Capacity Loss on 2011-2012 LEAFs

[SanDust]

If Andy Palmer is saying there isn't a problem with the batteries I'm willing to hear more. I'm inclined to believe Andy Palmer. He has always seemed to be a straight shooter. Mark Perry not so much.

 

[palmermd]

If Andy Palmer is saying there isn't a problem with the batteries I'm willing to hear more. I'm inclined to believe Andy Palmer. He has always seemed to be a straight shooter. Mark Perry not so much.

They are both paid by the same employer who asks them to say the company line. Until their bosses say to change the "official response" to these questions, every time it gets asked they will respond with the exact same answer. Even as evidence mounts they cannot change this response until it is official company recommendation to do so. Andy and Mark are both great guys, but you cannot expect them to give you their opinion on anything here, just the official company response. I feel bad for guys who are put into this situation. Fast moving evidence goes against the company position, but the company is slow moving and their responses have to stay in line with the official company position.

 

[spooka]

If Andy Palmer is saying there isn't a problem with the batteries I'm willing to hear more. I'm inclined to believe Andy Palmer. He has always seemed to be a straight shooter. Mark Perry not so much.

Mr. Palmer also needs to explain the range loss that is occurring, in what appears to be in direct correlation with the loss of capacity bars.

 

[spooka]

There are quite a few reasons you would not expect the the Casa Grande test cars to match the NREL study results.

First, the C. G. test cars were selected for study precisely because they were outliers from what most Phoenix LEAFs were experiencing, at least as indicated by those cars accelerated capacity bar losses.

It is possible that their unusual rate of capacity loss, up to "15%", is what is often reported, IIRC, is due in part to factors unrelated to battery use by the LEAF's drivers, such as reduced battery capacity at delivery, due to poor quality control at the factory, or poor battery care prior to delivery, such as long periods of 100% charge at high temperatures.

This accelerated degradation of the CS test group may also be accounted for largely or in part, by LEAF use habits of the five test vehicles outside of the controlled study, a few of which may have been:

Miles driven per day in the NREL study is 33 miles, in two trips. Obviously, many or all of the CS LEAFs frequently exceeded this range, with increased battery cycling required to drive up to twice the ~12,000 miles per year of the study, and using a higher percentage (far higher for the C.G. drivers with long commutes) of the total battery capacity on each day of driving.

Ambient temperatures for the NREL study apparently did not take into account the "garage heating effect", the propensity for EV drivers to maintain higher battery temperatures, by parking their cars overnight in garages, at higher-than-ambient temperatures. Of course, this would be expected to accelerate heat-related capacity loss in batteries, relative to those EVs that cooled their battery packs at night, with either ATM use, or space cooling.

The study apparently did not account for the heating effects (and possibly other degradation effects) of fast charging, which at least some of the C. S. test LEAFs, may have used frequently.

A big question I still have about the NREL study, is the capacity level and charging habits assumed.

If I understand correctly, it looks to me like the study reports use of 54% of battery capacity, to drive that 33 daily miles?

So, basically, they tested a Volt sized battery pack, with the daily driving range limited to the optimum Volt-range commute?

Obviously, if the C.G. LEAF drivers had limited their daily driving range to 33 miles, limited their their battery packs' charge to ~ten bars, and only discharged them to to ~four bars, and then only recharged them back up to ~ten bars, immediately before driving again, on every day of their ownership, we might expect them now to have very different capacity bar loss reports.

The main points I took from the study were that both heat and lack of cooling contribute to degradation of battery capacity. (Yes I am being Captain Obvious by stating this and we did not need a government study to confirm this). What I see in the graphs, regardless of the methods and assumptions that were made to obtain the data, is a baseline that agrees closely to what Nissan is stating the Leaf's battery life should be under similar conditions. I wonder if Nissan used this study as a part of their basis for the Leaf's stated battery stats. Probably not, since there is no huge initial capacity loss and then a leveling out that we have been told after the fact is "normal". The capacity loss in the graphs over time is very close to statements that Nissan makes about the battery pack. What we are seeing in reality differs from these graphs and is a good illustration of our concerns.

My Leaf is the poster child for this study since I have driven about 13,500 miles and have owned it for about 400 days (thats an average 33.75 miles/day for those of us that can't do the math in our heads, writer included) and I am down to 10 capacity bars. This study is based on a 33 mile/day average. I'd be happy to have the chart's predicted capacity but sadly, it looks like I am right there with the higher mileage Casa Grande Leafs.

It is interesting that the "garage heat effect" may be a reason for this degradation of capacity since Nissan and Blink/Ecotality's preference is that these vehicles be garaged. This recommendation by the manufacturer for the preferred parking and charging method, if followed by owners, may be a major reason our battery packs are having the unexpected reduction in capacity to the extent we are seeing.

 

[ALLWATZ]

They also pointed out "owners in America" so I guess that means other countries are not having an issue or are not complaining.

We have one from Hong Kong. But, I suspect that there's not as many LEAFs in any other country except Japan. And they likely won't have much problem, because it doesn't get that hot there. So, smaller countries, likely speaking different languages than english, are not likely to be reporting here.

But then, how many other places where they sell LEAF are as hot as Phoenix? The rest of the cars will, of course, degrade, just not in the volume of Phoenix and Texas.

We'll have to see how they do in Australia (http://green.autoblog.com/2012/06/19/nissan-leaf-goes-on-sale-in-australia-for-a-cool-52-000/" onclick="window.open(this.href);return false. In about a year we might have an answer as it is about the closest to our heat.

Another thing is if, as Andy Palmer is stating that it is just a faulty battery level display, why are Nissan Customer Service and the dealers telling everyone that things are normal and as expected. Obvious doublespeak for the press. If something is faulty, how can it be normal?

 

[nosuchthing]

I'm starting to get this impression that it is that 80% charging that accelerates the range loss. Just read the input from someone in San Diego. Same miles, length of ownership, same weather pattern as mine, and he lost a bar while I have not.

The only difference is that I refuse to charge to 80% and the SD guy did only that. It's 100% every night and that's all.

Now here is my unscientific idea why it happens. Battery plumps up when pumped up to 100% and shrivels when discharged. So I plump it up to the limit and shrivel it as much as possible during the day discharging it. I am forcing the battery to go through these motions like a muscle. If I was to plump it up to less than a maximum, guess what will happen? It will create its own new maximum limit and I will have lost a range bar.

It's the good old, use it or lose it.

Now, I know all the techies will be all over this, telling me why I'm wrong. All I can say is, I have 26,000 miles on the thing and still get my 73 freeway miles range with no bars lost. I've been saying this all along. Use the damn thing, don't be so nice to it. It's just a car. I'll be swapping that battery for more range anyway in less than 4-5 years. So, what the hell...

 

[JRP3]

So what you are saying is that counter to all known examples of battery degradation, you think fully cycling a battery is best for it, because a battery is like a muscle. OK.

 

[Stoaty]

The only difference is that I refuse to charge to 80% and the SD guy did only that. It's 100% every night and that's all.

Now here is my unscientific idea why it happens. Battery plumps up when pumped up to 100% and shrivels when discharged. So I plump it up to the limit and shrivel it as much as possible during the day discharging it. I am forcing the battery to go through these motions like a muscle.

No argument here, this is about as unscientific as it gets. For those who have lost capacity bars, it appears from the data we have that about half charge to 80%, half charge to 100%. There are many other variables that might explain why one person loses a bar and another person in a fairly similar environment doesn't (temperature where car is garaged, parking in the sun or not at work, working in a place that is much hotter (or cooler) than home, amount of QC, phase of the moon, etc.).

 

[RegGuheert]

All I can say is, I have 26,000 miles on the thing and still get my 73 freeway miles range with no bars lost.

That's good to hear! Where do you live?

 

[edatoakrun]

...My Leaf is the poster child for this study since I have driven about 13,500 miles and have owned it for about 400 days (thats an average 33.75 miles/day for those of us that can't do the math in our heads, writer included) and I am down to 10 capacity bars. This study is based on a 33 mile/day average. I'd be happy to have the chart's predicted capacity but sadly, it looks like I am right there with the higher mileage Casa Grande Leafs.

It is interesting that the "garage heat effect" may be a reason for this degradation of capacity since Nissan and Blink/Ecotality's preference is that these vehicles be garaged. This recommendation by the manufacturer for the preferred parking and charging method, if followed by owners, may be a major reason our battery packs are having the unexpected reduction in capacity to the extent we are seeing.

I have no idea what Blink/Ecotality told you.

I think Nissan did not give adequate warning about the effects of high heat, but, IMO, the recommendation to avoid 100% charging whenever possible, to extend battery life, was pretty clear.

="spooka

I have lost 2 bars, living in Phoenix:

Car has always been stored in garage. Sits in a parking lot for 8 hours during the day 3 days a week on average Bar 1 On or around Aug 1, 2012. Took possession of the car July 15th, 2011. (1 yr) 12,500 miles. 1 QC, all others L2 charging to 100%. VIN 004917.
Bar 2 August 26, 2012 (today!). (1yr, 1mo) 13,365 miles. 1 more QC. Only 1 month and 865 miles between bar loss

Not reported to Nissan. Will report this week.

Manufacturer date 05/11

http://www.mynissanleaf.com/viewtopic.php?f=30&t=8802&start=3078" onclick="window.open(this.href);return false;

So, just how hot is your garage at night, year-round?

How hot is the parking lot, where you park during the day?

With so few daily miles driven on average, why did you always recharge to 100%?

Did you re-charge to 100% every night, even when you had a mostly-charged battery?

Most importantly, do you believe that your two capacity bar loss actually represents a loss of more than 21% or more of your original battery capacity?

And is your belief based on an actual range test, on observations of metered or timed recharging, or only on the holy commandments of battery capacity, as carved on tablets here:

Real World Battery Capacity Loss
From MyNissanLeaf...

1 Loss of four battery capacity bars (33.75%)
2 Loss of three battery capacity bars (27.5%)
3 Loss of two battery capacity bars (21.25%)
4 Loss of one battery capacity bar (15%)...

http://mynissanleaf.com/wiki/index.php?title=Real_World_Battery_Capacity_Loss#four_bars" onclick="window.open(this.href);return false;

 

[EVDRIVER]

I'm starting to get this impression that it is that 80% charging that accelerates the range loss. Just read the input from someone in San Diego. Same miles, length of ownership, same weather pattern as mine, and he lost a bar while I have not.

The only difference is that I refuse to charge to 80% and the SD guy did only that. It's 100% every night and that's all.

Now here is my unscientific idea why it happens. Battery plumps up when pumped up to 100% and shrivels when discharged. So I plump it up to the limit and shrivel it as much as possible during the day discharging it. I am forcing the battery to go through these motions like a muscle. If I was to plump it up to less than a maximum, guess what will happen? It will create its own new maximum limit and I will have lost a range bar.

It's the good old, use it or lose it.

Now, I know all the techies will be all over this, telling me why I'm wrong. All I can say is, I have 26,000 miles on the thing and still get my 73 freeway miles range with no bars lost. I've been saying this all along. Use the damn thing, don't be so nice to it. It's just a car. I'll be swapping that battery for more range anyway in less than 4-5 years. So, what the hell...

If you rub the charge cable tree times each night your battery will last 3X longer. I charge to 80% almost every time and have one of the first LEAFs with no loss so far but my pack is always about 64 degrees. I also never deep discharge the pack. If anything a few 100% charges a month may better equalize the pack, not so much about the calisthenics though.

 

[Stoaty]

And is your belief based on an actual range test, on observations of metered or timed recharging, or only on the holy commandments of battery capacity, as carved on tablets here:

Hey, Nissan gave this to us on the mountain and told us to bring it down to the people. I think they called it the "Holey Service Manual".
Not sure if this was a misspelling and they meant that we should revere the Service Manual, or if it was kind of a Freudian slip, meaning there were lots of Holes in the Service Manual. :lol: Either way, until we receive another set of commandments from on high, it's the best we've got.

 

[palmermd]

If you rub the charge cable tree times each night your battery will last 3X longer.

Do you rub the cable towards the Leaf or towards the wall?

 

[LEAFfan]

208 this morning (all-time low for 100%).

That's only 74% which is a 21% to a 26% loss of capacity. Still 12 CBs? LOL, sounds like another Nissan trick played on you.

 

[gosashi]

They also pointed out "owners in America" so I guess that means other countries are not having an issue or are not complaining.

We have one from Hong Kong. But, I suspect that there's not as many LEAFs in any other country except Japan. And they likely won't have much problem, because it doesn't get that hot there. So, smaller countries, likely speaking different languages than english, are not likely to be reporting here.

But then, how many other places where they sell LEAF are as hot as Phoenix? The rest of the cars will, of course, degrade, just not in the volume of Phoenix and Texas.

Hi, I'm the owner from Hong Kong, not many Leaf report have problem is because most of Leaf is owned by company, less that 20 is private. Also not much people drive long distance like me, that's why they still have problem.
As I know total have 5 leaf have capacity drop, only me is private. All the Leaf have run more than 23000km and get the problem, my theory is no matter you take the car or not, when it run around 23000km it will get the problem. These information I get from the charging station provider, they work very close with those company which have Leaf.

 

[Herm]

Nissan and Mr Palmer has put the ball in the Leaf owner's community.. you guys with battery loss need to actually verify capacity but without using any of the Leafs own displays.. its all suspect. The only thing you can do is a complete cycle and recharge, measuring how much energy you put in.. yes this may require 20 hours of charging on 120V and a kill-a-watt meter... or just wait for the software update.

 

[Volusiano]

Nissan and Mr Palmer has put the ball in the Leaf owner's community.. you guys with battery loss need to actually verify capacity but without using any of the Leafs own displays.. its all suspect. The only thing you can do is a complete cycle and recharge, measuring how much energy you put in.. yes this may require 20 hours of charging on 120V and a kill-a-watt meter... or just wait for the software update.

You still have to use the mile/kwh display from the LEAF to make the calculation.

 

[Zythryn]

It would seem to me the most reliable test with relying on an Nissan displays would be range measurements. Make sure it is over a known route that has as controllable variables as possible.

 

[palmermd]

The only thing you can do is a complete cycle and recharge, measuring how much energy you put in.. yes this may require 20 hours of charging on 120V and a kill-a-watt meter... or just wait for the software update.

You still have to use the mile/kwh display from the LEAF to make the calculation.

Not true, the L1 charger which has been documented to charge at 78.3% efficient ( http://www.mynissanleaf.com/viewtopic.php?f=31&t=8583 ) will give you all the information you need. If you put in 20kw then the pack received 15.6kw. So for a new pack you should see 21kw into pack which should pull 26.8kW from the wall.

 

[edatoakrun]

It would seem to me the most reliable test with relying on an Nissan displays would be range measurements. Make sure it is over a known route that has as controllable variables as possible.

palmermd ...the L1 charger which has been documented to charge at 78.3% efficient ( http://www.mynissanleaf.com/viewtopic.php?f=31&t=8583" onclick="window.open(this.href);return false; ) will give you all the information you need. If you put in 20kw then the pack received 15.6kw. So for a new pack you should see 21kw into pack which should pull 26.8kW from the wall.

What are you folks saying?

After ~ 5000 posts on various threads complaining about "battery degradation", based on capacity bars, gid counts, gom readouts, and the examination of chicken entrails, you now want to actually try to collect data on battery capacity?

IMO, the suggestion of using my kill-a-watt is a good idea, and something I haven't tried yet.

The problem is, I don't have an earlier baseline of "from the wall" kWh use to compare my present metered charge to, while I do have range tests, which seem to show minimal loss of battery capacity in my LEAF:

I think that my range tests may indicate that whatever method my LEAF uses to calculate kWh, is variable, and has been significantly understating the recent amounts of kWh use, and has probably increasingly inflated all my m/kWh reports, from the dash, nav screen, and CW.

And of course, this could reflect with Tick Tocks observations of variable “gid” Wh values. Gids with higher Wh content could lower the calculated kWh numbers, and raise all the m/kWh results.

Maybe this is what I am seeing, from yesterdays range test. I tried to replicate as accurately as possible, my earliest range test,of almost a year, and almost 10,000 miles ago, to test this hypothesis.

I chose a day with very close to the original temperature condition, and drove the exact same route over the first 87 miles of the trip, using the same mode (eco) and used my original trip logs to closely replicate the same elapsed times for each of the three (same distance) legs of the trip.

The results from 8/30/12 were:

97.3 miles to VLB, 98.9 miles in total, by the odometer.

CW: 96.5 (~2.5% under-report) total miles, at 5.7 m/kWh, 16.8 kWh used from 100% to about the same capacity level, slightly past VLBW.

Compare this test with my first test on 9/7/11:

91.5 miles to VLB, 93.4 in total, by the odometer

CW: 91.1 (~2.5% under-report) total miles, at 4.9 m/kWh, 18.7 kWh used from 100% to about the same capacity level, slightly past VLBW.

I do not believe that the slight increase in range over the last year reflects any increase in battery capacity. On the contrary, I expect that my total capacity ( though maybe not the amount of kWh that the BMS is allowing me to access) has declined by an undetermined amount, but it cannot be detected due to the “noise” of uncontrolled variables in a range test...

http://www.mynissanleaf.com/viewtopic.php?f=31&t=9064&start=20" onclick="window.open(this.href);return false;

But it occurs to me that anyone should be able to use any meter, to measure kWh use from any charge (not just a "80%" or "100%" to LBW/VLBW/turtle range test) adjust the result for expected charge efficiency, and compare that to prior kWh use, either as calculated by the nav screen readout, or Carwings reported kWh use, to see if your LEAF's kWh use reports are accurate. I'll give it a try, with my LEAF, but won't be able to for a few days.

Remember, however:

edatoakrun

...even with a meter, there will probably be some variation in charging efficiency, especially with large battery temperature variations.

It probably would be much easier the control the recharge measurement variables, than the variables in a range test, IMO.

I think measuring the charge to "80%" might give more accurate results, If Phil's contention that this is more constant indication of total battery capacity than "100%" is correct.

If you have a meter, I'd suggest monitoring both timed charge levels.

http://www.mynissanleaf.com/viewtopic.php?f=31&t=9064&start=30" onclick="window.open(this.href);return false;