The 40KWH Battery Topic

[danrjones]

ok so that is .08% per month? I think I could live with that.

I have to put myself on record as saying I am not on board with daily readings having any major significance and yeah, this is coming from someone who has recorded stats EVERY day my LEAFs have been driven for a few days short of 7 years.

No its not. You are completely forgetting the 3 month adjustments. My last one was 1.47% just by itself.

I have now had the car for a year. It has lost 7.48% since I bought it.

I don't yet buy into the idea the new batteries are better in heat. This summer should tell me a lot.
I certainly have seen no sign of my SOH adjusting up as others have seen. TBD.

I guess you just need more time. My pack was in lockstep with yours. Nearly identical along with several others. After a year, I had lost 6.73% (must be that cooler climate, right?)

9+ (yeah, 3 adjustments later) months later, I had lost another .61%

Reread this forum. Compare losses in the first year against losses since then. We have people approaching 2½ years here.

It is not lockstep. How many miles did you have at 1 year of ownership? I just passed 5500 miles. Others with the same degradation might have two or three times the mileage. You can't separate out what is caused by mileage versus heat (or anything else) without a lot more data. A lot more than we have.

And if heat had no player in battery degradation on the newer packs, why does the pack adjustments slow during winter?

No offense but you come off as a bit overly optimistic, seeing what you want from limited data. We can all hope you are right, but I would not assume. If I go through a hot summer here and only loose 1-2% additional, I'll be pleasantly surprised.

 

[DaveinOlyWA]

No its not. You are completely forgetting the 3 month adjustments. My last one was 1.47% just by itself.

I have now had the car for a year. It has lost 7.48% since I bought it.

I don't yet buy into the idea the new batteries are better in heat. This summer should tell me a lot.
I certainly have seen no sign of my SOH adjusting up as others have seen. TBD.

I guess you just need more time. My pack was in lockstep with yours. Nearly identical along with several others. After a year, I had lost 6.73% (must be that cooler climate, right?)

9+ (yeah, 3 adjustments later) months later, I had lost another .61%

Reread this forum. Compare losses in the first year against losses since then. We have people approaching 2½ years here.

It is not lockstep. How many miles did you have at 1 year of ownership? I just passed 5500 miles. Others with the same degradation might have two or three times the mileage. You can't separate out what is caused by mileage versus heat (or anything else) without a lot more data. A lot more than we have.

And if heat had no player in battery degradation on the newer packs, why does the pack adjustments slow during winter?

No offense but you come off as a bit overly optimistic, seeing what you want from limited data. We can all hope you are right, but I would not assume. If I go through a hot summer here and only loose 1-2% additional, I'll be pleasantly surprised.

That is your statement. I am overly optimistic? Actually I am only reporting observations. As far as what would have happened on month 23 on my 40 kwh? Dk, didn't have it that long.

On your "winter time is best" argument. On my first full winter, I drove less than 1000 miles a month, very few DC sessions, Batt temps NEVER exceeded 80º and had my worst adjustment on my 40 kwh pack losing 1.7% SOH in just over 2300 miles.

As far as miles making a difference? Lets look at that statement. Not sure how you are arriving at that when many of us are seeing similar degradation rates in the first year in all different types of climate, driving a lot or driving a little so no common ground...

except ONE thing.

Its every 90 days... so miles driven? Sorry not seeing that correlation either.

I have had people comment on my blog about "having less data and more conclusions" and I tell them conclusions are only valid after the story is done. Data is what gets you in the neighborhood. How you take it is up to you which is why I post the data and I take off with it and you can follow my lead or make your own path.

 

[danrjones]

I'm not here to argue with you, just to share my data.
You might be right. But you could be completely wrong. Trying to arrive at a conclusion as to what degrades the battery when every's data was collected under different circumstances with a multitude of variables being different is suspect at best.

You would need one heck of a design of experiments, DOE, to compare data and reach a conclusion with multiple variables changing under the BEST controlled circumstances....

I'll keep reporting my data and we shall see where the SOH goes.

 

[Marktm]

You would need one heck of a design of experiments, DOE, to compare data and reach a conclusion with multiple variables changing under the BEST controlled circumstances....

I'll keep reporting my data and we shall see where the SOH goes.

I've always assumed (we all know you and me and being an a**h*** :mrgreen that the ahrs are the best direct measure of the battery energy/performance, of course determined by the SOC and voltage. VA for DC is essentially the same as Watts - I've been told!

Your ahrs have been amazingly stable - especially for the last year and several months if I've read your data properly, in fact it seems seasonal temps have had little to no affect on ahrs.

Any comments anyone?

 

[danrjones]

You would need one heck of a design of experiments, DOE, to compare data and reach a conclusion with multiple variables changing under the BEST controlled circumstances....

I'll keep reporting my data and we shall see where the SOH goes.

I've always assumed (we all know you and me and being an a**h*** :mrgreen that the ahrs are the best direct measure of the battery energy/performance, of course determined by the SOC and voltage. VA for DC is essentially the same as Watts - I've been told!

Your ahrs have been amazingly stable - especially for the last year and several months if I've read your data properly, in fact it seems seasonal temps have had little to no affect on ahrs.

Any comments anyone?

Honestly not sure which data you are looking at. My leaf spy AHr readings drop in accordance with my SOH. I've assumed SOH is calculated straight off AHr. Even if not, they both show the same degradation.

Now I still cannot answer whether my degradation is real or not. I only have anecdotal evidence from a few runs comparing my results against a better route planner, where 9% degradation best fits. But its not good data as I have no control over temp and winds which could mask real results.

 

[Marktm]

Honestly not sure which data you are looking at. My leaf spy AHr readings drop in accordance with my SOH. I've assumed SOH is calculated straight off AHr. Even if not, they both show the same degradation.

Now I still cannot answer whether my degradation is real or not. I only have anecdotal evidence from a few runs comparing my results against a better route planner, where 9% degradation best fits. But its not good data as I have no control over temp and winds which could mask real results.

When I plotted your data, to compare directly to mine, it struck me that your degradation was essentially during the first year - the second has been essentially flat amphours - nothing like mine. I would like to understand the differences as I'm trying to find a newer Leaf that will get me to my cabin ~100 miles - that will likely require the 40 amphours minimum - but with little degradation.

This is the plot of your amphours:

 

[DougWantsALeaf]

For cheap range, I would go for a heavily discounted 2019 Leaf Plus S with as few options as possible. After federal rebate, you are at mid 20's plus tax.

 

[DaveinOlyWA]

You would need one heck of a design of experiments, DOE, to compare data and reach a conclusion with multiple variables changing under the BEST controlled circumstances....

I'll keep reporting my data and we shall see where the SOH goes.

I've always assumed (we all know you and me and being an a**h*** :mrgreen that the ahrs are the best direct measure of the battery energy/performance, of course determined by the SOC and voltage. VA for DC is essentially the same as Watts - I've been told!

Your ahrs have been amazingly stable - especially for the last year and several months if I've read your data properly, in fact it seems seasonal temps have had little to no affect on ahrs.

Any comments anyone?

Honestly not sure which data you are looking at. My leaf spy AHr readings drop in accordance with my SOH. I've assumed SOH is calculated straight off AHr. Even if not, they both show the same degradation.

Now I still cannot answer whether my degradation is real or not. I only have anecdotal evidence from a few runs comparing my results against a better route planner, where 9% degradation best fits. But its not good data as I have no control over temp and winds which could mask real results.

Nothing more than a happy coincidence. Both values are taken directly from the bus. There are many many examples that show the two values diverging.

 

[danrjones]

Honestly not sure which data you are looking at. My leaf spy AHr readings drop in accordance with my SOH. I've assumed SOH is calculated straight off AHr. Even if not, they both show the same degradation.

Now I still cannot answer whether my degradation is real or not. I only have anecdotal evidence from a few runs comparing my results against a better route planner, where 9% degradation best fits. But its not good data as I have no control over temp and winds which could mask real results.

When I plotted your data, to compare directly to mine, it struck me that your degradation was essentially during the first year - the second has been essentially flat amphours - nothing like mine. I would like to understand the differences as I'm trying to find a newer Leaf that will get me to my cabin ~100 miles - that will likely require the 40 amphours minimum - but with little degradation.

This is the plot of your amphours:

40 amphour data.jpg

Except that is not my data. I bought the car in may 2019. I think you have confused someone else's data for mine. Mine to date has always been going down. I just hit my one year mark.

My current Ahrs are at 104.07.

 

[danrjones]

But I do have my records and you have inspired me. I'll post my chart later today.

 

[danrjones]

My AHr chart.

 

[LeftieBiker]

Right clicking on the word "image" will show the chart. Very regular drops!

 

[danrjones]

Right clicking on the word "image" will show the chart. Very regular drops!

Yes I was really hoping those drops would slow down. I know some on here have dramatically slowed or reversed after 1 year but haven't seen that myself. Next big update should be around June 10th.

 

[Marktm]

danrjones:
My apologies - careless reposting of jmurtagh13's data :roll: . Glad to see your data plotted yesterday.

Two years and one month with an upward correction of +0.38%. Giving me an increase in battery health over the last year of +0.03%
I've had 2 other upward corrections, last one being on 10/13/2019. Since March of last year the battery degradation has been fairly flat.
I keep the charge between 30 and 70%, Charge only at home and charge early morning when the battery is cooler. I'm at 18,400 miles.

....Date.......SOH.......HX......AH.....Chg
03/09/2018 99.10 98.86 115.00
07/14/2018 97.13 111.58 112.13 -1.97
09/21/2018 96.15 111.74 111.00 -0.98
10/18/2018 94.91 112.07 109.56 -1.24
12/31/2018 94.77 111.47 109.40 -0.14
01/15/2019 93.69 111.75 108.16 -1.08
01/21/2019 92.21 111.97 106.45 -1.48
03/01/2019 92.14 112.26 106.37 -0.07
04/06/2019 92.09 112.27 106.31 -0.05
06/13/2019 91.34 113.00 105.44 -0.75
07/01/2019 91.25 113.66 105.34 -0.09
07/10/2019 91.20 113.80 105.28 -0.05
07/12/2019 91.67 113.83 105.83 +0.47
07/28/2019 91.60 114.00 105.74 -0.07
09/10/2019 91.40 113.57 105.51 -0.20
10/13/2019 91.92 113.52 106.11 +0.52
11/11/2019 91.86 111.66 106.04 -0.06
12/10/2019 91.84 111.83 106.02 -0.02
01/10/2020 91.80 112.26 105.97 -0.04
02/10/2020 91.77 112.07 105.94 -0.03
03/10/2020 91.74 112.16 105.90 -0.03
04/10/2020 92.12 111.46 106.34 +0.38

 

[Marktm]

Right clicking on the word "image" will show the chart. Very regular drops!

Yes I was really hoping those drops would slow down. I know some on here have dramatically slowed or reversed after 1 year but haven't seen that myself. Next big update should be around June 10th.

Yes, looks somewhat similar to jmurtagh13's first year - hope it does level out over the next months.

 

[DougWantsALeaf]

Those adjustments back up are quite fascinating. I makes me feel like there is an algorithm artificially pre-lowering the SOH, and then giving it back as the battery ages against their internal model.

 

[Marktm]

What would be interesting is to know how EV manufacturers come up with their battery "capacity" - and is there any consistency between manufacturers.

My "24" kWh battery started at approx 66 amphours. At full charge (90%), with a fairly consistent 394 VDC that would result in ~26 KVAhrs. At "turtle" with a fairly consistent 330 VDC that would be ~22KVAhrs .

Data from jmurtagh13 and danrjones shows that initial amphours for the "40" kWh battery is 113-115, say 114. Using the same voltages as my 24 kWh battery (probably not correct due to chemistry changes), that would give an energy range of ~45 to 38 KVAhrs (essentially kWh).

I realize this is more "musing" than anything else, but seeing a fairly rapid drop in the "40" kWh battery down to around 105 amphours - and potentially then remaining along a fairly flat degradation line - it makes me wonder what is an accurate assessment of the original battery capacity.

I wonder if any of the EV "designers/engineers" have comments on this? Realizing that the bottom line is more about the EPA information :mrgreen:

https://pushevs.com/electric-car-range-efficiency-epa/

 

[danrjones]

....Date.......SOH.......HX......AH.....Chg
03/09/2018 99.10 98.86 115.00
07/14/2018 97.13 111.58 112.13 -1.97
09/21/2018 96.15 111.74 111.00 -0.98
10/18/2018 94.91 112.07 109.56 -1.24
12/31/2018 94.77 111.47 109.40 -0.14
01/15/2019 93.69 111.75 108.16 -1.08
01/21/2019 92.21 111.97 106.45 -1.48
03/01/2019 92.14 112.26 106.37 -0.07
04/06/2019 92.09 112.27 106.31 -0.05
06/13/2019 91.34 113.00 105.44 -0.75
07/01/2019 91.25 113.66 105.34 -0.09
07/10/2019 91.20 113.80 105.28 -0.05
07/12/2019 91.67 113.83 105.83 +0.47
07/28/2019 91.60 114.00 105.74 -0.07
09/10/2019 91.40 113.57 105.51 -0.20
10/13/2019 91.92 113.52 106.11 +0.52
11/11/2019 91.86 111.66 106.04 -0.06
12/10/2019 91.84 111.83 106.02 -0.02
01/10/2020 91.80 112.26 105.97 -0.04
02/10/2020 91.77 112.07 105.94 -0.03
03/10/2020 91.74 112.16 105.90 -0.03
04/10/2020 92.12 111.46 106.34 +0.38

One thing I find interesting is that HX (if it even means anything) does not seem to be as uniform from driver to driver. In the data above the car has a SOH of 92.12 and an HX of 111.46, but at one time the HX had hit 114. My HX is lower, at only 109.17, and yet my SOH as of this AM is 90.13. My HX has gradually increased more or less, except the one time I fast charged, and that caused a large upward spike for about 2 weeks. If HX is in someway related to internal resistance of the pack, say caused by use/cycles/ or heat, one would expect higher HX to lead to lower SOH, would you not?

 

[DougWantsALeaf]

My belief is that the reported SOH is now no longer the true pack value, rather a number that Nissan is overriding using a model to help manage longevity of the pack.

 

[lorenfb]

....Date.......SOH.......HX......AH.....Chg
03/09/2018 99.10 98.86 115.00
07/14/2018 97.13 111.58 112.13 -1.97
09/21/2018 96.15 111.74 111.00 -0.98
10/18/2018 94.91 112.07 109.56 -1.24
12/31/2018 94.77 111.47 109.40 -0.14
01/15/2019 93.69 111.75 108.16 -1.08
01/21/2019 92.21 111.97 106.45 -1.48
03/01/2019 92.14 112.26 106.37 -0.07
04/06/2019 92.09 112.27 106.31 -0.05
06/13/2019 91.34 113.00 105.44 -0.75
07/01/2019 91.25 113.66 105.34 -0.09
07/10/2019 91.20 113.80 105.28 -0.05
07/12/2019 91.67 113.83 105.83 +0.47
07/28/2019 91.60 114.00 105.74 -0.07
09/10/2019 91.40 113.57 105.51 -0.20
10/13/2019 91.92 113.52 106.11 +0.52
11/11/2019 91.86 111.66 106.04 -0.06
12/10/2019 91.84 111.83 106.02 -0.02
01/10/2020 91.80 112.26 105.97 -0.04
02/10/2020 91.77 112.07 105.94 -0.03
03/10/2020 91.74 112.16 105.90 -0.03
04/10/2020 92.12 111.46 106.34 +0.38

One thing I find interesting is that HX (if it even means anything) does not seem to be as uniform from driver to driver. In the data above the car has a SOH of 92.12 and an HX of 111.46, but at one time the HX had hit 114. My HX is lower, at only 109.17, and yet my SOH as of this AM is 90.13. My HX has gradually increased more or less, except the one time I fast charged, and that caused a large upward spike for about 2 weeks. If HX is in someway related to internal resistance of the pack, say caused by use/cycles/ or heat, one would expect higher HX to lead to lower SOH, would you not?

HX has become meaningless for Leaf2 vehicles. Previously, it was the ratio of battery resistance (new/present) as a percent and tracked SOH.