SOH not Dropping compared to AHr?

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Gorge

Active member
Joined
May 31, 2016
Messages
36
Location
Los Angeles, CA
Trying to figure out why my AHr and SOH aren't matching up. II've dropped a good amount of AHr, but my SOH isn't dropping at all. I've lost 2.5 AHr and my SOH hasn't dropped a single percentage. Is this normal?

May 2016:
AHr: 47.868
SOH: 72%

December 2016
AHr: 45.360
SOH: 72%
 
LeafMuranoDriver said:
Same here. SOH has been @ 99% pretty much since I've had it and Ahr has gone from 63 to 55.

not sure that is a good thing. generally means either your pack balance is out of whack or you might even have a failing cell. I think you would do good to do 4-5 full charges in a row making sure you drive to at least 60%? SOC or so...
 
DaveinOlyWA said:
LeafMuranoDriver said:
Same here. SOH has been @ 99% pretty much since I've had it and Ahr has gone from 63 to 55.

not sure that is a good thing. generally means either your pack balance is out of whack or you might even have a failing cell. I think you would do good to do 4-5 full charges in a row making sure you drive to at least 60%? SOC or so...
It's definitely not a good thing in the short term but I think it's okay in the long term.

All of the cells are usually balanced to within 13 mV +/- 2 mV when I charge to 100%. (I take LS screenshots almost every 100% charge)

I usually only charge to 100% 1-2 times per week and do not drive enough to get the stats up.

About a year ago I did a test to see if I drove more would the stats improve. I tried to drive 40+ miles per day, QC every 1-2 days and charge to 100% as much as I could when needed. All of the stats but SOH went up...

12/12/15 - 4,616 miles - 17 QC / 93 L2 - 259 GIDs - 20.1 kWh - 99% SOH - 82.84% Hx - 55.02 Ahr
12/30/15 - 5,358 miles - 22 QC / 111 L2 - 279 GIDs - 21.6 kWh - 99% SOH - 91.08% Hx - 59.12 Ahr

Stats increased 7-8% in 18 days.
 
LeafMuranoDriver said:
DaveinOlyWA said:
LeafMuranoDriver said:
Same here. SOH has been @ 99% pretty much since I've had it and Ahr has gone from 63 to 55.

not sure that is a good thing. generally means either your pack balance is out of whack or you might even have a failing cell. I think you would do good to do 4-5 full charges in a row making sure you drive to at least 60%? SOC or so...
It's definitely not a good thing in the short term but I think it's okay in the long term.

All of the cells are usually balanced to within 13 mV +/- 2 mV when I charge to 100%. (I take LS screenshots almost every 100% charge)

I usually only charge to 100% 1-2 times per week and do not drive enough to get the stats up.

About a year ago I did a test to see if I drove more would the stats improve. I tried to drive 40+ miles per day, QC every 1-2 days and charge to 100% as much as I could when needed. All of the stats but SOH went up...

12/12/15 - 4,616 miles - 17 QC / 93 L2 - 259 GIDs - 20.1 kWh - 99% SOH - 82.84% Hx - 55.02 Ahr
12/30/15 - 5,358 miles - 22 QC / 111 L2 - 279 GIDs - 21.6 kWh - 99% SOH - 91.08% Hx - 59.12 Ahr

Stats increased 7-8% in 18 days.

top end balance won't reveal a weak cell. reason is that at the top, higher cells basically hit a wall and cannot proceed allowing lower cells to catch up much quicker. this does not happen in the middle of the pack. What you want to do is look at cells way off the pack average when your SOC is below 20-25%. It is here the weak ones start to fall out
 
DaveinOlyWA said:
LeafMuranoDriver said:
DaveinOlyWA said:
not sure that is a good thing. generally means either your pack balance is out of whack or you might even have a failing cell. I think you would do good to do 4-5 full charges in a row making sure you drive to at least 60%? SOC or so...
It's definitely not a good thing in the short term but I think it's okay in the long term.

All of the cells are usually balanced to within 13 mV +/- 2 mV when I charge to 100%. (I take LS screenshots almost every 100% charge)

I usually only charge to 100% 1-2 times per week and do not drive enough to get the stats up.

About a year ago I did a test to see if I drove more would the stats improve. I tried to drive 40+ miles per day, QC every 1-2 days and charge to 100% as much as I could when needed. All of the stats but SOH went up...

12/12/15 - 4,616 miles - 17 QC / 93 L2 - 259 GIDs - 20.1 kWh - 99% SOH - 82.84% Hx - 55.02 Ahr
12/30/15 - 5,358 miles - 22 QC / 111 L2 - 279 GIDs - 21.6 kWh - 99% SOH - 91.08% Hx - 59.12 Ahr

Stats increased 7-8% in 18 days.

top end balance won't reveal a weak cell. reason is that at the top, higher cells basically hit a wall and cannot proceed allowing lower cells to catch up much quicker. this does not happen in the middle of the pack. What you want to do is look at cells way off the pack average when your SOC is below 20-25%. It is here the weak ones start to fall out
Got it, thanks for the info! I ran it down to 20% on the GOM last night.

LeafSpy showed 29% SOC, 18.2% GIDs, 54.14 AHr, 99% SOH, 81.57% Hx, Cells @ 3.804 / 3.817 / 3.826 (22 mV) - It bounced between 19 mV - 22 mV.

The AHr and Hx is the lowest readings I've ever gotten. :cry: I haven't been driving much lately plus the winter.

Doesn't seem like the cells are out of balance.
 
LeafMuranoDriver said:
DaveinOlyWA said:
LeafMuranoDriver said:
It's definitely not a good thing in the short term but I think it's okay in the long term.

All of the cells are usually balanced to within 13 mV +/- 2 mV when I charge to 100%. (I take LS screenshots almost every 100% charge)

I usually only charge to 100% 1-2 times per week and do not drive enough to get the stats up.

About a year ago I did a test to see if I drove more would the stats improve. I tried to drive 40+ miles per day, QC every 1-2 days and charge to 100% as much as I could when needed. All of the stats but SOH went up...

12/12/15 - 4,616 miles - 17 QC / 93 L2 - 259 GIDs - 20.1 kWh - 99% SOH - 82.84% Hx - 55.02 Ahr
12/30/15 - 5,358 miles - 22 QC / 111 L2 - 279 GIDs - 21.6 kWh - 99% SOH - 91.08% Hx - 59.12 Ahr

Stats increased 7-8% in 18 days.

top end balance won't reveal a weak cell. reason is that at the top, higher cells basically hit a wall and cannot proceed allowing lower cells to catch up much quicker. this does not happen in the middle of the pack. What you want to do is look at cells way off the pack average when your SOC is below 20-25%. It is here the weak ones start to fall out
Got it, thanks for the info! I ran it down to 20% on the GOM last night.

LeafSpy showed 29% SOC, 18.2% GIDs, 54.14 AHr, 99% SOH, 81.57% Hx, Cells @ 3.804 / 3.817 / 3.826 (22 mV) - It bounced between 19 mV - 22 mV.

The AHr and Hx is the lowest readings I've ever gotten. :cry: I haven't been driving much lately plus the winter.

Doesn't seem like the cells are out of balance.

well high SOH is always good and your low usage is probably contributing to the lower numbers but I don't think I have ever seen an ahr bounce around like yours. Since I work on the road, my LEAFing varies from 100 to 600 miles a week so pretty extreme so I also see my numbers bounce around but nothing compared to yours. I mean 4-5 ahr is waaaay beyond what I see!
 
Odd. I just checked LS. AHr at 45.257 and still sitting at 72% SOH. I should hit 41-42 AHr by the end of warranty, but I wonder if my SOH will ever drop.
 
DaveinOlyWA said:
well high SOH is always good and your low usage is probably contributing to the lower numbers but I don't think I have ever seen an ahr bounce around like yours. Since I work on the road, my LEAFing varies from 100 to 600 miles a week so pretty extreme so I also see my numbers bounce around but nothing compared to yours. I mean 4-5 ahr is waaaay beyond what I see!
Agreed. The swings can be quite big. All comes down to driving/charging.

I have not seen any other car with similar stats that has anything more than 92-95% SOH. Definitely unique.
 
Is there any back of the napkin calculation on the correspondence between AHr and SOH?

I've dropped almost 3 AHr (below 45 AHRr now) over the past 9 months and I'm still stuck at 72% SOH per LSP. Getting frustated at the lack of change. I see people with 42-43 AHr and 62-65% SOH. Not sure how I can drop another 4 AHr and see a 7-10% SOH decrease.
 
Dave,
How would you go about trying to charge/rehab weak cell(s) in a LEAF ?

I think you are saying repeat cycles of discharge to level of weakest cell followed by charge to 100%

Is this right ?
 
SageBrush said:
Dave,
How would you go about trying to charge/rehab weak cell(s) in a LEAF ?

I think you are saying repeat cycles of discharge to level of weakest cell followed by charge to 100%

Is this right ?

Can't really discharge to the level of the lowest cell because weaker cells will discharge quicker.

I am not a fan of discharging car to very low levels but had to because of my needs. So I found that yeah, getting to single digit GIDs and recharging to full on L2 created a very well balanced pack for me.

To add; my S30 has only been below 10 GIDs 4-5 times so far and part of that is NCTC which encourages me to not cut it close. I tend to now just stop. Summer driving is always more extreme so we shall see but so far, my S30 is not nearly as balanced as my previous 24 kwh packs were and the depth of cycling is the biggest process change.

Really too early to make any conclusions
 
Gorge said:
Is there any back of the napkin calculation on the correspondence between AHr and SOH?

I've dropped almost 3 AHr (below 45 AHRr now) over the past 9 months and I'm still stuck at 72% SOH per LSP. Getting frustated at the lack of change. I see people with 42-43 AHr and 62-65% SOH. Not sure how I can drop another 4 AHr and see a 7-10% SOH decrease.

because ahr is a measure of charge capacity, your drop could simply be an indication of a "healthier" battery that is simply way out of balance.
 
I have no idea what SOH and Hx measure, other than it is nice to see them high :)
When they do not correlate with remaining Ahr at full charge questions come up but I've only seen guesses as to why.

I do agree with Dave that cell that are unbalanced may be one possible answer and should be remediated if possible with charges up to 100% SOC. This is all black magic, and Nissan is not going out of its way to dispel the mystery.
 
SageBrush said:
I have no idea what SOH and Hx measure, other than it is nice to see them high :)
When they do not correlate with remaining Ahr at full charge questions come up but I've only seen guesses as to why.

I do agree with Dave that cell that are unbalanced may be one possible answer and should be remediated if possible with charges up to 100% SOC. This is all black magic, and Nissan is not going out of its way to dispel the mystery.
I charge to 100% every night so I would think it should be calibrated.. but who knows.
 
oleviking said:
My SOH has shown 83% since the day i leased the 2016 SV, don't know what to think about that, only 3,000 miles on it as of today.

See below in the signature my stats on 2016 Leaf SV. Mine went up when I ran it hard a few times. Long trip 6 QC sessions in one day. After each time the SOH went up and stayed. I have 17 k on the car since April. It seems to like to drive. My range has improved it seems as well. I noticed the pack balance seems to have a lot to do with that.
See if you can drive the car more.
 
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