Capacity Loss on 2011-2012 LEAFs

[RegGuheert]

I wanted to make a comment regarding my lost capacity bar just a few days ago. Prior to losing the capacity bar(Now have 10 vs. 11), I noticed my temperature bars totaled 6. After losing a capacity bar, my temperature guage now shows 7 bars.

Correct me if I wrong but, it seems the more the batteries are degraded due to heat, the hotter their temperature becomes...Does that mean they are working 'harder', thus are now giving off more heat?

My understanding is that yes, as the battery degrades its internal resistance increases = more internal heat generation.

I'm not too confident in Nissan's prediction of a declining rate of degradation. First, because of the aforementioned increase in heat generation which makes a bad situation worse. Second, because an owner trying to maintain the usefulness of the car will begin to use a greater percentage of SOC. Meaning more frequent charges, more charges to 100%, deeper discharges.

In a lab the batteries might show a declining rate of degradation. In the real world people will work them that much harder.

Agreed.

Also note that it seems that according to the service manual as the battery degrades Nissan adjusts the meaning of the bars as a function of temperature:

RELATIONSHIPS OF THE NUMBER OF LIGHTING SEGMENTS OF LI-ION BATTERY TEMPERATURE GAUGE AND LI-ION BATTERY TEMPERATURE
0 Bars: Up to -5C (23F)
1 Bar: -15C (5F) to -2C (28F)
2 Bars: -12C (10F) to 2C (36F)
3 Bars: -8C (18F) to 4C (39F)
4 Bars: -5C (23F) to 15C (59F)
5 Bars: -3C (27F) to 27C (81F)
6 Bars: 10C (50F) to 38C (100F)
7 Bars: 23C (73F) to 47C (117F)
8 Bars: 36C (97F) to 49C (120F)
9 Bars: 47C (117F) to 52C (126F)
10 Bars: 49C (120F) to 56C (133F)
11 Bars: 52C (126F) to 59C (138F)
12 Bars: 56C (133F) and above
Note:
- Li-ion battery temperature gauge shows Li-ion battery temperature by correcting it according to the battery capacity. Consequently, the number of lighting segments of Li-ion battery temperature gauge can be different regardless of the same Li-ion battery temperature.
- This graph shows corrected temperatures. These to not agree with the CONSULT temperature shown in data monitor item "BAT TEMP".

(Please note that I have interpreted the graph so that the range values can be read as numbers.)

Note the text in the first note. I am not at all sure what "correcting it according to battery capacity" means but perhaps they are attempting to calculate the temperature inside the cells by using a crude thermal model and adjusting losses in the battery based on degradation information. That would imply that they might show more temperature bars after the battery degrades than they did when it was new for the same temperature..

 

[RegGuheert]

My case is... don't you think it might be useful to document in the wiki the charger manufacturer/charging technology?

All of the cars use the same charger since it is included with the car. I believe it is made by Nichicon.

Note that the EVSE that you plug into the car for charging is not a charger, but rather it is a piece of safety equipment with a standardized connector and a cord which allows you to connect your car safely to your house for charging.

We already know that chargers can damage the electronics, but I think that there might some correlation with the charger manufacturer/charging technology and the battery capacity loss.

I absolutely agree that the charger can damage the batteries. What I'm not sure of in the case of the LEAF is whether the charger selects the charging current or whether the BMS for the car does it.

Looking at the WIKI and reading some posts, it has made be think that those who make L1 charging are in better shape than others, but maybe it's not the L1 mode that's beneficial, it's the charger manufacturer.

As mentioned, the manufacturer is the same, but if the stories of L1 charging being safer are true then it seems possible that Nissan might be able to improve the algorithm for the L2 charging mode to improve battery life, perhaps by trading off charging time and/or available charge in very hot conditions. OTOH it seems that one owner in Seattle has charged his LEAF about 600 times using L2 and has only lost a small amount of capacity.

Maybe we find that some charger manufacturer + manufacturing date, or L1/L2/L3 charging modes are more damaging than others.

It is conceivable that firmware revision plays a role here. In fact, I expect that it will become important in the future, as Nissan is likely to revise *something* in the car and firmware is a likely candidate. I also believe I heard that the 2013 LEAFs will include a different charger from a different manufacturer.

I have a strong feeling that there's not only one cause to the severe capacity loss, but a combination of factors, and one is the charger manufacturer/charging technology.

Agreed. Hopefully Nissan can improve the LEAF's battery charging technology to extend battery life in hot climates without greatly impairing available range.

 

[dusty2050]

Agree.. If any tempature range is bad for the car period then it SHOULD NOT be displayed as normal/white period!

So the contradiction still exists, that you should not allow the ambient temperature, hence eventually the battery temperature, to rise to 120F. But on the other hand, the battery temperature at 120F (7 bars) is considered normal according to Eric of Nissan.

1. Aren't you perhaps putting too much credence in the response of a NO-GAS-EV flunkee working under pressure a year ago?

I'm not putting credence on anybody. I'm just pointing out a contradiction. But on the other hand, that person Eric W. did put the caller on hold, supposedly to consult with somebody else (a manager/supervisor perhaps?) before giving the answer. Again, I'm not saying I believe one answer over the other. I'm just pointing out that there are contradictions given out by Nissan. Right now, I'm trusting my instinct that the 7th bar is in the bad range and not in the normal range like Nissan displays it.

2. Are you hypothesizing a 24-hour average ambient temperature of 120°F?

I don't need to hypothesize anything. It's a straight quote from the owner's manual not to allow the car to be at ambient temperature for longer than 24 hrs. I'm just saying that on the one hand, the manual says that ambient temperature, which eventually will transfer to battery temperature, of 120F for 24 hours is bad. But on the other hand, the temperature bar read out, whether it be at 7 or 8 or 9 or even 10 temperature bars, is displayed in the normal range (white color and not red like the 11 or 12th bar). For sure the 10th bar at 131F (whether it be at the low end or high end of the 10th bar), not a red bar, is much higher than 120F. Hence a contradiction exists in what Nissan says and displays.

3. I suspect you got that table from the Wiki, but I think you may be misreading what it is trying to say. Couldn't it be saying that 98.2°F is the high end for 7 bars? If those are low end numbers, what does it mean that the low end of 0 bars is 5°F?

Like I said above, it doesn't matter if the 7th bar has 98.2F as the high end or low end because the 10th bar at 131F, which is much greater than 120F, seems to be considered as normal by Nissan, hence displayed by Nissan as a white bar and not a red bar.

 

[Herm]

We now know the critical temperature is 105 F, and that is fairly close to the beginning of the 7th temperature bar.. so perhaps it should be colored caution yellow, then orange etc. Perhaps the car should limit how long the battery remains at 100% once you reach the 7th bar.

 

[EdmondLeaf]

We now know the critical temperature is 105 F,

any reference that this is a case?

 

[jfreire]

Note that the EVSE that you plug into the car for charging is not a charger

I'm sorry for the confusion. I meant "EVSE" and not "charger" (my bad! )

There are several EVSE models being used: The NISSAN EVSE than came with the car (110V and 220V models), Blink, AeroVironment, etc.

If the EVSE and the onboard charger negotiate the power to be delivered. Could it be that there's some bug in the BMS trigged by some negotiating nuances that are implemented differently from one EVSE model to another?
When people say they are better results with L1 vs L2 charging, are they changing EVSE models?

What makes some drivers in AZ have huge capacity loss, and not others? Are they using the same EVSE model?

I think it's important to add to the WIKI the EVSE model being used.

 

[DaveinOlyWA]

We now know the critical temperature is 105 F, and that is fairly close to the beginning of the 7th temperature bar.. so perhaps it should be colored caution yellow, then orange etc. Perhaps the car should limit how long the battery remains at 100% once you reach the 7th bar.

well now!! hmm, seems we need a definition of "critical"

would you say critical is the change in slope of the hockey stick or the end of the stick?

"some" Li chemistries state the sweet spot for longevity starts to end at 30C/86F so if we were labeling i would label 31+C as "concern" or 6 TBs.
7 TBs as "watch" 8 TBs as "warning" 9 TBs as "critical" 10 TBs as "danger" and 11 TBs as "dying" and 12 TBs as "dead"

once again, since we dont have a gradient colored TB scale, i guess we should apply our bountiful previous life experiences to this scale where the middle is good, the edges are not. kinda like every temperature scale we have ever seen

 

[edatoakrun]

Unfortunately, very few of those with bar losses have posted their actual range test observations that would allow us to understand the actual capacity losses those lost bars represent.

And none, that I am are of have posted their Carwings energy use reports. Carwings accurately report kWh consumption, and I have used both CW and range tests to monitor my LEAF's battery capacity for over a year now.

My own conclusion is that while a range test remains a valid method, Carwings gives more accurate capacity results, as it eliminates the variable driving conditions, on separate range tests.

edatoakrun

A few months after I got got my LEAF, with about 3,300 miles on the odometer, I decided to use a range test from a 100% charge to near the VLBW, to try to determine how driving variables effect energy use, and changes in range and/or battery capacity over time. After I realized that Carwings was updated and reporting consistently, I could further correlate range to actual kWh use, and battery capacity. When testing, I log speed, capacity bar disappearance (and appearance) , battery warnings, and (more recently) temperature. I would suggest any LEAF owner only interested in tracking battery capacity, just watch the total kWh use reports, to provide more precise information than provided by the dash displays...

edatoakrun

...CW indicated 17.5 kWh use in both recent tests (on 5/31/12, and 6/17/12) from 100% charge to just past VLBW, as opposed to 18.7 kWh in my first test, last Summer.

So, in the simplest analysis, I could conclude this about a 6% reduction in battery capacity was evidence of “degradation”.

However, I believe that there are other factors which cause both the “100%" charge level, and the level of the LBW, to occur at different levels of total capacity.

So, IMO, while my battery capacity at this point was probably reduced by some factor in a range centered pretty close to 6% between the first and two recent tests, I would not make an assertion of whether I can state that range is 3% to 9%, or 5%-7%.

And I would not make any assertion, of what part of this reduction was a permanent loss in battery capacity, as opposed as a reduction in access to my total battery capacity, imposed by my LEAF’s battery management system...

http://www.mynissanleaf.com/viewtopic.php?f=31&t=9064" onclick="window.open(this.href);return false;

The only specific we were given was that our car tested out at 85% capacity remaining, which was 2nd best of the cars they had. The best was supposedly 86%. This makes no sense to us, as it does not agree with our real world range loss from a year ago under similar driving conditions.

How much range do you suppose you've lost?

Assuming that 21 kWh usable is available when new (from 100% to turtle), 85% capacity remaining would indicate that you have 17.85 kWh usable now. At 4.0 mi/kWh that would represent a total range of 84 miles when new and now 71.4 miles.

But keep in mind that LBW appears to occur at the same point regardless of overall capacity loss - 49 GIDs or about 3.4 kWh before turtle.

Since one's "range anxiety" factor doesn't change - you still probably start looking for a charging station at LBW and avoid going below that if possible.

That means that your "safe" capacity has gone from 17.6 kWh to 14.45 kWh - a reduction in "safe" range closer to 18% than the indicated 15% - or 70 miles down to 58 miles at 4.0 mi/kWh.

This is worse if you normally charge to "80%" which is about 17.3 kWh usable before turtle when new and 14.7 kWh after 15% degradation.

Now your "safe" usable capacity has gone from 13.9 kWh to 11.3 kWh - at 4.0 mi/kWh that's 56 miles down to 45 miles.

That also means that drives that you used to make at 80% without issue - you now have no choice but to charge to 100%. When new your 80% "safe" range was 58 miles - after 1 year your 100% "safe" range is 56 miles.

Of course - in addition to this, the BMS could be doing something else weird which is giving the appearance of a more significant reduction in range. You wouldn't be the first to claim that.

Completely unacceptable after 1 year.

I'm shocked that they didn't do a driving range to LBW test with our car when they had it. I would think that would demonstrate the impact of this a lot more evident than some test that shows 85%.

I'm not. A properly instrumented bench test could be set up and repeated multiple times in 1 week with far less man-power than a behind the wheel test - and the data would very likely be more accurate. It would also be far easier to simulate different driving profiles. Given that the opposum's LEAF did see a decent number of miles, it's pretty clear that they did do some road testing to verify on-road behavior in the car. Perhaps other cars which showed more capacity loss got more road testing.

 

[RegGuheert]

Carwings accurately report kWh consumption,...

As you have been made aware previously, that statement is not generally true since LEAF firmware bugs in the early 2011 LEAFs cause Carwings data to be incorrect. While Nissan has made new firmware available for some affected LEAFs, they have not made it available to others, including our LEAF built June 15, 2011.

As an example of how far off Carwings is for our car, we drove 156 miles on Saturday at 4.7 mi/kWh efficiency indicated on the dash, which gives 33.2 kWh consumed. That sounds about right for draining the battery from full to LBW twice. Carwings, OTOH, reports 152.3 miles driven at 5.8 mi/kWh or 26.2 kWh consumed.

Which reminds me: I think I will bug Nissan again to try to get them to address this problem.

 

[azdre]

How much range do you suppose you've lost?

Our last range test, we averaged 5.0 miles /kWh (per dash) and drove 58.6 miles from 100% to LBW. According to the technical bulletin released a new battery should get 75-85 miles to LB, last summer we were right about 80.

http://www.mynissanleaf.com/viewtopic.php?f=31&t=8331&start=357" onclick="window.open(this.href);return false;

 

[edatoakrun]

Carwings accurately report kWh consumption,...

As you have been made aware previously, that statement is not generally true since LEAF firmware bugs in the early 2011 LEAFs cause Carwings data to be incorrect. While Nissan has made new firmware available for some affected LEAFs, they have not made it available to others, including our LEAF built June 15, 2011.

As an example of how far off Carwings is for our car, we drove 156 miles on Saturday at 4.7 mi/kWh efficiency indicated on the dash, which gives 33.2 kWh consumed. That sounds about right for draining the battery from full to LBW twice. Carwings, OTOH, reports 152.3 miles driven at 5.8 mi/kWh or 26.2 kWh consumed.

Which reminds me: I think I will bug Nissan again to try to get them to address this problem.

Yes, I think you should, as I have suggested before.

Nissan promised free Carwings for the first three years (IIRC?) as part of your purchase/lease contract.

If Carwings is not available and fully functional, you should demand any necessary repairs, just as for any other defect.

 

[DesertDenizen]

My Carwings stopped recording even its bad data back in May. I don't use it anyway so I don't concern myself about it. (It first stopped in Oct 2011, then when I signed in again in May it recorded its bad data for 5 days and then quit again.)

 

[opossum]

How much range do you suppose you've lost?

Here are the details on our range test from 6/12/12. By these numbers, we lost the last bar at 14.3 kWhr. That is NOT 85% remaining capacity.

We fell 16.4 miles short of the Nissan Technical Bulletin range for 5.0 miles per kWh in our range test tonight. Yikes! Where's our new battery pack, Carlos?!?!

Leaf Range Test, VIN #500

All readings @ 5.0m/kWhr avg.
bar 3 gone 52.8m
bar 2 gone 58.6m (NTB: 75-85m)
LBW 58.6m
VLBW 71.0m
Last bar gone 71.5m
Turtle (too chicken to find out)

 

[SierraQ]

Hi all!

I'm not sure this was discussed in the forum, but there are now so many pages and I'm not sure.

My case is... don't you think it might be useful to document in the wiki the charger manufacturer/charging technology?

We already know that chargers can damage the electronics, but I think that there might some correlation with the charger manufacturer/charging technology and the battery capacity loss.

Looking at the WIKI and reading some posts, it has made be think that those who make L1 charging are in better shape than others, but maybe it's not the L1 mode that's beneficial, it's the charger manufacturer.

Maybe we find that some charger manufacturer + manufacturing date, or L1/L2/L3 charging modes are more damaging than others.

An interesting theory but not likely a significant culprit otherwise we'd be seeing capacity issues everywhere. As it is there is strong evidence that this is solely related to heat and not methods of charging, driving, age, etc. Chargers damage batteries by overcharging or injecting current into them too fast. The Leaf does manage this. Whether it is ideally managed, especially in higher temps, who knows. Still, I don't believe there is clear evidence as yet whether L1 is better than L2. If it is the factor would more likely be the charging voltage/amperage/rate and not the manufacturer since these devices are glorified power switches. Some have reported higher GID counts under L1 but it could be coincidence or insignificant. We would need someone in AZ who has always charged at L1 to have a good comparison point. (Do we have someone like that?)

I have a strong feeling that there's not only one cause to the severe capacity loss, but a combination of factors, and one is the charger manufacturer/charging technology.

This is almost a given but the question is to what degree does each of these factors contribute? Most of us assumed for a long time that 80% vs. 100% charging would be the biggest factor but these Leafs have proven that wrong at least in the short-term.

 

[TonyWilliams]

We fell 16.4 miles short of the Nissan Technical Bulletin range for 5.0 miles per kWh in our range test tonight.

All readings @ 5.0m/kWhr avg.
LBW 58.6m
VLBW 71.0m

Please confirm that you reset the economy meter (miles/kWh) prior to the beginning of this run?

At 5 miles/kWh multiplied by 21 kWh (new battery) equals 105 miles of range/autonomy. Your actual range was about 77 miles (I gave you 6 miles from VLB to Turtle at 5 miles/kWh). In addition, I'm not factoring the increase in range from your above sea level elevation and that brutal Arizona heat (meaning less air resistance from higher density altitude).

I'm coming up with 73% of new battery range. With two battery capacity bars missing, you are at 72% - 78% (per the Nissan Service Manual), which falls online perfectly with the data.

In two to three weeks, I expect a lot of smoke and mirrors.

 

[opossum]

Please confirm that you reset the economy meter (miles/kWh) prior to the beginning of this run?

We most certainly did. We used the energy numbers on the big screen in the center, not the tiny screen behind the steering wheel (sorry for not knowing the official names for these displays). Carwings was not involved at all, either.

At 5 miles/kWh multiplied by 21 kWh (new battery) equals 105 miles of range/autonomy. Your actual range was about 77 miles (I gave you 6 miles from VLB to Turtle at 5 miles/kWh). In addition, I'm not factoring the increase in range from your above sea level elevation and that brutal Arizona heat (meaning less air resistance from higher density altitude).

I'm coming up with 73% of new battery range. With two battery capacity bars missing, you are at 72% - 78% (per the Nissan Service Manual), which falls online perfectly with the data.

Exactly! We were getting awesome range all summer in 2011. We were MORE than happy with the range and rarely needed more than 80% (but the days we did were not predictable).

In two to three weeks, I expect a lot of smoke and mirrors.

Tony, I continue to hate you just a little bit for your continued pessimism regarding Nissan's potential handling of this issue... I mean realism... I mean pessimism. :lol: Some of us really need a positive response from them! :?

 

[JPWhite]

Tony, I continue to hate you just a little bit for your continued pessimism

Tony isn't being negative. He's positive it'll turn out bad

 

[RegGuheert]

Yes, I think you should, as I have suggested before.

Nissan promised free Carwings for the first three years (IIRC?) as part of your purchase/lease contract.

If Carwings is not available and fully functional, you should demand any necessary repairs, just as for any other defect.

O.K. I called them up and dropped it off for them to look at tomorrow. They didn't want to hear my suggestion to apply NTB11-041a even though it does not apply to our car, but I printed out a couple of pages from it and had it stapled to my work order anyway. (I am, after all, one of those unpleasant Nissan LEAF owners!)

I also took a photograph of the firmware versions in the car and I have no intention of accepting the car back if they do not update Boot Ware (NK1) and Application (NK2) to at least 147. (They are currently 127.) We'll see how that goes.

 

[TonyWilliams]

Leaf Range test:
bar 2 gone 58.6m
LBW 58.6m

Another interesting tidbit. As I predicted, we will soon have LEAFs getting LBW with two or more fuel bars displayed.

 

[edatoakrun]

How much range do you suppose you've lost?

Here are the details on our range test from 6/12/12. By these numbers, we lost the last bar at 14.3 kWhr. That is NOT 85% remaining capacity.

We fell 16.4 miles short of the Nissan Technical Bulletin range for 5.0 miles per kWh in our range test tonight. Yikes! Where's our new battery pack, Carlos?!?!

Leaf Range Test, VIN #500

All readings @ 5.0m/kWhr avg.
bar 3 gone 52.8m
bar 2 gone 58.6m (NTB: 75-85m)
LBW 58.6m
VLBW 71.0m
Last bar gone 71.5m

Turtle (too chicken to find out)

The only way to I can see to reconcile your report of kWh use, 25%-30% below that usually seen on new LEAFs, and the "85% capacity remaining" report you state came from Nissan, is that your charge level was limited to a significantly lower percentage of total battery capacity, presumably by the BMS.

Any of the other LEAFs tested get their "capacity remaining" results from Nissan, yet?

How do they match up against your kWh use results results, from a gid/Soc meter, range test calculation, or CW report?