Cold weather

[GaslessInSeattle]

Thanks, it's encouraging to hear that I'm not alone here.

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]

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.

Excellent idea. Here's my protocol for the cold weather part of the equation.

Please drive all the way to Very Low Battery. Super mega extra credit for a run to turtle. Astronomical stupendous extra credit if you have a Gidmeter. <<--- we might be able to get a loaner to a dedicated data collector.

At the conclusion of your data run, I'd like:


Gid count, if available, at start-
Assumed battery temperature -
Dash miles/kWh ---------------
Miles traveled total ------------

Miles driven at Low Battery ------
How many fuel bars showing-----
Gid count, if available------------

Miles driven at Very Low Battery -
How many fuel bars showing-----
Gid count, if available-------------

Miles driven at Turtle, if applicable-
Gid count, if available--------------

Heater nominal power use kW----

Your t-shirt size:
shipping address:

No GuessOmeter data is requested, nor desired. No CarWings data.

An ideal run will be mostly level, with a mostly stable low temperature, with no extreme power used, particularly at lower battery levels (below the first Low Battery Warning). It will have charged to 100% the night before at roughly the same temp that the data run was made, and have 4 hour minimum between the charge and the beginning of the data run.

If you have your "end of charge" text message at the end of the charge, and then get another one 1.5 hours later, after the cell balancing top off is complete, there's no need to wait the full 4 hours.

Happy data collecting!

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.

Bad assumption. The cold weather package does nothing to extend range. It merely protects the otherwise unheated/uncooled battery from physically freezing at -30C. That's why it comes on at -20C, and only heats to -10C, and continues the cycle.

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.

I don't know how much heat the battery would get in a preheat cabin event, or how long it would take. If the car were cold soaked at -19C, the 300w battery heaters won't even come on, and if you pre-warmed your car to 25C (the default setting) for 2 hours, I sincerely doubt that the densely packed battery in a metal container at the bottom of the heated cabin (heat still rises) would see any temperature rise. Good test though.

My continued suggestion to preheat the battery is to apply something like an electric seat heater for a motorcycle. It doesn't get too hot, it handles the moisture, it's durable, it's easy to install and they're relatively cheap. Plus, heat rises, so if you affix these on to the bottom of the battery, and warm up to 30C-40C, I predict you'll have a pleasant increase in range in 20-25% range over a -19C battery.

Obviously, I'm not using Climate Control in that 20-25% figure, but if you preheat your car fully (whatever that means to you), and only use the seat and wheel heaters, I'm going to say everything will work out about as best as can be expected.

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.

Let's let the data lead us... not the other way around.

 

[GaslessInSeattle]

Tony, I ask this with sincerity, what information can I give you that would satisfy you that the prewarming tools the car comes with and that I am using in combination with my protocal are making a difference and are worthy of factoring in to the kind of estimates you are creating? It appears that if I can't give you an accurate recharging kW reading, that you will dismiss anything I say. I went to give you charging kW's but realized that since I preheat from 80% to 100%, that I could not give you an accurate kW reading for charging or recharging in that manner, only a mileage range at a given ambient air temp on a consistent driven track over the last 4 months over a 40 degree drop in temp. I am concerned that your data will not reveal the phenomenon I am seeing and thus leave people with an unnecessarily low bar for their driving.

also, if what I'm doing is not warming the battery, how can it be explained that the battery temp gauge goes from 4 to 5 bars? I would not have said this would have made a difference before I stumbled upon it during my cold whether transition anxiety phase, so I certainly understand your doubts.

 

[edatoakrun]

"TonyWilliams"...No CarWings data...

Let's let the data lead us... not the other way around.

 

[DaveinOlyWA]

George, it sounds like you might have something but your benefits are bring negated by the amount of power bring used by preheating so long. Preheating more than 10 minutes its a waste of electricity.

Even if it is free to you, this is not a viable options for most of us

 

[GaslessInSeattle]

the amount of energy to charge from 80% to 100% vs "preheat" from 80% to 100% doesn't actually seem to add that much to the cost per mile, especially when you factor in that this allows me to drive without climate control on at all and still remain warm, reducing the cost per mile I'm getting while driving. the net expense for my winter timing driving is up about 7/10 of a penny per mile and I'm using climate control some of the time as well. I'm still seeing 80+ miles at highway speeds in hilly Seattle Metro. With the climate control on full blast, the cost per mile can nearly double, and I have certainly not doubled the cost of my driving with extensive preheating. In this climate, most of the energy is going to charging the battery. I don't know at what temperature it becomes prohibitively expensive, good to consider though. In such cases, extensive preheating may have to be reserved for when you have to max out the range. The good thing is that it appears possible to substantially extend the range in moderately cold temps with a little planning.

Also, as an aside, one of the reasons turning off climate control helps so much is that it appears that using the fan increases how much cold air is drawn in from outside. turning off climate control retains the heat better by reducing the circulation of outside air to the inside to a minimum, which just happens to be enough to keep the windows clear at moderate speeds.

I wish there was a way to adjust the amount of air that is coming from the outside. in the summer time I want lots of fresh air to cut down on AC use, in the winter time, I want to minimize it to reduce the need to heat the cold air.

George, it sounds like you might have something but your benefits are bring negated by the amount of power bring used by preheating so long. Preheating more than 10 minutes its a waste of electricity.

Even if it is free to you, this is not a viable options for most of us

 

[lukati]

Also, as an aside, one of the reasons turning off climate control helps so much is that it appears that using the fan increases how much cold air is drawn in from outside. turning off climate control retains the heat better by reducing the circulation of outside air to the inside to a minimum, which just happens to be enough to keep the windows clear at moderate speeds.

You may have said this elsewhere, but what are your exact A/C settings during your morning drive with a preheated car? My main problem is keeping the windshield from fogging up while I am trying to maintain heat in the cabin.

 

[amtoro]

Also, as an aside, one of the reasons turning off climate control helps so much is that it appears that using the fan increases how much cold air is drawn in from outside. turning off climate control retains the heat better by reducing the circulation of outside air to the inside to a minimum, which just happens to be enough to keep the windows clear at moderate speeds.

You may have said this elsewhere, but what are your exact A/C settings during your morning drive with a preheated car? My main problem is keeping the windshield from fogging up while I am trying to maintain heat in the cabin.

I have found that I can preheat and then drive my entire commute un-fogged and fairly warm during rainy or humid days.

I have been turning on the defogger but then I press the A/C button to turn it off, then I just set the fan speed to the minimum and the temperature just at the point where the energy usage gauge stays below 1.5 kW; as the drive progresses, and the car eventually loses the heat from the prewarming, I gradually reduce the temperature in the climate control, just to avoid the energy consumption to go up.

After 20 miles, I can feel that my feet are getting just a bit cold but not enough to complain.

On a regular, dryer day, just keep the climate control off but press the recirculation button to avoid the cold air that comes in by the feel vent as the car moves forward. This is not a problem in city driving as not much air is pushed in.

 

[GaslessInSeattle]

If your main problem is fogging, I suggest doing a prolonged preheat for say an hour, then open up all the doors and let out the humid air, do this repeatedly until you can preheat without seeing condensation on the inside of the windows. as we breath, we give off quite a bit of moisture. With the heating and cooling of the car there can be a gradual build up of moisture in the upholstery and since we don't have all that waste heat from an ICE we need to dry the car out on occasion or it will get moist and dank. I have found once the car has been dried out, that if you continue to use the prewarming daily that it tends to keep it in check. of course this is also effected by how humid your climate is.

as for the setting, EVNOW came up with the best way to defog without using power (for some reason you can't turn on the fan without it turning on Climate Control). I start by setting up the climate control to the temp I like, which is around 70 before turning it off. I adjust the mode button to foot/defog and then the last thing I do is use the on/off button to turn the climate control off. I look at the screen to verify that it says "climate control off", if I don't, it's surprising how easy it is to having it quietly running in the background. hitting any button after you turn climate control off will turn it back on again, so be careful, even using the up or down button for the fan turns it on.

In foot defog mode with climate control off, the only thing pushing air over the windshield is the forward movement of the car, so it only works well at at least moderate speeds and is quite sustainable in terms of taking care of the fog at highway speeds. Eventually your feet will start to get cold because of the cold outside air that trickles in through the vent. I have experimented with blocking the foot vent, which is just an open pipe facing down at the floor, just lower and to the right of the steering column base. If you block this vent, your feet will stay much warmer, but you MUST remember to unblock the vent before the next prewarming, so I only block it for long trips as it's not easy. I do not bother using the recirculate button, as it seems to rather quickly raise the humidity and cause fogging.

Once the car gets cold enough that you are uncomfortable, you can simply hit the on/off button and turn the climate control on, it will automatically come on to the temperature you previously set, so it requires minimal messing with while driving. it will stay on foot defog and you simply adjust the fan to the minimum speed necessary to be comfortable, as the higher the speed, or so it seems to me, the more outside air is drawn in, requiring more energy for the heater to keep the car warm. I just use the on off switch to toggle climate control as needed, it's the most hassle free way I've figured out how to manage it. I never use power defog, it compresses and cools the air, simply making it uncomfortable and requiring the use of the heater.

I have put some serious thought into this, but in the end it's simply my experience and you will need to adjust things to your liking and experiment.

hope that's useful!

Also, as an aside, one of the reasons turning off climate control helps so much is that it appears that using the fan increases how much cold air is drawn in from outside. turning off climate control retains the heat better by reducing the circulation of outside air to the inside to a minimum, which just happens to be enough to keep the windows clear at moderate speeds.

You may have said this elsewhere, but what are your exact A/C settings during your morning drive with a preheated car? My main problem is keeping the windshield from fogging up while I am trying to maintain heat in the cabin.

 

[TonyWilliams]

"TonyWilliams"...No CarWings data...

Let's let the data lead us... not the other way around.

As soon as somebody can provide some accurate CarWings stuff, I'm on board.

 

[TonyWilliams]

Tony, I ask this with sincerity, what information can I give you that would satisfy you that the prewarming tools the car comes with and that I am using in combination with my protocal are making a difference and are worthy of factoring in to the kind of estimates you are creating?

Well, one test that I find of value is whether a cabin preheat will heat the battery any (as previously stated).

Obviously, preheating the cabin for comfort is fine, and prewarming lessens whatever heat a driver might want. How to quantify that, I dont know. We both agree; preheating is good for comfort and to save energy heating the cabin, once underway. However, if I want maximum range, I wouldn't use climate control after a preheat.

The best way to prepare for the longest range in winter is to also heat the battery. While I don't think heating the cabin will offer any significant battery temperature (and therefore range), clearly anything that will heat it helps; oil pan type heaters are the most energy efficient solution. Heating the whole garage obviously will have benefits, but is grossly inefficient. Finishing a charge to 100% just before departure has some benefit, I'm sure, but to what degree, I don't know. I suspect it's marginal.

The best solution, charging wise, to heat the battery would be a healthy DC charge at 100+ amps!! Nothing will beat an oil pan type heater, however.

It appears that if I can't give you an accurate recharging kW reading, that you will dismiss anything I say.

Yes, of course. I'll dismiss anything based on fuzzy or inaccurate data. Would you expect something different?

I went to give you charging kW's but realized that since I preheat from 80% to 100%, that I could not give you an accurate kW reading for charging or recharging in that manner, only a mileage range at a given ambient air temp on a consistent driven track over the last 4 months over a 40 degree drop in temp. I am concerned that your data will not reveal the phenomenon I am seeing and thus leave people with an unnecessarily low bar for their driving.

I think you're talking about from the wall kW readings. Im pretty confident that data can be reasonably accurate with a correction for 84-85% charger efficiency. Almost any viable data is probably good; just state the parameters. If it's from the already known flawed data providers of the GOM and CW, then I would also dismiss that data. Bad data helps nothing.

I have to stress the basic premise of this type of data collection. We really want to isolate one variable at a time. If we understand the battery performance at all temperatures, then whatever you do to change that parameter will have data to back up your actions.

If the data supports my latest suggestion that battery capacity is changed at 1% per 4F, and you heat the battery up from 0F to 80F, I would guess your battery improved by 10% by virtue of increased battery capacity, not reduced energy usage by preheating the cabin? Make sense?

also, if what I'm doing is not warming the battery, how can it be explained that the battery temp gauge goes from 4 to 5 bars? I would not have said this would have made a difference before I stumbled upon it during my cold whether transition anxiety phase, so I certainly understand your doubts.

Going from 4 to 5 bars tells me that the battery could have went from 49.9F to 50.1F. We can't use the temperature gauge for much, until Gary can read the data off the CAN bus. I'm confident the battery is warmed during charging, but we don't know how much without viable data.

Viable, preferably raw, data.

 

[edatoakrun]

"TonyWilliams"...No CarWings data...

Let's let the data lead us... not the other way around.

As soon as somebody can provide some accurate CarWings stuff, I'm on board.

Which you will discover...by not looking at it?

Did you not, just a few days ago, cut your "rule of thumb" for available capacity loss at lower temperatures by half, essentially to the same estimate that I posted over 2 months ago, using CW Data?

TonyWilliams
Edit - 21 January 2011- please pencil in a change to the temperature data to reflect:

"5. Temperature Decrease: Subtract 1% loss from range for each 4F/2C below 70F/20C"

http://www.mynissanleaf.com/viewtopic.php?f=31&t=4295&start=270" onclick="window.open(this.href);return false;

edatoakrun
...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%. ...

...this approximately 40 degree decrease in temp when charging, and 50 degree reduction when driving, resulted in about 10% recorded range reduction. I expect that If I’d done the 8/30 trip in “sauna” mode, with the windows up and AC off, it would result in more like 11-12%...

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

My results may prove to have been correct by coincidence, or they might be proven in the future, by more data, to have been way off, as would your nearly-identical recently updated "rule of thumb", then also be proven wrong.

I encourage all to continue to collect data from other sources, including the cold weather observations you propose. I just think its unfortunate that you seem to be so determined to ignore any potential source of information on this and other LEAF topics, and seem to suggest that others do the same.

If Carwings does not give reliable reports now, it is entirely possible it could be in the future, and give far more useful and accurate information than the methods you are now pursuing.

I believe I was the first to post the one fault I am sure exists in my CW reports, the 2.5% constant "miles driven" underestimate, last September. If there are other CW inaccuracies I have not detected, I certainly want to hear about them, and will try and see if they are consistent with my LEAF operation.

So, I'd suggest other LEAF drivers take a look at CW. If it works, we can use it. If it doesn't, maybe we can make suggestions to Nissan, to correct its errors.

 

[DaveinOlyWA]

What we really need is Gary our someone to capture and display battery temperature readings.

In my observations(all of which were initially disputed by someone) I went from accessing about 21.5 kwh in summer to about 17.5 kwh in winter.

I wad so shocked that I was gonna mid my 100 mile goal that I dud it the very next day but using freeway run but getting the very same 17.5 kwh.

The only thing different was the 40 degrees.
Now how much is that air temperature difference being translated to the battery?

We know from Nissans test thatthe temp in the battery is much higher than ambient air temps

 

[Bassman]

I'm seeing roughly a 10 to 12 % reduction in range from summer to winter on my 126 mile roundtrip commute. It is especially eveident on my trip back home, as the car is charging in an outside parking lot and the day time temps have been mostly in the 40s to low 50s and decrease to the mid 30s and low 40s as I get closer to my home. In the Summer I typically get home with one to two bars and a mileage guesometer reading of 10 to 15 miles to go. In the winter, I get home with a low battery warning about 1 to 2 miles from my home, and on really cold days, I sometimes get home and pull into the garage with the very low battery warning just occurring. A couple times, I've had to reduce my speed to 25 mph for the last 10 miles in order to insure I get home. On those times. I attribute the reduced range to cold temps and a temporarily unbalanced battery pack.

 

[TonyWilliams]

I'm seeing roughly a 10 to 12 % reduction in range from summer to winter on my 126 mile roundtrip commute. ..... in the 40s to low 50s and decrease to the mid 30s and low 40s as I get closer to my home..... I attribute the reduced range to cold temps and a temporarily unbalanced battery pack.

Good stuff. If the battery were 40F, my current battery capacity formula would suggest 70F-40F=30F temp delta, 30/4=7.5% battery loss.

I presume that you run the climate control, and that would account for the remaining 2.5-4.5%.

Would you be interested in doing a run with no climate control on your return trip, and then running it all the way to Turtle? I'll send you a nice 5 ounce 100% organic cotton shirt with the LoveMyLEAF logo.

Now is the time to collect this data!

See this thread for details:

http://www.mynissanleaf.com/viewtopic.php?p=167334#p167334" onclick="window.open(this.href);return false;

 

[TonyWilliams]

"TonyWilliams"...No CarWings data...

Let's let the data lead us... not the other way around.

As soon as somebody can provide some accurate CarWings stuff, I'm on board.

Which you will discover...by not looking at it?

Did you not, just a few days ago, cut your "rule of thumb" for available capacity loss at lower temperatures by half, essentially to the same estimate that I posted over 2 months ago, using CW Data?

<snip>
I encourage all to continue to collect data from other sources, including the cold weather observations you propose. I just think its unfortunate that you seem to be so determined to ignore any potential source of information on this and other LEAF topics, and seem to suggest that others do the same.

I feel like ground hog day! At your suggestion, I did look at two separate cars (neither my own) which had both versions of CW. I find them both to be inaccurate, and posted my specific findings in this thread. So, I dismiss you contention that I won't look at it. If something changes with CW in the future, I'll be happy to revisit. In the interim, I would suggest that it's not up to the standard of "raw" data. Again, I won't be using known faulty data.

To answer the next question, yes I changed the formula to reflect viable DATA. That's not the only change, and there will likely be more. I thought your CW estimate was now 8F to 1% ?

 

[GaslessInSeattle]

Are you doing any prewarming while plugged in at work before heading home? are you using climate control on the way home? From what I've seen around here, most of the loss people are reporting is attributable to the use of climate control. Some is due to cold, but the use of preheating appears to have the double benefit of reducing climate control use while driving, even eliminating it, and apparently warming the battery.

let us know if prewarming for say a half an hour or more with no climate control on the way home helps your range, it would be helpful to me at the very least. With extensive prewarming, I have returned my range to practically what it was in the summer on a consistent track and near exact driving conditions and speeds.

I'm seeing roughly a 10 to 12 % reduction in range from summer to winter on my 126 mile roundtrip commute. It is especially eveident on my trip back home, as the car is charging in an outside parking lot and the day time temps have been mostly in the 40s to low 50s and decrease to the mid 30s and low 40s as I get closer to my home. In the Summer I typically get home with one to two bars and a mileage guesometer reading of 10 to 15 miles to go. In the winter, I get home with a low battery warning about 1 to 2 miles from my home, and on really cold days, I sometimes get home and pull into the garage with the very low battery warning just occurring. A couple times, I've had to reduce my speed to 25 mph for the last 10 miles in order to insure I get home. On those times. I attribute the reduced range to cold temps and a temporarily unbalanced battery pack.

 

[edatoakrun]

To answer the next question, yes I changed the formula to reflect viable DATA. That's not the only change, and there will likely be more. I thought your CW estimate was now 8F to 1% ?

My CW observations have been consistent for the last 6 months now, ever since I had the update, for temperature effects, as well as for all other data.

I believe you may be confused, because, both reduced available battery capacity, and separately, lower m/kWh performance, seem to correlate to lower temperatures, as I believe that I have stated...repeatedly.

I am confused by your posts, of how (or if) you are trying to determine these two distinct cold-weather effects.

I agree with Dave that battery pack temperature info, during charging and while driving, could be very useful.

Anyone have suggestions on that subject?

 

[GaslessInSeattle]

edatoakrun I can understand your frustration, I felt similarly. I can say I think Tony is one of the few people bothering to really nail this down even if at times he may have come across to some as a little overly confident in his extrapolations considering the relatively warmer climate he lives in. He is now attempting to get what he feels is the most reliable data from drivers in colder climates and that is good. His focus is on what he thinks is the only truly reliable data and I can understand that, it's a noble pursuit.

my approach at this point is more focused on outcomes than narrowing the focus to only the things that we can identify empirically, perhaps you and I are on the same page here. To some, only a pure data driven study is viable, but that's not always how it's done in the scientific community. Outcomes style research is used in health care where the number of variables is so complex that direct cause and effect relationships are hard to determine and where the outcome is more important than the cause. not knowing the exact battery temp at time of charge, discharge and recharge is just one of the things that muddies the water here for determining how big the glass is that we are trying to fill, the battery management system of the car focuses on floating voltages, which from reading elsewhere is not an exact science by nature, we don't really even know if turtle or end of charge occurs at the same volume of electrons each time... to me it all looks like pea soup so if something consistently works for improving winter time range purely from miles driven in a given cold ambient temp, it's more important to me that we identify it than understand why for now, we can figure out why later. what we need, is a cold whether protocol for people like bassman who are coming close to the max of their range on their commute as it gets colder and facing running out of range and having to use another car. the need for a reasonable cold whether protocol is also needed for prospective Leaf owners who expect to be driving the car close to it's max and need a level of assurance that with reasonable effort they will be able to get to work reliably throughout the year. To me, it's as much about the future of EV's as it is about the Leaf, and overly conservative numbers will hurt all players. We should all keep working toward what seem ultimately to be common goals. Unfortunately, and likely for a while more, we will all be subject to a level of uncertainty about this subject.

 

[derkraut]

I've been out of town for a couple weeks; so I charged the Leaf (for storage purposes) to 50% before I departed. At that time, the temperature in my garage was 70deg., and the battery temperature showed 6 bars.

A few days later, I remotely checked the SOC, and it showed 42%, with the battery temp @ 5 bars. Next day, it showed 50% again, with 6 bars. So, as the temperature in my garage went up & down, so did the SOC, commensurate with the battery temperature. In my case, a single bar difference in battery temperature resulted in about 20% change in SOC. I'm a bit surprised, because I didn't think it would be so significant.
Geez! I'm happy I live in San Diego.