the available information to create (calculate) the SOC value (that it crudely displays), and probably uses in the Range calculation.

The lowest, weakest, least-charged cell-pair is what really determines when the car will stop. The pack voltage (sum of all the cell-pairs) can look good, like the battery has a good SOC, and the Pack Voktage could be used to calculate an "apparent" SOC estimate. However, one low cell-pair COULD stop the car long before this "apparent" SOC goes low.

Further, it was just reported in another thread (I cannot remember which one) information (apparently from the Service Manual) that indicated that the PACK voltage IS used to derive the "SOC", not the "lowest cell-pair" information.

Then, this "apparent" SOC could be still relatively high, but the car's "protect-the-lowest-cell" monitoring MIGHT shut down the driving much earlier than expected.

IF TRUE, this could explain the several cases of "unexpected exhaustion", and the lack of the "Low Battery" warnings (assuming that they are indeed, as reported, based on this "apparent" SOC).

Under the typical conditions where the 96 cell-pairs are well matched, and equalized to the same "individual" SOC, using the Pack voltage to calculate the "apparent" SOC is a reasonable, and even typical choice.

But in some cases of mis-match, especially before a sufficient number of equilization cycles are completed, even well-matched cell-pairs can have an SOC substantially different from the "apparent" Pack SOC.

It would appear that deriving the estimated SOC from the LOWEST cell could allow the car to create more timely warnings.

garygid-Your knowlege is amazing!! Thank You for helping a novice figure out how EV`s function

Thanks, but I could be wrong.

For now, I suspect that it is better/best to make sure (how?) that your battery is WELL equalized before attempting to drive anywhere the range limits or onto the lower SOC values.

Some report VERY GOOD low end warnings and LONG turtle mode driving. PROBABLY (my present guess) is that they have well-equalized battey cells, that are also well matched.

So, when somebody gets few/no/short warnings before "running dry", there is SOMETHING that needs attention.

Of course there COULD be poorly-matched cell-pairs, but only dealer service (or CAN buss reading) will reveal that.

If all your cells are WELL equalized, and you still "unexpectedly run dry" (even when watching for "Low Battery" warnings), then you PROBABLY have a low-capacity cell-pair and a dealer should at least do a diagnostic to see if there is a "strange/low" cell-pair. The diagnostic should NOT be done at full charge, but probably something like 30% to 50% ... as low as you can safely go and still get to the dealer.