Cold weather

[TonyWilliams]

...haven't charged more than 90% in weeks, garage 42 outside 35 degrees, rainy, no preheat. She went 41.5 miles, got several low battery warnings, she turned off the heat, gom said 1 mile left then she got home before -- came up.... 3.1ish... How many more miles could you drive once the -- comes up in cold weather?

There's no easy answer to your question. It would depend on many factors. Obviously, she was aware that the heater kills range, and wisely turned it off.

We don't know if your car was charged to 80%, but assuming it was, the range was 3.1-ish multiplied by 17 = 52.7 miles, minus (70F-38F=32F / 4 = 8%) an 8% reduction for an assumed battery temperature of 38F.

So, I get 48.5 miles of range. She drove 41.5, so perhaps 7 miles remained at 3.1 miles/kWh.

That's not allowing for any possible losses for cell imbalances, which may be a factor in having not charged to 100%. Also, I doubt seriously that she would have gotten 7 miles after VLB (the second battery warning) while driving at 3.1m/kWh.... more like 3 miles.

So, best guess; 3 to 7 miles. Have you considered charging up to 100% ?

 

[ovev]

On a recent data run from 100% to Turtle, here's the data from the dash followed by the crazy CarWings data:

Assumed battery temperature at start: -13C (8.6F) up to -10C ambient (14F)
Final Dash Km/kWh: 7.0 (4.34 miles/kWh)
Km traveled total: 125.1 (77.56 miles)

Calculated Battery Capacity: 17.87 kWh - 85% of 21kWh

>>>TonyWilliams wrote: Could you log into CarWings and tell us what it reports for total kWh burned for this trip?<<<

Distance traveled: 127.6 Km (the 2.5km discrepancy was actual driving, and accurate)
Average Energy Economy: 8.1 km/kWh <<<<<--- the usual crazy data
Electricity Consumption: 15.7 KWh <<<<-----------not even close to the same data
Travel time: 3.6h

You guys are welcome to use CarWings and the GuessOmeter. I won't.

Free T-shirt !!! Please volunteer a bit of your time to help provide cold weather data here.

I find the consumption data in carwings correct. The driving distance is however too low in carwings (off by 2,5%). My dash average energy economy correlates with the carwings data, but not the distance data. The total kW consumption data in carwings seems to be match the dash distance data combined with the average energy economy data.
For some reason both the carwings and the dash average economy data is given in kW/km, my average being .19kW/km.

Example:

Dash:
Driving distance: 90.6km
Average energy economy: .16kW/km
Calculated consumption: 14.496 kW

Cawings:
Driving distance: 88.7km
Average energy economy: .16kW/km
Consumption: 14.5kW


Why such differences in carwings data? Different continents yes and different methods of displaying the data.
Somebody at Nissan need to check their math.

 

[coqui]

Ted...
When I lived in Calgary a lot of employers provided plug in locations for the ICE cars block heaters. You may be able to extend range for the Leaf by using those as your L1 charger.

 

[coqui]

With regard to this discussion, then, which is better for the potential longevity of the battery?
(a) always charge to 80% (recommended by Nissan), or
(b) charge to 100% sometimes as this contributes to cell balancing.

 

[edatoakrun]

I find the consumption data in carwings correct. The driving distance is however too low in carwings (off by 2,5%). My dash average energy economy correlates with the carwings data, but not the distance data...

I noticed the same 2.5% discrepancy in my LEAF back in September on p 2 of the "My carwings energy numbers - CORRECT post NTB11-041 update" thread below:

http://www.mynissanleaf.com/viewtopic.php?f=31&t=5423" onclick="window.open(this.href);return false;

You are the first post since, that I've seen, that confirms the same constant of about 2.5%. Some have since speculated that this is a GPS effect, but I am sceptical that would lead to such consistent results.

Do you have a US or Euro spec LEAF?

When you say "dash" do you mean behind the wheel or Nav screen? Do either match the CW reports of kW/km (rather than m/kWh) for a given trip?

I have resisted the temptation to reset either on my car, to keep my "since delivery" averages, as posted on the thread above.

 

[ovev]

I have a Euro spec Leaf.

I use the data from the screen behind the wheel. This always matches the Carwing reports for average energy data, but not for the distance traveled.

 

[edatoakrun]

TonyWilliams"]On a recent data run from 100% to Turtle, here's the data from the dash followed by the crazy CarWings data:

Assumed battery temperature at start: -13C (8.6F) up to -10C ambient (14F)
Final Dash Km/kWh: 7.0 (4.34 miles/kWh)
Km traveled total: 125.1 (77.56 miles)

Calculated Battery Capacity: 17.87 kWh - 85% of 21kWh

>>>TonyWilliams wrote: Could you log into CarWings and tell us what it reports for total kWh burned for this trip?<<<

Distance traveled: 127.6 Km (the 2.5km discrepancy was actual driving, and accurate)
Average Energy Economy: 8.1 km/kWh <<<<<--- the usual crazy data
Electricity Consumption: 15.7 KWh <<<<-----------not even close to the same data
Travel time: 3.6h

You guys are welcome to use CarWings and the GuessOmeter. I won't....

I assume this is from your non-updated LEAF?

As long as you refuse to get CW updated, I would expect you will continue to get incorrect kWh consumption reports.

However, you may be able to recover some or all of the correct CW info you have missed, by looking into whether your pre-update CW reports can be corrected by a constant.

IIRC, this seemed to me to (likely) be the case, but since I had the update done almost 6 months ago, I have had no reason to pursue the subject.

 

[edatoakrun]

I have a Euro spec Leaf.

I use the data from the screen behind the wheel. This always matches the Carwing reports for average energy data, but not for the distance traveled.

What does your Nav screen say? Mine still is at 4.4, and Behind The Wheel still at 4.3, as it has been since September.

...This could also explain the similar (identical?) 2.5% discrepancy between “dash” and “screen” miles/kWh, which have remained the same on my car, both before and after the update.

Meaning the higher screen number (4.4 m/kWh {NAV} screen, 4.3 m/kWh dash {behind the wheel}, on my car since delivery) rather than the dash, may be correct....

http://www.mynissanleaf.com/viewtopic.php?f=31&t=5423&start=20" onclick="window.open(this.href);return false;

{edit}

 

[edatoakrun]

see replies below

...The only limitation is that the CarWings data will always be extrapolated to determine useful battery capacity, unless the car was run all the way to dead...

As with any other method. That is precisely why I suggest those who do discharge past VLB, check their CW report of kWh use, to see if this will accurately determine total available capacity, at different temperatures.

How would the CarWings kWh report from any previous trip (assuming its accurate, and that you have whichever firmware update that makes it accurate) be different than dividing miles/kWh from the dash into odometer miles driven?


This is the best method you now have, but there may be a better way.

The LEAF gives two different m/kWh readouts, both rounded to the nearest 0.1 m/kWh.

It is entirely possible that CW will give more precise results, and also can tell you which vehicle readout is correct.


Actually, that's the first logic test that I would apply to CarWings data. If the data differs between the two, I would continue to think CW to be inaccurate, as it is with it's 2.5% mileage error, even post update. However, if they do match, I merely have another source of the same info.

The way that you appear to be using the data, with historical perspective, seems reasonable. The data wouldn't even have to be accurate, just indexed properly to provide a reference for identical trips in different conditions.

TonyWilliams
...Secondly, CarWings kWh data can serve little useful purpose in estimating the capacity of a trip not yet taken

I disagree.

Knowing total available battery capacity in advance allows you to plan trips, and adjust your route, speed and CC use accordingly, to avoid extremely low SOC, or even "dead" conditions.

While i agree with your statement as stated, I don't agree with the premise. I've been doing exactly what you're suggesting for 17,000 miles without once referencing CarWings for critical info.

Sorry, but you don't know what you're missing, so you are unable to make the comparison.

have made many trips (including both those I referenced above) that exceed the maximum range that your chart predicts. This is mostly due to a higher ratio of ascent energy recovery I have seen, about 80% rather than the 50%, on your chart.

Regen is tough. I haven't spent much energy developing a list of parameters to determine what your regen might provide. I'm sure you'll agree that if I started at the top of a mountain with 100% charge, I will get precisely ZERO regen going down the hill.

Also, if the battery is cold, the regen can be severely limited. Finally, if I hit the brake with too much vigor, or hit a big bump, the regen is immediately reduced and hydraulic brakes are increased.

So, at least three major factors affect regen; High SOC, battery temperature, and brake pedal use. Minor factors are things like ECO or D mode, amongst others.

I don't believe that the entire regen and reuse of that regen'd power is 80%, even in the most advantageous circumstances, but even if it is, there are too many scenarios where it is close to zero.

Therefore, until logical data can be collected for all conditions, and a logical way to present the data for its use, 50% regen efficiency is the best middle ground I can come up with for now.

I expect it would be nearly impossible to get a ratio of 50% or lower on any public road, under the most adverse conditions.

The majority of ascent energy is recovered WITHOUT the use of regen at all. In many circumstances, roads are graded to allow you almost 100% recovery, which is the case whenever you coast or apply energy to increase your speed on a descent, rather than accept energy back into the battery using regen to arrest your speed.

CW regen reports are a good place for you to look for more on this...

But the relatively minor reduction in available battery capacity down to about 25 F

We would have to qualify what minor is, but the data will bare out something. One thing that I hope is that the data is at least linear!

Again, to those in extremely cold climates, please help us gather data ! See my thread for Free T-shirt !!! Please volunteer a bit of your time to help provide cold weather data here, "Wanted: Extreme Cold Weather Range Data".

 

[TonyWilliams]

I find the consumption data in carwings correct. The driving distance is however too low in carwings (off by 2,5%)....

Why such differences in carwings data? Different continents yes and different methods of displaying the data.
Somebody at Nissan need to check their math.

Yes, you have the updated firmware specifically to fix CarWings.

So, the old CarWings had accurate distance, but wildly inaccurate consumption rate and total.

New CarWings has inaccurate (by 2.5%) distance, but accurate consumption rate and total.

 

[TonyWilliams]

As long as you refuse to get CW updated, I would expect you will continue to get incorrect kWh consumption reports.

That data is not from my car. Here's another event, also not from my car, but with the "new" CarWings. Not looking too good to me:

130 miles (209.4 km) New CarWings says 132.9
6.4 miles/kwh
Calculated battery capacity: 20.3kWh New CarWings says 21.8kWh
temps 65 to 75 degrees
no climate control
level city streets

No thanks, I'll not be basing any data on either new or old CarWings.

 

[DaveinOlyWA]

With regard to this discussion, then, which is better for the potential longevity of the battery?
(a) always charge to 80% (recommended by Nissan), or
(b) charge to 100% sometimes as this contributes to cell balancing.

charge to 100% if 80% causes you to see VLB frequently

as far as cell balancing; have we "actually" determined this? do we know how cell balancing is handled now? i honestly dont know. i know there has been a lot of discussion here about it but all speculation i think. please correct me if i am wrong.

i think #1 should be do what you need to do to keep from walking

i have mine set to charge to 100% but only charge to that point maybe 5=10 times a month depending on what i am doing. its more in Summer because we venture out more

 

[GaslessInSeattle]

One assumption we need to question is whether the total amount of charge taken up during charging truly reflects the charge used by a previous trip.

Which is why just use miles traveled divided miles/kWh.

but if your source of kWh used is based on the next charging, the outcome may be inaccurate for the reasons I stated in my post or for other reasons not yet known.

... I'm still working on doing loops around a consistent track here under pretty controlled driving habits and varying temps with no climate control and I have to say I'm still unclear as to what is causing what exactly.

If the climate control is off, and your driving the same loop in the same manner, and get different kWh data at different temps, what other variables are there?

I already stated possibilities, which you snipped out, there certainly could be other reasons.

In any case, if there is a consistent way to do better than Tony's chart we better nail it down, as the Jalopniks out there are going to use overly conservative numbers as cannon fodder for their war on EV's.

I just want to be clear that I don't fudge anything to make the car seem better than it is. I don't care what knuckle draggers think, since even if the LEAF went 200 miles, it wouldn't be enough. I'm only trying to establish a baseline. Yes, you should be able to beat it! But, an inexperienced EV driver won't.

you have repeatedly missed my point, almost as a style of argument. while going on and on about a 2.5% discrepancy in carwings, you have recently admitted to a much larger discrepancy in your own chart in the cold whether numbers. without stating the chart is a work in progress, you posted this chart in response to many folks who posted about low mileage concerns in cold whether. The numbers you stated in the chart, you later said were extrapolations as a rule of thumb due to the fact that it doesn't get that cold where you've been doing your testing. While I appreciate that you are now polling those in more extreme climates, I would ask you to be careful, creating inaccurate numbers can be discouraging and lead people to accept that the car is more limited than it really is, just as fudging in the other direction has negative repercussions. While I applaud your efforts in this ongoing project, I do think there are some assumptions you need to be more careful about and it seems like you are a smart person and will account for these at some point if they prove worthy. I think it's going to take someone with more technical electrical training than me to get through to you, if in fact what I'm seeing bears out over time. As I have said, I am finding there are some relatively simple things that average new owners can do by learning how to use the tools on the dash and by charging habits and prewarming, that can lead to substantial improvements over your numbers. I think there is more to this whole story that will come out over time as we continue to try and nail it down. By nature, it appears to be an inexact science. ironically, the GOM seems to be a valuable tool in giving "in the moment" feedback on how driving habits are effecting range, combined with the MPkW trip average and the energy meter, allowing me to get where I need to go, as fast as I can, given the remaining range, down to a few miles of reserve... not bad for the first mass produced EV!

 

[TonyWilliams]

you have repeatedly missed my point, almost as a style of argument. while going on and on about a 2.5% discrepancy in carwings, you have recently admitted to a much larger discrepancy in your own chart in the cold whether numbers. without stating the chart is a work in progress, you posted this chart in response to many folks who posted about low mileage concerns in cold whether. The numbers you stated in the chart, you later said were extrapolations as a rule of thumb due to the fact that it doesn't get that cold where you've been doing your testing. While I appreciate that you are now polling those in more extreme climates, I would ask you to be careful, creating inaccurate numbers can be discouraging and lead people to accept that the car is more limited than it really is, just as fudging in the other direction has negative repercussions.

I think this will (hopefully) be my last comments on this issue. I don't believe CarWings, either new or old firmware, is accurate. Knock yourself out using it. I've posted very recent data of two full runs from 100% charge, with dash numbers, and with new and old CarWings data for comparison, neither or which are accurate. There's nothing more I can, or will do, to expand on this issue. It is not suitable for my purposes. I won't be using until such time that it can be made accurate, if ever.

The entire thread that details the evolution of the range data is detailed in several hundred posts. Go check it out. It is nothing BUT a work in progress; a work in progress that to this very date, I am now compensating folks for data. The current version states all the usual disclaimers. Honestly, if you've got a better mouse trap, let's see it. I'm not convinced that the "very accurate" GOM is it, nor is CW, so, again, I will use neither for precisely the reasons stated.

Over and over, I've changed data on the chart as new data becomes available that I'm confortable with. It has done nothing but evolve, now at version 7d. I guess I take offense with your comment, but that's the price I pay for posting my work on the internet for all to critique, and freely use, and modify.

I do not accept, or worry, about the crux of your point; whether somebody will somehow find my estimate of the LEAF's range is slightly low, and therefore cause for criticism from knuckle draggers. Honestly, I don't care.

If you can add data to the cold weather issue, I would find that a much more useful task for both of us.

 

[TonyWilliams]

(b) charge to 100% sometimes as this contributes to cell balancing.

as far as cell balancing; have we "actually" determined this? do we know how cell balancing is handled now? i honestly dont know. i know there has been a lot of discussion here about it but all speculation i think. please correct me if i am wrong.

Here's my empirical data and thoughts on the issue:

In the times when my battery has not performed as expected at the lower 15% of capacity, and I subsequently have charged to 100%, and left enough time (1 to 4 hours) for the expected small charge that happens exactly once, the battery then changed it's performance back to the original capacity.

Those times when I charged to 80%, I have never received that small charge 1 to 4 hours later. The same with other opportunity charges, although it would be rare that I'd charge for an hour someplace, and then wait around 1 to 4 hours at the end of the charge with the EVSE still plugged in to give it that opportunity to balance and subsequently charge more.

I don't think Nissan is going to tell us what we need to know, so all we have to date is empirical data. I don't believe that the cell balancing happens anywhere but after a 100% charge.

 

[DaveinOlyWA]

(b) charge to 100% sometimes as this contributes to cell balancing.

as far as cell balancing; have we "actually" determined this? do we know how cell balancing is handled now? i honestly dont know. i know there has been a lot of discussion here about it but all speculation i think. please correct me if i am wrong.

Here's my empirical data and thoughts on the issue:

In the times when my battery has not performed as expected at the lower 15% of capacity, and I subsequently have charged to 100%, and left enough time (1 to 4 hours) for the expected small charge that happens exactly once, the battery then changed it's performance back to the original capacity.

Those times when I charged to 80%, I have never received that small charge 1 to 4 hours later. The same with other opportunity charges, although it would be rare that I'd charge for an hour someplace, and then wait around 1 to 4 hours at the end of the charge with the EVSE still plugged in to give it that opportunity to balance and subsequently charge more.

I don't think Nissan is going to tell us what we need to know, so all we have to date is empirical data. I don't believe that the cell balancing happens anywhere but after a 100% charge.

how often should you go to 100% if you never get below 20% and normally dont charge beyond 80-90%? does cell balancing happen to even the smallest degree at anytime other than 100% and what triggers the cell balancing? if what you say is true, there is a trigger based on differences in voltages between cell pairs. so the trigger must have parameters

i am not asking these questions expecting you to have answers. just wondering how this cell balancing works. it would have to communicate between different computers on the car which means that someone with a Can logger should be able to capture this data. we might not be able to tell what its saying since we have no parameters to compare other than it happens at near full charge

(since i have received my "GID meter" my max SOC has been 98.9 which i checked less than an hour after charge was completed

is it possible that cell balancing after that time would have pushed it up higher? maybe this is what we need to monitor?

 

[DaveinOlyWA]

(b) charge to 100% sometimes as this contributes to cell balancing.

as far as cell balancing; have we "actually" determined this? do we know how cell balancing is handled now? i honestly dont know. i know there has been a lot of discussion here about it but all speculation i think. please correct me if i am wrong.

Here's my empirical data and thoughts on the issue:

In the times when my battery has not performed as expected at the lower 15% of capacity, and I subsequently have charged to 100%, and left enough time (1 to 4 hours) for the expected small charge that happens exactly once, the battery then changed it's performance back to the original capacity.

Those times when I charged to 80%, I have never received that small charge 1 to 4 hours later. The same with other opportunity charges, although it would be rare that I'd charge for an hour someplace, and then wait around 1 to 4 hours at the end of the charge with the EVSE still plugged in to give it that opportunity to balance and subsequently charge more.

I don't think Nissan is going to tell us what we need to know, so all we have to date is empirical data. I don't believe that the cell balancing happens anywhere but after a 100% charge.

how often should you go to 100% if you never get below 20% and normally dont charge beyond 80-90%? does cell balancing happen to even the smallest degree at anytime other than 100% and what triggers the cell balancing? if what you say is true, there is a trigger based on differences in voltages between cell pairs. so the trigger must have parameters

i am not asking these questions expecting you to have answers. just wondering how this cell balancing works. it would have to communicate between different computers on the car which means that someone with a Can logger should be able to capture this data. we might not be able to tell what its saying since we have no parameters to compare other than it happens at near full charge

(since i have received my "GID meter" my max SOC has been 98.9 which i checked less than an hour after charge was completed

is it possible that cell balancing after that time would have pushed it up higher? maybe this is what we need to monitor?

 

[Herm]

We dont know what the parameters that trigger balancing are, I'm sure Nissan closely monitors it, but if you never discharge your pack all the way it does not really matter if the pack is balanced or not.. cell balance becomes important in eeking out the last little bit of range out of the battery.. reconsider your driving habits if you need to do that often since its stressful to the battery.

 

[planet4ever]

One assumption we need to question is whether the total amount of charge taken up during charging truly reflects the charge used by a previous trip.

Which is why just use miles traveled divided miles/kWh.

but if your source of kWh used is based on the next charging, the outcome may be inaccurate for the reasons I stated in my post or for other reasons not yet known.

Why would you think that? He just said that he calculates kWh as (miles traveled) / (miles/kWh), both numbers that are available immediately on the dash.

Ray

 

[GaslessInSeattle]

my understanding is that this whole time he's been focusing on the kW reading from the EVSE/wall meter.

bottom line for me either way, if it's intended that some degree of cold whether protocol will be applied before driving the car, why not test it under the conditions it's designed for and/or try and to better identify a decent cold whether protocol that the average driver can follow to maximize range. Certainly, the Leafs with the cold whether package should be tested plugged in in extreme temperatures to see how well the battery warmer helps with range. All Leafs come with the prewarming ability, which can be used to warm the core of the car and apparently the battery and should be tested in this mode as well.

IMHO, finding a decent cold whether protocol for extended range is key to showing what these cars can really do, and that's my focus. Truly empirical data, with direct cause and effect delineations is hard to come by here due to apparent unknowable vacillations in factors. In such cases, an outcomes approach to research can be very helpful.

I think a group of us needs to focus on a cold whether protocol, test it out and put it forth to the community. Tony's chart will be helpful for knowing what to expect if you do no preparation at all for driving in the cold but we need some solid outcomes to give folks who would be able to own the leaf if only they knew with some assurance that they could drive it consistently further than Tony's worst case scenario.

And Tony, I mean no disrespect whatsoever in pressing my points. If I'm off base and my efforts turn up nothing useful, then so be it, but so far, myself and some others are coming up with very different cold whether range numbers than your chart suggested. If there is something helpful to uncover here, I'm sure we would all like to know.

Why would you think that? He just said that he calculates kWh as (miles traveled) / (miles/kWh), both numbers that are available immediately on the dash.

Ray