Stoaty's Battery Degradation spreadsheet now for prospects!

[Weatherman]

What are the approximate Amp/Hrs at one bar lost, two bar lost, and three bar lost?

As far as the AHrs are concerned, somewhere around:

55.5 - 12th bar goes poof
51.5 - 11th bar goes poof
48.8 - 10th bar goes poof
46.0 - end of the line. ready for a nursing home. (or a new battery, if you can get one before your warranty clock expires)

 

[WetEV]

(30 k mile update)

http://avt.inel.gov/pdf/energystorage/DCFC_Study_FactSheet_30k.pdf" onclick="window.open(this.href);return false;

Don't get fooled by seasonality. Get a year of data before trying to make sense of it.

 

[RegGuheert]

Don't get fooled by seasonality. Get a year of data before trying to make sense of it.

+1

I think you can see some seasonality in the data. This report was compiled at the beginning of August this year. Notice how the third 10,000-mile period lost between 6% and 9% capacity. That was likely the only period that was fully done in the heat of the year. My guess is the second period was done during the wintertime. It will be interesting to see what the fourth 10,000 miles does to these batteries.

Finally, I will note that the summer of 2012 was considerably hotter in Phoenix than the summer of 2013. This could skew Stoaty's calibration a bit since I think the model uses multi-year averages for climate while most of the cars used for calibration were exposed to the hottest summer ever in Phoenix.

 

[RegGuheert]

46.0 - end of the line. ready for a nursing home. (or a new battery, if you can get one before your warranty clock expires)

Not necessarily. It all depends how far you need to drive. A LEAF which only needs to travel 25 miles should have no problems operating with four bars gone.

The big question I have in my mind is whether the batteries will "fall of a cliff" beyond this point. So far, we do not have any data, since, to my knowledge, all LEAF batteries that have lost their fourth bar have been taken into the dealer for warranty replacement. But eventually we will have data for how LEAFs do with four, five, six, seven and perhaps more bars lost. We intend to keep ours that long if at all possible.

 

[Weatherman]

46.0 - end of the line. ready for a nursing home. (or a new battery, if you can get one before your warranty clock expires)

Not necessarily. It all depends how far you need to drive. A LEAF which only needs to travel 25 miles should have no problems operating with four bars gone.

I really feel sorry for the first LEAF owner who reaches "end-of-life" on their battery (about 46 Ahrs) just a hair after 5 years or 60,000 miles. Most likely will be a California resident, the way things are going.

 

[thankyouOB]

the tooth fairy will fix it for those owning the car after five years; that, or the SYB.*


*Steal Your Battery Program

 

[TimLee]

The big question I have in my mind is whether the batteries will "fall off a cliff" beyond this point. So far, we do not have any data, since, to my knowledge, all LEAF batteries that have lost their fourth bar have been taken into the dealer for warranty replacement. But eventually we will have data for how LEAFs do with four, five, six, seven and perhaps more bars lost. We intend to keep ours that long if at all possible.

That is the big uncertainty.
If capacity doesn't fall off a cliff, my 2011 LEAF might be pretty useful down to 55% capacity with my 32 miles round trip to downtown. And with my low miles per year, the LEAF might be 10 years old by then.
But the lower capacity goes, the harder you push the battery. More 100% charging, more DCQC.
I quit doing the round trip to downtown starting with only an 80% charge more than a year ago, even though I only lost the first capacity bar early this summer.

 

[Stanton]

But for now I plan to avoid the P3227 software update, so unfortunately the data won't be going into improvement of Stoaty's model. I don't like the change in regeneration that P3227 does that most are reporting. But my guess is that the dealer will do it whether I want it or not at my three year battery test on May 18, 2014.

The way I look at it is you can take your medicine now or take it later; if you ever expect to benefit from the 5yr/60k mile warranty, you HAVE to have it. I also think the update is worth it to get the OBC update (and avoid a costly trip to the dealer).

 

[edatoakrun]

Don't get fooled by seasonality. Get a year of data before trying to make sense of it.

+1

I think you can see some seasonality in the data...

Of course you can see that battery heat appears to be the predominant factor in battery capacity loss in Phoenix, as I mentioned on the thread covering this study a few weeks back.

...The expected accelerated loss of capacity in summer, as well as additional loss of capacity from fast charging, are both showing up IMO, with ~14% capacity loss on L2, and ~17% loss on DC.

Which should hardly be surprising, as Nissan (in the sales contract disclaimer) listed high battery temperatures first among the conditions to be avoided to maintain battery capacity.

And the failure of the model to reflect (and LEAF drivers generally to understand) the seasonal nature of capacity loss due to climate (as the hysteria over LEAF "premature battery degradation" predictably peaks every Summer along with average temperatures) is a situation I have been commenting on for several years now.

But even the two study LEAFs enduring the battery heating resulting from several DC charges each day including at least some Summer Phoenix heat (I wish we hade exact dates) only lost a total of ~ 17% of capacity over 30k miles.

When we get the 40 k report, do you really think it very likely that even the DC-charged LEAFs will lose another ~13% (and for the somewhat-less-abused L2-charged LEAFs, another ~16%) of capacity in just ~2-3 months and ~10k miles to ~"catch up" with the model's prediction of 30% capacity loss in one year at 40 k miles?

Could happen, but unlikely, IMO.

 

[smkettner]

Prediction is.... No warranty for me

 

[RegGuheert]

Prediction is.... No warranty for me

Agreed, but the model seems to be *underpredicting* the losses you have seen by a little bit. I put in Anaheim for city and it didn't think you would lose your second bar until past about 40,000 miles when you lost it at 36. You still might make it, but it will be close.

 

[Stoaty]

Ed, I had a look at the study of the Leafs. The battery aging model can't be applied to the study Leafs for a several reasons:

1) As per the instructions, periods of time less than one year are not considered to be meaningful. Calendar aging is a major part of capacity loss in any climate, and wasn't captured well with this artificial setup.
2) We don't know how much time the Leaf was parked in the sun, or where it was stored when not being driven
3) We don't know the efficiency with which the Leafs were driven
4) If the test was started in October as per the statement, had 20,000 miles by March 8, then 30,000 miles probably wouldn't include July, August or September (didn't see the exact dates), some of the hottest months.

The basic conclusion from the study is that you can drive a Leaf 30,000 miles in Phoenix over 9 months during the cooler part of the year and only lose about 14% of capacity if you don't use QC. That isn't a surprise to anyone, but also isn't of much help for the Phoenix owners.

 

[Stoaty]

Testing the battery aging model against the measured loss in the study referenced by Ed, and assuming Phoenix, 4 miles per kwh, no solar loading, and 30,000 miles in one year gives:

Predicted Capacity Loss - 22%

Actual Capacity Loss (after 9 months calendar aging and 30,000 miles) - 14%

So the question is, "Would a 9 month old Leaf sitting around for 3 months in Phoenix during a hot summer lose 8% battery capacity?" It wouldn't surprise me if it would lose that much, as calendar capacity loss is greatest in the first year, and in high ambient temperatures.

Bottom line: while not directly comparable, the Battery Aging Model would likely not be far off if the test Leaf sat through a hot Phoenix summer before doing the capacity loss measurement.

 

[TimLee]

; if you ever expect to benefit from the 5yr/60k mile warranty, you HAVE to have it. I also think the update is worth it to get the OBC update (and avoid a costly trip to the dealer).

Yes, if you have any possibility of qualifying for the inadequate 5yr/60K mile capacity warranty, you eventually HAVE to have it. But the only thing having P3227 done sooner does for you is letting you know sooner where you are, other than the charging software CORRECTION.
But with my low miles per year and southeast TN climate, the chances of qualify for 5yr/60K mile capacity warranty without taking adverse "atypical normal behaviour" negative action to degrade the battery capacity is probably less than 10%.
The only L2 EVSE that I have ever used were Blink and Eaton. I doubt there is a GE Wattstation within 500 miles of me.
I don't want to have the regeneration degraded unnecessarily. I still think I'll wait. Maybe with four to six months of pre-P3227 software data from Leaf Spy Pro telling me approximately where I am I may decide differently and think I need the post-P3227 software better capacity accuracy to forecast where I am and help educate my actions. But from what I have learned on MNL, I will wait on the P3227 software change a bit longer.

 

[RegGuheert]

Prediction is.... No warranty for me

Agreed, but the model seems to be *underpredicting* the losses you have seen by a little bit. I put in Anaheim for city and it didn't think you would lose your second bar until past about 40,000 miles when you lost it at 36. You still might make it, but it will be close.

I took another look at how the tool could be used to predict whether or not you will make the warranty window. What I did in your case was to preserve the city (I used Anaheim, perhaps there is a better one?) and miles per year, but I adjusted the solar loading and efficiency until I got a match for both the times and miles where you lost your first two bars. Using these settings, the tool predicts that you will cross below 70% at 56,000 miles. Depending upon at what capacity level your car removes the fourth bar should make the difference. Note that some LEAFs have lost the fourth bar with the capacity meter reading 69%.

Here is what I used and what I got:


If it were me, I think would drive it to about 58,000 miles and if it has not lost the fourth bar by then, I would then just park it and drive it about once a month until that bar disappears. Then you can get a new (hopefully improved) battery and will end up getting a good, long life out of the vehicle. Of course that all assumes that you have something else to drive in the meantime.

 

[smkettner]

Thanks for the support

I just put new tires on that will drop my efficiency down from 4.5. Use of climate control will be more. Using midnight start timer instead of 6:30 end timer (100%). Not driving as conservative. Yet trying to drive less. May as well enjoy the vehicle and not worry so much about making the battery last 120,000 miles.

I do have an F150 that gets 14mpg that might be worth driving for a new battery. But then If I am so close I would not be suprised if Nissan had a few 10 bar batteries sitting around for warranty people like me right at the edge.

 

[edatoakrun]

...If it were me, I think would drive it to about 58,000 miles and if it has not lost the fourth bar by then, I would then just park it and drive it about once a month until that bar disappears...

If it were me and I thought I really had lost ~30% capacity at ~58,000 miles, whatever the bar display or an App/gid meter shows, I would bring it in for the warrantee and see what happens, before parking the LEAF for months or doing anything else.

IMO, Nissan is unlikely to deny warranty service to nine-capacity bar LEAFs, when every LEAF driver knows how to make that ninth bar disappear...

 

[RegGuheert]

But then If I am so close I would not be suprised if Nissan had a few 10 bar batteries sitting around for warranty people like me right at the edge.

It's a possibility, but I doubt it. It seems to me that Nissan will want to be putting the "hot battery" into any LEAF that loses capacity as fast as yours does. If I am right, then that would mean a new, better battery, which should extend you quite a bit beyond the next 60,000 miles.

If it were me and I thought I really had lost ~30% capacity at ~58,000 miles, whatever the bar display or an App/gid meter shows, I would bring it in for the warrantee and see what happens, before parking the LEAF for months or doing anything else.

IMO, Nissan is unlikely to deny warranty service to nine-capacity bar LEAFs, when every LEAF driver knows how to make that ninth bar disappear...

It certainly doesn't hurt to ask! Of course the dealerships do not have the power to make such a decision, but they are the proper point of contact to take it up the chain.

 

[nogajim]

My predicted loss over 2.55 years in Atlanta was 15.74, but my actual is 18.52. I am not sure of any one thing that might cause the difference. My Ahr, mileage and 80% GIDS were collected today. I estimated my days in the sun as 3. In the summer, it is mostly in my garage, the rest of the year it parks outside with partial shade.

It does not predict that I will qualify for the warranties.

Thanks for making this great tool available!
Jim

 

[Stoaty]

My predicted loss over 2.55 years in Atlanta was 15.74, but my actual is 18.52. I am not sure of any one thing that might cause the difference. My Ahr, mileage and 80% GIDS were collected today. I estimated my days in the sun as 3. In the summer, it is mostly in my garage, the rest of the year it parks outside with partial shade.

Have you had the P3227 update? The spreadsheet was calibrated with post-P3227 data and is not expected to be valid for those who don't have the update. If you have had the update, please enter the requested information in the thread "Tuning the Battery Aging Model" (unless you already did and I just forgot). I need more data from hotter climates for further tuning.