Capacity Loss on 2011-2012 LEAFs

[EdmondLeaf]

Steve,
Did you allowed time for cell balancing after charge finished, wonder if cell balancing is needed, because your car is so new and not many miles. Do 100 again, and I am waiting for your 80%. If your 100 won't change then I predict 220 for your 80%

 

[shay]

Here are my results after borrowing a SOC/GID meter; I also uploaded to "turbo2ltr" online spreadsheet and will cross-post in the "281" thread. In addition, I did a (timer off) over-night charge to allow for cell balancing with basically no change.

After 80% charge: 217 gids (77.2%)
After 100% charge: 261 gids (92.8%)

~8700 miles after 9 months
only charge to 100% about 5 times/month (rest of time 80% with 6am end-only timer)
never "top-off", never sits at 100% overnight
garaged night/weekends, outside during the day

How hot does your garage get if you park in the garage?

 

[EdmondLeaf]

All DFW cars with GID measured were/are parked outside (including summer heat), which IMPO may affect battery capacity. tzzhc4 have lowest GID (250 at 100%) and his car completed whole summer heat. Stanton (261 at 100%) his car was delivered in Sep. 11, so it was exposed to some heat but not same as tzzhc4. mkjayakumar (262 at 100%) car was purchased Feb. 12 but was on dealer lot from Sep. 11, he got it with 90 miles on the clock. Cheezmo just reported (265 at 100%), but in my understanding this is his first measurement so will probably change. Steve got his car in March 12, therefore was not exposed to summer heat. tzzhc4 is keeping his car in CC garage with temp around 80F.
Only thing I can say that cars in DFW have lower GID comparing to cars in SoCal https://lh4.googleusercontent.com/-...AAAAAAAUA/UmolUPY1l6Q/s1118/SoCal%20Leafs.png, but we still need more data points

1 report from Austin area mckemie (256 at 100%) if possible parked in the shade during summer days of 2011

 

[surfingslovak]

All DFW cars with GID measured were/are parked outside (including summer heat), which IMPO may affect battery capacity.

Please don't forget that Gid counts might decline temporarily when it's hot out. It may sound counter-intuitive, but there is some evidence of that. Additionally, the folks that lost a capacity bar in Phoenix were all down 20%, and if nothing else, there is a discrepancy between Gid count and capacity loss. There are not enough of these meters out there. Less than 50 cars have been measured, and even fewer than that measured on a consistent basis.

 

[LEAFfan]

LBW is at the 8.5% SOC point?

No, LBW is at 17.4% on the BCM or Gid meter. VLBW is at 8.5%. Turtle varies between 1.4% and 2.4% depending on speed.

 

[tbleakne]

Yesterday I went in for 1-year check-up. I requested a battery cell loss report. The service rep told me they called Nissan, Nissan checked my Vin number, (-2500), and they told him that some LEAFs, including mine, did not support the battery cell analysis. Has anyone else been told that ? My report card was all 5-stars.

Update on my capacity loss. With recent cooler over-night minimum temperatures, mild day-time temperature, I was hoping for some better scores, but I was disappointed to see a little further loss (some temps missing):

Date, Temp F, %goal, gids, gids%, voltage
5-26, 66, 100%, 270, 96.0, 394.0V
5-30, --, 80%, 225, 80.0, 387.5V
6-2, --, 80%, 223, 79.3, 387.5V
6-3, 67, 80%, 223, 79.3, 387.5V
6-4, 62, 80%, 222, 79.0, 388.0V
6-5, 65, 100%, 267, 95.0, 392.5V
6-6, 59, 80%, 223, 79.3, 388.0V

The lower 100% voltage on 6-5 indicates some cell imbalance, so perhaps the drop of 3 more gids from 5-26 100% charge is not all permanent.

On pg 43 of this thread Ticktock reports:

I took mine in 3 months ago and got them to run the cell pair test. Despite confirming the loss in capacity/range, all the cells came back in good shape (only 60mV difference between the highest and the lowest cell pair).

I claim 60mv actually is significant. Assume the 96 cell-pairs are uniformly distributed across this 60mv span from lowest to highest. The total loss in maximum pack voltage should be:
96*(60mv)/2 = 2.88V
My data indicates there is about 25 gids of capacity in the top 3 volts of total pack voltage, which is 2 kWhs. This is only the capacity loss due to the measured variation. All the cells, including the most healthy, have additional loss to account for your total loss.

If, instead, all the voltage deviation (highest voltage is weakest cell when fully charged) was concentrated in just a couple of cell pairs, I would think you would be on your way to having a case for partial cell replacement.

 

[Stanton]

Here are my results after borrowing a SOC/GID meter; I also uploaded to "turbo2ltr" online spreadsheet and will cross-post in the "281" thread. In addition, I did a (timer off) over-night charge to allow for cell balancing with basically no change.

After 80% charge: 217 gids (77.2%)
After 100% charge: 261 gids (92.8%)

~8700 miles after 9 months
only charge to 100% about 5 times/month (rest of time 80% with 6am end-only timer)
never "top-off", never sits at 100% overnight
garaged night/weekends, outside during the day

How hot does your garage get if you park in the garage?

I don't think it ever gets above 90F at night (I have a cheap thermometer on the wall).

 

[LEAFfan]

Please don't forget that Gid counts might decline temporarily when it's hot out. It may sound counter-intuitive, but there is some evidence of that. Additionally, the folks that lost a capacity bar in Phoenix were all down 20%, and if nothing else, there is a discrepancy between Gid count and capacity loss.

Sorry, but no evidence of that here. The % stays pretty consistent over the seasons, and I've had my BCM for quite some time.
You also need to stop exaggerating about the capacity losses here. There is only one driver that I'm aware of with a 20% capacity loss. The rest are at a 15% loss/11 bars. And if he is really at a 20% loss, then he is only 1% away from losing his second capacity bar. We will have to wait and see.

 

[mwalsh]

With recent cooler over-night minimum temperatures, mild day-time temperature, I was hoping for some better scores, but I was disappointed to see a little further loss (some temps missing):

My readings have been extremely consistent this week. Every morning thus far I've seen 92.1% and 259 Gids, even though I've had a touch of voltage fluctuation. I personally think the cooler mornings may have something to do with this. You can check my Google spreadsheet for more info:

https://docs.google.com/spreadsheet/ccc?key=0AnSYHt_rpvYydGlLZ3dOZ1dfTlFRS2JsTlo1V1ptVHc" onclick="window.open(this.href);return false;

This is the last week I'll be driving very carefully (65mph max) to see how I fare. Going back to whatever feels comfortable next week (between 65mph and 70+mph). I'll keep noting readings, but you can expect them to be lower at both the mid-point and end-point.

 

[leafkabob]

Please don't forget that Gid counts might decline temporarily when it's hot out. It may sound counter-intuitive, but there is some evidence of that. Additionally, the folks that lost a capacity bar in Phoenix were all down 20%, and if nothing else, there is a discrepancy between Gid count and capacity loss.

Sorry, but no evidence of that here. The % stays pretty consistent over the seasons, and I've had my BCM for quite some time.
You also need to stop exaggerating about the capacity losses here. There is only one driver that I'm aware of with a 20% capacity loss. The rest are at a 15% loss/11 bars. And if he is really at a 20% loss, then he is only 1% away from losing his second capacity bar. We will have to wait and see.

OK, my ears are burning so you must be talking about me.

My car read 81.1% on Leaffan's gauge. I dropped my 12th bar the next day. So either the 81.1 was not a true reading of my battery capacity, or the 12th bar doesn't drop at exactly 15% loss.

 

[surfingslovak]

Sorry, but no evidence of that here. The % stays pretty consistent over the seasons, and I've had my BCM for quite some time. You also need to stop exaggerating about the capacity losses here. There is only one driver that I'm aware of with a 20% capacity loss. The rest are at a 15% loss/11 bars. And if he is really at a 20% loss, then he is only 1% away from losing his second capacity bar. We will have to wait and see.

LEAFfan, I have noted three owners that reported Gid readings between 224 to 228 in recent weeks: TickTock, LEAFfan and Leafkabob. That's about 20% down from the full count (281). If you read my post carefully, you would see that we are in agreement. I just don't understand your capacity calculation method, and we will have to agree to disagree there. On that note, what has your Gid count (or ScanGauge percentage) done lately?

My car read 81.1% on Leaffan's gauge. I dropped my 12th bar the next day. So either the 81.1 was not a true reading of my battery capacity, or the 12th bar doesn't drop at exactly 15% loss.

Indeed! Thank you for confirming that again. For what it's worth, my percentage dropped 99% to 95% over the past two months without any apparent causality. The car was very consistent between December and April, and although it's warmer here now, it's 68F outside as of this writing. There was a change of drivers and charging patterns, but I don't think that it would have any effect in such a short period of time.

 

[EdmondLeaf]

Mike (mwalsh), May 29, when your GID was lowest (222) you still finished your trip with average number GID left (80), wonder if your speed was lower/efficiency higher, or just like every other day?

 

[mwalsh]

Mike (mwalsh), May 29, when your GID was lowest (222) you still finished your trip with average number GID left (80), wonder if your speed was lower/efficiency higher, or just like every other day?

Going to put that initial lower reading down to an anomaly. Like you said, I still finished with an average number. No difference at all in the way I drove.

 

[LEAFfan]

Please don't forget that Gid counts might decline temporarily when it's hot out. It may sound counter-intuitive, but there is some evidence of that. Additionally, the folks that lost a capacity bar in Phoenix were all down 20%, and if nothing else, there is a discrepancy between Gid count and capacity loss.

Sorry, but no evidence of that here. The % stays pretty consistent over the seasons, and I've had my BCM for quite some time.
You also need to stop exaggerating about the capacity losses here. There is only one driver that I'm aware of with a 20% capacity loss. The rest are at a 15% loss/11 bars. And if he is really at a 20% loss, then he is only 1% away from losing his second capacity bar. We will have to wait and see.

OK, my ears are burning so you must be talking about me.

My car read 81.1% on Leaffan's gauge. I dropped my 12th bar the next day. So either the 81.1 was not a true reading of my battery capacity, or the 12th bar doesn't drop at exactly 15% loss.

No, the only one that may be down 20% is TickTock's. When I told you that you were 13-14% down when it read 81% is correct. If I had based your 100% charge on 281/100%, then you would have had a reading of a 19% loss and would have already lost a bar. So I believe my method is pretty accurate by basing it on 94-95% instead of 100%. A QC to 80%/ten bars also gives a really accurate reading with my BCM.

 

[LEAFfan]

Sorry, but no evidence of that here. The % stays pretty consistent over the seasons, and I've had my BCM for quite some time. You also need to stop exaggerating about the capacity losses here. There is only one driver that I'm aware of with a 20% capacity loss. The rest are at a 15% loss/11 bars. And if he is really at a 20% loss, then he is only 1% away from losing his second capacity bar. We will have to wait and see.

LEAFfan, I have noted three owners that reported Gid readings between 224 to 228 in recent weeks: TickTock, LEAFfan and Leafkabob. That's about 20% down from the full count (281). If you read my post carefully, you would see that we are in agreement. I just don't understand your capacity calculation method, and we will have to agree to disagree there. On that note, what has your Gid count (or ScanGauge percentage) done lately?

When you say "20% down", are you saying the BC has lost 20%? Because that's just not true. If that were the case, they would lose another capacity bar in just 1% more. The most my capacity is down is around 9% based on an 80% QC of 71%. When the car was fairly new, I remember getting 79% on a QC and sometimes 80%. With L2, I could get 82%.
My BC hasn't changed since the last check a few days ago. It's still around 9% loss. It's nowhere near 20% and only TickTock's may be at a 20% BC loss, but I don't know what per cent he's getting after an 80 or 100% L2 charge. Like I said before, IF he's at a 20% capacity loss, he will lose another bar shortly. Leafkabob just lost a bar so I doubt if he's that close to losing another one either. Remember, his reading was 81% after a 100% charge with L2. Mine was 86% after a 100% L2 charge.
I hope this makes things clearer, or is it still as clear as mud?

 

[TickTock]

I am getting 65% (183/281) on an 80% charge and my last 100% charge was 80% (224/281). Still 11 capacity bars.

 

[LEAFfan]

I am getting 65% (183/281) on an 80% charge and my last 100% charge was 80% (224/281). Still 11 capacity bars.

Thanks! That means you aren't really at a 20% capacity loss, but still at 15%. I don't know why my method (for a 100% charge) works with my BCM, but it does and it's very accurate. I base the 80% reading on 80% and the 100% charge reading on 95%. So with both of your readings, I predict you are at a 15% capacity loss right now. Please keep us posted as it gets hotter.

 

[RegGuheert]

I am getting 65% (183/281) on an 80% charge and my last 100% charge was 80% (224/281). Still 11 capacity bars.

I believe that 1 GID is 0.33333% of the NEW capacity of your battery such that a charge to 300 GIDs when new would equal a 100% charge. Also, at 80 Wh/GID, 300 GIDs equals 24 kWh. As Ingineer has told us, the 100% setting is really 93.6% of the total. That is why a new LEAF has 281 GIDs with a 100% charge.

Based on this belief, I would say TickTock's 80% charge ending at 183 means that he has 61% of his toal new battery capacity when he charges to 80%. When he charges to 100% (93.6%) he has 74.6% of new capacity. Both numbers are approximately 19% lower than what would be expected from a NEW LEAF battery.

ETA: This makes a little more sense if you figure an 80% charge is 232 GIDs. That equals 77.3% of full, not 80%. Now the ratios for TickTock's readings are correct: 61/77.3=74.6/93.6=79%

ETA2: If that 79% number is correct, he is close to the second bar, which is at 78.75% IIRC.

 

[LEAFfan]

Based on this belief, I would say TickTock's 80% charge ending at 183 means that he has 61% of his toal new battery capacity when he charges to 80%. When he charges to 100% (93.6%) he has 74.6% of new capacity. Both numbers are approximately 19% lower than what would be expected from a NEW LEAF battery.
ETA: This makes a little more sense if you figure an 80% charge is 232 GIDs. That equals 77.3% of full, not 80%. Now the ratios for TickTock's readings are correct: 61/77.3=74.6/93.6=79%

But that's not what I was saying. I realize you can get there with the 'math', but it doesn't tell you the actual BC unless you do all the figuring. With my BCM, I can read the loss in seconds. Telling someone that they are 19-20% lower than when new means nothing unless they do the math to figure out the 'real' capacity loss %. Remember, I'm not measuring SoC, but BC. So when I say no one here has lost 20% BC, I'm correct. And since my BCM is based on the raw number 281, I don't need Gids to know my BC. Some people are just too quick to judge before they get all the facts.

 

[RegGuheert]

But that's not what I was saying.

Understood.

I'm proposing a new model for what a GID really means. I mentioned this idea the other day and I'm developing it a little further. I think it fits the data pretty well, but we shall see. I realize TickTock just recently dropped his first bar, but perhaps there is a 20-day running average or something that delays the disappearance of a bar.