The 40KWH Battery Topic

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SageBrush said:
lorenfb said:
SageBrush said:
What you say makes sense: if baseline heat generation in the battery is say 2% of the power draw then a 25% increase in resistance would presumably (?) increase heat generation up to 2*1.25 = 2.5% of the power draw. No big deal.

above is battery power loss - from an increase in battery resistance only

SageBrush said:
But then I start from
P = I*I*R and I conclude that an increase in R to R1 would lead to a drop in I = sqrt (R/R1)
Then e.g., an increase in R of 25% would lead to a drop in I to sqrt(0.75) = 86.6%

above is total power loss - from a total load resistance increase

You're confusing the two different situations.
I'm obviously being dense about this, thanks for the patience.

If I just consider the battery in isolation, is my use of I*I*R correct ?
That is, does an increase of R to R1 reduce the current to sqrt(R/R1) ?

Yes, for a short circuit test of the battery, i.e. you connect the two terminals of the battery together (no load) and the battery resistance
increased. Typically the resistance would decrease as it heated. Or you used to different external resistors and did that test.
 
lorenfb said:
SageBrush said:
lorenfb said:
above is battery power loss - from an increase in battery resistance only



above is total power loss - from a total load resistance increase

You're confusing the two different situations.
I'm obviously being dense about this, thanks for the patience.

If I just consider the battery in isolation, is my use of I*I*R correct ?
That is, does an increase of R to R1 reduce the current to sqrt(R/R1) ?

Yes, for a short circuit test of the battery, i.e. you connect the two terminals of the battery together (no load) and the battery resistance
increased. Typically the resistance would decrease as it heated. Or you used to different external resistors and did that test.

:: light bulb ignites ::
I think I finally get it

(R1 - R) acts as a additional serial resistor in my simple circuit
 
Hi!

Strange thing happened in the last two days. From Saturday to Sunday the SOH dropped from 96.91% to 96.70%, then from Sunday to Monday the SOH dropped to 97.48%. Without any reason.
The car was not QC-d, the battery was not overheated, I charged using L1 charger (220V/10A) from Friday to Saturday to 92% SOC (from around 40-50%, used 8 hours of charging with the charge timer) and did not even use the car on the weekend, despite this, the SOH dropped 0.5%. Also Hx dropped from 114.58% to 114.23%.

Funny thing, that with a full charge I still get over 97% capacity, if I check the GIDs. I still can charge over 485 GIDS (488-490 some times, which is 97.6-97.8%, for a couple weeks ago I was able to charge till 38.1kWh capacity, which is way over 98%) which is 97.4% or above, and over 37kWh estimated capacity.

I think SOH & Hx are totally wrong with the new Leaf, and since the battery chemistry is totally different from the previous models, also the values mean totally different things, or are not even meaning anything regarding SOH, they are only some numerical data read from the CAN and interpreted as SOH, because it showed some correlation between bar lost and SOH value drop in the past, but only Nissan Engineers know what this values mean.
 
Strange thing happened in the last two days. From Saturday to Sunday the SOH dropped from 96.91% to 96.70%, then from Sunday to Monday the SOH dropped to 97.48%. Without any reason.

That last number is higher, not lower...

I agree that Hx is now useless (if it was ever really useful) but SOH seems to still be valuable, at least if you don't count very small changes as significant. BTW, if the above increase with the last number isn't a typo, that would be, I think, the first rise in SOH for a 40kwh pack we've seen.
 
kovadam said:
Hi!

Strange thing happened in the last two days. From Saturday to Sunday the SOH dropped from 96.91% to 96.70%, then from Sunday to Monday the SOH dropped to 97.48%. Without any reason.
The car was not QC-d, the battery was not overheated, I charged using L1 charger (220V/10A) from Friday to Saturday to 92% SOC (from around 40-50%, used 8 hours of charging with the charge timer) and did not even use the car on the weekend, despite this, the SOH dropped 0.5%. Also Hx dropped from 114.58% to 114.23%.

Funny thing, that with a full charge I still get over 97% capacity, if I check the GIDs. I still can charge over 485 GIDS (488-490 some times, which is 97.6-97.8%, for a couple weeks ago I was able to charge till 38.1kWh capacity, which is way over 98%) which is 97.4% or above, and over 37kWh estimated capacity.

I think SOH & Hx are totally wrong with the new Leaf, and since the battery chemistry is totally different from the previous models, also the values mean totally different things, or are not even meaning anything regarding SOH, they are only some numerical data read from the CAN and interpreted as SOH, because it showed some correlation between bar lost and SOH value drop in the past, but only Nissan Engineers know what this values mean.

Well, when it happens again in approximately 90 days, it will be less strange. My Hx is over 120
 
Just as a point of reference. My brand 2019 SL Plus w/62 kWh battery, manufacture date 2/19. 46 miles on odometer after driveling it home from dealership.

YcqWEqKl.jpg


yP5YNyKl.jpg
 
Sorry, it was a typo, 96.48, but after I left work in afternoon it was only 96.41%, so within 10 hours it dropped again 0.07% without any reason, the Hx dropped again a bit. Will see how this evolves, the car is 6 months old and has around 14000km on ODO.
 
Just as a point of reference. My brand 2019 SL Plus w/62 kWh battery, manufacture date 2/19. 46 miles on odometer after driveling it home from dealership.

The 98.96 SOH may be an indication that the 62kwh pack loses capacity at at least the same rate as the 40kwh pack. Where do you live, Jeryr?
 
LeftieBiker said:
Just as a point of reference. My brand 2019 SL Plus w/62 kWh battery, manufacture date 2/19. 46 miles on odometer after driveling it home from dealership.

The 98.96 SOH may be an indication that the 62kwh pack loses capacity at at least the same rate as the 40kwh pack. Where do you live, Jeryr?

Tampa Florida area.
 
So far - knock on virtual wood here - I've noticed my SOH decreasing by about 0.01 about every 2 days, regardless of miles. I guess that would come out to a 2% decrease per year, assuming my drop is even statistically relevant at this point. That would be a 20% loss of SOh in the 10 year warranty period, which is not enough to get a new battery. of course we aren't even close to the hottest time of the year yet. Only been in the low 90's so far.

I have been googling for 2020 leaf info but haven't found much yet. My plan since I got such a good deal on this one is to trade it in in a year or two for a new one with more range, so I'm curious what 2020 will bring.
 
I would expect your degradation to be less linear and more dependent on temperature, so little capacity loss in the cooler months, and much more in the hot months. How much more? I don't know - I tried my best to keep my car's pack cool in the hottest weather, and I have a 40kwh Leaf. Please keep us posted, maybe in a new, 62kwh battery topic...?
 
So it seems I will be the first one, who gets a new battery pack after 4-5 years for the 40kWh Leaf.

The SOH drop did not stopped, as written above, it started to decline in bigger steps from 96.91% in just 4 days. Now I'm at 95.71%. The last 0.07% happed in one hour standing the car in the parking lot (wake up with 95.78% SOH and 100% SOC then drove the kids to school, etc, I drove about 30km, then left the car for 1 hour parking, then the SOH was 95.71%) . The temperature is currently 8°C here, so it is not the heat (battery pack between 16 and 20°C), it's raining, and quite cold.

I did not QC-d the car at least for 2 weeks, and then also only for 10-15 minutes to reach 50-60% SOC. The Hx floats around 114.18-114.20%.

So the car has 13.500km, and is about 6 months old, and already lost over 4% SOH. So 1 year = 8% SOH loss, 2 years, and I get 1 bar capacity loss. Then every year 1 bar capacity minus, so when the car will be 5 years old, I'm down to 66%, and can ask for a warranty replacement.

Seems really bad for me.... :(
 
Bump it up? You mean the SOH? Or Hx?

The degradation was never fast, there were 2 times, when I lost 0.5%, but usually it was 0.01% / day or couple of days (like 2-3 days -0.01%). But now, in 4 days I lost more than 1.2%, in quite big chunks, so this started to worry me. I'm curious when I drive home from work, what will be the SOH. Now the car is in a garage, outside about 8-10°C inside may be 15°C. SOC is around 85%, SOH was 95.71% when I parked. Will see and report when I leave the garage.
 
Im curious to know if there are 18/19 MY that have more than 40,000 mi to see where their SOH is (besides the one in Phoenix that apparently still had 92 pct, but that one I recall was sitting in extreme heat last year and driven hard).
 
Jerryr said:
Just as a point of reference. My brand 2019 SL Plus w/62 kWh battery, manufacture date 2/19. 46 miles on odometer after driveling it home from dealership.

YcqWEqKl.jpg


yP5YNyKl.jpg

So this is not a full charge then.

If you get the chance post the same at full charge.
 
kovadam said:
So the car has 13.500km, and is about 6 months old, and already lost over 4% SOH. So 1 year = 8% SOH loss, 2 years, and I get 1 bar capacity loss. Then every year 1 bar capacity minus, so when the car will be 5 years old, I'm down to 66%, and can ask for a warranty replacement.

Seems really bad for me.... :(

The first 5% of capacity is often lost faster than later capacity. Not linear.

Battery_Degradation.jpg
 
In the previous 3 LEAFs, I saw the opposite where it maintained "new" status for probably (don't have specific stats on the 2011) the first 6 months or more. The 2016 went 14 months and over 29,000 miles at 100% SOH and 99.64% of its original ahr
 
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