Turning Over a New LEAF: My Response to a Lost Capacity Bar

[LTLFTcomposite]

You can BTW extend for six months assuming it's a Nissan lease.

Whatchutalkinboutwillis?

You can extend the lease for six months at the same rate.

And the residual drops accordingly?
I leased for 36 months specifically to coincide with the bumper to bumper warranty. My luck some other expensive repair would pop up in that time frame (didn't someone here say they had a headlight go bad and it was nearly a grand to replace it?) so I probably wouldn't extend but good to know it's an option.

 

[DaveinOlyWA]

i dont think its outrageous to have a temporary loss in extreme temps which does happen in cold and hot. i do not have access to 21 Kwh in winter like i do in Summer. i tested that theory twice. once before the GID, once after and the results were probably temp related since i got access to just over 19 Kwh once and just under 19 Kwh the 2nd time. so the winter hit is less performance and less capacity.

so to have the same but to a lesser degree for Summer i can believe. problem with that i see. it would appear that a portion of the summer loss is permanent and likely to be cumulative.

i expected to have at least 5% after a year and up to 10% degradation after 18 months. i thought there would be a big chunk lost at first (still do) and then it would taper off to 1-2 % a year ending at 20% after 5

so could have been

year 1; 10% lost
year2-5 2% lost total 20%

or

year 1; 15% loss
year 2-5; 1% loss total 20%

now that i have not seen any real loss yet. i expect when it starts it will be 10-15% that everyone else is seeing before it levels off. for those few who are seeing more. that might be temporary due to the heat.

 

[klapauzius]

i dont think its outrageous to have a temporary loss in extreme temps which does happen in cold and hot. i do not have access to 21 Kwh in winter like i do in Summer. i tested that theory twice. once before the GID, once after and the results were probably temp related since i got access to just over 19 Kwh once and just under 19 Kwh the 2nd time. so the winter hit is less performance and less capacity.

so to have the same but to a lesser degree for Summer i can believe. problem with that i see. it would appear that a portion of the summer loss is permanent and likely to be cumulative.

i expected to have at least 5% after a year and up to 10% degradation after 18 months. i thought there would be a big chunk lost at first (still do) and then it would taper off to 1-2 % a year ending at 20% after 5

so could have been

year 1; 10% lost
year2-5 2% lost total 20%

or

year 1; 15% loss
year 2-5; 1% loss total 20%

now that i have not seen any real loss yet. i expect when it starts it will be 10-15% that everyone else is seeing before it levels off. for those few who are seeing more. that might be temporary due to the heat.

I think the mechanisms for heat and cold are different. Whenever Thermodynamics is involved,
things are irreversible.

Understand that the higher/lower power/cap relationship between warm and cold is due to the normal battery chemistry going faster/slower at higher/lower temps. That is the normal function
of the battery. These changes take place on a rather fast timescale (i.e. however long it takes the battery pack to reach a given temperature, a few hours maybe).

Degradation is a totally different animal, that is the chemical process that destroys, if my understanding is correct, the electrodes of the battery. I takes place on a timescale of several years ( or so we hope) AND it is, unlike the normal battery operation, NON-reversible.
So hot temps speed this decay up, low temps slow it down, but ill goes in just one direction.

Put a rotten steak in the freezer and it wont become fresh and tasty again.

It might be however that there is an artificial intervention involved in the process, TickTocks cap vs temperature data indicate an almost linear relationship between temperature and capacity, but opposite to what you would expect from chemistry. So maybe the BMS is doing something...?

 

[klapauzius]

If everyone wants to chip in for my electric bill, I'll charge my car in my air conditioned shop for the next week and see if I get a bar back.. lol

I think this test would work within the time frame to cool the battery pack to whatever ambient temperature your workshop has.

So here is the experiment:

1) Set your workshop to various temps, e.g. 65-70-75-80-85-90,

2) measure the battery pack temperature, when it reaches the set temperature on the thermostat, charge to full

3) measure gids (or true capacity if you have access to more sophisticated measures)

4) plot gids/cap vs. temps.

You could try one temperature setting each day. If the BMS would somehow reduce capacity because of higher temperatures, this should show it.

The thermodynamic process that destroys the battery is of course irreversible and cold temps merely slow it down, but artificial interventions could create the illusion of temporary loss.
It seems like grasping after straws though...

 

[jspearman]

Thanks for the thoughtful post, Shrink. I am in a similar boat, since this is my wife's daily driver and she is reluctant to trade the car for another. Are there any women on this forum?

I'm interested to see what kind of depreciation that car dealers assign to the loss of bars after trading electric cars becomes more common. I think you are right that they likely had no idea what they were looking at, except a shiny electric car with low mileage. I think we will hang on until Nissan proposes some kind of solution.

 

[leafkabob]

Thanks for the thoughtful post, Shrink. I am in a similar boat, since this is my wife's daily driver and she is reluctant to trade the car for another. Are there any women on this forum?

I'm interested to see what kind of depreciation that car dealers assign to the loss of bars after trading electric cars becomes more common. I think you are right that they likely had no idea what they were looking at, except a shiny electric car with low mileage. I think we will hang on until Nissan proposes some kind of solution.

Same boat here too. Our Leaf is my wife's daily driver and she is very reluctant for me to push Nissan to any resolution that would cause her to lose the leaf. She said the thought of going back to an ICE turns her stomach. It does me too, which makes this a real quandry.

 

[DaveinOlyWA]

I think the mechanisms for heat and cold are different. Whenever Thermodynamics is involved,
things are irreversible.

Understand that the higher/lower power/cap relationship between warm and cold is due to the normal battery chemistry going faster/slower at higher/lower temps. That is the normal function
of the battery. These changes take place on a rather fast timescale (i.e. however long it takes the battery pack to reach a given temperature, a few hours maybe).

Degradation is a totally different animal, that is the chemical process that destroys, if my understanding is correct, the electrodes of the battery. I takes place on a timescale of several years ( or so we hope) AND it is, unlike the normal battery operation, NON-reversible.
So hot temps speed this decay up, low temps slow it down, but ill goes in just one direction.

Put a rotten steak in the freezer and it wont become fresh and tasty again.

It might be however that there is an artificial intervention involved in the process, TickTocks cap vs temperature data indicate an almost linear relationship between temperature and capacity, but opposite to what you would expect from chemistry. So maybe the BMS is doing something...?

right and the issue we probably have here is the battery management not working well in temps hotter than expected.

suppose, we charge to 100% of available capacity in a garage. its 85 or whatever. we leave garage hit the 110º pavement. we drive just a few miles, SOC still near enough to 100% that the additional heat created pushes the battery over its limits. granted, just a little. but that little tiny bit is lost capacity, never to return. this can add up to the significant loss AZ'ers are seeing over time.

that is one probably mechanism. the other is Battery management itself. it is out and about, temps are high. charging starts and battery management purposefully restricts access to the full capacity as a protection measure against the still high temps. so instead of going to the 100% of available capacity, it stops short at say 90% to give that extra head room in case temps spike up again. this will come back.

 

[Kataphn]

Are there any women on this forum?

Yes, woman here...there are several of us that post from time to time.

 

[LEAFfan]

There are drivers now that are close to losing their third bar so I highly doubt if these bars are going to come back when the weather cools. The cooler weather (winter) may slow down the degradation until the heat comes again (it only takes 87F or higher to start the larger degradation process and we have those temps most of the year), but another bar will disappear during the summer and the degradation will once again accelerate.

 

[shrink]

Some new data:

Leaffan was generous enough to come over and take some reading with his Scan Gauge today.

On the new 2012 LEAF that now has about 100 miles on it, a 100% charge resulted in 95.3%.

My 2011 LEAF on 5/25/2012 had 85.7% on the same gauge. I lost my 1st bar on 6/21/2012. I believe leafkabob lost his 1st capacity bar one day after an 81.1% reading on his LEAF.

95.3% - 81.1% = 14.2%

So, that's just about the 15% capacity loss listed in the service manual.

 

[DANandNAN]

Time for some more garage photos with the new Leaf. Great color choice (both times). We just got back from the dealer, still can't pull the trigger - I need ( :roll: ) it to have the 6.6 for some reason. Come on 2013's!

 

[klapauzius]

There are drivers now that are close to losing their third bar so I highly doubt if these bars are going to come back when the weather cools. The cooler weather (winter) may slow down the degradation until the heat comes again (it only takes 87F or higher to start the larger degradation process and we have those temps most of the year), but another bar will disappear during the summer and the degradation will once again accelerate.

Where do the 87F come from? My understanding
was that the battery degradation is a continuous function
of temperature?

 

[cwerdna]

I wonder if the '12 Leafs will exhibit even more rapid heat-related battery degradation/capacity loss given the (additional?) battery insulation on the '12.

 

[LEAFer]

Some new data:

Leaffan was generous enough to come over and take some reading with his Scan Gauge today.

On the new 2012 LEAF that now has about 100 miles on it, a 100% charge resulted in 95.3%.

My 2011 LEAF on 5/25/2012 had 85.7% on the same gauge. I lost my 1st bar on 6/21/2012. I believe leafkabob lost his 1st capacity bar one day after an 81.1% reading on his LEAF.

95.3% - 81.1% = 14.2%

So, that's just about the 15% capacity loss listed in the service manual.

Useful data, but not conclusive. On the new LEAF in particular, you need to repeat after several charges to make sure battery is balanced. Also, there seems to be a break-in effect, where the SOC will go up in the early weeks. TonyWilliams's LEAF reached 279/281 last week, although I don't know if he kept (or posted) data from the day it was new (May). Repeat in a month to confirm.

 

[LakeLeaf]

95.3% - 81.1% = 14.2%

So, that's just about the 15% capacity loss listed in the service manual.

If 95.3% is the highest reading you get, then shouldn't your calculation be:

81.1 / 95.3 = .85099 - or a 14.9% loss?

A few more weeks of hot weather and you may be over the claimed 15% in 5 years.

 

[DaveinOlyWA]

95.3% - 81.1% = 14.2%

So, that's just about the 15% capacity loss listed in the service manual.

If 95.3% is the highest reading you get, then shouldn't your calculation be:

81.1 / 95.3 = .85099 - or a 14.9% loss?

A few more weeks of hot weather and you may be over the claimed 15% in 5 years.

you could look at it that way if considering accessible loss only but you would have to redo your numbers since 1% is not accessible either.

now, if considering pack health, then the 14.2% is correct since it only accounts for capacity and not what is available to use

 

[edatoakrun]

...there seems to be a break-in effect, where the SOC will go up in the early weeks. TonyWilliams's LEAF reached 279/281 last week, although I don't know if he kept (or posted) data from the day it was new (May). Repeat in a month to confirm.

The gid count was lower on delivery? That's interesting. Anybody else tracking gids on a LEAF from new?

You suppose that new LEAFs may be delivered with an initial restriction on the "100%" charge level, that then adjusts, up or down, in response to the battery pack's temperature experience?

Except for the relatively short-term QC effects, I expect that Tony's battery has stayed pretty cool?

 

[turbo2ltr]

Yeah there is definitely a break in period. Took about 2000 miles for me, but my guess is it's more charge cycle based so YMMV.

 

[edatoakrun]

Yeah there is definitely a break in period. Took about 2000 miles for me, but my guess is it's more charge cycle based so YMMV.

I don't understand what you mean by "break in". You are referring to your LEAF, last winter, right?

You had a record of increasing gid or SOC count?

Increasing kWh use for the "100%" charge?

Longer range?

Other?

 

[mwalsh]

Do you have reports of that happening last year? Some folks have lost 2 bars, surely they would have lost 1 bar last year and then had it reappear as the weather cooled and the battery regenerated. Are there any posts about that?

That didn't happen. My best guess is what has been proposed elsewhere - that we had unreported capacity, which kept us all looking like we had 100% of capacity (or thereabouts) until spring of this year.