Capacity Loss on 2011-2012 LEAFs

[opencar]

What were your battery app readings (AHr, CAP%, Health, GIDs) when you lost your bar?

Honestly, I wasn't watching it that closely, but last time I checked 2 weeks ago I was just a hair over 85%. That was yesterday, and today they are:
Ahr: 55.73
CAP%: 84.12%
HEALTH: 81.13%
GIDS: 196 (69.8%)
All cells are actually rather tightly grouped, with only 17mv differential.

I did a 100% charge for the first time today since losing a bar:
AHr: 55.43
CAP%: 83.65%
HEALTH: 80.52%
GIDS: 226 (80.4%)

was there a consensus about the AHr for 1st bar loss? i'm at 55.86 and in the middle of the San Diego heat week. now at 26 months, 23K mi, should be soon.

 

[DaveEV]

was there a consensus about the AHr for 1st bar loss? i'm at 55.86 and in the middle of the San Diego heat week. now at 26 months, 23K mi, should be soon.

Seems to be between 55.25 and 55.75 Ah - there doesn't seem to be an exact number.

Currently at 55.75 Ah, but was as low as 55.64 Ah a few days ago.
GIDs at 80% are 196, GIDs at 100% are 234 (cut it off before it completely finished, may have had another GID or two left).

 

[opencar]

was there a consensus about the AHr for 1st bar loss? i'm at 55.86 and in the middle of the San Diego heat week. now at 26 months, 23K mi, should be soon.

Seems to be between 55.25 and 55.75 Ah - there doesn't seem to be an exact number.

Currently at 55.75 Ah, but was as low as 55.64 Ah a few days ago.
GIDs at 80% are 196, GIDs at 100% are 234 (cut it off before it completely finished, may have had another GID or two left).

thanks for the comparison Drees; i'm at 55.4 Ahr now still w/ 12 bars. I'm thinking the San Diego heat this week will push me into the lower 55's. My LEAFs a daily driver so no way i'm getting the battery below 80 degrees this week.

 

[DaveEV]

was there a consensus about the AHr for 1st bar loss? i'm at 55.86 and in the middle of the San Diego heat week. now at 26 months, 23K mi, should be soon.

Seems to be between 55.25 and 55.75 Ah - there doesn't seem to be an exact number.

Currently at 55.75 Ah, but was as low as 55.64 Ah a few days ago.
GIDs at 80% are 196, GIDs at 100% are 234 (cut it off before it completely finished, may have had another GID or two left).

thanks for the comparison Drees; i'm at 55.4 Ahr now still w/ 12 bars. I'm thinking the San Diego heat this week will push me into the lower 55's. My LEAFs a daily driver so no way i'm getting the battery below 80 degrees this week.

It's physically impossible when my garage won't get below 80F. Garage has been between low-upper 80F range the last 4 days or so. Battery temps have been getting to the low 90s, so still not too bad, but the warm nights are keeping the battery from cooling down at all.

 

[edatoakrun]

was there a consensus about the AHr for 1st bar loss? i'm at 55.86 and in the middle of the San Diego heat week. now at 26 months, 23K mi, should be soon.

Seems to be between 55.25 and 55.75 Ah - there doesn't seem to be an exact number.

Currently at 55.75 Ah, but was as low as 55.64 Ah a few days ago.
GIDs at 80% are 196, GIDs at 100% are 234 (cut it off before it completely finished, may have had another GID or two left).

thanks for the comparison Drees; i'm at 55.4 Ahr now still w/ 12 bars. I'm thinking the San Diego heat this week will push me into the lower 55's. My LEAFs a daily driver so no way i'm getting the battery below 80 degrees this week.

My LEAF lost its twelfth Capacity bar on 8/22/13, the morning after a DC which heated my battery to the 103.0-109.1 range, the first 7 temperature-bar-dash display since the Summer of 2011.

After the DC to 196 gids, I had 55.50 AHr, and 12 bars. During the next ~50 miles driving, AHr dropped to 55.49.

The next morning, with ~20,708 miles, and after L1 charging to 235 gids (100%") overnight, and with battery temps 82.8-89.6, I still had 55.49 AHr, but only 11 capacity bars.

Subsequently the AHr increased back to a maximum of 56.17 AHr on 8/24-8/25, coinciding with lower ambient and battery temperatures (despite having used three more DC charges) during my 5 day, ~730 mile Bay Area trip.

At 21,381 miles last night, after a week of higher ambient/battery temperatures, AHr have declined slightly, back to 55.92.

All temperatures, gids, and AHr, and gids above are App-reported.

My LEAF never got its twelfth capacity bar back (didn't one or two report that happening last fall?) But one of you folks on the cusp of bar loss might want to try a fast charge to heat up your battery to see if that induces bar loss, and to see if you could see what level of reported AHr incrase (which may occur due to decreasing seasonal ambient temperatures) would cause the twelfth bar to reappear at a later date.

 

[dgpcolorado]

It's physically impossible when my garage won't get below 80F. Garage has been between low-upper 80F range the last 4 days or so. Battery temps have been getting to the low 90s, so still not too bad, but the warm nights are keeping the battery from cooling down at all.

Would it be cooler if you parked outside? Aren't you in Encinitas? I thought it got reasonably cool there near the coast at night. (It has been three decades since I've lived in SD so perhaps it is has warmed up since then.)

 

[DaveEV]

It's physically impossible when my garage won't get below 80F. Garage has been between low-upper 80F range the last 4 days or so. Battery temps have been getting to the low 90s, so still not too bad, but the warm nights are keeping the battery from cooling down at all.

Would it be cooler if you parked outside? Aren't you in Encinitas? I thought it got reasonably cool there near the coast at night. (It has been three decades since I've lived in SD so perhaps it is has warmed up since then.)

The overnight low has barely gotten under 70F if at all the last couple nights, but the bigger issue is that the plug won't reach the car in the driveway - need another 3-4 ft at least - or perhaps use my EVSE upgrade.

Besides, the last time I tried parking outside it didn't seem to make a big difference in battery temps by morning - certainly less than the 10F difference in garage vs outside low might seem to indicate. Maybe I should try again and record better data.

 

[opencar]

It's physically impossible when my garage won't get below 80F. Garage has been between low-upper 80F range the last 4 days or so. Battery temps have been getting to the low 90s, so still not too bad, but the warm nights are keeping the battery from cooling down at all.

Would it be cooler if you parked outside? Aren't you in Encinitas? I thought it got reasonably cool there near the coast at night. (It has been three decades since I've lived in SD so perhaps it is has warmed up since then.)

The overnight low has barely gotten under 70F if at all the last couple nights, but the bigger issue is that the plug won't reach the car in the driveway - need another 3-4 ft at least - or perhaps use my EVSE upgrade.

Besides, the last time I tried parking outside it didn't seem to make a big difference in battery temps by morning - certainly less than the 10F difference in garage vs outside low might seem to indicate. Maybe I should try again and record better data.

I can't remember who did the background work, but i verified that the thermal mass of the battery has characteristics of about 1 deg/hr cool down at rest and 2 deg/hr heat up during charging even assuming a big thermal gradient between ambient and battery temps. thus if you are a daily driver in the San Diego summer,you'll be hard pressed to ever cool the battery down to ambient no matter if you park outside at night.

 

[ColumbiaRiverGorge]

was there a consensus about the AHr for 1st bar loss? i'm at 55.86 and in the middle of the San Diego heat week. now at 26 months, 23K mi, should be soon.

Seems to be between 55.25 and 55.75 Ah - there doesn't seem to be an exact number.

Currently at 55.75 Ah, but was as low as 55.64 Ah a few days ago.
GIDs at 80% are 196, GIDs at 100% are 234 (cut it off before it completely finished, may have had another GID or two left).

I am currently at 55.15 Ah (83.24%) and Hlth 69.24%. I keep thinking any day now I will lose my first bar. Charging to 80% has given me nine bars for the last five weeks. I have been able to get my battery temps. down to 65-75 degrees every night, even if I hit 100 degrees in the day Quick Charging. I park it outside and use two ground fans that blow air all night under the car. For the last fourteen months I have been using these fans, whether the LEAF is in the garage or not.

 

[dgpcolorado]

I can't remember who did the background work, but i verified that the thermal mass of the battery has characteristics of about 1 deg/hr cool down at rest and 2 deg/hr heat up during charging even assuming a big thermal gradient between ambient and battery temps. thus if you are a daily driver in the San Diego summer,you'll be hard pressed to ever cool the battery down to ambient no matter if you park outside at night.

I wouldn't expect to get down to ambient, especially for a car that is charging or being driven regularly. But even 2-4ºF lower over an extended period might slow degradation a bit. However, a 10ºF difference between inside and outside might not lower the battery temperature enough to be worth the trouble. A 20ºF difference lowers the battery temperature quite a bit IME. Wind helps too, no surprise.

The overnight low has barely gotten under 70F if at all the last couple nights, but the bigger issue is that the plug won't reach the car in the driveway - need another 3-4 ft at least - or perhaps use my EVSE upgrade...

I guess I am glad I mounted my EVSE upgrade near the garage door. It reaches the back of the garage or outside easily. Just luck: my electrical panel was there so I put the outlet next to it to make the installation easier.

 

[opencar]

was there a consensus about the AHr for 1st bar loss? i'm at 55.86 and in the middle of the San Diego heat week. now at 26 months, 23K mi, should be soon.

Seems to be between 55.25 and 55.75 Ah - there doesn't seem to be an exact number.

Currently at 55.75 Ah, but was as low as 55.64 Ah a few days ago.
GIDs at 80% are 196, GIDs at 100% are 234 (cut it off before it completely finished, may have had another GID or two left).

I am currently at 55.15 Ah (83.24%) and Hlth 69.24%. I keep thinking any day now I will lose my first bar. Charging to 80% has given me nine bars for the last five weeks. I have been able to get my battery temps. down to 65-75 degrees every night, even if I hit 100 degrees in the day Quick Charging. I park it outside and use two ground fans that blow air all night under the car. For the last fourteen months I have been using these fans, whether the LEAF is in the garage or not.

hmmm, i thought there was a pretty narrow range for Ah tied to bar loss. your car + drees info seem to indicate the range is at least 55.1 to 55.8 and probably more....so much for predicting timing.

 

[TimLee]

Why is battery capacity in A-hr? I understand that the battery fully charged voltage is around 393 V and you can convert it to kW-hr, actual energy storage, but why not just have it in kWh storage to start with?

 

[surfingslovak]

Why is battery capacity in A-hr? I understand that the battery fully charged voltage is around 393 V and you can convert it to kW-hr, actual energy storage, but why not just have it in kWh storage to start with?

The Ah value comes straight from the CAN bus, and is worth displaying. Everything else, aside from GIDs is interpretative, which is fine, but until the community has better grasp of how to put this puzzle together, it makes sense to expose some of the raw values. Also, the Ah should not be multiplied with the top voltage measured on a full charge. This is inaccurate and misleading. There is a nominal voltage for this purpose, which is around 360V.

 

[TimLee]

Also, the Ah should not be multiplied with the top voltage measured on a full charge. This is inaccurate and misleading. There is a nominal voltage for this purpose, which is around 360VWh storage to start with?

What is the A-hr value for a brand new just manufactured LEAF battery? Is it 66.7 A-hr, which at a nominal 360 volts would be the design capacity of 24 kWh, although only around 21.5 kWh is usable?

 

[surfingslovak]

Also, the Ah should not be multiplied with the top voltage measured on a full charge. This is inaccurate and misleading. There is a nominal voltage for this purpose, which is around 360VWh storage to start with?

What is the A-hr value for a brand new just manufactured LEAF battery? Is it 66.7 A-hr, which at a nominal 360 volts would be the design capacity of 24 kWh, although only around 21.5 kWh is usable?

Yes, the spec sheet says 66.6 Ah, if memory serves, and when multiplied with the nominal voltage (also from the spec sheet), we indeed get the rated capacity of about 24 kWh. This is the basis of the formula Jim used for simulated GIDs before he figured out how to read the real thing off the CAN bus. The inaccuracy observed with simulated GIDs was likely due to the SOC not being the real thing, but an adjusted or compensated value. Still, the fact the we were able to compute GIDs from other data with reasonable level of accuracy shows that our understanding how all these values relate to each other is improving. This would not have been possible just a year ago. I think everyone involved deserves big kudos for their work.

About usable capacity: Nissan measures stored energy via GIDs, which are then adjusted based on the open-circuit battery pack voltage. It's difficult to predict battery losses accurately, and the 21.x kWh figure you mentioned includes those as well. That's why usable battery capacity can fluactuate a bit day-to-day. It depends on how fast you drive, and some other factors, especially the pack temperature. Additionally, what's left in the pack after turtle mode to protect it from bricking needs to substracted from the stored energy total as well, when figuring what's available to the driver.

Since the battery is not charged to its full potential, which occurs at about 4.17V cell voltage, the total stored energy is only about 22.5 kWh (281 GID x 0.080 kWh/GID). Since the LEAF never charges the battery to its full rated capacity, the maximum SOC on a full charge is about 94%. The rest follows from there.

 

[opencar]

was there a consensus about the AHr for 1st bar loss? i'm at 55.86 and in the middle of the San Diego heat week. now at 26 months, 23K mi, should be soon.

Seems to be between 55.25 and 55.75 Ah - there doesn't seem to be an exact number.

Currently at 55.75 Ah, but was as low as 55.64 Ah a few days ago.
GIDs at 80% are 196, GIDs at 100% are 234 (cut it off before it completely finished, may have had another GID or two left).

I am currently at 55.15 Ah (83.24%) and Hlth 69.24%. I keep thinking any day now I will lose my first bar. Charging to 80% has given me nine bars for the last five weeks. I have been able to get my battery temps. down to 65-75 degrees every night, even if I hit 100 degrees in the day Quick Charging. I park it outside and use two ground fans that blow air all night under the car. For the last fourteen months I have been using these fans, whether the LEAF is in the garage or not.

as predicted, I lost the first bar at 55.29 Ahr. Does anyone have consensus data for Ahr reading that triggers loss of the 2nd bar? At 26 months, 23K mi, seems as tho i'm on my way to the warranty milestones.

 

[TickTock]

Lost my first bar for the third time this morning - almost 2 months after getting reset to 12 at the dealer on 7/10/2013 (was down three bars when it went in). 46.99 Ahr/71.6% SOH & 201 gids at 100% charge is the current state but none of these correspond to a 1 bar loser. My car's capacity bars have just not caught up yet.

One thing that can be taken away from this is the Ahr value is not directly tied to cap bars. It may be based on it and just highly filtered but you may not see consistent AHr values we read associated with bar loss.

 

[jhm614]

Lost my first bar for the third time this morning - almost 2 months after getting reset to 12 at the dealer on 7/10/2013 (was down three bars when it went in). 46.99 Ahr/71.6% SOH & 201 gids at 100% charge is the current state but none of these correspond to a 1 bar loser. My car's capacity bars have just not caught up yet.

One thing that can be taken away from this is the Ahr value is not directly tied to cap bars. It may be based on it and just highly filtered but you may not see consistent AHr values we read associated with bar loss.

It is disturbing to me that your dealer has reset your capacity bars (twice no less). Since the cap warranty is based on bars, it just feels wrong. (I understand that the first reset pre-dated the capacity warranty by several months.) Has anyone else's bars been reset?

For reference, here's my 4BL info from this a.m. AHr = 45.99 / 69.42%

 

[phxsmiley]

They didn't reset my Cap bars when I had the update done. We think it might be just this one dealer in the area. jhm614, you should be getting your replacement soon, I suspect. They left a message that the batteries are here in the West coast tomorrow.

My readings from this morning: 47.26AH, Health: 51.42%

 

[opencar]

Lost my first bar for the third time this morning - almost 2 months after getting reset to 12 at the dealer on 7/10/2013 (was down three bars when it went in). 46.99 Ahr/71.6% SOH & 201 gids at 100% charge is the current state but none of these correspond to a 1 bar loser. My car's capacity bars have just not caught up yet.

One thing that can be taken away from this is the Ahr value is not directly tied to cap bars. It may be based on it and just highly filtered but you may not see consistent AHr values we read associated with bar loss.

It is disturbing to me that your dealer has reset your capacity bars (twice no less). Since the cap warranty is based on bars, it just feels wrong. (I understand that the first reset pre-dated the capacity warranty by several months.) Has anyone else's bars been reset?

For reference, here's my 4BL info from this a.m. AHr = 45.99 / 69.42%

yea, that's first i've heard anyone getting a bar reset for the SW upgrade; doesn't sound right.