DougWantsALeaf
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Re: The 40KWH Battery Topic

Mon Oct 11, 2021 8:59 am

So a 8% drop in first year, then 1-1.5% a year there after.
2019 S Plus (93.7% SOH) & 2019 SV Plus (91.6% SOH) Both Silver
2013 Leaf SV sold 2019 with 11 bars
100 Mile Club Member (Number 87)
Max Miles on 13 Leaf: 120 miles
Max Miles on 19 SV+: 242 Highway miles @ 4.5 miles/kWh

DaveinOlyWA
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Re: The 40KWH Battery Topic

Tue Oct 12, 2021 6:17 am

DougWantsALeaf wrote:
Mon Oct 11, 2021 8:59 am
So a 8% drop in first year, then 1-1.5% a year there after.
sometimes. I have seen 5ish% the first year, 3ish the 2nd then 1ish after (like Gerry's) but no matter how the first few years look, most seem to merge together within 2% after 3 years or so.
2011 SL; 44,598 mi, 87% SOH. 2013 S; 44,840 mi, 91% SOH. 2016 S30; 29,413 mi, 99% SOH. 2018 S; 25,185 mi, SOH 92.23%. 2019 S Plus; 25,047 mi, 92.12% SOH
My Blog; http://daveinolywa.blogspot.com" onclick="window.open(this.href);return false;

SageBrush
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Re: The 40KWH Battery Topic

Tue Oct 12, 2021 6:36 am

DaveinOlyWA wrote:
Tue Oct 12, 2021 6:17 am
but no matter how the first few years look, most seem to merge together within 2% after 3 years or so.
Can you rewrite that in English ?
2013 LEAF 'S' Model with QC & rear-view camera
Bought Jan 2017 from N. California
Two years in Colorado, now in NM
03/18: 58 Ahr @28k miles. 10/21: 53.4 Ahr @ 40k miles
-----
2018 Tesla Model 3 LR, Delivered 6/2018

DaveinOlyWA
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Re: The 40KWH Battery Topic

Wed Oct 13, 2021 6:04 am

SageBrush wrote:
Tue Oct 12, 2021 6:36 am
DaveinOlyWA wrote:
Tue Oct 12, 2021 6:17 am
but no matter how the first few years look, most seem to merge together within 2% after 3 years or so.
Can you rewrite that in English ?
@3 years most are between 89 to 91% SOH
2011 SL; 44,598 mi, 87% SOH. 2013 S; 44,840 mi, 91% SOH. 2016 S30; 29,413 mi, 99% SOH. 2018 S; 25,185 mi, SOH 92.23%. 2019 S Plus; 25,047 mi, 92.12% SOH
My Blog; http://daveinolywa.blogspot.com" onclick="window.open(this.href);return false;

goldbrick
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Re: The 40KWH Battery Topic

Wed Oct 13, 2021 10:05 am

One question I have is whether the BMS is programmed to use up any hidden 'extra' capacity to force the SOH to follow a fixed trajectory or if all the batteries tend towards the mean as they age. Or it could be a combination of both but it's odd how closely the population of batteries seen here is tending towards a fixed SOH trajectory.

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Stanton
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Re: The 40KWH Battery Topic

Wed Oct 13, 2021 12:23 pm

goldbrick wrote:
Wed Oct 13, 2021 10:05 am
One question I have is whether the BMS is programmed to use up any hidden 'extra' capacity to force the SOH to follow a fixed trajectory or if all the batteries tend towards the mean as they age. Or it could be a combination of both but it's odd how closely the population of batteries seen here is tending towards a fixed SOH trajectory.
While that might be a good "conspiracy theory", I think it's just a sign that (after 10+ years) they have finally improved the chemistry and/or manufacturing process.
2011 Blue Ocean SV w/OVMS
12v LiFePO4 battery w/Antigravity Battery Tracker
FIAMM 74100 horns/Wet Okole seat covers/Tor's heater mod/Dala's CAN-bridge
Lizard Pack (Rev E) installed @51 months/41k miles
40 kWh Pack (Gen2) installed @115 months/85k miles

goldbrick
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Re: The 40KWH Battery Topic

Wed Oct 13, 2021 1:10 pm

Even if the BMS was programmed this way I wouldn't assign any malevolent intent to anyone. It may just be a good way to make all cars behave 'the same' as much as possible. Many manufacturing calibrations do exactly this so that the embedded control algorithms are normalized to a common model.

I think we can all agree that we don't really know how the BMS handles SOH or even what it exactly means. There is an obvious 3 month time frame that results in step changes in the reported SOH and also cases where the SOH has increased at these points. To me, this implies the BMS is doing something more than just reporting the status of a continuous, inevitable decline in battery capacity. AFAIK, no one here knows enough about the internal BMS programming to know what exactly it is doing but that's fine with me. I check my SOH about once a year now and that is all the resolution I need.

SageBrush
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Re: The 40KWH Battery Topic

Wed Oct 13, 2021 1:30 pm

goldbrick wrote:
Wed Oct 13, 2021 1:10 pm
I think we can all agree that we don't really know how the BMS handles SOH or even what it exactly means.
We know the cell voltages. End of story, +/- some calibration drift
2013 LEAF 'S' Model with QC & rear-view camera
Bought Jan 2017 from N. California
Two years in Colorado, now in NM
03/18: 58 Ahr @28k miles. 10/21: 53.4 Ahr @ 40k miles
-----
2018 Tesla Model 3 LR, Delivered 6/2018

DougWantsALeaf
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Re: The 40KWH Battery Topic

Wed Oct 13, 2021 3:41 pm

True, but the BMS is managing access to the top end of the pack voltage, no? It feels like the bms has a relatively simple algorithm which limits a bit more aggressively for cars which charge to 100% frequently or DC charge frequently. That said, there does. Not appear to be much of a difference after a couple years. Even the brutalized packs are not much different than the pristinely managed packs from the little we have seen.

Livery cars with crazy high cycles are down a few % more, but that's somewhat to be expected.
2019 S Plus (93.7% SOH) & 2019 SV Plus (91.6% SOH) Both Silver
2013 Leaf SV sold 2019 with 11 bars
100 Mile Club Member (Number 87)
Max Miles on 13 Leaf: 120 miles
Max Miles on 19 SV+: 242 Highway miles @ 4.5 miles/kWh

DaveinOlyWA
Posts: 15808
Joined: Sat Apr 24, 2010 7:43 pm
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Location: Olympia, WA
Contact: Website

Re: The 40KWH Battery Topic

Thu Oct 14, 2021 6:14 am

goldbrick wrote:
Wed Oct 13, 2021 10:05 am
One question I have is whether the BMS is programmed to use up any hidden 'extra' capacity to force the SOH to follow a fixed trajectory or if all the batteries tend towards the mean as they age. Or it could be a combination of both but it's odd how closely the population of batteries seen here is tending towards a fixed SOH trajectory.
Doubt if its that simple. Probably just have a better chemistry and better management in play.

I was collecting LS data to delve into the possibility of any emerging trends but the sample size is limited and no definitive patterns have emerged.

The next step is getting LS shots at full charge as it seems the full charge SOC runs between 100.00% (shocking aint it?) to 97.5% to see if there is any pattern there?
2011 SL; 44,598 mi, 87% SOH. 2013 S; 44,840 mi, 91% SOH. 2016 S30; 29,413 mi, 99% SOH. 2018 S; 25,185 mi, SOH 92.23%. 2019 S Plus; 25,047 mi, 92.12% SOH
My Blog; http://daveinolywa.blogspot.com" onclick="window.open(this.href);return false;

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