Cold weather

[Ted]

I have the cold weather package, and boy is the heated steering wheel nice. I've only tried pre-heating for 15 or 20 minutes at most. I'm going to try a longer preheat this week and see what difference it may make. I'll post any results I come up with.

have you tried charging to 80% the night before and then charging to 100% in the morning while prewarming the cabin for a substantial amount of time, say 45 minutes to an hour? this is working well here, but I have no idea at what point doing this becomes less effective. also, do you have the CWP?

All interesting discussion. I think it would be good to point out though that we are all dealing with fundamentally different conditions. At Seattle temperatures I can believe tht the range isn't much affected, although i would think there would be some loss. I have experienced similar performance here in the fall and when cold temperatures were around freezing overnight and rising to 5 degrees celsius or so during othe day. This past week my drafty, unheated garage has been in the -20 degrees Celsius range and the temperature outside the door in the minus -30's. This has changed virtually everything when it co me to energy use and range.

The Leaf is still working though and hasn't left me stuck anywhere.

 

[GaslessInSeattle]

don't be afraid to let it charge to 100% using the preheat function. the preheat system will keep going for something like 2 hours, maybe longer, which should help substantially in getting the car warmer. Give yourself plenty of time and monitor the charging progress the first few times at a given ambient temp. if you are not making any progress with the charging you may need to turn preheat off for a bit. my suspicion is that the preheat warms the battery from the inside while charging and also by heating up the mass of the car (the main heat vents blast down onto the floor during preheat, perhaps helping to heat the battery) and seemingly allows the battery to take up more of a charge. If you do this frequently, your wall to wheels MPkW will go down somewhat, but you are still way ahead of the cost per mile of an ICE.

lucky you for having the CWP! from what I can tell it's worth it's weight in gold. without it, you can see half your range go up in smoke to the climate control compress/cool/reheat downward spiral.

looking forward to hearing if this is useful even in extreme cold.

I have the cold weather package, and boy is the heated steering wheel nice. I've only tried pre-heating for 15 or 20 minutes at most. I'm going to try a longer preheat this week and see what difference it may make. I'll post any results I come up with.

have you tried charging to 80% the night before and then charging to 100% in the morning while prewarming the cabin for a substantial amount of time, say 45 minutes to an hour? this is working well here, but I have no idea at what point doing this becomes less effective. also, do you have the CWP?

All interesting discussion. I think it would be good to point out though that we are all dealing with fundamentally different conditions. At Seattle temperatures I can believe tht the range isn't much affected, although i would think there would be some loss. I have experienced similar performance here in the fall and when cold temperatures were around freezing overnight and rising to 5 degrees celsius or so during othe day. This past week my drafty, unheated garage has been in the -20 degrees Celsius range and the temperature outside the door in the minus -30's. This has changed virtually everything when it co me to energy use and range.

The Leaf is still working though and hasn't left me stuck anywhere.

 

[planet4ever]

I have what may be an interesting, though far from extreme, data point. I charged to 80% last night then made one trip (with two stops) this evening. The total mileage was just a hair under 40 miles, but I hit LBW at 38.3 miles, with m/kWh saying 3.2. I know, that's low, but not too unexpected since most of the trip was on the freeway (60-62 mph) and I had the heater on the whole time for my wife's comfort. One factor making the data point interesting is that the last mile and a half (starting shortly after LBW) was city streets, and I had 3.3 m/kWh when I got home. A short period of slow (and stop for lights) driving at the end of a much longer freeway trip shouldn't have caused much change in average m/kWh, so I have to believe it was really almost 3.3 when I got LBW. (I am assuming that the displayed value is truncated rather than rounded.)

The second edge condition involved is that my car sits outside, and our temperature range was about 41 last night up to low fifties today. The car said the outside temperature was 50 two miles after I left home shortly before 6 PM, and I had 4 battery temp bars. That crept up to 5 bars shortly before the end of the first half of our trip, but was back to 4 bars when we started home after dinner. The outside temperature as reported by the car was 48 when I got home.

I have just over 5000 miles on the car, and I've been treating the battery fairly gently, so it shouldn't have lost any noticeable amount of capacity, except temporary losses due to temperature or cell balancing. So, crunching the numbers:

• Assume 21 kWh usable capacity at 70°F and LBW hitting at 17% capacity.
• At 70°F, 80% = 16.8 kWh and 17% = 3.6 kWh, for a nominal difference of 13.2 kWh.
• (38.3 miles) / (3.3 m/kWh) = 11.6 kWh actually used (possibly 11.7 kWh if really 3.26 m/kWh).
• Observed loss: 1 - 11.6/13.2 = 12%.
• Predicted loss for temperature (1% per 4°F): 5%.

Am I seeing 7% loss due to cell imbalance? It's been 3 weeks since I charged to 100%, but I am usually plugged in for 6 hours or longer after my 80% charge completes.

I should point out that if I were to assume 20 kWh nominal (70°F) usable capacity, the nominal usage to LBW would be 12.6 kWh, so my 11.6 is only an 8% loss, leaving just 3% to be accounted for by cell imbalance.

Ray

 

[mdh]

I have what may be an interesting, though far from extreme, data point. I charged to 80% last night then made one trip (with two stops) this evening. The total mileage was just a hair under 40 miles, but I hit LBW at 38.3 miles, with m/kWh saying 3.2. I know, that's low, but not too unexpected since most of the trip was on the freeway (60-62 mph) and I had the heater on the whole time for my wife's comfort. One factor making the data point interesting is that the last mile and a half (starting shortly after LBW) was city streets, and I had 3.3 m/kWh when I got home. A short period of slow (and stop for lights) driving at the end of a much longer freeway trip shouldn't have caused much change in average m/kWh, so I have to believe it was really almost 3.3 when I got LBW. (I am assuming that the displayed value is truncated rather than rounded.)

The second edge condition involved is that my car sits outside, and our temperature range was about 41 last night up to low fifties today. The car said the outside temperature was 50 two miles after I left home shortly before 6 PM, and I had 4 battery temp bars. That crept up to 5 bars shortly before the end of the first half of our trip, but was back to 4 bars when we started home after dinner. The outside temperature as reported by the car was 48 when I got home.

I have just over 5000 miles on the car, and I've been treating the battery fairly gently, so it shouldn't have lost any noticeable amount of capacity, except temporary losses due to temperature or cell balancing. So, crunching the numbers:

• Assume 21 kWh usable capacity at 70°F and LBW hitting at 17% capacity.
• At 70°F, 80% = 16.8 kWh and 17% = 3.6 kWh, for a nominal difference of 13.2 kWh.
• (38.3 miles) / (3.3 m/kWh) = 11.6 kWh actually used (possibly 11.7 kWh if really 3.26 m/kWh).
• Observed loss: 1 - 11.6/13.2 = 12%.
• Predicted loss for temperature (1% per 4°F): 5%.

Am I seeing 7% loss due to cell imbalance? It's been 3 weeks since I charged to 100%, but I am usually plugged in for 6 hours or longer after my 80% charge completes.

I should point out that if I were to assume 20 kWh nominal (70°F) usable capacity, the nominal usage to LBW would be 12.6 kWh, so my 11.6 is only an 8% loss, leaving just 3% to be accounted for by cell imbalance.

Ray

Interesting... i live in the Bay Area California and noticed something rather similar during our recent drop in temperature. Do you know if cell re-balancing happens only when we charge to 100%?

 

[TonyWilliams]

I should point out that if I were to assume 20 kWh nominal (70°F) usable capacity, the nominal usage to LBW would be 12.6 kWh, so my 11.6 is only an 8% loss, leaving just 3% to be accounted for by cell imbalance.

Ray,

Your analysis seems well done, and I have been pondering whether 70F is indeed exactly 21kWh. I'm happy to announce that we're moving into the fine tuning of the data phase... a long way from last summer with claims thrown all over the place.

The recent run in Florida to 130 miles with temps at 65-75 only had 20.3kWh in the battery used, although there may have been a few tenths more to Turtle:

130 miles (209.4 km)
6.4 m/kwh
Calculated battery capacity: 20.3kWh
temps 65 to 75 degrees
no climate control.

LBW - 105.8 miles (15.2 to VLB)
VLB - 121 miles (9 to end)
end - 130 miles

LBW-->>VLB ratio = 59%

 

[edatoakrun]

I should point out that if I were to assume 20 kWh nominal (70°F) usable capacity, the nominal usage to LBW would be 12.6 kWh, so my 11.6 is only an 8% loss, leaving just 3% to be accounted for by cell imbalance.

Ray,

Your analysis seems well done, and I have been pondering whether 70F is indeed exactly 21kWh. I'm happy to announce that we're moving into the fine tuning of the data phase... a long way from last summer with claims thrown all over the place.

The recent run in Florida to 130 miles with temps at 65-75 only had 20.3kWh in the battery used, although there may have been a few tenths more to Turtle..

I suggest, again, that you may find Carwings the best source of information on this subject.

Why don't you check CW for your 100% to VLBW, turtle, or stop trips at different temperatures, and see if it gives you accurate available kWh?

As I posted last 9/11, after a 93+ mile drive, using the remaining charge estimates then available from your chart:

According to CW, on this drive I used 18.7 kWh to drive 91.1 miles at average energy economy of 4.9 m/kWh...

Extrapolating from the chart, it appears CW may be saying the 1.7 kWh (8.5% from the chart, of 20.4 total kWh-anyone have a better number?) I had left at or near VLBW implies total available battery capacity of about 20.4 kWh.

So, from the limited info I can gather, looks to me that Carwings may now be accurate as to energy use.

Posts from others who can take the charge lower could verify this...

Comments from the SOC meter crowd, and also those who have metered L2 charging and can determine charge efficiency, as a % from Carwings reports, would also be greatly appreciated...

http://www.mynissanleaf.com/viewtopic.php?f=31&t=5423&start=10" onclick="window.open(this.href);return false;

And using CW to estimate cold weather effects I posted on 11/12:

On 11/8 I attempted to replicate the route and conditions of an earlier trip, which I had kept careful notes of, to try to see what sort of range reduction is caused by reduced m/kWh due to lower temperatures, and what proportion of this reduction is due to reduced battery capacity. I did this on a dry day with windows up, without using the heater or windshield wipers. I believe that I got about 5% reduction in battery capacity, and a slightly larger decrease in driving efficiency (m/kWh) resulting in a total range reduction of over 10%...

My trip (each time with a 1 1/2 hour break at the halfway point (for a hike around Burney Falls) on 8/30 was 87.6 miles by odometer (85.5 miles by Carwings-see other thread for info on this 2.5% discrepancy) with between 5,000 and 5,500 ft. of total ascent and descent, carwings reports 16.8 kWh consumed and 5.1 m/kWh. I believe my total battery capacity after charging to 100%, was about 20.4 kWh.

When I made the (almost) identical drive on 11/8 of 88 miles (85.9 as reported by CW) CW reported 17.6 kWh consumed and 4.9 m/kWh. I believe my total battery capacity when I left home with a 100% charge was probably close to 19.4 kWh...

Both initial charges were done to 10 bars, with a top-off to 100 % many hours later, and were all done in an open carport.

On 8/30 the overnight low was in the low 60’s, and the top off was done when the ambient temp had warmed to the mid 80’s , and my best estimate that the battery was probably in the 70’s at this time. The drive was done in temperatures of 80-95 degrees. I believe (but did not record) that the battery temp indicator remained at 6 bars for the entire trip.

The 11/8 top-up charge was done when the overnight low was 35. I doubt that the battery temp was much higher than this. The temperature during the drive ranged from 47 to 36 degrees. Battery temp showed 4 bars until the recharge session, and it was at 5 bars for the rest of the trip....

http://www.mynissanleaf.com/viewtopic.php?f=31&t=6701&hilit=+carwings&start=60" onclick="window.open(this.href);return false;

My CW results for available battery capacity for every long trip at every temperature have been predictably between these two extremes. Sorry, but that's about the greatest temp differential and discharge level (VLBW) I can comfortably make.

 

[TonyWilliams]

My mindset has been, to date, if it's the GOM/DTE gauge, or CarWings, I won't waste my time considering that data. That's probably why I've overlooked the data you presented earlier. So, let's see if it even makes sense.

Aug 30, CarWings reports:
16.8 kWh consumed 5.1 m/kWh
Calculated battery capacity: 20.4 kWh
Probable battery temp: 70F-80F

Nov 8, CW reported on same basic trip:
17.6 kWh consumed and 4.9 m/kWh
Calculated battery capacity: 19.4 kWh
Probable battery temp: 35F-40F

70F - 38F = 32 degree delta / 4 = 8% * 21kWh = 1.68kWh, or 19.32kWh <<--pretty darn close!

If we change the 21kWh index to 25C/77F (not quite as easy for a rule of thumb):

77F - 38F = 39 degree delta / 4 = 9.75% * 21kWh = 2.0475kWh, or 18.95kWh

If we change the 70F temp to 20kWh:

70F - 38F = 32 degree delta / 4 = 8% * 20kWh = 1.6kWh, or 19.4 kWh <<---- hmmmmmmmmm

I think we'll have to stick this formula into the other performances.

Thanks for the heads up on the CarWings data.

 

[edatoakrun]

My mindset has been, to date, if it's the GOM/DTE gauge, or CarWings, I won't waste my time considering that data. That's probably why I've overlooked the data you presented earlier. So, let's see if it even makes sense.

Aug 30, CarWings reports:
16.8 kWh consumed 5.1 m/kWh
Calculated battery capacity: 20.4 kWh
Probable battery temp: 70F-80F

Nov 8, CW reported on same basic trip:
17.6 kWh consumed and 4.9 m/kWh
Calculated battery capacity: 19.4 kWh
Probable battery temp: 35F-40F

70F - 38F = 32 degree delta / 4 = 8% * 21kWh = 1.68kWh, or 19.32kWh <<--pretty darn close!

If we change the 21kWh index to 25C/77F (not quite as easy for a rule of thumb):

77F - 38F = 39 degree delta / 4 = 9.75% * 21kWh = 2.0475kWh, or 18.95kWh

If we change the 70F temp to 20kWh:

70F - 38F = 32 degree delta / 4 = 8% * 20kWh = 1.6kWh, or 19.4 kWh <<---- hmmmmmmmmm

I think we'll have to stick this formula into the other performances.

Thanks for the heads up on the CarWings data.

You seem to be trying to plug my results into "rules of thumb", that they do not support.

To restate, my observations lead me to believe that My LEAFs battery capacity is about 20.4 kWh at about 75-80 F, and 19.4 kWh at about 35-40 F.

This is a decrease in available battery capacity of about 5% over about 40 degrees F, or about 1% for every 8 degrees F, over this temperature range.

As I pointed out in my earlier posts, a similar variance in temperature while driving may have a greater effect in reducing my range, by reducing m/kWh, than does the lower available kWh due to lower battery temperature, over those temperature variations that I have encountered.

I could have made errors in my observations. It is impossible to exactly replicate speed and driving technique over several trips, and there could be still other unknown variables, that explain the results that I got.

That's why I suggest it would be useful for others to check their own CW reports, to see if they show similar results.

 

[TonyWilliams]

It seems that your CarWings data does in fact correlate nicely with my rule of thumb. Where's the disconnect here? Edit: Ok, I see what your theory is now, after skimming too fast; 8F per 1%.

I prefer more "raw" data, like the data run that was just done in Ontario, from 100% to turtle, and more extreme temperature to make a forecast on lesser temperature deltas. I'm going to go back and re-calculate that Ontario data with a higher temps and lower capacity factors like I did with your data.

Folks reading this in cold climates. I have and will continue to send out a free t-shirt for data! That's the only thing that will nail this down, and now is the time to do it. See my thread, "Wanted: Extreme Cold Data" (or a similar name!@/?)

Obviously, any data that is deemed accurate will be useful to the end result. 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.

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

 

[planet4ever]

I suggest, again, that you may find Carwings the best source of information on this subject.

Not for me, it isn't. I just checked Carwings, and it says I haven't driven the car since Oct 14. I guess that could be because I always hit either the XM or Zero Emission button as soon as I turn the car on. :twisted:

Besides, wasn't there some sort of Carwings firmware update last summer? I don't have it, if so, and I don't trust anything Carwings would try to tell me.

Ray

 

[edatoakrun]

...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.

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.

I 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. But the relatively minor reduction in available battery capacity down to about 25 F (the lowest ambient charge temperature I've encountered) has allowed me to accurately plan longer trips, as well as my more frequent 10 and 11 bar charge trips, in cold weather, and reach my destination very close to my desired battery SOC. This is usually near LB for everyday driving, but also past VLB on occasion, when I have the need to do so.

 

[GaslessInSeattle]

I've been trying to say something along these lines for a while now, nice to see you chime in here!

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. it seems intuitive that this would be the case but assumes that the the charge always ends at the same upper limit. I don't really know enough about floating voltages and variations in a batteries capacity based on differences in how it's charged, but I have begun to wonder if the prewarming process, for instance, allows us access to a higher upper limit, effectively a higher charge limit because of the way it happens... slower, warmer or other reasons, like maybe it's designed with the assumption that people will be mostly charging to 100% and then prewarming, so maybe it over rides the normal battery management floating voltage limit. It would also make sense that since we are charging the middle part of the battery that both the upper the lower limits of actual KW capacity not well represented by floating voltages but rather fluctuate depending on things like battery temp at time of driving into VLB as well as battery temp at time of reaching full charge or rate of charge (a slower rate allowing for ions to better saturate the cells before reaching the floating voltage cut off. there are a lot of potential factors, or so it seems to me.

In any case, I applaud Tony for his strident efforts to pin down the limits on what looks like a rather slippery beast and also believe we need to keep pushing to figure out why we are seeing so many variations that do not fit easily into a model for range and temp in real word driving. Many folks, it seems are convinced that the lower MPkW's they are seeing are due to the effect of cold on the car, not just the increased use of Climate Control... 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.

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. for sure, if we take a regular ice, without a block warmer and with heavy summer time oil in it's crank case, not applying any cold whether protocals, we could make an ICE look much worse in cold whether than they can be. Using a cold soaked battery as the base line is problematic, as the car appears to be designed to allow the driver to mitigate the effect of cold on the car. I've realized I can not determine the KW uptake of the battery in a consistent way because I top off using prewarming, which does not destinguish between energy used for charging the battery and energy used for heating and of course the car refuses to tell me the actual battery temp. If I don't charge the car back up in this way, I'm going to end up with a lower KW reading or so it would follow. frustrating... and yet, very happy to find it's quite doable to get a good range in cold whether.

g

...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.

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.

I 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. But the relatively minor reduction in available battery capacity down to about 25 F (the lowest ambient charge temperature I've encountered) has allowed me to accurately plan longer trips, as well as my more frequent 10 and 11 bar charge trips, in cold weather, and reach my destination very close to my desired battery SOC. This is usually near LB for everyday driving, but also past VLB on occasion, when I have the need to do so.

 

[edatoakrun]

I've been trying to say something along these lines for a while now, nice to see you chime in here!

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...

I don't think it ever will, precisely, due to the many variables you mention, and probably some others, that only Nissan engineers may know.

That is why the CW reports of kWh "Electricity Consumption" from daily "driving history", and also from "Electric Rate Simulation" for each "trip" (any start/stop cycle) are so valuable, if we can determine them to be accurate.

From what I can see, they seem to be so.

 

[Blackhouse]

My wife had her first range anxiety event. It was her typical 30-40 mile daily drive, some steep hills, lots of freeway and a few stops. We always charge to 80% on those typical days, charging done 7 hours prior to depart, 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. I don't know her m/kw but lately she is 3.1ish, she came home a couple times with 2.9 lowest. My new rule of thumb is to always charge more and/or preheat if going more than 40 miles off of an 80% charge in cold weather. How many more miles could you drive once the -- comes up in cold weather?

 

[surfingslovak]

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.

George, excellent point. This is a great discussion, and perhaps I can make a quick comment.

I've been experimenting with several ideas that would allow more dynamic battery capacity estimates. This would be based strictly on instrument readouts. It looks like it's possible, but it won't be as accurate as if we utilized CAN bus data directly. I believe that the best accuracy we can hope for, all things considered, is about 2 or 3%. This could easily translate to 2 or 3 miles range difference, and it might not be always acceptable.

TEG brought up an interesting idea on the Tesla board. What if we came up with a connected device, be it a smartphone or a tablet computer, that could access the CAN bus and deliver a more accurate real-time battery capacity and range prediction? Some say that this cannot be done, and if it was possible, Nissan would have already implemented it.

With all due respect, I disagree with this view. I think that with the known CAN bus codes, and our current understanding of the battery, we should be able to come up with better DTE gauge.

 

[TonyWilliams]

Besides, wasn't there some sort of Carwings firmware update last summer? I don't have it, if so, and I don't trust anything Carwings would try to tell me.

Ray

I don't have the update, either.

 

[TonyWilliams]

...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?

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.

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.

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]

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.

... 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?

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.

 

[TonyWilliams]

I think that with the known CAN bus codes, and our current understanding of the battery, we should be able to come up with better DTE gauge.

Wouldn't that be awesome !

 

[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.

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