Discuss data from the LEAF Battery app, and Comparisons

[opencar]

Well, I just lost my first capacity bar, and I thought it would be helpful to post before and after data.

Definitely helpful. Looks like your first screenshot was April 13th from the date in the picture?

Losing nearly 3Ah or 5% in two months is pretty extreme for a car which is already 2 years old - it really is more proof that suggests that the Ah / capacity readings are adjusted or normalized for temperature some how.

Coincidentally, the SOC is nearly the same in both pics and the pack voltages are basically the same, too - at least as expected the later pic has a slightly lower SOC% and also has slightly lower cell voltages.

In your 2nd pic, your pack is definitely pretty warm for San Diego, especially for mid-morning (mid-upper 80s) - out of curiosity, how much driving/charging was done before that? My car has been showing temps like in your first pic in the mornings - mid 70s - 5 temp bars. I have seen low 80s a few times after sitting in the sun all day before it cooled off the last week or so.



Edit: Just noting in this thread as well that it appears that the threshold for losing a bar is right around 55.25 Ah...

I'm going to go out on a limb and estimate that you will lose bars at these Ah readings:

11: 55.25
10: 52.00
9: 48.75
8: 45.50
7: 42.25
6: 39.00

thanks for the estimates drees. i'll post when I lose the first bar. when i do a run at 70+ mph on the freeway i'll get into the low 80 degree range despite ambient being in the 60s. i typically get out of the garage in the mid 70 degrees after a charge to 80% in the morning these days.

 

[LEAFfan]

Has anyone else noticed that in a hot climate the 2013 BP doesn't get as hot as previous packs and cools much quicker? I'm believing that it is from Nissan's BP tweaking of the chemistry.

 

[Stoaty]

Has anyone else noticed that in a hot climate the 2013 BP doesn't get as hot as previous packs and cools much quicker? I'm believing that it is from Nissan's BP tweaking of the chemistry.

How would tweaking the chemistry affect the thermal mass of the pack? Seems to me that it would have more to do with the housing and how the cells are packaged.

 

[surfingslovak]

Has anyone else noticed that in a hot climate the 2013 BP doesn't get as hot as previous packs and cools much quicker? I'm believing that it is from Nissan's BP tweaking of the chemistry.

How would tweaking the chemistry affect the thermal mass of the pack? Seems to me that it would have more to do with the housing and how the cells are packaged.

+1

 

[LEAFfan]

Has anyone else noticed that in a hot climate the 2013 BP doesn't get as hot as previous packs and cools much quicker? I'm believing that it is from Nissan's BP tweaking of the chemistry.

How would tweaking the chemistry affect the thermal mass of the pack? Seems to me that it would have more to do with the housing and how the cells are packaged.

Because adding something like sulfer to the pack can make it withstand the heat better. There's a link to NEC's research, perhaps you missed it?
Sorry Stoaty, but I'm not buying into your idea that the 2013 pack will stay 10F above ambient for so many hours. That may be true for earlier packs, but it is definitely not valid for mine.

 

[JPWhite]

Because adding something like sulfer to the pack can make it withstand the heat better.

As true as that might be, heat is heat, withstanding heat better does not reduce actual temperature.

 

[Stoaty]

Because adding something like sulfer to the pack can make it withstand the heat better. There's a link to NEC's research, perhaps you missed it?
Sorry Stoaty, but I'm not buying into your idea that the 2013 pack will stay 10F above ambient for so many hours. That may be true for earlier packs, but it is definitely not valid for mine.

I think you have me confused with someone else. I never said that any pack on any Leaf would stay 10 degrees F. above ambient for many hours. However, that is certainly possible if the Leaf is parked on pavement that has been heated to much higher than ambient temperature.

The only statement I have made is that I estimated the thermal time constant (the time to move 63% of the way from the current temperature to ambient, when parked in a constant temperature with no solar loading) to be around 9-10 hours. My test is not ideal though, because it involved driving 20 miles before the cold soak (68 degrees F.) and there may have been heat in the cells that had not equilibrated with the temperature sensors in the battery pack. If I get around to repeating my test, the proper way to do it would be to put it out in the sun for 6-8 hours--right outside my condo--and then move it inside. That way there wouldn't be any extra heat at the cell level that might skew the number.

 

[LEAFfan]

Because adding something like sulfer to the pack can make it withstand the heat better.

As true as that might be, heat is heat, withstanding heat better does not reduce actual temperature.

Ya, that's true. So maybe the 'vents' in each module could keep the pack cooler and dissipate the heat faster?

 

[DaveEV]

when i do a run at 70+ mph on the freeway i'll get into the low 80 degree range despite ambient being in the 60s. i typically get out of the garage in the mid 70 degrees after a charge to 80% in the morning these days.

Yeah, I've also found that freeway or aggressive driving will bump up pack temps. I did about 10 miles / 15 min of spirited driving (30-50 mph, very little full acceleration, but lots of 40-50 kW acceleration and 30 kW deceleration, think windy road driving) the other evening - Ambient temps in the low-mid 60s, pack temps started in the mid 70s ended around 80. Pretty good rise for 15 min of driving - more than I usually see in normal driving where I generally accelerate between 20-30 kW.

I usually drive on the freeway at 65 mph, but don't do a lot of it so haven't really paid attention to temp gain there.

My pack temps are also typically mid 70s after a couple hours charging back to 80% with the garage temp around 70. Commute to work (40-55 mph surface streets, 12-13 mi) will generally bump temps up another degree at most, but on a cool day like today there was no change. Need to try parking outside one night to see how much lower battery temps get.

Seems like all the ~June '11 San Diego LEAFs are similar in terms of Ah readings except davewill who did a lot of QC and more driving the last month.

Ya, that's true. So maybe the 'vents' in each module could keep the pack cooler and dissipate the heat faster?

Quite possible. And also possible the '13 cells have lower internal resistance which would mean less heating when discharging / charging. That could be why the '13 Nissan seems to let the '13 QC a bit faster than the '11-12.

 

[opencar]

Based on the thermal time constant for battery pack cooling (estimated at 9-10 hours), I have changed my charging routine during the summer. I now get home about 7:00 PM, let the battery pack cool for 5-6 hours, charge back to 70% Gids (2-2.5 hours), then let the battery pack cool for another 4-5 hours before taking my Leaf out to the hot San Fernando Valley. I believe that my pack will be less likely to get above 86 degrees using this charging schedule (as long as ambient temp doesn't go much above 90 degrees). Somewhere between 90-95 degrees forecast maxium temp I will leave the Leaf at home and take the ICE.

my experience looking at the data over the past month is consistent w/ Stoaty's post. given that i charge daily to 80% and use the car daily and the time constant is so long, i doubt that the battery pack ever achieves ambient temps, rather it'll always be about 5-10 degrees F above ambient

 

[LEAFfan]

Ya, that's true. So maybe the 'vents' in each module could keep the pack cooler and dissipate the heat faster?

Quite possible. And also possible the '13 cells have lower internal resistance which would mean less heating when discharging / charging. That could be why the '13 Nissan seems to let the '13 QC a bit faster than the '11-12.

Ah, I believe you're on to something. So the 'tweaking' may allow less resistance and lower pack temps and explains the QCing to 90% in 30 minutes. That sounds more effective than the vents.

 

[LEAFfan]

I think you have me confused with someone else. I never said that any pack on any Leaf would stay 10 degrees F. above ambient for many hours.

Sorry Stoaty, I did confuse what you said with someone else. I confused your 9-10 hours with the other 10 degrees.

 

[LEAFfan]

Based on the thermal time constant for battery pack cooling (estimated at 9-10 hours), I have changed my charging routine during the summer. I now get home about 7:00 PM, let the battery pack cool for 5-6 hours, charge back to 70% Gids (2-2.5 hours), then let the battery pack cool for another 4-5 hours before taking my Leaf out to the hot San Fernando Valley. I believe that my pack will be less likely to get above 86 degrees using this charging schedule (as long as ambient temp doesn't go much above 90 degrees). Somewhere between 90-95 degrees forecast maxium temp I will leave the Leaf at home and take the ICE.

my experience looking at the data over the past month is consistent w/ Stoaty's post. given that i charge daily to 80% and use the car daily and the time constant is so long, i doubt that the battery pack ever achieves ambient temps, rather it'll always be about 5-10 degrees F above ambient

It sounds like that's true for the '11-'12s, but it doesn't hold true for my '13. Mine has constantly been way below ambient temps. Like Thursday, the ambient was 112F, and the highest TS was 101F with the other two 99F. The other day when it was 105 ambient, I noticed the highest TS was only 95-96F.

 

[vrwl]

Based on the thermal time constant for battery pack cooling (estimated at 9-10 hours), I have changed my charging routine during the summer. I now get home about 7:00 PM, let the battery pack cool for 5-6 hours, charge back to 70% Gids (2-2.5 hours), then let the battery pack cool for another 4-5 hours before taking my Leaf out to the hot San Fernando Valley. I believe that my pack will be less likely to get above 86 degrees using this charging schedule (as long as ambient temp doesn't go much above 90 degrees). Somewhere between 90-95 degrees forecast maxium temp I will leave the Leaf at home and take the ICE.

my experience looking at the data over the past month is consistent w/ Stoaty's post. given that i charge daily to 80% and use the car daily and the time constant is so long, i doubt that the battery pack ever achieves ambient temps, rather it'll always be about 5-10 degrees F above ambient

It sounds like that's true for the '11-'12s, but it doesn't hold true for my '13. Mine has constantly been way below ambient temps. Like Thursday, the ambient was 112F, and the highest TS was 101F with the other two 99F. The other day when it was 105 ambient, I noticed the highest TS was only 95-96F.

Makes you wonder if they've somehow routed some of the air conditioned cabin air into the battery chamber.

 

[myleaf]

Based on the thermal time constant for battery pack cooling (estimated at 9-10 hours), I have changed my charging routine during the summer. I now get home about 7:00 PM, let the battery pack cool for 5-6 hours, charge back to 70% Gids (2-2.5 hours), then let the battery pack cool for another 4-5 hours before taking my Leaf out to the hot San Fernando Valley. I believe that my pack will be less likely to get above 86 degrees using this charging schedule (as long as ambient temp doesn't go much above 90 degrees). Somewhere between 90-95 degrees forecast maxium temp I will leave the Leaf at home and take the ICE.

my experience looking at the data over the past month is consistent w/ Stoaty's post. given that i charge daily to 80% and use the car daily and the time constant is so long, i doubt that the battery pack ever achieves ambient temps, rather it'll always be about 5-10 degrees F above ambient

It sounds like that's true for the '11-'12s, but it doesn't hold true for my '13. Mine has constantly been way below ambient temps. Like Thursday, the ambient was 112F, and the highest TS was 101F with the other two 99F. The other day when it was 105 ambient, I noticed the highest TS was only 95-96F.

LEAFfan, I am wondering what temperature you are seeing in the morning before driving. I am seeing 91 - 93. In the afternoon heat I am seeing up to about 105 with a 110 ambient. But I my drive home is on surface streets.

 

[LEAFfan]

LEAFfan, I am wondering what temperature you are seeing in the morning before driving. I am seeing 91 - 93. In the afternoon heat I am seeing up to about 105 with a 110 ambient. But I my drive home is on surface streets.

This morning at 5:30 AM the garage was down to 87F and the highest TS was 87F. Now, five hours later the garage is 94F and the highest TS is 88F. When I drove yesterday in 109F OAT, the highest TS was 91F. I'm really believing that the chemistry tweaking may be keeping the BP temps lower due to lower resistance as drees hypothesized.
I'm waiting to hear from some more Phoenix area 2013 drivers with the App and see if they have observed a similar thing.

 

[davewill]

... In your 2nd pic, your pack is definitely pretty warm for San Diego, especially for mid-morning (mid-upper 80s) - out of curiosity, how much driving/charging was done before that? My car has been showing temps like in your first pic in the mornings - mid 70s - 5 temp bars. I have seen low 80s a few times after sitting in the sun all day before it cooled off the last week or so. ...

As I mentioned in my post, the elevated temps were because I was out of town in the inland empire and had been using DCQC a bit. Those temps were taken the next morning after QCing the night before. After that shot was taken, the battery temps got up to 101 while doing the last QC (to 40%) to get me the rest of the way home, and the CAP value got down to 54.8 or so. It's been 4 days since then, and my battery temps have stabilized at 75-77 (it took almost 36 hours to do so, with a little driving and two 80% L2 charges), and the CAP value this morning was 55.12 Ah.

 

[DaveEV]

This morning at 5:30 AM the garage was down to 87F and the highest TS was 87F. Now, five hours later the garage is 94F and the highest TS is 88F. When I drove yesterday in 109F OAT, the highest TS was 91F. I'm really believing that the chemistry tweaking may be keeping the BP temps lower due to lower resistance as drees hypothesized.

It's hard to believe that your pack is getting down to ambient temperatures overnight and then staying there... It should take quite a few hours for the pack to equalize to ambient - and if ambient temperatures are falling, the pack will always be warmer than the minimum temp.

It looks like outdoors the low was around 75F this morning around 5:30-6:00 in Phoenix. Just like your garage will never hit that minimum temperature thanks to it's thermal mass and insulating walls, your battery pack will never hit your garage minimum temperature thanks to it's thermal mass and insulating case.

 

[Stoaty]

I saw the transition from 5 temperature bars to 6 yesterday on my way home from work. To my surprise battery temperatures were a bit higher than I expected. Minimum was 77.3, maximum was 78.6. This was at about 37% SOC (all info from Leaf Battery App). I am wondering if a slightly higher temperature is needed to bump the temperature bars to 6 when the SOC is fairly low. I think I recall seeing the cutoff at around 76 degrees a week or two ago, perhaps when SOC was higher.

 

[KJD]

I have only had the Battery App running for about 10 days so far so my results are very tentative. It does appear to me that the pack heats up quite easily and takes a long time to cool down. The pack in my car is often about 8 to 10 degrees warmer in the morning than the overnight low.

I have tried parking outdoors and indoors and found very little change in morning pack temps. I expected a bigger difference. I have also compared charging every day and every other day. Charging seems to add a little bit of heat but not as much as I thought it would.

One night I parked the car outside with a 20 inch box fan blowing air under the car all night long. The temps seemed to be about the same as parked outside with no fan.

I am curious how these observations on temps compare with what others are seeing.