2016-2017 model year 30 kWh bar losers and capacity losses

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joeriv said:
That's a wonderful chart - put's everything I read about battery health in one place - what is the source?
Click to expand...

now THAT is a toughie. I collected it from Facebook? a few years back.

If you need a chuckle, use Google picture search. the results are comical
 
borugee said:
If you need 40% of battery for your daily commute what is your choice?
1. Charge to 100% daily (Battery will operate at 60%-100% - BMS is happy, LeafSpy Happy, Your SOH most likely show good numbers, battery is balanced with every charge.). This is also easy to achive, and more flexibility during the day as we have a fully charged battery.
2. Change to 70% using timers ; Operate between 30%-70% (You get 40% of capacity for your commute). BMS not happy, Battery not balanced, LeafSpy numbers will drop. And pray for battery longevity!! (This also use less energy from grid, as no use of balancing energy).
Click to expand...
This is really excellent food for thought - or fodder for discussion ;) . I tend to operate my vehicle in the 100% to 40% area. Makes good use of the capabilities of the vehicle. I have some extra range if I need it. And I have gotten good battery longevity. Now to operate in the 70% to 30% scenario is an alternative strategy that is being advocated by a number of owners on this site. That substantially reduces the capability of your vehicle, and you may not be doing the battery pack any favors. So?
 
Leafchacho said:
Sadly I am adding mine to the list. Lost my first bar on 10/13/2017... Friday the 13th . About right, I guess.

2016 SV
Mfg 1/16
Original Purchase 11/16 (50 miles on odo)

On 10/16/17 Leafspy Pro reported.

AHr = 64.77
SOH = 81%
395.19V
Hx = 79.38
odo = 6,765
1 QC, 165 L1/L2

296 GIDs - 81.1%
SOC 97.8%
22.9 kWh Ramain

It has been dropping like a rock. When I purchased it used on 8/17/17 it was reading.

Ahr = 69.91
SOH = 87%
HX = 84.52
odo = 4,488
Click to expand...
Can you update your location info via your user name in the upper right > User Control Panel > Profile tab? That way, we don't need to ask in future posts/threads or do sleuthing to deduce it. Right now, I don't think I know where your Leaf resides.
 
Dooglas said:
borugee said:
If you need 40% of battery for your daily commute what is your choice?
1. Charge to 100% daily (Battery will operate at 60%-100% - BMS is happy, LeafSpy Happy, Your SOH most likely show good numbers, battery is balanced with every charge.). This is also easy to achive, and more flexibility during the day as we have a fully charged battery.
2. Change to 70% using timers ; Operate between 30%-70% (You get 40% of capacity for your commute). BMS not happy, Battery not balanced, LeafSpy numbers will drop. And pray for battery longevity!! (This also use less energy from grid, as no use of balancing energy).
Click to expand...
This is really excellent food for thought - or fodder for discussion ;) . I tend to operate my vehicle in the 100% to 40% area. Makes good use of the capabilities of the vehicle. I have some extra range if I need it. And I have gotten good battery longevity. Now to operate in the 70% to 30% scenario is an alternative strategy that is being advocated by a number of owners on this site. That substantially reduces the capability of your vehicle, and you may not be doing the battery pack any favors. So?
Click to expand...

Great advice but there are key points you need to understand.

SOC related degradation has two different components, low and high. The high is VERY dependent on temperature and high soc should be as minimized as possible in warmer temps and by warmer, I don't mean very warm. Like anything over 70º

The other thing to avoid is low SOCs for any period of time in any temperatures. If you are getting home with Batttery warnings active, you need to increase your morning SOC if you do not charge at work.

The other thing to realize is the reduced range in Winter. My guideline? If your trip is more than 40 miles roundtrip, charge to 100% (adjust for your situation and level of degradation)

The ideal goal is to finish your overnight charge less than a few hours before leaving in the morning and getting home with at least 20% SOC if you are on TOU. The reality is even if on TOU, you should ALWAYS plug in ASAP if LBW is on even if just for an hour. Trust me, the extra $1.25 you pay for that charge is a bargain compared to getting another battery or increasing your public charging usage at an EVgo station!
 
Dave, please reference the study that shows that time spent at "low" SOC is detrimental to lithium ion battery capacity life. The only one I've seen suggests that the lower the SOC, the better.
 
I've seen plenty of studies that reference degradation due to low SoC (high DoD) during use; li-ion isn't NiMH. Battery University has a summary: http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

Similar to a mechanical device that wears out faster with heavy use, the depth of discharge (DoD) determines the cycle count of the battery. The smaller the discharge (low DoD), the longer the battery will last. If at all possible, avoid full discharges and charge the battery more often between uses. Partial discharge on Li-ion is fine. There is no memory and the battery does not need periodic full discharge cycles to prolong life. The exception may be a periodic calibration of the fuel gauge on a smart battery or intelligent device. (See BU-603: How to Calibrate a “Smart” Battery)

The following tables indicate stress related capacity losses on cobalt-based lithium-ion. The voltages of lithium iron phosphate and lithium titanate are lower and do not apply to the voltage references given.

Note: Tables 2, 3 and 4 indicate general aging trends of common cobalt-based Li-ion batteries on depth-of-discharge, temperature and charge levels, Table 6 further looks at capacity loss when operating within given and discharge bandwidths. The tables do not address ultra-fast charging and high load discharges that will shorten battery life. Not all batteries behave the same.

Table 2 estimates the number of discharge/charge cycles Li-ion can deliver at various DoD levels before the battery capacity drops to 70 percent. DoD constitutes a full charge followed by a discharge to the indicated state-of-charge (SoC) level in the table.

Depth of discharge

Discharge cycles
(NMC / LiPO4)

Table 2: Cycle life as a function of
depth of discharge. A partial discharge reduces stress and prolongs battery life, so does a partial charge. Elevated temperature and high currents also affect cycle life.

Note: 100% DoD is a full cycle; 10% is very brief. Cycling in mid-state-of-charge would have best longevity.

100% DoD ~300 / 600
80% DoD ~400 / 900
60% DoD ~600 / 1,500
40% DoD ~1,500 / 3,000
20% DoD ~1,500 / 9,000
10% DoD ~10,000 / 15,000

Lithium-ion suffers from stress when exposed to heat, so does keeping a cell at a high charge voltage. A battery dwelling above 30°C (86°F) is considered elevated temperature and for most Li-ion a voltage above 4.10V/cell is deemed as high voltage. Exposing the battery to high temperature and dwelling in a full state-of-charge for an extended time can be more stressful than cycling. Table 3 demonstrates capacity loss as a function of temperature and SoC. . . .
Click to expand...

For long term storage (9-10 months in the case of the study below) the situation seems less clear, and dependent on specific Li-ion chemistry. This study from 2016 compares NCA, NMC and LFP at various temps, and SoCs from 0 to 100%:
Calendar Aging of Lithium-Ion Batteries
Click to expand...
http://jes.ecsdl.org/content/163/9/A1872/F2.expansion.html

General aging behavior.—For the three types of lithium-ion cells
examined, Figures 2a–2c show the capacity fade after a storage period
of 9–10 months. As expected, they all exhibit an increased calendar aging
with higher storage temperature. However, no steadily increasing
degradation with SoC is observed. Instead, there are plateau regions,
covering SoC intervals of more than 20%–30% of the cell capacity,
in which the capacity fade is similar. A marked step in the capacity
curves is observed at about 60% SoC for the NCA and NMC cells
and above 70% SoC for the LFP cells. For the observed relationships
between storage SoC and capacity fade, no simple linear, polynomial,
or exponential approximations are possible without considerable deviation
in certain SoC regions. Hence, the measurement of calendar aging for only
three SoCs, as is the case in most publications, is not sufficient to precisely
describe calendar aging with respect to the SoC when the qualitative
characteristics over the entire SoC range are not known. . . .
Click to expand...
There seems to be little difference between storage at 0% and 30% SoC for most of the chemistries.

FWIW, Jeff Dahn recently recommended keeping the battery between 30-70% when possible, but charging to 100% for trips as needed. See the tmc thread on that: https://teslamotorsclub.com/tmc/thr...tion-on-long-term-battery-preservation.97134/

I've long seen 30 deg. C (86 deg. F) as given by the BU quote above as the general point at and above which li-ion heat-related degradation accelerates rapidly. Probably the specific chemistry used will move the temp slightly one way or the other, but I doubt it changes the general point.
 
I'd be wary of storing a car pack at 10% or less, not just because it leaves very little range available, but because there are other factors like load after startup that might stress the cells at that low a SOC. Were the above stats derived with cells under laboratory conditions?
 
We have a 2016 LS model--manuf: 01/2016, purchased 05/2016. Lost the first bar in 05/2017 at about 9,500 miles. For first six months of ownership, we would recharge to 100% every night so that we would have full range available the next day. Then about Jan of this year (2017), read about impact of maintaining a full charge, so we began to fully charge only about every 3rd or 4th night (or when we needed a full charge). Located in Georgia, so temps are fairly high here.
 
LeftieBiker said:
I'd be wary of storing a car pack at 10% or less, not just because it leaves very little range available, but because there are other factors like load after startup that might stress the cells at that low a SOC. Were the above stats derived with cells under laboratory conditions?
Click to expand...
Naturally, at various temps. They also recharged the cells occasionally to do the capacity tests, then brought them back to the specified storage SoC - details in the study. Having gotten used to L-A battery behavior back in the day, I wouldn't want to deliberately store a battery at a very low state of charge on general principle, unless I knew for a fact that it was beneficial for that chemistry.

IIRR, Nissan's service manual did recommend shipping LEAFs with batteries in the 30%-50% or maybe it was 30%-80% range, so take your pick.
 
GRA said:
I've seen plenty of studies that reference degradation due to low SoC (high DoD) during use; li-ion isn't NiMH. Battery University has a summary: http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

Similar to a mechanical device that wears out faster with heavy use, the depth of discharge (DoD) determines the cycle count of the battery. The smaller the discharge (low DoD), the longer the battery will last. If at all possible, avoid full discharges and charge the battery more often between uses. Partial discharge on Li-ion is fine. There is no memory and the battery does not need periodic full discharge cycles to prolong life. The exception may be a periodic calibration of the fuel gauge on a smart battery or intelligent device. (See BU-603: How to Calibrate a “Smart” Battery)

The following tables indicate stress related capacity losses on cobalt-based lithium-ion. The voltages of lithium iron phosphate and lithium titanate are lower and do not apply to the voltage references given.

Note: Tables 2, 3 and 4 indicate general aging trends of common cobalt-based Li-ion batteries on depth-of-discharge, temperature and charge levels, Table 6 further looks at capacity loss when operating within given and discharge bandwidths. The tables do not address ultra-fast charging and high load discharges that will shorten battery life. Not all batteries behave the same.

Table 2 estimates the number of discharge/charge cycles Li-ion can deliver at various DoD levels before the battery capacity drops to 70 percent. DoD constitutes a full charge followed by a discharge to the indicated state-of-charge (SoC) level in the table.

Depth of discharge

Discharge cycles
(NMC / LiPO4)

Table 2: Cycle life as a function of
depth of discharge. A partial discharge reduces stress and prolongs battery life, so does a partial charge. Elevated temperature and high currents also affect cycle life.

Note: 100% DoD is a full cycle; 10% is very brief. Cycling in mid-state-of-charge would have best longevity.

100% DoD ~300 / 600
80% DoD ~400 / 900
60% DoD ~600 / 1,500
40% DoD ~1,500 / 3,000
20% DoD ~1,500 / 9,000
10% DoD ~10,000 / 15,000

Lithium-ion suffers from stress when exposed to heat, so does keeping a cell at a high charge voltage. A battery dwelling above 30°C (86°F) is considered elevated temperature and for most Li-ion a voltage above 4.10V/cell is deemed as high voltage. Exposing the battery to high temperature and dwelling in a full state-of-charge for an extended time can be more stressful than cycling. Table 3 demonstrates capacity loss as a function of temperature and SoC. . . .
Click to expand...

For long term storage (9-10 months in the case of the study below) the situation seems less clear, and dependent on specific Li-ion chemistry. This study from 2016 compares NCA, NMC and LFP at various temps, and SoCs from 0 to 100%:
Calendar Aging of Lithium-Ion Batteries
Click to expand...
http://jes.ecsdl.org/content/163/9/A1872/F2.expansion.html

General aging behavior.—For the three types of lithium-ion cells
examined, Figures 2a–2c show the capacity fade after a storage period
of 9–10 months. As expected, they all exhibit an increased calendar aging
with higher storage temperature. However, no steadily increasing
degradation with SoC is observed. Instead, there are plateau regions,
covering SoC intervals of more than 20%–30% of the cell capacity,
in which the capacity fade is similar. A marked step in the capacity
curves is observed at about 60% SoC for the NCA and NMC cells
and above 70% SoC for the LFP cells. For the observed relationships
between storage SoC and capacity fade, no simple linear, polynomial,
or exponential approximations are possible without considerable deviation
in certain SoC regions. Hence, the measurement of calendaraging for only
three SoCs, as is the case in most publications, is not sufficient to precisely
describe calendar aging with respect to the SoC when the qualitative
characteristics over the entire SoC range are not known. . . .
Click to expand...
There seems to be little difference between storage at 0% and 30% SoC for most of the chemistries.

FWIW, Jeff Dahn recently recommended keeping the battery between 30-70% when possible, but charging to 100% for trips as needed. See the tmc thread on that: https://teslamotorsclub.com/tmc/thr...tion-on-long-term-battery-preservation.97134/

I've long seen 30 deg. C (86 deg. F) as given by the BU quote above as the general point at and above which li-ion heat-related degradation accelerates rapidly. Probably the specific chemistry used will move the temp slightly one way or the other, but I doubt it changes the general point.
Click to expand...

What has been presented is what some of us Leaf owners have implemented, as a result of past experiences with Lithium batteries
over 10-15 years, thereby reducing our Leaf's battery capacity degradation. Most factors mentioned contributing to degradation should
be somewhat intuitive to most with any experience with portable electronic devices, e.g. laptops, cameras, cell phones, & etc.
Most importantly though is that any device, e.g. Lithium batteries, which stores energy in a chemical reaction has a finite life.
 
BiscuitEater said:
We have a 2016 LS model--manuf: 01/2016, purchased 05/2016. Lost the first bar in 05/2017 at about 9,500 miles. For first six months of ownership, we would recharge to 100% every night so that we would have full range available the next day. Then about Jan of this year (2017), read about impact of maintaining a full charge, so we began to fully charge only about every 3rd or 4th night (or when we needed a full charge). Located in Georgia, so temps are fairly high here.
Click to expand...
I suspect you too have one of the early batch of bad batteries. No charging plan is goin to help them. Might as well charge it whatever is best for you and wait for a replacement which is in our near future.
 
jbuntz said:
BiscuitEater said:
We have a 2016 LS model--manuf: 01/2016, purchased 05/2016. Lost the first bar in 05/2017 at about 9,500 miles. For first six months of ownership, we would recharge to 100% every night so that we would have full range available the next day. Then about Jan of this year (2017), read about impact of maintaining a full charge, so we began to fully charge only about every 3rd or 4th night (or when we needed a full charge). Located in Georgia, so temps are fairly high here.
Click to expand...
I suspect you too have one of the early batch of bad batteries. No charging plan is goin to help them. Might as well charge it whatever is best for you and wait for a replacement which is in our near future.
Click to expand...

Sounds more like low mileage along with maintaining a high SOC in very warm weather.
 
DaveinOlyWA said:
jbuntz said:
BiscuitEater said:
We have a 2016 LS model--manuf: 01/2016, purchased 05/2016. Lost the first bar in 05/2017 at about 9,500 miles. For first six months of ownership, we would recharge to 100% every night so that we would have full range available the next day. Then about Jan of this year (2017), read about impact of maintaining a full charge, so we began to fully charge only about every 3rd or 4th night (or when we needed a full charge). Located in Georgia, so temps are fairly high here.
Click to expand...
I suspect you too have one of the early batch of bad batteries. No charging plan is goin to help them. Might as well charge it whatever is best for you and wait for a replacement which is in our near future.
Click to expand...

Sounds more like low mileage along with maintaining a high SOC in very warm weather.
Click to expand...


Nope that's not it, I too have a 2016 Leaf SV with a bad battery that's degrading really fast, I already lost my first bar too and I live in a cool climate. My friend has a 2013 Leaf with almost 60k miles and still has all 12 bars! He lives in my area too and he doesn't baby his battery either.
 
LeftieBiker said:
In order for the "bad batch" hypothesis to be true, the 2017 and late 2016 packs would have to be much better. Do we have any evidence of that...?
Click to expand...

My 30kwh pack seems to be doing pretty well (relatively speaking), but then I have better access to covered parking since last year, so I don't have to park under the sun like I did with the 2013 leaf. There are times when I'm still parking under the sun, but there's definitely been at least a 50% reduction in exposure to high ambient temperatures.
 
LeftieBiker said:
In order for the "bad batch" hypothesis to be true, the 2017 and late 2016 packs would have to be much better. Do we have any evidence of that...?
Click to expand...


Based on what I've been seeing reported there seems to be quite a few people with 30kwh packs that were manufactured last part of 2015 with rapid degradation (mine included). Doesn't seem to matter if you take care of your battery and live in a cool climate, still degrades fast. This isn't enough to technically claim a "bad batch" but I don't know what else you'd call it? Now I have been reading some with later 2016 as well as 2017 30kwh packs that seem to be degrading really fast too. Seems hit or miss though as you get others with hardly any degradation being reported. Any way you look at it there's something not right with these 30kwh packs!
 
DaveinOlyWA said:
jbuntz said:
BiscuitEater said:
We have a 2016 LS model--manuf: 01/2016, purchased 05/2016. Lost the first bar in 05/2017 at about 9,500 miles. For first six months of ownership, we would recharge to 100% every night so that we would have full range available the next day. Then about Jan of this year (2017), read about impact of maintaining a full charge, so we began to fully charge only about every 3rd or 4th night (or when we needed a full charge). Located in Georgia, so temps are fairly high here.
Click to expand...
I suspect you too have one of the early batch of bad batteries. No charging plan is goin to help them. Might as well charge it whatever is best for you and wait for a replacement which is in our near future.
Click to expand...

Sounds more like low mileage along with maintaining a high SOC in very warm weather.
Click to expand...
I see you are on a roll with your pet notion, and common sense is out the window.
It should have occurred to you that there is a large group of 2013-2015 LEAFS in the same area, no doubt treated the same way, that do not show anywhere near that rate of battery degradation.
 
rcm4453 said:
LeftieBiker said:
In order for the "bad batch" hypothesis to be true, the 2017 and late 2016 packs would have to be much better. Do we have any evidence of that...?
Click to expand...


Based on what I've been seeing reported there seems to be quite a few people with 30kwh packs that were manufactured last part of 2015 with rapid degradation (mine included). Doesn't seem to matter if you take care of your battery and live in a cool climate, still degrades fast. This isn't enough to technically claim a "bad batch" but I don't know what else you'd call it? Now I have been reading some with later 2016 as well as 2017 30kwh packs that seem to be degrading really fast too. Seems hit or miss though as you get others with hardly any degradation being reported. Any way you look at it there's something not right with these 30kwh packs!
Click to expand...

It seems to me that this pack was poorly designed. Unless I start seeing evidence that those made from late 2016 on are much better, I'm not buying the "bad batch" idea.
 
My 2016 LS lost its first bar this weekend after only 4,946 miles in Austin, TX.

LeafSpy stats when I leased the car 2/2/17:
AHr: 73.81
SOH: 92% 384.97V
Hx: 88.91%
odo: 221
1 QCs
16 L1/L2s

LeafSpy stats when it lost its first bar 10/29/17:
10/28
AHr: 63.92
SOH: 80% 391.06V
Hx: 78.47%
odo: 4,946
3 QCs
143 L1/L2s

I typically only charge 2-3 times a week when the battery is less than 50% charged. When I do charge, I charge to 100% because Nissan says it is safe to do so and I don't want the added complication of doing otherwise.

With the car having been built in April 2016 and sold many months later in Feb 2017, I have a feeling it sat in a dealer lot fully charged through a hot and destructive Texas summer. Aside from road trip to San Antonio over Labor Day that included a QC each way, I can't think of anything I did that could have come close to pushing the limits of an EV battery in less than one year of ownership.
 

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