The 40KWH Battery Topic

[LeftieBiker]

I used to think that Hx was the SOH of the pack at the moment the reading was taken, and that SOH was a longer term average. This jibed well with LeafSpy readings from 24kwh packs, but when the 40kwh pack arrived, Hx was suddenly nonsensical. So, in short, no.

 

[DougWantsALeaf]

Leftie

Do we have any reason to believe that the SOH isn’t accurate or a good relative measure any more?

 

[LeftieBiker]

Leftie

Do we have any reason to believe that the SOH isn’t accurate or a good relative measure any more?

No. It seems to be just Hx that has changed.

 

[WetEV]

Leftie

Do we have any reason to believe that the SOH isn’t accurate or a good relative measure any more?

No. It seems to be just Hx that has changed.

SOH is an estimate. Accuracy isn't better than -3% +10%.

 

[danrjones]

I put 8% degradation into ABRP and went up to a mountain pass and back this last weekend for hiking.

The predicted results from ABRP exactly matched my arrival there and round trip.

But it's also possible other errors just happen to offset ABRP to make it appear like 8% degradation was correct. Not proof but interesting.

 

[cwerdna]

Has anyone figured out a relationship between HX, which people seem to think is a measurement of the internal resistance of the battery, and SOH?

Tracking my data HX has been a bit odd. While SOH has slowed to a crawl during the winter, HX started going down in the early winter, I did one fast charge and it shot back up and then reduced a bit after that then started climbing again. Why would HX drop at the start of the cooler temps but now in late winter start rising with the same cooler temps? Seems a bit strange to me. Interesting to plot though. I'd also be curious to compare HX from one person to the next. We seem to focus a lot on SOH. (Assuming HX actually means anything)

Who knows?

AFAIK, Nissan still has never acknowledged or released any documentation on the values that Leaf Spy renders as SOH, Hx nor anything else.

I've pointed people to some historical posts about SOH and Hx at https://www.mynissanleaf.com/viewtopic.php?p=497564#p497564 before. https://www.mynissanleaf.com/viewtopic.php?f=44&t=14285&p=516444&hilit=soh#p516444 was a more recent comment on SOH.

FWIW, on my 24 kWh Leaf, SOH and Hx became quite divergent ages ago. Right now, my SOH is 80.89%. My Hx is 73.28%. I've never ever seen my SOH below 80.00%. The earliest log entry I have on my current Leaf Spy phone has an entry from 10/19/18. Back then my SOH was 83.52% and Hx was 78.20. A quick skim shows my highest Hx between that date and now was 80.76 but almost every Hx entry is below 80.

 

[DaveinOlyWA]

Leftie

Do we have any reason to believe that the SOH isn’t accurate or a good relative measure any more?

I think he is referring to Hx as not being reliable or a good metric to go by.

SOH and ahr seem to align rather well as the pack ages.

I have been gathering (trying to anyway) gather data about Hx issue since Feb 2018 where its randomness achieved a whole new level of weird but even when specifying parameters, 80-90% of responses were all but unusable so not a lot of decent data out there.

As far as Hx; It would appear that for most, it starts out very high during the period when loss is greatest. That is the most common characteristic. There is "some" evidence that higher use of DC sees the higher numbers exceeding 120%. With NCTC all but gone for the Plusses, might have more light on that in 6-12 months.

After that; its mostly two groups, maybe 3. As the degradation slows going into month 12-18, the Hx starts dropping hovering around 100%

Then we have a group that has continued degradation that is only "medium better" than the initial drop and has Hx below 100.

Problem with all this is huge gaps in data gathering. Some people only check their stats 2-3 times a year OR LESS.

The other big issue is people injecting their own opinions into what is important and submitting only that info w/o understanding that data gathering is "supposed" to be unbiased. We are only crunching numbers, not evaluating charging habits.

Come Summer, will be doing another round of data gathering... Hopefully with better results.

 

[danrjones]

I have been checking out the chargers around my area under construction (See my posts in the Eastern Sierra District 9 thread for those updates)

I again charged up to 100% to do this AM run. ABRP had the round trip with 100% at start and a return SOC at 29%. I again set my battery degradation to 8%. But this time ABRP was less accurate, I returned home with only 25%. I had set the temp in ABRP for 44F so that was accurate. But I had a bit of a head wind one direction, tail wind the other. Tinkering AFTER the trip with ABRP by adding a slight head wind it then gave me 26%. One note about ABRP is that it does not let you set separate winds for each segment. So to be more realistic I'd need to actually route plan it in two pieces, one with a head wind and one with a tail wind. Anyway, 8% degradation still seems to hold up pretty accurately but small changes in ABRP can drastically alter the end results. I know I had a head wind but I don't know how much, so its hard to be accurate enough to really gauge if the 8% degredation in my 2018 is REAL.

As a side note, my stats were:
Start 100% SOC (Dash) / 98.7% Leafspy
36 miles north using 14.3 kWh at 2.51 miles / kWh. 55% SOC (Dash) / 60.1% Leafspy
36 miles south using 8.35 kWh at 4.32 miles / kWh. 25% SOC (Dash) / 35.4% Leafspy

Note that there is elevation gain heading north, so that is not all wind in the difference. These used KWh also don't seem to match the % readings.

I guess my other take home (which I knew), for my area the 2018 40 KWh range is really only about 100 miles on the highways.

 

[danrjones]

I'm coming up on my next three month adjustment. The battery has been in a fridge so I'm hoping it will be small to none.
Currently have just under 4700 miles.

I have more data than this but have removed the linear data between the drops to make it more readable for this forum.
All my data is available if anyone ever wants it.


Date SOH AMPHr Hx
05/03/2019 97.63 112.70 97.50
06/13/2019 97.42 112.46 101.25
06/14/2019 96.49 111.39 101.58
06/15/2019 96.28 111.15 101.58
06/16/2019 95.64 110.41 101.67
06/17/2019 95.42 110.15 101.82
06/19/2019 95.40 110.13 102.15
09/11/2019 94.64 109.25 106.48
09/12/2019 94.50 109.09 106.47
09/13/2019 93.73 108.20 106.48
09/14/2019 93.30 107.71 106.45
12/10/2019 93.11 107.49 106.14
12/11/2019 92.90 107.24 106.10
12/11/2019 92.76 107.08 106.10
12/12/2019 92.34 106.60 106.12
12/13/2019 92.13 106.35 106.10
12/14/2019 91.78 105.95 106.09
02/28/2020 91.72 105.88 107.13

 

[DaveinOlyWA]

I'm coming up on my next three month adjustment. The battery has been in a fridge so I'm hoping it will be small to none.
Currently have just under 4700 miles.

I have more data than this but have removed the linear data between the drops to make it more readable for this forum.
All my data is available if anyone ever wants it.


Date SOH AMPHr Hx
05/03/2019 97.63 112.70 97.50
06/13/2019 97.42 112.46 101.25
06/14/2019 96.49 111.39 101.58
06/15/2019 96.28 111.15 101.58
06/16/2019 95.64 110.41 101.67
06/17/2019 95.42 110.15 101.82
06/19/2019 95.40 110.13 102.15
09/11/2019 94.64 109.25 106.48
09/12/2019 94.50 109.09 106.47
09/13/2019 93.73 108.20 106.48
09/14/2019 93.30 107.71 106.45
12/10/2019 93.11 107.49 106.14
12/11/2019 92.90 107.24 106.10
12/11/2019 92.76 107.08 106.10
12/12/2019 92.34 106.60 106.12
12/13/2019 92.13 106.35 106.10
12/14/2019 91.78 105.95 106.09
02/28/2020 91.72 105.88 107.13

You don't drive much. What are your charging habits?

 

[danrjones]

You don't drive much. What are your charging habits?

I drive a lot, just all in town as a daily driver, so its not a lot of miles. Death by a thousand inches.

Most of the time I charge about every 3rd night for two hours, which usually puts me between 70 to 80%.
I've probably charged to full 6 times total for the car, twice last weekend for some test trips to visit chargers they are building around me.
I've done a total of one QC in the time I've owned it.

I'd like to think its been treated quite well, except for the hot summer it went through. And will go through again soon.

 

[DaveinOlyWA]

You don't drive much. What are your charging habits?

I drive a lot, just all in town as a daily driver, so its not a lot of miles. Death by a thousand inches.

Most of the time I charge about every 3rd night for two hours, which usually puts me between 70 to 80%.
I've probably charged to full 6 times total for the car, twice last weekend for some test trips to visit chargers they are building around me.
I've done a total of one QC in the time I've owned it.

I'd like to think its been treated quite well, except for the hot summer it went through. And will go through again soon.

You have a good charging plan and heat is a problem but its not the main issue. Maintaining an applicable SOC is. Range helps a lot with that.

 

[danrjones]

I'm coming up on my next three month adjustment. The battery has been in a fridge so I'm hoping it will be small to none.
Currently have just under 4700 miles.

I have more data than this but have removed the linear data between the drops to make it more readable for this forum.
All my data is available if anyone ever wants it.


Date SOH AMPHr Hx
05/03/2019 97.63 112.70 97.50
06/13/2019 97.42 112.46 101.25
06/14/2019 96.49 111.39 101.58
06/15/2019 96.28 111.15 101.58
06/16/2019 95.64 110.41 101.67
06/17/2019 95.42 110.15 101.82
06/19/2019 95.40 110.13 102.15
09/11/2019 94.64 109.25 106.48
09/12/2019 94.50 109.09 106.47
09/13/2019 93.73 108.20 106.48
09/14/2019 93.30 107.71 106.45
12/10/2019 93.11 107.49 106.14
12/11/2019 92.90 107.24 106.10
12/11/2019 92.76 107.08 106.10
12/12/2019 92.34 106.60 106.12
12/13/2019 92.13 106.35 106.10
12/14/2019 91.78 105.95 106.09
02/28/2020 91.72 105.88 107.13

My 3 month adjustment has started today.

I was really hoping, given my battery has been in a cold soak the last 3 months, that I wouldn't see one. But I am.
This AM it was 91.57%. I'll update again when it is finished in a few days.

 

[jmurtagh13]

My 2018 leaf just reached 2 years old and 18K miles.
First year lost almost 7% battery capacity, second year lost only 0.4%
I keep the charge between 25 and 70%, no QC and charge early morning after the battery has some time to cool.
I live in Atlanta and it was hot last summer.
Really curious what happens this summer, will it continue at this low rate of degradation or was the BMS just making up for the first year.

Date -------- SOH ---- HX ---- AH ---- Change
03/09/2018 99.10 098.86 115.00
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

 

[LeftieBiker]

I hope that mine follows that pattern.

 

[DaveinOlyWA]

My 2018 leaf just reached 2 years old and 18K miles.
First year lost almost 7% battery capacity, second year lost only 0.4%
I keep the charge between 25 and 70%, no QC and charge early morning after the battery has some time to cool.
I live in Atlanta and it was hot last summer.
Really curious what happens this summer, will it continue at this low rate of degradation or was the BMS just making up for the first year.

Date -------- SOH ---- HX ---- AH ---- Change
03/09/2018 99.10 098.86 115.00
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

LOL!! Its hot EVERY summer in Atlanta!

Yeah I traded up at 21 months and 25k miles but mine did pretty much the same. It simply stopped the 90 day adjustments. Just like mine; I notice one of your adjustments went up.

 

[HerdingElectrons]

You don't drive much. What are your charging habits?

I drive a lot, just all in town as a daily driver, so its not a lot of miles. Death by a thousand inches.

Most of the time I charge about every 3rd night for two hours, which usually puts me between 70 to 80%.
I've probably charged to full 6 times total for the car, twice last weekend for some test trips to visit chargers they are building around me.
I've done a total of one QC in the time I've owned it.

I'd like to think its been treated quite well, except for the hot summer it went through. And will go through again soon.

Have you considered aiming for a SOC of 65% or less & charge every night for 1 hour or w/e amount of time you typically need to get back to the 65% mark?

This is what I do but drive more miles per day so I have a 2 hour timer that I use near daily that ends right before I leave in the morning & I have the 2nd timer configured for an extra hour of charging that starts at 8:10pm when I need additional charging. And for the majority of the time when I don't need the extra hour I just plug the car in after 8:15 & then I just get the 2 hours in the morning.

 

[danrjones]

You don't drive much. What are your charging habits?

I drive a lot, just all in town as a daily driver, so its not a lot of miles. Death by a thousand inches.

Most of the time I charge about every 3rd night for two hours, which usually puts me between 70 to 80%.
I've probably charged to full 6 times total for the car, twice last weekend for some test trips to visit chargers they are building around me.
I've done a total of one QC in the time I've owned it.

I'd like to think its been treated quite well, except for the hot summer it went through. And will go through again soon.

Have you considered aiming for a SOC of 65% or less & charge every night for 1 hour or w/e amount of time you typically need to get back to the 65% mark?

This is what I do but drive more miles per day so I have a 2 hour timer that I use near daily that ends right before I leave in the morning & I have the 2nd timer configured for an extra hour of charging that starts at 8:10pm when I need additional charging. And for the majority of the time when I don't need the extra hour I just plug the car in after 8:15 & then I just get the 2 hours in the morning.

I could indeed adjust my charge time, which I have set to about ~2 hrs after I depart but also set to "full charge has priority", to maybe about 3 hrs after I really depart. Right now it seems to get me right around 80%. But the battery really should be fine charging to 80%. If Nissan didn't build it well enough to survive my (non harsh, only one QC) charging habits and low mileage, that will be on them to fix it.

I'll update my stats in about a day or two when it is done adjusting.

 

[DougWantsALeaf]

The evidence is a bit dubious as to how much QC hurts the new batteries if at all.

 

[lorenfb]

The evidence is a bit dubious as to how much QC hurts the new batteries if at all.

You do agree that heat causes Leaf battery degradation, right? So whether heat results from ambient temperature, QCing,
or from the motor requiring battery current, all do affect degradation. Yes, the effects differ based on the degree to which
the battery temperature rises and the length of time at that temperature. Given that Leaf lacks TMC, my view is to avoid or
at least minimize the length of time the battery temperature exceeds 95-100F. With my 40kWh Leaf, I avoid the QCing and
avoid driving over 55-60 MPH.