Capacity Loss on 2011-2012 LEAFs

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Leafer77,

There is definitely something not right here but the numbers argue against each other. My Leaf 4201 was manufactured less than a month after yours, I live very close to you just west of I15 and had the same Poway dealership replace my battery under warranty 3 weeks ago - you can follow that in the earlier posts.

My Leaf registered 3.8 kw/mile. Did I misinterpret that yours is 4.6?
Next my battery dropped the 4th bar at only 43,000 miles. I was averaging 11,300 miles per year. You averaged 16,000 miles per year, re-charged the car twice a day in the last year, whereas I only occasionally re-charged the car during the last 4 months before the replacement. I used a fast charger only 4 times.

I drove mostly highway speeds the same as you in our area, the same climate. The car was outside most of the day and garage kept at night. I very rarely accelerated past 65. I was "gentle" with it.

And yet you got 17,000 more miles out of your battery than I did before the 4th bar dropped!

The only significant difference might be that I am on the side of Black Mountain so 800 ft. elevation changes were common. I don't know what elevation changes you experienced in your daily commute but to get such longevity from the battery I am guessing it was relatively flat. Am I right?

The chief factor in re-chargeable battery desegregation is the number of charge/discharge cycles. You had far more of these cycles than I did so how could your battery have lasted so long without dropping the 4th bar?

One thing I can tell you is that Nissan's battery test is instantaneous and they informed me that the results could vary if another test was taken the same day. My detailed cell print outs showed some cells "healthier" than they were in the previous years report, but this is no excuse for the meter not dropping the 4th bar. Do you have copies of the previous cell health reports?
 
That is not true.
Click to expand...

Oh yes it is read this: http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

But this is not the main issue here. Can someone please tell me how 2 Leafs , manufactured at almost the same time, driven over the same time period in the same climate, with similar driving speeds and re-charging and one of them got 17,000 more miles out of their battery?

The article states that if the battery doesn't have memory it is better to do partial charging. This is the opposite of the what the dealership has told me numerous times, in fact they congratulated me for not "topping off" the charge and only recharging when it was low.

I had to charge my Leaf 100% for over 1 1/2 year to make up for capacity loss to maintain my normal use range and would be in the red almost daily. Maybe the answer is instead of charging once a day to 100% we all should be charging twice a day to 80% to extend the life of an older battery? Problem here is that the electric rates are high during the day but that doesn't matter if your employer is supply day time power. If not, charging twice a day will increase your electric bill. The last month with the old battery it was cheaper for me to drive our Civic!
 
electricfuture said:
But this is not the main issue here. Can someone please tell me how 2 Leafs , manufactured at almost the same time, driven over the same time period in the same climate, with similar driving speeds and re-charging and one of them got 17,000 more miles out of their battery?
Click to expand...

My bet is on Standard Deviation.
 
electricfuture said:
That is not true.
Click to expand...
Oh yes it is read this: http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
Click to expand...
You know the fact that it's written down somewhere doesn't necessarily make it true. You are obviously free to believe whatever you wish, but we have collectively amassed a pretty impressive data sample from a large number of privately owned LEAFs. This data speaks a pretty clear language, which has been distilled in the aging model Stoaty has been expertly managing.

electricfuture said:
But this is not the main issue here. Can someone please tell me how 2 Leafs , manufactured at almost the same time, driven over the same time period in the same climate, with similar driving speeds and re-charging and one of them got 17,000 more miles out of their battery?
Click to expand...
I'm not sure what you are referring to, but there are almost no two identical LEAFs. Microclimates, such as the temperature in your garage, its door exposure and where you park your LEAF during the day all matter too.

electricfuture said:
The article states that if the battery doesn't have memory it is better to do partial charging. This is the opposite of the what the dealership has told me numerous times, in fact they congratulated me for not "topping off" the charge and only recharging when it was low.
Click to expand...
Most dealers are utterly clueless in these matters. The best ones will parrot whatever they might have read somewhere.

electricfuture said:
I had to charge my Leaf 100% for over 1 1/2 year to make up for capacity loss to maintain my normal use range and would be in the red almost daily. Maybe the answer is instead of charging once a day to 100% we all should be charging twice a day to 80% to extend the life of an older battery?
Click to expand...
Welcome to the future. We had these debates back in the day, and the difference between 80% and 100% was immaterial at best. If you are open to it, I would heartily recommend this video, which Dave referenced on this forum a while ago. I think it surfaced on the Tesla forum originally.


[youtube]http://www.youtube.com/watch?v=pxP0Cu00sZs[/youtube]
 
OK ladies and germs, back to the topic at hand: capacity bar loss! We had a bit of a heat wave here in Dallas the last couple of days (hit 80 degrees) and I lost my 3rd bar around 33k miles and 47 AHrs; thought it was going to go as soon as it warmed up in March (like last year), but I got an early surprise. That maintains my trajectory for a 4th bar loss later this year, especially since the timers have been cancelled and now I'm charging to 100% every night as soon as I get home (it can bake in the garage overnight)!
 
This is a very serious conversation that could impact many leaf owners. Thanks surfingslovak, I watched the video and as you stated it is about the temperature and as I stated it is about the number of cycles. The Professor clearly stated that major performance improvement can be made using better chemistry (Tesla) or additives (Nissan's lizard battery). However this does not answer the question of a 17,000 mile difference, nor does "standard deviation" with a data point so far out in left field.

So for two identical battery packs used over the same time period in the same geographical area it is all about the temperature and the number of cycles. Leafer77 definitely recharged a lot more than myself, so cycling battery life advantage: electricfuture.

My location is on the ocean side of the mountain with ocean breezes naturally cooling the house needing air conditioning only 1-2 weeks per year and the same for heating. My usage was almost always to cooler areas going toward the coast, but I do not know which micro-climate Leafer77 drove in and parked during the day. But I can tell you that only 10 miles east of my location temperatures are routinely 5-10 degrees hotter. So it appears it appears the temperature advantage was probably mine as well.

So if anything my battery should have lasted longer than Leafer77, not the other 17,000 mile way around. Maybe my battery was defective?
 
electricfuture said:
Leafer77,

There is definitely something not right here but the numbers argue against each other. My Leaf 4201 was manufactured less than a month after yours, I live very close to you just west of I15 and had the same Poway dealership replace my battery under warranty 3 weeks ago - you can follow that in the earlier posts.

My Leaf registered 3.8 kw/mile. Did I misinterpret that yours is 4.6?
Next my battery dropped the 4th bar at only 43,000 miles. I was averaging 11,300 miles per year. You averaged 16,000 miles per year, re-charged the car twice a day in the last year, whereas I only occasionally re-charged the car during the last 4 months before the replacement. I used a fast charger only 4 times.

I drove mostly highway speeds the same as you in our area, the same climate. The car was outside most of the day and garage kept at night. I very rarely accelerated past 65. I was "gentle" with it.

And yet you got 17,000 more miles out of your battery than I did before the 4th bar dropped!

The only significant difference might be that I am on the side of Black Mountain so 800 ft. elevation changes were common. I don't know what elevation changes you experienced in your daily commute but to get such longevity from the battery I am guessing it was relatively flat. Am I right?

The chief factor in re-chargeable battery desegregation is the number of charge/discharge cycles. You had far more of these cycles than I did so how could your battery have lasted so long without dropping the 4th bar?

One thing I can tell you is that Nissan's battery test is instantaneous and they informed me that the results could vary if another test was taken the same day. My detailed cell print outs showed some cells "healthier" than they were in the previous years report, but this is no excuse for the meter not dropping the 4th bar. Do you have copies of the previous cell health reports?
Click to expand...

I cleaned up my data so that its easier to read:

Car Details:

Silver Nissan Leaf 2011
Date car purchased: 5/31/2011
Manufactured Date: 4/11
Garaged at home and sometimes uncovered at work.

Commute information:

Mostly highway driving 55mph - 65mph. (San Marcos to Kearny Mesa, or surface street driving in San Marcos. No significant elevation changes in my commute, besides what you normally see on Highway 15. Almost always using Eco Mode, which I still use.

Date first bar disappeared: 8/24/2012
Approximate Mile's when bar disappeared: 21,085
1 month of 100% charging via L2, thereafter 80% L2.
(5/31 - 2/1) Nightly charge, except weekends where it typically charged just once for the entire weekend.
(2/2 - Present) Charge twice a day 80% L2. Night and when I arrive to work.
4.5 KWH

Lost my second bar: 7/8/2013.
Approximate Mileage: 36,360
Still performing a L2 charge twice a day 80% L2. Night and when I arrive to work.
4.8 KWH

Lost my third bar: 6/13/2014.
Approximate Mileage: 52,109
Performing a L2 charge twice a day to %100. Once in at 1:10am and at work.
4.4 KWH

Lost my fourth bar around: 1/6/2015.
Approximate Mileage was around: 61,150
Performed an L2 charge twice a day to 100%. Once in at 1:10am and at work.
4.0 KWH

The Nissan Leaf Battery Test at the Escondido (not Poway) dealership, did not provide any great level of detail. I just saw that I passed with no issues. Maybe I should have went to the Poway dealership.

 
^^^Interesting data. Ignoring the 1st bar loss since it's twice the capacity of the subsequent bars, I see a significant difference when charging to 100% over the 80% charges.
2nd bar loss: 15,275 mi, ~11 months (2x 80% L2 charges)
3rd bar loss: 15,749 mi, ~11 months (2x 80% L2 charges)
4th bar loss: 9,041 mi, ~7 months (2x 100% L2 charges)

This has been mentioned by several others before. More battery degradation means more 100% charging to keep the vehicle useful, and thereby accelerating the battery decline even faster. :( That said, I still think it's best to drive these vehicles as much as possible. In the end, the batteries degrade (heat is a major factor, as is "spirited driving", quick charging, average battery %SOC, etc. Unfortunately, ultimately calendar time will get us all, including us low mileage users) :(
 
="surfingslovak"
...we have collectively amassed a pretty impressive data sample from a large number of privately owned LEAFs. This data speaks a pretty clear language, which has been distilled in the aging model Stoaty has been expertly managing...
Click to expand...
That "data sample" has little relevance, as unfortunately, there has in fact been very little effort by forum members to collect data on actual capacity loss, only of unverified LBC ("gid") estimates of capacity loss.

Even the largest sample of ineffective data can not answer a question.

Actual data on capacity loss from high-integrity sources is available, which IMO, indicates just how gullible you have to be, to believe the LBC ("gid") estimates, which Stoaty's aging model is designed to replicate.

DC Fast Charger Use, Fees, Battery
Impacts and Temperature Impacts
on Charge Rates - EV Roadmap

http://avt.inl.gov/pdf/prog_info/DCFCEVRoadmap7PortlandOregonJuly2014.pdf" onclick="window.open(this.href);return false;

DC Fast Charging Impact Study on 2012 Leafs
• Percentage Range and Capacity at 50,000 miles compared to testing
when new

<page 15>

L2 Average DCFC Average
Range 79.0% 69.3%
Capacity 75.2% 72.6%
Click to expand...

from:

INL L2 vs DC initial capacity test results after 50k mi+

http://www.mynissanleaf.com/viewtopic.php?f=27&t=14271&start=40" onclick="window.open(this.href);return false;

The only way you ever could have reconciled the LOWER rate of actual capacity loss over kWh throughput discussed on the thread above, of LEAF battery packs being treated to conditions of extremely high temperatures, and twice-daily "100%" to shutdown cycling, compared with LBC/"gid" estimates from LEAFs experiencing far lower battery temperatures, in a moderate California Climate, is if calendar aging over such a relatively short time, was in fact, a predominate factor in capacity loss.

And since my pack is now only a few months short of the oldest ones delivered, (and, BTW, has seen as many warm California Summers as any) I can report that the ~23% LBC ("gid") loss estimate on my LEAF (fairly typical for 33k+ miles) is now overstating actual average available capacity loss, between "100%" charge and turtle since delivery, as verified by both recharge capacity and range tests, by close to 100%.

And as the increase in low speed efficiency in the L2 test LEAFs above would imply, my LEAF's range loss from new (in my typically low speed driving) is considerably less than its capacity loss, and still only a single-digit percentage loss, since delivery.
 
According to LeafSpy my capacity loss is within 2% of the prediction model, slightly worse, so I think it does a pretty good job of estimating. The perceived range loss matches the capacity loss quite well too.
 
Leafer77,

Thanks for the additional information. I am west of you in a cooler climate. The only difference I see in your driving habits are your 55-65 speed range - very brave on I15! I do 65 in ECO mode. Also Kearney Mesa where you park could be pretty warm during the day - i.e. 80's in the summer.

You do not experience the elevation change I make daily, and possibly most importantly you do not have a passenger whereas I almost always do adding 125 lbs.

So other than defective battery components on my car, I am guessing that my battery's 17,000 mile shorter life is primarily due to elevation changes with an additional load. Climate appears to have had little effect in the comparison. If anything climate would have favored added longevity to my battery not yours.

So Gentlemen, if you are nearing 60,000 miles and the 4th bar has not yet dropped I suggest loading the car with sand bags (don't over load your shocks or storage lids though), driving it up and down hills, re-charging at a quick charge station to 80% and then take it home and top off the charge to 100%. Do this 10-12 times and I suspect you will see the bar drop. Of course if you can do this in either hot or cold weather even better!
 
electricfuture said:
Leafer77,

Thanks for the additional information. I am west of you in a cooler climate. The only difference I see in your driving habits are your 55-65 speed range - very brave on I15! I do 65 in ECO mode. Also Kearney Mesa where you park could be pretty warm during the day - i.e. 80's in the summer.

You do not experience the elevation change I make daily, and possibly most importantly you do not have a passenger whereas I almost always do adding 125 lbs.

So other than defective battery components on my car, I am guessing that my battery's 17,000 mile shorter life is primarily due to elevation changes with an additional load. Climate appears to have had little effect in the comparison. If anything climate would have favored added longevity to my battery not yours.

So Gentlemen, if you are nearing 60,000 miles and the 4th bar has not yet dropped I suggest loading the car with sand bags (don't over load your shocks or storage lids though), driving it up and down hills, re-charging at a quick charge station to 80% and then take it home and top off the charge to 100%. Do this 10-12 times and I suspect you will see the bar drop. Of course if you can do this in either hot or cold weather even better!
Click to expand...

Funny thing you mentioned a passenger. I had a carpool passager who weighed close to 210lbs for the first 20,000 miles until he bought his own Nissan Leaf 2011 SL.

He drives almost the exact identical route that I do. He's down three capacity bars, but is under 50,000 miles currently.
 
I think our battery (in our 2015 LEAF S) is heading for an early demise; here is some data after only about 600 miles:

12/28/2014, 215 miles, 1QCs+10L1s/L2s: 97.3% SOC = 292 GIDS

01/31/2015, 652 miles, 1QCs+24L1s/L2s: 97.3% SOC = 281 GIDS

I understand that degradation won't be linear, but this seems to be VERY different than what others are reporting.

Hmm.
 
Yeah, looks very similar to the infamous "early gid fold" pattern... Seriously, don't sweat it, after 14 charge cycles and 600 miles there's just not enough data to draw any conclusions. The controller is likely still learning about the pack.
 
Valdemar said:
Yeah, looks very similar to the infamous "early gid fold" pattern... Seriously, don't sweat it, after 14 charge cycles and 600 miles there's just not enough data to draw any conclusions. The controller is likely still learning about the pack.
Click to expand...

The only problem is that the number of GIDs has declined with every charge. If it was up and down a bit, I wouldn't worry about it, but I have at least 10 data points showing a consistently declining capacity.

However, I hope you are correct. :)
 

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