Cooler (colder) weather improving range in Portland Oregon

[chennu]

HI,
for the past few days, temperatures have dipped into the high 40's at night and hovered around a max of 70 during the day. i have been leaving my car out of the garage to let it cool down and then do a 80% charge at 2am; start 100% at 6am ish ( and leave shortly after it ends - say after an hour and half.) Today on a lark i checked the GIDs and was pleasantly surprised to see it at 273 (a number i have not seen since April). I wonder if the BMS is messing around limiting charge to 80% and 100% based on tmperature rise during the charging cycle.

really need the LeafScan to log temperature vs charge to understand this.


Anyone else see this?

Srinivas

 

[mwalsh]

Today on a lark i checked the GIDs and was pleasantly surprised to see it at 273 (a number i have not seen since April).

What have your Gids (or Gidometer based SOC) been over the summer? Edit: Never mind, I see that you've been mid-260s via some of your other posts.

 

[mkjayakumar]

I noticed somewhat similar behavior here in Dallas on a slightly cooler day 2 weeks ago with high of low 70s with a much larger range than I what typically got throughout summer. But then again it shot back to 90s and maybe I was dreaming.

Srinivas, your handle should be 'cheenu' maybe ? -

Jay

 

[DaveEV]

All this does is confirm that GIDs are compensated for battery temperature since there is no way that cooling a battery will magically improve it's capacity. So cold temps mean that a GID holds less energy - warm temps mean that a GID holds more energy.

TickTock documented this a while back and has a pretty chart somewhere showing the rise in GID counts as winter approached.

 

[mwalsh]

TickTock documented this a while back and has a pretty chart somewhere showing the rise in GID counts as winter approached.

Yes. He saw the same ~10 Gid increase as fall came on last year.

 

[edatoakrun]

TickTock documented this a while back and has a pretty chart somewhere showing the rise in GID counts as winter approached.

Yes. He saw the same ~10 Gid increase as fall came on last year.

But not a very significant increase in charge capacity, much less any increase in range, as I understand his reports:

https://docs.google.com/spreadsheet/ccc?key=0An7gtcYL2Oy0dHNwVmRkNkFnaEVOQTVENW5mOTZlb0E&pli=1#gid=3" onclick="window.open(this.href);return false;

Has anyone actually seen "improving range" as this thread is titled?

 

[garygid]

Although the lower temperature might not change the actual battery
capacity, the BMS could be programmed to charge the battery more
in lower temperatures and less when the temperatures are higher.

Thus, it would appear to us as if the battery has a higher usable
capacity in lower temperatures, and less usable capacity in
higher temperatures.

Maybe.

 

[mwalsh]

TickTock documented this a while back and has a pretty chart somewhere showing the rise in GID counts as winter approached.

Yes. He saw the same ~10 Gid increase as fall came on last year.

But not a very significant increase in charge capacity, much less any increase in range, as I understand his reports:

https://docs.google.com/spreadsheet/ccc?key=0An7gtcYL2Oy0dHNwVmRkNkFnaEVOQTVENW5mOTZlb0E&pli=1#gid=3" onclick="window.open(this.href);return false;

Has anyone actually seen "improving range" as this thread is titled?

10 Gids should mean an additional 2-3% on the Gidometer. So maybe a couple of miles difference is all.

 

[Stanton]

Expecting to experience something similar here in Dallas, although we won't see those temps for at least another month. I am interested to see if I get my 10 bars @80% back (been at 9 bars lately).

 

[mksE55]

Expecting to experience something similar here in Dallas, although we won't see those temps for at least another month. I am interested to see if I get my 10 bars @80% back (been at 9 bars lately).

sorry to say your about to lose a capacity bar soon, call Nissan and get a case number when you do. Hopefully Nissan will have battery plan soon and we can all stop waiting for the shoe to drop.

 

[edatoakrun]

Has anyone actually seen "improving range" as this thread is titled?

10 Gids should mean an additional 2-3% on the Gidometer. So maybe a couple of miles difference is all.

Except that gid variation in Wh seems to far exceed that 2-3%.

So the gid meter is not very useful, IMO, in determining actual kWh capacity or range.

Which is why I asked, has anyone actually seen driving range increases?

Increased range would, IMO, be highly suggestive of the BMS managing charge, presumably to limit damage when the battery is warmer.

FYI, I have never been able to see evidence of this BMS behavior in my own battery, in my own range tests. But it could be happening, at a fairly minor level. My battery, while probably having experienced higher ambient heat than you do in Portland, still only rarely gets much over 100F, and I have never Q.C.ed

So, my suspicion is if there is active BMS limiting the hot-battery charge level, you will probably only see much of it in fairly hot climates, or with Q.C. use heating the battery.

 

[smkettner]

I have the feeling recent lower temps have helped range. A few hot days a few weeks ago it seemed like 55 mile range would be about max on 80%. Now with cooler days and cooler nights (including adding a fan to bring cool night air into garage) I am getting 65 miles on 80% charge(and maybe more). These are rough estimates based on LBW or VLBW +GOM < 8. Mixed driving with about half at 60 max on freeway and usually CC set to 74F.

On edit:
Down to just 5 temperature bars after vehicle sat in the cool morning air at work. Back to 6 after a couple errands but have not seen 5 bars in several months.

 

[chennu]

addressing the question whether range improved. answer is most definitely yes. i usually drive about 40 miles daily and previously i used to have 4 bars and now i atleast have 5 and in some case 6 bars remaining at end of day.. and the GOM is now again back over 100 (barely at 101) when i start out in the morning..

 

[DaveEV]

It seems quite clear to me that the GOM gets pessimistic when the temperature goes up and gets optimistic when the temperature goes down. I have seen this myself in the last couple days with the bit of cooler weather. Last week when it was warmer, I got home with after LBW with 5 mi on the GOM. Then I went and drove another 5 mi - and got home with 4 mi still on the GOM! It's pretty clear that there is more capacity hiding below LBW when temps are warm than when it isn't.

There is no physical way that lower temperatures would result in an improvement in battery capacity - it's the opposite!

I would definitely make a Pizza bet that actual range to turtle has not changed.

 

[Stanton]

There is no physical way that lower temperatures would result in an improvement in battery capacity - it's the opposite!

Up to a point, I believe that IS true. For example, if you're crossing the threshold from 6TB to 5TB, I think you'll see an INCREASE in range (I did last Fall); however, going from 5B to 4TB will most definitely result in a DECREASE in range (getting too cold). That's why I'm not convinced I'll lose a capacity bar before the temps moderate here, even though I know I'm on the cusp (obviously this only delays the inevitable). Bottom line: every Leaf has a different combination of operational data, and it's difficult to predict exactly when/how our cars will react w.r.t. capacity.

 

[TonyWilliams]

Come on, this is getting nutty. First, I suspect you're talking about idiot GOM miles, which is fine to talk about, like astrology.

Cold batteries store less energy. Nissan LEAFs with non-temperature regulated batteries go less distance (range) with a cold battery than one that is warmer, all other things being equal.

Anything you claim to contradict that simple premise is a quaint anecdote, and nothing more.

There is no physical way that lower temperatures would result in an improvement in battery capacity - it's the opposite!

Up to a point, I believe that IS true. For example, if you're crossing the threshold from 6TB to 5TB, I think you'll see an INCREASE in range (I did last Fall); however, going from 5B to 4TB will most definitely result in a DECREASE in range (getting too cold). That's why I'm not convinced I'll lose a capacity bar before the temps moderate here, even though I know I'm on the cusp (obviously this only delays the inevitable). Bottom line: every Leaf has a different combination of operational data, and it's difficult to predict exactly when/how our cars will react w.r.t. capacity.

 

[Stanton]

Come on, this is getting nutty. First, I suspect you're talking about idiot GOM miles, which is fine to talk about, like astrology.

Cold batteries store less energy. Nissan LEAFs with non-temperature regulated batteries go less distance (range) with a cold battery than one that is warmer, all other things being equal.

Anything you claim to contradict that simple premise is a quaint anecdote, and nothing more.

Not talking about COLD batteries: talking about batteries @90F vs batteries @70F. You WILL see a decrease in capacity for 70F vs 50F. It has been demonstrated that a HOT Leaf holds less capacity (either due to the BMS or the pack itself).

 

[edatoakrun]

Come on, this is getting nutty. First, I suspect you're talking about idiot GOM miles, which is fine to talk about, like astrology.

Cold batteries store less energy. Nissan LEAFs with non-temperature regulated batteries go less distance (range) with a cold battery than one that is warmer, all other things being equal.

Anything you claim to contradict that simple premise is a quaint anecdote, and nothing more.

Not talking about COLD batteries: talking about batteries @90F vs batteries @70F. You WILL see a decrease in capacity for 70F vs 50F. It has been demonstrated that a HOT Leaf holds less capacity (either due to the BMS or the pack itself).

And since no one has proposed any other reason other than adaptive BMS for the recovery of capacity Ticktock observed last Winter, there could be some BMS limiting of the % charge at high heat levels.

The problem is, gid reports (as TickTock also observed) are not reliable, and range tests will be reduced by both the lower capacity of the cooler battery, and cooler ambient conditions.

So the most reliable observations would seem to be re-charge monitoring, as adjusted for the assumed lower capacity of the cooler battery. I hope some others in Phoenix and in other hot climates are doing just that.

But again, my battery frequently exceeded 90 F during daytime, and occasionally was even at those temperatures during charging, over the last two Summers, with no apparent charging limitation. So I think you may only have a chance of seeing it, above the other "noise" of capacity monitoring, in very hot climates.