The 40KWH Battery Topic

DaveinOlyWA said:

The 98% reading on a "full" charge is normal and means pack was under the impression that more balancing was coming. I saw the same on my car and guess what? The move from 98% to 100% REDUCED my GOM by one mile.

Either way, its a waste of time to wait on 100%. I only did it because I didn't set a timer and had no appt so I pushed the issue.

Click to expand...

I still am curious what the Leafspy reading is for a true empty pack. 0%? 5%? what is the lowest anyone here has ever gotten down to?

danrjones said:

DaveinOlyWA said:

The 98% reading on a "full" charge is normal and means pack was under the impression that more balancing was coming. I saw the same on my car and guess what? The move from 98% to 100% REDUCED my GOM by one mile.

Either way, its a waste of time to wait on 100%. I only did it because I didn't set a timer and had no appt so I pushed the issue.

Click to expand...

I still am curious what the Leafspy reading is for a true empty pack. 0%? 5%? what is the lowest anyone here has ever gotten down to?

Click to expand...

tl;dr
0% remaining per LeafSpy is when a cell hits the anti-bricking voltage.

The thing to keep in mind here is that capacity** is defined as the AUC (area under the curve) from a maximum allowable cell voltage down to a minimum allowable cell voltage where the car shuts down. Your question then can be phrased as "is the shutdown cell voltage the same as the dead_and_killed cell voltage, and second, which low cell voltage does LeafSpy use ?

So far as I know (@GerryAz ?), the reserve to prevent bricking is a voltage allowance that is not reported by the Canbus (and therefore not by LeafSpy.)

It isn't hard to figure out, by the way. Check the cell voltage histogram at a SoC below 5% and compare the low cell voltage to the industry standard capacity test parameters.



**
At a defined C rate, but skip that detail for now

SageBrush said:

danrjones said:

DaveinOlyWA said:

The 98% reading on a "full" charge is normal and means pack was under the impression that more balancing was coming. I saw the same on my car and guess what? The move from 98% to 100% REDUCED my GOM by one mile.

Either way, its a waste of time to wait on 100%. I only did it because I didn't set a timer and had no appt so I pushed the issue.

Click to expand...

I still am curious what the Leafspy reading is for a true empty pack. 0%? 5%? what is the lowest anyone here has ever gotten down to?

Click to expand...

tl;dr
0% remaining per LeafSpy is when a cell hits the anti-bricking voltage.

The thing to keep in mind here is that capacity** is defined as the AUC (area under the curve) from a maximum allowable cell voltage down to a minimum allowable cell voltage where the car shuts down. Your question then can be phrased as "is the shutdown cell voltage the same as the dead_and_killed cell voltage, and second, which low cell voltage does LeafSpy use ?

So far as I know (@GerryAz ?), the reserve to prevent bricking is a voltage allowance that is not reported by the Canbus (and therefore not by LeafSpy.)

It isn't hard to figure out, by the way. Check the cell voltage histogram at a SoC below 5% and compare the low cell voltage to the industry standard capacity test parameters.



**
At a defined C rate, but skip that detail for now

Click to expand...

I don't need to over complicate it. Maybe I'm asking the wrong question. I'm not willing to take my leaf down until it stops moving. But I bet someone has, and I just wanted to know if that shows 0% on Leafspy. I recall someone here in the past saying their car stopped at 5%, not 0%, but I cannot find that post.

Realize that allowing the pack to discharge that low isn't good for it. Anything below 5% is definitely in "emergency use only" territory.

danrjones said:

I still am curious what the Leafspy reading is for a true empty pack. 0%? 5%? what is the lowest anyone here has ever gotten down to?

Click to expand...

Dan, back in August of 2019 I did an experiment like what you are asking;

- at 6% dash SOC LS Pro indicated 14.8% SOC

- at 4% dash SOC LS Pro indicated 13.1% SOC

- at 2% dash SOC LS Pro indicated 10.4% SOC

- at 1% dash SOC LS Pro indicated 9.8% SOC

- at ---% dash SOC LS Pro indicated 9.2% SOC

going from 1% to --- was several additional low speed miles & that was as low as I was comfortable going and that point on the center console screen I finally got the VLB warning but I never got a turtle indicator on my dash so that's even lower SOC so presumably closer to 5% LS Pro SOC

alozzy said:

Realize that allowing the pack to discharge that low isn't good for it. Anything below 5% is definitely in "emergency use only" territory.

Click to expand...

Yes, that's why I don't want to do it.

But what I would like to know is if the LeafSpy App shows actual useable battery, or if it includes portions that the driver can't actually use.

In other words, can you drive the vehicle until Leafspy shows ZERO percent SOC? Or does the vehicle stop you at 5%? Or maybe 8%?


That knowledge goes back to properly calculating degradation.

In an olde post DaveInOly said:

But I did hit 8 GIDs once @ 305.72 Volts or a Leaf Spy SOC of 2.9% and realize despite having 36 power segments (that replaced the 8 double wall circles) they disappear in chunks hence the nonsensical search for a definitive Turtle number.

Click to expand...

If each Gid is 77.5 Wh then 8 Gids = 77.5 * 8 = 0.62 kWh

It's not hard to imagine that the SoC of 2.9% would drop to zero once the 0.6 kWh is spent.
But it is not possible to include an anti-bricking reserve of at least 1.5 kWh and come up with a small enough pack
2.1/0.029 = 72.4 kWh

During my last full discharge test (62 kWh battery), the car shut down at 10 "GIDS" with 1.5% SOC as displayed by Leaf Spy. The dashboard SOC display goes to ---% while there is still significant energy remaining. I drove 15.1 miles after the dash display went to ---% SOC that evening and then ran HVAC in the driveway until shutdown.

Edited to add: The lowest cell voltage at shutdown was 2.746 and pack voltage was 285.16 at that point (as displayed by Leaf Spy). The voltages recovered a little by the time I finished writing down information. The GIDS at shutdown, overall pack voltage, and perhaps even minimum cell voltage depend upon temperature and how well balanced the pack cell voltages are.

danrjones said:

DaveinOlyWA said:

The 98% reading on a "full" charge is normal and means pack was under the impression that more balancing was coming. I saw the same on my car and guess what? The move from 98% to 100% REDUCED my GOM by one mile.

Either way, its a waste of time to wait on 100%. I only did it because I didn't set a timer and had no appt so I pushed the issue.

Click to expand...

I still am curious what the Leafspy reading is for a true empty pack. 0%? 5%? what is the lowest anyone here has ever gotten down to?

Click to expand...

Highly dependent on cell balance and the approach to zero. I got my 2016 down to 1.4% but my 2018 started losing power pips at 1.7% so didn't take it lower. My Plus hasn't been below 4% (which was 12 miles past zero % SOC on the dash)

EDIT;

Ok, looks like the 2nd half of my comment didn't take? Pitfalls of voice text in a loud environment, I guess.

But one thing that I noticed is if you are on the freeway, the Turtle will arrive much quicker. If on the streets, slower, but to get the max range, you are better to park it when it loses its first power circle. I know someone who did that and milked it over 3 miles to home. I think he was going until he lost 3 power circles, then stopped for 15 mins, started back up and the circles returned but disappeared quickly but every time he did that, he was able to get another half mile down the road or so. He ended up dying in his driveway but he didn't shut the car off and was able to push it the last little bit. Too bad he didn't have LEAF Spy. Would be interested to see what his SOC was

Regarding this notion of trying to measure battery capacity or degradation, I note that the Leafspy measurement of
Ahr * 0.360 Volts (in kWh)
Gives a different result than
Reading the kWh remaining and dividing it by the SoC remaining.

The latter calc approaches (maybe reaches -- I don't have the data to say) the top calc as the SoC approaches 100%
I presume this means that the SoC percentage is a fraction of total Ahr remaining. Since the pack voltage decreases as the charge is used, the kWh per percent SoC drops progressively.

Take home message:
Trend data over time, and shoot for similar conditions. Certainly SoC, and also pack temperature.

In this case I'm just going for simple napkin math.

It sounds like Leafspy might be showing us about 1.5% on both the top and bottom that you cannot use.
So if we take my numbers and then adjust them, we have:

96.7-20.1% = 76.6 -> 76.6/.97 = 78.97% of useable battery

26.31 kWh /.7897 = 33.32 kWh useable battery

Degradation -> 33.32/36 = 92.5%

OR

33.32/38 = 87.6%

Most of the reports I've seen still say it is 36 useable of 40 kWh... so that means my degradation is actually around 92%.
But do I actually believe this math? Not really. Too many assumptions, unknowns and inaccuracies in my data.

My recollection is that the 40kWh packs are 40.xx kWh gross & 38.6kWh is what Nissan is allowing for usable capacity. I believe I got that from a video Q&A session when the 2018 Leaf was being released that I believe Cwerdna linked to but I will have to do some digging to see if my memory is accurate

Most of the reports I've seen still say it is 36 useable of 40 kWh... so that means my degradation is actually around 92%.

Click to expand...

Hopefully you mean 8% degradation, 92% remaining capacity.

LeftieBiker said:

Most of the reports I've seen still say it is 36 useable of 40 kWh... so that means my degradation is actually around 92%.

Click to expand...

Hopefully you mean 8% degradation, 92% remaining capacity.

Click to expand...

Yes sorry, that was suppose to be implied by the math.

2 year update on my 2019 Leaf S

Date SOH Ahr Hx Odo # L1/L2 Days Loss
3/8/2019 99.39% 114.74 104.14% 649 24 0
3/8/2021 91.80% 105.97 94.66 12700 481 731 7.59%

when I was commuting, I would charge to 100% and not even worry about it. This last year I have let it sit without driving much at about a 70% charge. Garaged in So Cal, no Quick Charge port.

My 2018 skipped its last 3 month update (would have been Dec 7th)

Checked at lunch today and sure enough, its going through an update. So even with the skipped update in December, the next update is right on the 3 month schedule. The last update was in September, and SOH went up. Now its taking away what it gave me.

As of lunch today:
SOH: 89.37
AMPHr: 103.17
Hx: 102.81

~9200 miles.

Here is a 12 bar 100K mile 40kWh Leaf.

https://youtu.be/bmcJbvmeXcM

Interestingly, he is under 85% SoH. While close, I have seen now a few places where someone is at 83-84% but still showing 12 bars. Either Nissam expanded the top bar a bit, or there is in fact a small hidden buffer.

Oddly, I am excited to see our first verified 11 bar 40kWh Leaf to understand what SoH is at that change.

DougWantsALeaf said:

Here is a 12 bar 100K mile 40kWh Leaf.

https://youtu.be/bmcJbvmeXcM

Interestingly, he is under 85% SoH. While close, I have seen now a few places where someone is at 83-84% but still showing 12 bars. Either Nissam expanded the top bar a bit, or there is in fact a small hidden buffer.

Oddly, I am excited to see our first verified 11 bar 40kWh Leaf to understand what SoH is at that change.

Click to expand...

Not un normal for the first bar to leave at 83 something percent. What is his % of ahr? Looks like he is 84.9% of his original ahr (using 115) so, he is close. Guessing nothing will happen until its a bit warmer.

Rather see his history. Obviously not linear but what has he lost in last 2 years? Last year?

danrjones said:

My 2018 skipped its last 3 month update (would have been Dec 7th)

Checked at lunch today and sure enough, its going through an update. So even with the skipped update in December, the next update is right on the 3 month schedule. The last update was in September, and SOH went up. Now its taking away what it gave me.

As of lunch today:
SOH: 89.37
AMPHr: 103.17
Hx: 102.81

~9200 miles.

Click to expand...

My adjustment is taking its time. Still going down as of lunch today.

SOH: 88.03%


This has been a big adjustment. I'll be blunt, I'm glad I'm getting rid of it later this year. I don't really want to try and sell it with a bar missing.
Whether the real battery degradation is 12% I don't know. I've treated the battery and car about as well as possible, except the hot summer ambient temps here. Would imagine missing a bar would make resale harder.

I wish Nissan would publish their BMS algorithm. I don't know what drives the large drops beyond general age.

My SoHs are stable right now, but I do get nervous with each quarterly update. 6 down and 3 up so far. The downs are always worse than the ups. Next quarterly for the S+ is this week...holding my breath. My charging regimen is now DC charging only on a trip when needed (sad for my NCTC), keep battery between 30% and 70% unless driving far.

https://drive.google.com/file/d/1xzcLfY_I2SSK8U8YmfpdlIDucnmRfMQZ/view?usp=drivesdk