Possible Widespread 2018-19 Traction Battery Quick Charge Problems

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arnis said:
Though we can be sure when that if it is 38*C outside, pack is higher than 38*C.

Oh? How do you know this?

I looked at my Leafspy logs for over the past 2 years, and filtered out the all of the measurements of 35C or more. The highest battery temperatures are 28C.

Continuing down, at 32C there are a few points of battery temperatures higher than ambient. They are the highest temperatures the battery has ever been, on a trip in multiple charges, both QCs and L2s. Peak temperature was 38.4C 08/10/2017 2nd longest day I've ever done. On a hot day, as well.

What I observe, and I'm clueless if this is just me or typical, is that the battery temperature is usually between the daily high and the daily low temperature in the summer. In the winter, the garage stays warmer than outside, and so does the battery.
 
For a 24 kWh LEAF, my experience is that pack temperature pretty closely tracks **average** daily ambient but we do not put big demands on the car, we try to keep it in the shade, and it does not cook in a closed garage in the summer.

http://mynissanleaf.com/viewtopic.php?f=27&t=24351&p=501195#p501195
 
Battery pack follows ambient slowly, but after a drive,
pack is warmer than before the drive.
In winter, around 10 degrees. In summer, at least 5 degrees (celsius, not fahrenheit).
This applies to after "considerable ride" (at least 2/3 of battery capacity).
Aka expected DC charge after that.
 
DaveinOlyWA said:
Pack Volts Pack Amps Pack T1 F Pack T2 F Pack T4 F
344.5 0 83.1 80.1 75
344.83 0 83.1 80.1 75
344.83 0.061 82.9 80.1 75
349.25 -85.082 82.9 79.9 75
351.36 -119.445 82.9 79.9 74.8



338.11 0 104 100 91.2
338 0 104 100 91.2
338.4 -0.03 104 100 91.2
338.3 0.061 104 100 91.2
338.4 0.122 104 100 91.2
341.57 -74.065 104 100 91.2
342.34 -77.453 104 100 91




348.48 0 111.2 106.7 97
348 0 111.2 106.7 97
348.67 0.061 110.7 106.2 96.4
349.73 -16.509 110.7 106.2 96.4
351.36 -68.023 110.7 106.2 96.4
351.84 -68.542 110.7 106.2 96.4

Here's the data for my 2016 leaf s30 (all numbers pulled from the Chademo station display):

** this data gathered at the minute interval
V in Volts : I in amps : Time (SOC %) since charging started.
337 : 60 : 2s (11%)
350 : 106 : 30s
351 : 106 : 60s
354 : 106 : 120s
357 : 106 : 180s (18%)
359 : 106 : 240s (22%)
361 : 106 : 300s (24%)
364 : 106 : 380s (29%)
366 : 106 : 480s (33%)
380 : 106 : 975s (60%)

** this data is from the same charging session but gathered at the Voltage interval.
V in Volts : I in amps : Time (SOC %) since charging started.
382 V : 106 : 1040s (62%)
383 V : 106 : 1088s (64%)
384 V : 106 : 1124s (66%)
385 V : 106 : 1162s (68%)
386 V : 106 : 1214s (70%)
387 V : 106 : 1253s (72%)
388 V : 106 : 1289s (74%)
389 V : 106 : 1342s (76%)
390 V : 106 : 1383s (78%)
391 V : 106 : 1432s (80%)
392 V : 106 : 1470s (82%)
393 V : 106 : 1506s (84%)
394 V : 106 : 1555s (86%)

Not sure how you're going to get battery resistance from these numbers, especially since the charge session seems to be current-limited.

Edit: The day was ~63 degrees F ambient, but I don't know what the actual battery temp was. Leaf Spy reported the same 63.7 F after the battery temp gauge had gone up from 5 bars to 7 bars. So I don't trust its temp reading.
 
Oils4AsphaultOnly said:
DaveinOlyWA said:
Pack Volts Pack Amps Pack T1 F Pack T2 F Pack T4 F
344.5 0 83.1 80.1 75
344.83 0 83.1 80.1 75
344.83 0.061 82.9 80.1 75
349.25 -85.082 82.9 79.9 75
351.36 -119.445 82.9 79.9 74.8



338.11 0 104 100 91.2
338 0 104 100 91.2
338.4 -0.03 104 100 91.2
338.3 0.061 104 100 91.2
338.4 0.122 104 100 91.2
341.57 -74.065 104 100 91.2
342.34 -77.453 104 100 91




348.48 0 111.2 106.7 97
348 0 111.2 106.7 97
348.67 0.061 110.7 106.2 96.4
349.73 -16.509 110.7 106.2 96.4
351.36 -68.023 110.7 106.2 96.4
351.84 -68.542 110.7 106.2 96.4

Here's the data for my 2016 leaf s30 (all numbers pulled from the Chademo station display):

** this data gathered at the minute interval
V in Volts : I in amps : Time (SOC %) since charging started.
337 : 60 : 2s (11%)
350 : 106 : 30s
351 : 106 : 60s
354 : 106 : 120s
357 : 106 : 180s (18%)
359 : 106 : 240s (22%)
361 : 106 : 300s (24%)
364 : 106 : 380s (29%)
366 : 106 : 480s (33%)
380 : 106 : 975s (60%)

** this data is from the same charging session but gathered at the Voltage interval.
V in Volts : I in amps : Time (SOC %) since charging started.
382 V : 106 : 1040s (62%)
383 V : 106 : 1088s (64%)
384 V : 106 : 1124s (66%)
385 V : 106 : 1162s (68%)
386 V : 106 : 1214s (70%)
387 V : 106 : 1253s (72%)
388 V : 106 : 1289s (74%)
389 V : 106 : 1342s (76%)
390 V : 106 : 1383s (78%)
391 V : 106 : 1432s (80%)
392 V : 106 : 1470s (82%)
393 V : 106 : 1506s (84%)
394 V : 106 : 1555s (86%)

Not sure how you're going to get battery resistance from these numbers, especially since the charge session seems to be current-limited.

Edit: The day was ~63 degrees F ambient, but I don't know what the actual battery temp was. Leaf Spy reported the same 63.7 F after the battery temp gauge had gone up from 5 bars to 7 bars. So I don't trust its temp reading.


sounds like you are looking at ambient temp on LS.

Batt temps comes in triplicate.
 
DaveinOlyWA said:
sounds like you are looking at ambient temp on LS.

Batt temps comes in triplicate.

So here's the thing, the 3 bar graph (T1, T2, T4) on the second tab of Leaf Spy, also only showed between 61F - 63.7F. Did my sensors get moved somehow?!
 
Oils4AsphaultOnly said:
** this data gathered at the minute interval
V in Volts : I in amps : Time (SOC %) since charging started.
337 : 60 : 2s (11%)
350 : 106 : 30s

Not sure how you're going to get battery resistance from these numbers, especially since the charge session seems to be current-limited.

Edit: The day was ~63 degrees F ambient, but I don't know what the actual battery temp was. Leaf Spy reported the same 63.7 F after the battery temp gauge had gone up from 5 bars to 7 bars. So I don't trust its temp reading.

The key data for calculation of battery resistance need to be gathered at the immediate start of the charging session.

Example:

1. Obtain the battery voltage before the QC session starts from LeafSpy or at the moment the QC voltage number appears from the charger
before the current begins;
example - 337 volts
2. The battery voltage and QC current the moment the actual charging current begins;
example - 350 volts, 106 amps
3. Calculate the resistance;
(350 - 337) / 106 = .122 ohms or 122 mohms

We can't use those values because the battery had about 30 seconds of charging which skews the voltage change. If the battery voltage
had been obtained, e.g. 330, before the QC current began, then using some of the data from above;

Example:
(337 - 330) / 60 = .117 ohms or 117 mohms

Thanks for what you obtained. Next time will do the trick.
 
lorenfb said:
Oils4AsphaultOnly said:
** this data gathered at the minute interval
V in Volts : I in amps : Time (SOC %) since charging started.
337 : 60 : 2s (11%)
350 : 106 : 30s

Not sure how you're going to get battery resistance from these numbers, especially since the charge session seems to be current-limited.

Edit: The day was ~63 degrees F ambient, but I don't know what the actual battery temp was. Leaf Spy reported the same 63.7 F after the battery temp gauge had gone up from 5 bars to 7 bars. So I don't trust its temp reading.

The key data for calculation of battery resistance needs to be gathered at the immediate start of the charging session.

Example:

1. Obtain the battery voltage before the QC session starts from LeafSpy or at the moment the QC voltage number appears from the charger
before the current begins;
example - 337 volts
2. The battery voltage and QC current the moment the actual charging current begins;
example - 350 volts, 106 amps
3. Calculate the resistance;
(350 - 337) / 106 = .122 ohms or 122 mohms

We can't use those values because the battery had about 30 seconds of charging which skews the voltage change. If the battery voltage
had been obtained, e.g. 330, before the QC current began, then using some of the data from above;

Example:
(337 - 330) / 60 = .117 ohms or 117 mohms

Ah! I did record it, but forgot to report it! V0 = 338.30V

And I didn't read my own scribbles correctly. That was a 339, not 337.

But even so, that first number (V1) wasn't exactly the very first number either. So either way, my data's junk.

Just found a new chademo station closer to where I live, so will try this again and hope to get better results.
 
Oils4AsphaultOnly said:
lorenfb said:
Oils4AsphaultOnly said:
** this data gathered at the minute interval
V in Volts : I in amps : Time (SOC %) since charging started.
337 : 60 : 2s (11%)
350 : 106 : 30s

Not sure how you're going to get battery resistance from these numbers, especially since the charge session seems to be current-limited.

Edit: The day was ~63 degrees F ambient, but I don't know what the actual battery temp was. Leaf Spy reported the same 63.7 F after the battery temp gauge had gone up from 5 bars to 7 bars. So I don't trust its temp reading.

The key data for calculation of battery resistance needs to be gathered at the immediate start of the charging session.

Example:

1. Obtain the battery voltage before the QC session starts from LeafSpy or at the moment the QC voltage number appears from the charger
before the current begins;
example - 337 volts
2. The battery voltage and QC current the moment the actual charging current begins;
example - 350 volts, 106 amps
3. Calculate the resistance;
(350 - 337) / 106 = .122 ohms or 122 mohms

We can't use those values because the battery had about 30 seconds of charging which skews the voltage change. If the battery voltage
had been obtained, e.g. 330, before the QC current began, then using some of the data from above;

Example:
(337 - 330) / 60 = .117 ohms or 117 mohms

Ah! I did record it, but forgot to report it! V0 = 338.30V

And I didn't read my own scribbles correctly. That was a 339, not 337.

But even so, that first number (V1) wasn't exactly the very first number either. So either way, my data's junk.

Just found a new chademo station closer to where I live, so will try this again and hope to get better results.

The most accurate method is to just use LeafSpy for all three data points; V0 - before the charge starts, V1 - the voltage when
the charging current begins, I1 - the peak charging current (probably 100 amps) at the start, all within a few seconds.
 
WetEV said:
arnis said:
Though we can be sure when that if it is 38*C outside, pack is higher than 38*C.

Oh? How do you know this?

I looked at my Leafspy logs for over the past 2 years, and filtered out the all of the measurements of 35C or more. The highest battery temperatures are 28C.

Continuing down, at 32C there are a few points of battery temperatures higher than ambient. They are the highest temperatures the battery has ever been, on a trip in multiple charges, both QCs and L2s. Peak temperature was 38.4C 08/10/2017 2nd longest day I've ever done. On a hot day, as well.

What I observe, and I'm clueless if this is just me or typical, is that the battery temperature is usually between the daily high and the daily low temperature in the summer. In the winter, the garage stays warmer than outside, and so does the battery.
You live in a mild climate (I lived in King County for about 9 years myself).

https://web.archive.org/web/20170717073322/http://www.mynissanleaf.com/viewtopic.php?t=22134 had his (presumably '13) battery up to 137 F or or 58.3 C.

My current Leaf has no CHAdeMO, but on hot summer days on weekends, I sometimes cannot avoid my battery reaching past 90 F (~32.2 C) without even charging.

if OAT is at 38 C and the pack has adapted to that temp, even L2 charging will raise it a few degrees.
 
cwerdna said:
WetEV said:
What I observe, and I'm clueless if this is just me or typical, is that the battery temperature is usually between the daily high and the daily low temperature in the summer. In the winter, the garage stays warmer than outside, and so does the battery.
You live in a mild climate (I lived in King County for about 9 years myself).

Which doesn't matter that much for the question at hand, the battery temperature is usually between the daily high and daily low in Summer. I suspect that this should be true for most people, unless they have a hot garage or other factors. Or perhaps with a low daily temperature range like we often have in winter the battery will be above the high temperature for the day. When the daily low is 2 C, the high is 3 C and the garage is at 5 C, a morning battery temperature of 8 C is easy to explain. Often drops a degree during the day, the reverse of the summertime pattern of warming during the day.

cwerdna said:
{knightmb} had his (presumably '13) battery up to 137 F or or 58.3 C.

Sure, with a 640 mile road trip. Well beyond the "should have taken the other car range".

cwerdna said:
My current Leaf has no CHAdeMO, but on hot summer days on weekends, I sometimes cannot avoid my battery reaching past 90 F (~32.2 C) without even charging.

What was the daily high temperature on those hot summer days?

cwerdna said:
if OAT is at 38 C and the pack has adapted to that temp, even L2 charging will raise it a few degrees.

Yes, but the pack doesn't adapt all that fast. Yes, L2 charging will raise it a few degrees. But that is, at least for me, usually in the cool of the morning.
 
lorenfb said:
The most accurate method is to just use LeafSpy for all three data points; V0 - before the charge starts, V1 - the voltage when
the charging current begins, I1 - the peak charging current (probably 100 amps) at the start, all within a few seconds.

Okay, I got good results this time:
V0 = 343.42
V1 = 345.94 @ 50A (t0 + 1s)
V2 = 350 @ 105A (t0 + 2s)

So ... (350 - 343) / 105 = 0.07

That sound about right? My battery's SOH is 90.18%

Edit: One observation. On Monday, with ambient temps at 63F, going from 11% SOC to 85% SOC over 25mins resulted in the battery temp bar going from 5-bars to 7-bars. Today, with ambient temps at 73F, going from 22% SOC to 93% SOC over 26mins resulted in the battery temp bar going from 5-bars to only 6-bars. I wish I had a working temp sensor to get the actual battery temperature!
 
Oils4AsphaultOnly said:
lorenfb said:
The most accurate method is to just use LeafSpy for all three data points; V0 - before the charge starts, V1 - the voltage when
the charging current begins, I1 - the peak charging current (probably 100 amps) at the start, all within a few seconds.

Okay, I got good results this time:
V0 = 343.42
V1 = 345.94 @ 50A (t0 + 1s)
V2 = 350 @ 105A (t0 + 2s)

So ... (350 - 343) / 105 = 0.07

That sound about right? My battery's SOH is 90.18%

Edit: One observation. On Monday, with ambient temps at 63F, going from 11% SOC to 85% SOC over 25mins resulted in the battery temp bar going from 5-bars to 7-bars. Today, with ambient temps at 73F, going from 22% SOC to 93% SOC over 26mins resulted in the battery temp bar going from 5-bars to only 6-bars. I wish I had a working temp sensor to get the actual battery temperature!

Good data. Thanks for gathering the data.

The resistance of .07 ohms (70 mohms) is basically the same, i.e. when comparing values at the same temps and not having controlled
tests, as what Dave's 2018 (40kWh) Leaf yielded and my 2013 (production 9/13). As I mentioned before, one would expect the battery
resistance to become lower as the battery capacity increased, i.e. more parallel cells with the same chemistry, but that has not occurred.
So with longer charging times, the later Leaf's will develop more internal heat, and retain that additional heat longer (assuming
the same battery thermal resistance).

Here're my 2013 Leaf data:


11/20/14 -13,700 miles, 76 mohms per LeafDD, 20 Deg, 73% SOC
11/27 -13,800 miles, 67 mohms per LeafDD, 25 deg, 63% SOC
11/30 - 13,900 miles, 56 mohms per LeafDD, 27 deg, 71% SOC
12/2 - 14.100 miles, 55 mohms per LeafDD, 28 deg, 67% SOC
12/16 - 14,500 miles, 89 mohms per LeafDD, 15 deg, 93% SOC
12/27/14 - 14,800 miles, 103 mohms per LeafDD, 11 deg, 24% SOC
3/10 - 17,400 miles, 60 mohms per LeafDD, 30 deg, 73% SOC
3/14 - 17, 550 miles, 56 mohms per LeafDD, 32 deg, 47% SOC
4/14 - 19,100 miles, 59 mohms per LeafDD, 25 deg. 38% SOC
5/4 - 19,989 miles, 64 mohms per LeafDD, 24 deg. 48% SOC
5/15 - 20,400 miles, 73 mohms per LeafDD, 20 deg. 41% SOC
5/22 - 20,700 miles, 58 mohms per LeafDD, 28 deg. 50% SOC
12/10/15 - 28,000 miles, 90 mohms per LeafDD, 19 deg. 92% SOC
4/5 - 32,000 miles, 74 mohms per LeafDD, 24 deg, 55% SOC
5/16 - 33,700 miles,89 mohms per LeafDD, 22 deg, 47% SOC
5/16 - 33.700 miles, 58 mohms per LeafDD, 31 deg, 76% SOC
10/5 - 39,300 miles, 100 mohms per LeafDD, 22 deg, 50% SOC
10/6 - 39,400 miles, 61 mohms per LeafDD, 30 deg, 51% SOC
10/7 - 39,500 miles, 80 mohms per LeafDD, 25 deg, 56% SOC
10/15 - 40,000 miles, 71 mohms per LeafDD, 27 deg, 45% SOC
10/30 - 41,000 miles, 74 mohms per LeafDD, 23 deg, 66% SOC
12/26/16 - 43,000 miles, 110 mohms per LeafDD, 13 deg, 77% SOC
6/10/17 - 49,600 miles, 89 mohms per LeafDD, 19 deg, 70% SOC
 
lorenfb said:
So with longer charging times, the later Leaf's will develop more internal heat, and retain that additional heat longer (assuming
the same battery thermal resistance).

I don't follow you. Slower charging means less current. Power loss is I^2 * R. Resistance is basically the same, currect? Twice as long of charging time at half the current means one quarter the power loss and twice the time, for a net of half the heating.
 
Yeah, I don't see this either. I also don't see how the battery will retain heat any differently than the current battery if the thermal resistance and capacitance are the same. Truthfully, given the greater capacity, the new battery should perform better from a heat generation standpoint given equivalent loads.
 
WetEV said:
lorenfb said:
So with longer charging times, the later Leaf's will develop more internal heat, and retain that additional heat longer (assuming
the same battery thermal resistance).

I don't follow you. Slower charging means less current. Power loss is I^2 * R. Resistance is basically the same, currect? Twice as long of charging time at half the current means one quarter the power loss and twice the time, for a net of half the heating.

I think you're mixing a few things together from lorenfb's statement.

The internal resistance is essentially the same, therefore, the cells in the larger battery pack are probably arranged with the same number of series and parallel cells. Since the resistance is the same, and the charging current is the same, then it will simply take longer to charge the larger batteries versus the 24kwh battery. Longer charge-time would mean more internal heat generated.
 
Joe6pack said:
Yeah, I don't see this either. I also don't see how the battery will retain heat any differently than the current battery if the thermal resistance and capacitance are the same. Truthfully, given the greater capacity, the new battery should perform better from a heat generation standpoint given equivalent loads.

The 24kwh battery only accepts the full charge rate (~45kw I think?) for a limited time (until 80%?), after that tapering begins.

The 30kwh battery (and likewise the 40kwh) can accept the full charge rate for a longer period of time. So the loads (and power delivery) are NOT equivalent.
 
That's a big maybe. At some point you hit steady-state where any additional heat generated above some temperature is equivalent to the heat dissipated for a given charge rate - otherwise, thermal runaway. Also, we don't know how temperature affects resistance. It could be that resistance decreases or increases with temperature.

Overall, given the lower C-rate for an equivalent charge rate, the new battery should perform better thermally assuming equivalent mass, thermal capacitance and thermal resistance. Given the lengths Nissan has gone to (and caught all kinds of grief for), I don't see how the new battery will perform worse from a heat generation standpoint when compared to the previous smaller batteries.
 
WetEV said:
lorenfb said:
So with longer charging times, the later Leaf's will develop more internal heat, and retain that additional heat longer (assuming
the same battery thermal resistance).

I don't follow you. Slower charging means less current. Power loss is I^2 * R. Resistance is basically the same, currect? Twice as long of charging time at half the current means one quarter the power loss and twice the time, for a net of half the heating.
I'll guess he meant that a longer range car will charge for a longer time per session. This depends on specific use obviously.

This resistance data makes me more confident in my assertion that the battery has heat dissipation problems worse than my 24 kWh pack and readily apparent as summer approaches.
 
SageBrush said:
This resistance data makes me more confident in my assertion that the battery has heat dissipation problems and those are going to be readily apparent in the summer.

Good point.

Joe6pack said:
Also, we don't know how temperature affects resistance. It could be that resistance decreases or increases with temperature.

Actually, if you review data taken from my 2013 (24kWh) and Dave's 2018 (40kWh) Leafs, you'll find that the battery resistance has
a negative temperature coefficient (resistance decreases with temp), about - 4/6 mohms/C. It's non-linear, i.e. the change becomes
less as the temp increases.

What is still unknown, though, for the various Leafs is the thermal resistance (heat conductance) of the various batteries. Has the thermal
resistance of the cells increased as the battery capacities increased, resulting in potentially longer heat-soaking of the battery cells?
The QC tapering being used in the 40kWh Leaf obviously indicates potential thermal problems, e.g. battery heat accumulation with
successive QCs.
 
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