Cold weather performance

[travisty]

Somewhat a hijack (sorry) but i wanted to get some clearification

I'm driving and my Leaf gets to 1 bar and says 2 miles left on the guessometer, I still have around 10 miles left?

 

[surfingslovak]

Somewhat a hijack (sorry) but i wanted to get some clearification

I'm driving and my Leaf gets to 1 bar and says 2 miles left on the guessometer, I still have around 10 miles left?

There are about 3 kWh of energy left in the battery at that point, less if it's below freezing outside and the battery pack temperature is low. Would you know what energy economy you are getting? Multiply that number by 3 kWh, and you have your remaining range. For example, I'm typically seeing 4.3 or 4.4 miles/kWh. This would yield about 13 miles of range (4.4 x 3). Note that the car could come to a stop prematurely, it all depends on the condition of the battery. So far, we have seen good and fairly predictable performance in low state of charge.

Seems like as little as the battery temp gauge tells us, that there can be a big difference between 4 and 5 bars. the colder it gets, the longer I have to preheat to topp off the battery. At some point, and I'm not sure how cold, the prewarming no longer charges the battery. In this case, I still charge to 80% and then prewarm then charge most of the rest of the way and prewarm some more... if I really need to eek out every mile of the range for a long trip. Heating/charging till you see 5 bars seems to make quite a difference. We haven't seen much whether below 30 here... I kind of wish it would dip into the teens to see if I can still get the 80ish miles I'm seeing in the 30's.

Thank you for sharing this, it's an interesting insight. I believe that the difference between 4 and 5 bars on the temperature gauge is about 25F, which translates to 5 or perhaps as much as 10% more battery capacity.

 

[travisty]

Thanks surfingslovak

I abused the car the first few days :twisted: and now I'm going back to my normal driving so getting now around 3.7-3.8 (most of my driving is 55+ and few stops @ 20 F).

So that's good to know, even when the car says it's at zero I still have around 10 miles to get home.

/hijack

 

[GRA]

Thanks for your replies.

It makes me feel a lot better knowing that other people are getting simular ranges. Maybe I panick a bit too much with the car reaches low battery warning. Having two small children in the car with freezing temperatures outside (and inside ) makes your worry a bit more.

I have been looking forward to getting this car for 1 1/2 years. The adjustment is probably bigger than I had expected and maybe in a months time I am completly used to living with range anxiety.

I think your range anxiety is entirely reasonable for the reason you state if needing that kind of range year-round is typical for you, although greater familiarity with the car will probably increase your miles/kWH. The question is, do you want to put up with not being able to use the heater in your $38,000 car and forcing your passengers to bundle up for the next umpteen winters, especially once the battery starts to age and lose capacity? I'd agree that a PHEV or at least a BEV with a longer range (none available for you at the moment, unless you can afford a Tesla S) would suit you better. If Coda survives and ever sells outside California, that might work for you.

I wouldn't necessarily jump on a Volt right away, if you're willing to put up with the hassle for this winter. There will be several more PHEVs available later in the year, probably including models from Toyota, Ford and Honda, so it might be worth waiting to see if they would work better for you. See

http://www.mynissanleaf.com/viewforum.php?f=10" onclick="window.open(this.href);return false;

 

[GaslessInSeattle]

Somewhat a hijack (sorry) but i wanted to get some clearification

I'm driving and my Leaf gets to 1 bar and says 2 miles left on the guessometer, I still have around 10 miles left?

I would caution anyone from going much past the very low battery warning if the battery is cold and or if you have to do much in the way of elevation gain at the end of your drive. It's been a while since my early turtle experiments, but I noticed it took me less to turtle the car than others and I also noticed the distance you can go in turtle is very relative to elevation gain. coming home always involves hills for me.

If you are driving on flat terrain in mild climates, no biggy, but if it's cold out and or you are doing a lot of hills, better to aim to have zero be your destination by adding the trip odometer readings to the GOM number, assuring you are on target for destination distance and moderating driving as necessary to avoid a gap. when you first see "---" add three miles to your odometer reading and, IMHO, that should be as far as you can consistently push it. Actual zero is where I set my target and I just drive moderating speed and acceleration to make it work. Having a little left in reserve and not planning to use it is good planning, at least it's what's comfortable for me.

in general, for maximum cold whether range, I prewarm enough to warm up the mass of the car, I leave mode set to foot defog then press the on off button till I see "climate control off" on the screen, it's quite comfortable. if you don't have the CWP so I've also added a dr scholls seat warmer ($25), which uses an imperceptible amount of electricity and helps reduce the eventual use of climate control.

 

[kmp647]

http://blog.nissan-global.com/EN/?p=2457" onclick="window.open(this.href);return false;


Chillin with the leaf

It may not go far , but it does goes well in the snow!

 

[planet4ever]

"Only" 2-3 bars? That could equate to close to 1/3 of a charge remaining!

More like 1/4 (3/12 = 1/4), which was her old standard for "better fill it up immediately". But I did see your smiley!

No smiley needed. Your calculation is worthless, lpickup. You need to look at Tony's chart. 2-3 bars is somewhere between 26% and 36.3%. Definitely more than 1/4 and could be even more than 1/3.

Ray

 

[planet4ever]

only set an END timer and the car will eventually figure out how to end within an hour of that time. For example, I set an END timer of 6am and my Leaf typically finishes around 5:30am, which leaves the batts reasonably warm when I leave. There was a period when I "confused" the charging cycle and it was finishing charges around 3am, but eventually it moved the charging window back towards 6am.

No way! You're giving the timer logic intelligence that I've never seen. I've had an 80% end-only timer set at 6 AM for months, and I've been getting, and keeping, all the "timer stopped" emails. The time on those messages is varying from 2:12 to 4:23, always at least 1½ hours before my end time, and the estimation is not getting any better over the months.

I suppose my experience might be different from yours both because I am doing an 80% charge and because I am using a 12A EVSE upgrade. It is possible that a bug in the timer logic is taking the end time as being for 100% even though the timer says 80%. But if the logic is confused by my 12A rather than 16A input I would expect it to underestimate charging time.

By the way, my car lives outside, and it's been weeks since I saw more than 4 battery temp bars, even here in "sunny" California. Our temperatures have been running around 35°F low to 60°F high. Since the battery is probably charging at 40°F or less I assume its total capacity is significantly reduced. I don't know whether the timer tries to compensate for that in its estimation, but if not that might cause it to overestimate charging time this month.

Ray

 

[surfingslovak]

I would caution anyone from going much past the very low battery warning if the battery is cold and or if you have to do much in the way of elevation gain at the end of your drive. It's been a while since my early turtle experiments, but I noticed it took me less to turtle the car than others and I also noticed the distance you can go in turtle is very relative to elevation gain. coming home always involves hills for me.

If you are driving on flat terrain in mild climates, no biggy, but if it's cold out and or you are doing a lot of hills, better to aim to have zero be your destination by adding the trip odometer readings to the GOM number, assuring you are on target for destination distance and moderating driving as necessary to avoid a gap. when you first see "---" add three miles to your odometer reading and, IMHO, that should be as far as you can consistently push it. Actual zero is where I set my target and I just drive moderating speed and acceleration to make it work. Having a little left in reserve and not planning to use it is good planning, at least it's what's comfortable for me.

George, you raise very good points. It's always better to err on the side of caution, and I never experienced turtle mode before I started range testing for the reverse SOC project and partaking in the 100-miles challenge.

Having said that, I believe that knowledge is power and given the limited range of the vehicle, many owners will come to test it, especially in winter. You are right, I largely drive on flat terrain and in fairly good weather. However, it does get cold here at night, and I park the Leaf outside. I experienced turtle mode during one of my tests when going up a steep incline. Although I made it to my destination, I attribute it to one part luck, and one part preparation. I believe that I benefited from all the work Tony Williams and others have done on this forum. It also helps to experiment with low state of charge in a safe environment. Preparation is key, much like what your are doing in wintery conditions.

Having said that, I would not recommend driving beyond the low battery warning with any regularity. This warning usually announces itself by three flashing dashes ("---"). If you must do so, please slow down, and avoid any inclines if you can. The battery pack voltage can drop precipitously in low state of charge, and we have seen a few instances where the Leaf would come to a dead stop prematurely.

If you must drive in these conditions, please realize that there is likely only about 1.6 kWh of usable energy left in the pack when you see three flashing dashes on the GOM. Please reduce this number by about 20% when it's cold out. If you multiply this figure by your energy economy, you will get the estimated remaining range. It's only going to be a few miles, and it pays to slow down and turn off heating or A/C if you need to continue.

 

[GaslessInSeattle]

Looks like we are on the same page. I very much appreciate all the work folks are putting into figuring out the limits in a variety of conditions and regions of the country.

what I have grown to appreciate, kind of ironically, after all this, is the GOM. If I know how far I'm going and zero out the trip odometer at the beginning, I can, with 100% accuracy (so far) reach my destination at zero miles left, having gone at the maximum average speed I can given the charge I have and distance I need to go. By adding the miles driven to the GOM, as long as I'm driving somewhere between 60 and 80 miles (I don't shoot for 100 miles given the hills around here), I can drive more or less aggressively, reaching my destination as fast as possible, with 100% assurance I'm not going to run out of range or take any longer than I need to to get where I need to go... and that's with nearly 100% highway driving. People get discouraged from using the GOM because of the wild fluctuations at the upper end of the charge, but it gets better and better toward the end, taking into account a myriad of factors, a variety of factors I can't not accurately factor using the charts unless i'm in very consistent driving conditions.

In technical diving we used to use something called "the wheel" to determine decompression. before computers this was the best way to factor in a multi stage dive (diving a variety of depths for a varying amount of time). I imagine we could come up with some kind of a wheel to adjust the charts for all the varying factors. In the end, I use the charts for ball park figures, try and adjust for battery temp if the battery is not cold soaked (which it rarely is for me), and rely on the GOM for pin point precision. This seems to quell the winter time range anxiety quite well.

we are all very fortunate to have this forum to share all this info, I feel sorry for the folks who are trying to figure it all out on their own.

I would caution anyone from going much past the very low battery warning if the battery is cold and or if you have to do much in the way of elevation gain at the end of your drive. It's been a while since my early turtle experiments, but I noticed it took me less to turtle the car than others and I also noticed the distance you can go in turtle is very relative to elevation gain. coming home always involves hills for me.

If you are driving on flat terrain in mild climates, no biggy, but if it's cold out and or you are doing a lot of hills, better to aim to have zero be your destination by adding the trip odometer readings to the GOM number, assuring you are on target for destination distance and moderating driving as necessary to avoid a gap. when you first see "---" add three miles to your odometer reading and, IMHO, that should be as far as you can consistently push it. Actual zero is where I set my target and I just drive moderating speed and acceleration to make it work. Having a little left in reserve and not planning to use it is good planning, at least it's what's comfortable for me.

George, you raise very good points. It's always better to err on the side of caution, and I never experienced turtle mode before I started range testing for the reverse SOC project and partaking in the 100-miles challenge.

Having said that, I believe that knowledge is power and given the limited range of the vehicle, many owners will come to test it, especially in winter. You are right, I largely drive on flat terrain and in fairly good weather. However, it does get cold here at night, and I park the Leaf outside. I experienced turtle mode during one of my tests when going up a steep incline. Although I made it to my destination, I attribute it to one part luck, and one part preparation. I believe that I benefited from all the work Tony Williams and others have done on this forum. It also helps to experiment with low state of charge in a safe environment. Preparation is key, much like what your are doing in wintery conditions.

Having said that, I would not recommend driving beyond the low battery warning with any regularity. This warning usually announces itself by three flashing dashes ("---"). If you must do so, please slow down, and avoid any inclines if you can. The battery pack voltage can drop precipitously in low state of charge, and we have seen a few instances where the Leaf would come to a dead stop prematurely.

If you must drive in these conditions, please realize that there is likely only about 1.6 kWh of usable energy left in the pack when you see three flashing dashes on the GOM. Please reduce this number by about 20% when it's cold out. If you multiply this figure by your energy economy, you will get the estimated remaining range. It's only going to be a few miles, and it pays to slow down and turn off heating or A/C if you need to continue.

 

[lpickup]

we are all very fortunate to have this forum to share all this info, I feel sorry for the folks who are trying to figure it all out on their own.

Amen to that!

 

[lpickup]

Are you sure that the current time on the charge timer is set correctly. The charge timer has its own clock (not same as dash display).

I'll check that. The dash (next to the speedo) and LCD screen clocks both read Eastern Time Zone, but I'll see if there is a third clock I need to set somewhere. That's a good theory.

Well both the time on the LCD screen (in the upper right) and the time in the lower left of the Charge Timer screen (that says: "The current time is...") both read correctly, so I'm reasonably sure that the timer has access to the correct time.

 

[ovev]

only set an END timer and the car will eventually figure out how to end within an hour of that time. For example, I set an END timer of 6am and my Leaf typically finishes around 5:30am, which leaves the batts reasonably warm when I leave. There was a period when I "confused" the charging cycle and it was finishing charges around 3am, but eventually it moved the charging window back towards 6am.

No way! You're giving the timer logic intelligence that I've never seen. I've had an 80% end-only timer set at 6 AM for months, and I've been getting, and keeping, all the "timer stopped" emails. The time on those messages is varying from 2:12 to 4:23, always at least 1½ hours before my end time, and the estimation is not getting any better over the months.

I suppose my experience might be different from yours both because I am doing an 80% charge and because I am using a 12A EVSE upgrade. It is possible that a bug in the timer logic is taking the end time as being for 100% even though the timer says 80%. But if the logic is confused by my 12A rather than 16A input I would expect it to underestimate charging time.

By the way, my car lives outside, and it's been weeks since I saw more than 4 battery temp bars, even here in "sunny" California. Our temperatures have been running around 35°F low to 60°F high. Since the battery is probably charging at 40°F or less I assume its total capacity is significantly reduced. I don't know whether the timer tries to compensate for that in its estimation, but if not that might cause it to overestimate charging time this month.

Ray

I see excactly the same charging behavior as Stanton. My car used to finish charging to 80% somewhere between 10-30 minutes before the charging end set time of 7 am. Then I went on a trip where I needed 3 cycles of 100% charges and drives to LBW. The next 4 days the car stopped charging to my usual 80% anywhere between 2:30 am - 05:30 am. Then it suddenly returned to finish charging some 10-40 minutes before set time. I am using a 10A EVSE on 230V.

 

[surfingslovak]

People get discouraged from using the GOM because of the wild fluctuations at the upper end of the charge, but it gets better and better toward the end, taking into account a myriad of factors, a variety of factors I can't not accurately factor using the charts unless i'm in very consistent driving conditions.

This an interesting and astute observation. I was going to bring it up in another thread, but it might be better to expand on the topic here. Although I'm still suspicious of the GOM, for reasons I will explain later, I found it to be quite accurate when the battery gauge is between 2 and 7 bars. I would not recommend using it outside of this range.

As a positive example, please have a look at the first three images below. After much handwringing, I came up with a range estimate of 44 miles. Guess how much the GOM is showing: 41 miles. This was hardly worth all the effort! Or was it?

I did extensive testing in predictable conditions and with consistent driving, and I can attest that the GOM is not accurate at high SOC. I'm unable to offer a reasonable explanation for this behavior, since I can usually ballpark my total range more accurately using simple methods, and without having access to all the good information that's flying over the CAN bus.

Be it as it may, it looks like I will complete this test drive after approximately 90 miles. That was easy to predict, since our weather has been consistent and I've been consistently getting energy economy figures between 4.2 to 4.5 m/kWh for over a month now. I'm estimating my current available battery capacity to be 20.5 kWh, based on several metrics collected over the course of a month or so as well. And I drive on flat roads.

So how is possible then, that the GOM gave me a range estimate of 118 miles after a full charge 48 hours ago? That's 30% more than my actual will be for this charge, and it does not correlate with my last few trips either. I would consider this to be very inaccurate, and I have seen this behavior very consistently. The GOM fails to deliver on what should be an easy estimate. Wonder if others have as well?

Hours to charge at 120V at 49% SOC:

Click to enlarge

Trip energy economy at 49% SOC:

Click to enlarge

Gids at 49% SOC:

Click to enlarge

Original GOM range prediction:

Click to enlarge

 

[GaslessInSeattle]

People get discouraged from using the GOM because of the wild fluctuations at the upper end of the charge, but it gets better and better toward the end, taking into account a myriad of factors, a variety of factors I can't not accurately factor using the charts unless i'm in very consistent driving conditions.

This an interesting and astute observation. I was going to bring it up in another thread, but it might be better to expand on the topic here. Although I'm still suspicious of the GOM, for reasons I will explain later, I found it to be quite accurate when the battery gauge is between 2 and 7 bars. I would not recommend using it outside of this range.

As a positive example, please have a look at the first three images below. After much handwringing, I came up with a range estimate of 44 miles. Guess how much the GOM is showing: 41 miles. This was hardly worth all the effort! Or was it?

I did extensive testing in predictable conditions and with consistent driving, and I can attest that the GOM is not accurate at high SOC. I'm unable to offer a reasonable explanation for this behavior, since I can usually ballpark my total range more accurately using simple methods, and without having access to all the good information that's flying over the CAN bus.

Be it as it may, it looks like I will complete this test drive after approximately 90 miles. That was easy to predict, since our weather has been consistent and I've been consistently getting energy economy figures between 4.2 to 4.5 m/kWh for over a month now. I'm estimating my current available battery capacity to be 20.5 kWh, based on several metrics collected over the course of a month or so as well. And I drive on flat roads.

So how is possible then, that the GOM gave me a range estimate of 118 miles after a full charge 48 hours ago? That's 30% more than my actual will be for this charge, and it does not correlate with my last few trips either. I would consider this to be very inaccurate, and I have seen this behavior very consistently. The GOM fails to deliver on what should be an easy estimate. Wonder if others have as well?

the sample rate of the computer is pretty short and rapid it seems. If you go down a hill toward your house or do something else, like drive exceptionally slowly just before you turn the car off, it will take that average and multiply it over the entire pack once fully charged. If that doesn't account for the difference you are seeing, I don't know how else to explain it. Air integrated dive computers work pretty much the same way and really can't be relied on too heavily for the time remaining for air. the more you drive conservatively, the more you can expect to see the number drop like a stone if you suddenly have to use more power. My car does the exact opposite of yours, I go up steep hills toward home and find that it typically gives me an overly conservative estimate the next day. conversely, I've driven the kids to daycare and ended up with a 101 mile estimate on an 80% charge once at the daycare, which is all down hill from my house.

Rather than bother with all the calculations from the charts, given this hilly terrain, I tend to keep track of how many bubbles I'm using for acceleration, if I need to stretch things out, I stick to 2-3 bubbles, I watch the MPkWh average for the trip and triangulate those against the GOM number and bars. About all I care about is keeping the GOM from dropping precipitously, below the target destination, in the beginning. I add the estimate to the miles driven and make sure i'm within the target destination and surf my way there, expecting to see a bloated figure early on, then more accurate as I approach the destination. When I'm loosing miles too fast, I slow down to two bubbles, if I'm way ahead, I'll be less conservative and drive between 3-4 bubbles. ... it really works remarkably well. The sample the computer uses gets multiplied less and less as the charge gets lower, so the GOM number fluctuates less and less. Its unintuitive that a number that would be so inaccurate early on in the drive would be pin point accurate toward the end, but that is what I've found. I don't even sweat it anymore, as long as I have a decent GPS estimate of total distance at the beginning. this allows me to drive up to 75 mph down hill, slowing on up hills and leveling out at about 60-65 on straightaways. And, I can reach the destination without looking at the speedometer at all. I find the speed is less important than the power meter reading. For me, to hit the destination on the dot (zero GOM) the main focus is on the bubbles and trip MPkW's. between the bubbles and MPkW avererage I can do virgin voyages with near 100% predictability, except for consistent uphill mountain pass driving, i'm not adept at that yet mainly because we don't have our QC network in place yet so I haven't attempted the passes yet. the difference with cold whether seems to be all about eliminating Climate control use and warming the battery up before long trips.

You mostly hear people bash the range estimating tools of the Leaf, but after 11,000 miles, I've come to appreciate the tools that came with the car and have learned to rely on them, even though they seemed very quirky at first.

 

[edatoakrun]

You may want to take a look at your energy economy curve from CW monthly “rank” reports.

In my case, throw out May to July (before CW update) and you get a fairly benign picture of reduced cold weather efficiency.

I live at 2000 ft. in far north California, where average temperatures are 60’s at night, and 90’s during the Day, in Summer, and 30’s to 50’s in the winter (snowed a bit last night!).

In fact, I rarely use the heater (other than to preheat) but often used the AC, and I do drive slower after dark and in the rain, so the curve would be a bit steeper, if adjusted for driving style.


Month and Year Grade Rank Energy Economy
May/2011 Gold 492 5.4 miles/kWh
Jun/2011 Gold 695 5.7 miles/kWh
Jul/2011 Gold 1651 5.3 miles/kWh
Aug/2011 Bronze 3622 4.2 miles/kWh
Sep/2011 Silver 3457 4.5 miles/kWh
Oct/2011 Silver 3640 4.2 miles/kWh
Nov/2011 Gold 2792 4.2 miles/kWh
Dec/2011 Gold 2827 4.0 miles/kWh
Jan/2012 Gold 2547 4.2 miles/kWh
Feb/2012 Gold 2346 4.4 miles/kWh

 

[DurkaDurka]

Reserved: 05/28/2010
Ordered: 07/29/2011
Delivery: 12/21/2011
Sold Leaf: 01/23/2012
Bought Volt: 01/23/2012
EVSE: GE Wattstation

So, how much of a bath did you take when you sold the LEAF and bought a Volt? Are you happy with the Volt?