The 62kWh Battery Topic

Put 132 highway miles on it from the screen shot above...Speed ranged from 55 to 70 mph...every looks normal, range is back and the lower end of the pack seems well balanced.

Happy Camper


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Well my Hx has been dropping like a rock over the past 6 months from 108% in September to 103% now. My last adjustment early this month dropped from 90.52% to 89.26%. It had been cold, so maybe it will spring back a little, but that Hx drop does seem to foreshadow so in SoH. (SV Plus built May 2019)

DougWantsALeaf said:

Well my Hx has been dropping like a rock over the past 6 months from 108% in September to 103% now. My last adjustment early this month dropped from 90.52% to 89.26%. It had been cold, so maybe it will spring back a little, but that Hx drop does seem to foreshadow so in SoH. (SV Plus built May 2019)

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Not a good sign...but could only mean minor temporary changes due to weather. In a few cases, a 2nd round of faster degradation is seen (usually covering the 87-83% SOH range) with Hx below 100.

There is also some evidence that cold weather seems to put changes on hold. I frequently go as much as 10 days with only the Hx changing but it bounces up and down in a very small range making the overall change for the period near zero. I am still above 117.

I've been keeping a casual comparison for myself between the degradation of my Bolt pack Vs what seems to be typical based on reports here from the LEAF+ pack. I feel a bit stymied though by LeafSpy, since I cannot convince myself whether the reported Ahr is nominal or usable. A Google search says '62 kWh' is nominal, and ~ 59 kWh are usable capacity in a new pack. My calculation using the EPA data says that 62 kWh were usable in a new pack.

I'd like to hear opinions backed up by data. Best would be a 0 - 100% charging episode with metered energy recorded, although I realize that an educated guess regarding charging losses would have to be taken.

Thanks.

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For anybody curious, my Bolt is 8 months old since its battery transplant done as part of the fire recall.
When new, Torque Pro showed 188 Ahr nominal. This is also (so far as I know) the figure of merit GM uses when deciding whether a pack has degraded enough to invoke warranty coverage. Usable capacity is 94.8% of nominal, and nominal voltage is 350V. So the 188 Ahr nominal of a new pack is equal to 188*0.948*.35 = 62.3 kWh usable (going from "100%" to "-3.2%" on Torque Pro reporting of the car's DIC

As of Mid March my nominal capacity is 186 Ahr, although I've seen some jumping around a bit I ascribe to calibration games. I'm comfortable saying that any degradation if present has been minor and well within that which we usually see from new packs completing their SEI fomation process.

I will save you the trouble of looking back through this thread for my previous posts of battery statistics gathered from full discharge tests every 3 months. Here is the latest data after 3-1/2 years of use in the Phoenix area. The charging energy was measured with a revenue-accuracy meter ahead of my AeroVironment EVSE from shutdown (main contactor opened while running climate control in the driveway to full charge). Voltage at my house is typically a little over 240 and the EVSE allows the maximum current the car will draw. The charging energy would be higher with lower voltage or lower current. As you can see, my LEAF battery lost a little less than 2 ampere-hours during 9 months from the first to the fourth full discharge test so similar to your Bolt after 8 months.

Calculations for initial discharge test:
173.35 AHr * 360 V / 1000 = 62.4 kWh
62.4 kWh / 65.95 kWh = 94.6% charging efficiency

GerryAZ said:

Calculations for initial discharge test:
173.35 AHr * 360 V / 1000 = 62.4 kWh
62.4 kWh / 65.95 kWh = 94.6% charging efficiency

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Much appreciated.
Am I understanding correctly that you calculated efficiency from LeafSpy Ahr and a presumed nominal voltage of 360V ?

If correct, then a couple questions come to mind:
1. Metered energy must be usable + losses, so the calculation must presume that the LSpy Ahr is also usable ?

2. Is there a valid reason to think that the LEAF pack and the Bolt pack have different nominal voltages ? I'm thinking **perhaps** based on ending and starting cell voltages, but not based on chemistry. When I compere Torque Pro Ahr and kWh values in the Bolt, they make sense based on 350V nominal pack, which is also the nominal that GM publishes.

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I've been waiting for my pack to warm up to over 60F to take a "0%" to "100%" charging measurement. I don't have an RGM or a CT, but Torque Pro reports current and voltage after the OBC at short intervals and I am able to log the session so I plan a spreadsheet calc. I have a pack resistance value from Torque Pro of 128 mOhm, so I expect about 90 watts of resistance losses in the pack using my 40 Amp EVSE, or about 650 Wh over the ~ 7 hour session.

As an aside, Torque Pro will also report current and voltage entering the OBC. I'm not inclined to log those value for hours, but I can certainly take a couple immediate measurements to calculate OBC efficiency.

One interesting note Gerry, probably not a surprise since I live in a cold climate: my 2019 S+ now has almost exactly the same number of miles that yours had in 2022, 43,400 or so, yet my SOH is still 93.36 where yours was in the 89% range at that mileage.

SageBrush said:

As an aside, Torque Pro will also report current and voltage entering the OBC. I'm not inclined to log those value for hours, but I can certainly take a couple immediate measurements to calculate OBC efficiency.

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Here is one measurement
https://photos.app.goo.gl/D4dPD1HnpMAD5NXK9

95% OBC efficiency

Nissan specifications list the nominal voltage as 360 so that is what I used in the calculations. Obviously, the voltage of the pack varies from below 300 to over 400.

dmacarthur said:

One interesting note Gerry, probably not a surprise since I live in a cold climate: my 2019 S+ now has almost exactly the same number of miles that yours had in 2022, 43,400 or so, yet my SOH is still 93.36 where yours was in the 89% range at that mileage.

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I am not surprised (and not concerned) that my battery has more deterioration than yours--one of the costs of living in a hot climate, but I don't need a snow shovel!

GerryAZ said:

Nissan specifications list the nominal voltage as 360 so that is what I used in the calculations. Obviously, the voltage of the pack varies from below 300 to over 400.

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I logged a charging session yesterday.
Charging stated at 57F average pack temp and ended at 60F

I should have logged AC voltage and current. Next time. I know from prior fiddling that my AC voltage is mostly 242V, so I used that. I charged at 40 Amps. Pack SoC was read off Torque Pro's 'Raw' SoC measurement. I started the charge at 6.3% SoC and ended at 95%, although the 40 Amps continued past 97% 'Raw' SoC

A 0% to 100% 'Raw' charge would have taken 69.4 kWh from the utility meter. The EPA CSI report says it took 73.6 kWh to do the same 0% - 100% of a new tested Bolt, so I calculate 6% loss of capacity. The calc presumes that the EVSE at 32 Amps used by the EPA has similar charger efficiency. I suspect not better, perhaps worse.

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Regarding Voltage,
The Bolt pack was 325V at 6% 'Raw' SoC
At 95% 'Raw' SoC max cell voltage was 4.18

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I'm definitely a fan of these charging tests to follow pack degradation. On the other hand, trying to figure out usable capacity ends up with results that have quite a bit more uncertainty.

I finally broke the 90% barrier for SOH on my 2020 SL. Not for bragging of course, but to continue with the public data collection. So far, compared to my previous 2013 SV, at nearly +61,450 miles, my SOH had dropped to 73.15%
Range degradation was quite noticeable by then on my 2013 SV. On my 2020 SL, range degradation is technically there, but I'm still able to charge up to over +56 kW at full so my driveable range via the Dash (not LeafSpy and using the hidden reserve) has remained unchanged and I still easily get over +215 miles of range. My actual 100% to 0% battery shutdown range still remains at around +250 miles for in-town driving and roughly +220 miles of "conservative" highway/Interstate driving. So far, despite me doing absoutely nothing to baby my battery, it seems to be holding up very well compared to my 2013 SV. So bigger is better I believe when it comes to long term battery degradtion for the Leaf. It really seems like there is a path to battery technology that can function without an active cooling system should the chemistry and technology be financially feasible of course.

I will second what Knightmb said--my 2019 battery is doing much better than the 2015 (which was much better than the 2011). At 64,048 miles and 38 months of use in the Phoenix, AZ area the SOH is 84.92% according to Leaf Spy. I believe the larger capacity (fewer charge cycles) is the main reason followed by possible chemistry changes (wish we had detailed information from Nissan). Again, some loss of real world range but not enough to worry about. The 2015 was suffering noticeable range loss by this much time and distance; unfortunately the 2011 met its demise at 50,422 miles.

almost 29,000 when I took this screen shot...2019 is doing good!

NOTE: the low voltages are in the module that was replaced....at lower SOC the voltages match up nicely...



Click For Full-Size Image.

Sadly, my SV+ adjusted down about % and is now at.88.06% SoH, a 1.12% drop, ouch.

I was hopeful that some longer drives and a modestly recovering Hx (104.04%) would have given me a lift, but no luck.


Dave, and data that the 40/62 batteries are aging better in the 2020s or 2021s?

knightmb said:

I finally broke the 90% barrier for SOH on my 2020 SL. Not for bragging of course, but to continue with the public data collection. So far, compared to my previous 2013 SV, at nearly +61,450 miles, my SOH had dropped to 73.15%
Range degradation was quite noticeable by then on my 2013 SV. On my 2020 SL, range degradation is technically there, but I'm still able to charge up to over +56 kW at full so my driveable range via the Dash (not LeafSpy and using the hidden reserve) has remained unchanged and I still easily get over +215 miles of range. My actual 100% to 0% battery shutdown range still remains at around +250 miles for in-town driving and roughly +220 miles of "conservative" highway/Interstate driving. So far, despite me doing absoutely nothing to baby my battery, it seems to be holding up very well compared to my 2013 SV. So bigger is better I believe when it comes to long term battery degradtion for the Leaf. It really seems like there is a path to battery technology that can function without an active cooling system should the chemistry and technology be financially feasible of course.

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We are on nearly identical tracks. What is your build date? After my last adjustment, I am just under 91% SOC and 45,000 miles. Your Hx is "low" at least when compared to mine. Do you know what yours was last year?

I have a few examples of lower Hx having slightly higher rate of degradation. So far, nothing else matters including extremely hot places, cold places, etc.

DougWantsALeaf said:

Sadly, my SV+ adjusted down about % and is now at.88.06% SoH, a 1.12% drop, ouch.

I was hopeful that some longer drives and a modestly recovering Hx (104.04%) would have given me a lift, but no luck.


Dave, and data that the 40/62 batteries are aging better in the 2020s or 2021s?

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Don't be sad. A few cars suggest a quicker drop to the upper 80's happening on lower mileage cars. A far fetched theory perhaps but maybe simply protecting the pack of a car with lesser demands against unwarranted frequent full charges with larger protected (and hidden) buffer.

DaveinOlyWA said:

We are on nearly identical tracks. What is your build date? After my last adjustment, I am just under 91% SOC and 45,000 miles. Your Hx is "low" at least when compared to mine. Do you know what yours was last year?

I have a few examples of lower Hx having slightly higher rate of degradation. So far, nothing else matters including extremely hot places, cold places, etc.

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2020 Leaf SL Plus - (Manufacture Date March 2020)
If you look through some of my earlier post in this topic you can probably find the Hx values, I'm not sure what it was last year. :?

knightmb said:

DaveinOlyWA said:

We are on nearly identical tracks. What is your build date? After my last adjustment, I am just under 91% SOC and 45,000 miles. Your Hx is "low" at least when compared to mine. Do you know what yours was last year?

I have a few examples of lower Hx having slightly higher rate of degradation. So far, nothing else matters including extremely hot places, cold places, etc.

Click to expand...

2020 Leaf SL Plus - (Manufacture Date March 2020)
If you look through some of my earlier post in this topic you can probably find the Hx values, I'm not sure what it was last year. :?

Click to expand...

I have you at 36 k and 107 then 53 k and 98...
To compare, I am at 116 right now. Still don't know what Hx really does or what it signifies other than the current theories but it appears that higher Hx seems to allow more manipulations of the reserve.

I am at 26K miles for reference.