Big jump in Capacity....Whats going on?

Hello all,
Has anyone ever experienced a noticeable jump in their battery capacity?
For the first year of my used 2015 LEAF ownership the capacity hovered around 60Ahrs(284GIDs fully charged,SOH 97, Hx92).
About 3 months ago the capacity slowly began dropping until it hit a low of 55.5Ahrs(255GIDs fully charged, SOH 89, Hx82)
Starting 3 weeks ago the capacity has climbed back to 61Ahrs (291GIDS fully charged,SOH 98, Hx92). :?:

How common/uncommon is this?

I suspect it is not worth the time to talk to a Tech at the dealer(and have the battery test done), based on other forum member's experiences.

Thanks for any opinions.

Have your usage or charging patterns changed? I saw capacity (at least according to Leaf Spy) increase with frequent quick charging and also with more aggressive driving; capacity decreased with gentle driving and slower charging with my 2015.

My 2014, now with about 28000 miles on it has done this. I got it from my Dad in September, and how it's used has changed a lot.

It used to be driven not very much, not much highway driving 55 mph max, and never DCFC'd. It was in western NY, in a garage, so great for temperature. It was also not always recharged after every trip, so it spent most of it's time maybe in the 50-75% SOC range I guess.

Initially, it said around 60 Ah, 94% SOH.

Now it's in Michigan, and temperatures shouldn't be an issue. About 4000 miles in 3 months of use, 27 QCs, sometimes 75 on the highway, and now it claims 66.8 Ah and 102% SOH.

It doesn't go as far as the GOM now predicts (as much as 100 miles at full SOC), but that's alright, we understand and it's a fun car. I haven't noticed if the imaginary extra range goes away at the beginning, middle or end of the trip.

The $64,000 question here is: "Have you been doing a lot of quick charges lately?"

LeftieBiker said:

The $64,000 question here is: "Have you been doing a lot of quick charges lately?"

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Nope. I have seen the Capacity bump occur from DCFC not long after getting the car, but it was minimal.
# of DCFC is steady at about 2/month

"Have your usage or charging patterns changed? "

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Nope. 2-3 100km round trips to work per week(with an L2 charge to 100% at work) + an 80km trip to the In-laws on the weekend.

" I haven't noticed if the imaginary extra range goes away at the beginning, middle or end of the trip"

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Agreed. This small a change in Ahrs is not really enough to be obvious in the short term if it indeed exists, and the first 8% always disappeared quickly.

Did you happen to capture the cell voltage screen for these readings?

i have seen variable capacity due to imbalance of one or more cells.

When there is a significant voltage difference then the capacity drops; and when the balance is very tight the capacity increases.

Did you happen to capture the cell voltage screen for these readings?

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I saw no reason to watch the voltages carefully because capacity loss is expected.(Although that big of a loss was a bit concerning).
What has me a bit disturbed is the increase up to "Better than new" condition. In my mind that suggests something isn't working correctly.

PS: Interestingly, yesterday's TRIP_LOG has it at 62.9Ahrs and SOH 101.4.

Virtuallydead said:

Did you happen to capture the cell voltage screen for these readings?

Click to expand...

I saw no reason to watch the voltages carefully because capacity loss is expected.(Although that big of a loss was a bit concerning).
What has me a bit disturbed is the increase up to "Better than new" condition. In my mind that suggests something isn't working correctly.

PS: Interestingly, yesterday's TRIP_LOG has it at 62.9Ahrs and SOH 101.4.

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The BMS estimates capacity, and that is what LeafSpy reads is the BMS's estimate.

The error bar of the estimate is at least +10% -3%. So if the real SOH is 92%, the estimated SOH might be anywhere between 89% and 102%

My driving went from predictable to variable. This change caused SOH to change from a number that didn't change much day to day and month to month to a number that varied a lot. So I spent some time playing with my Leaf trying to find things that increased SOH, and was able to raise it by roughly 10%, and lower it by roughly 3%. I strongly doubt that changing charging and driving habits actually change the real capacity of the battery.

I have not investigated what balance and cell voltages have to do with this. Improving the balance of the battery would increase the usable capacity of the battery.

You do realize that GIDS, SOH, HX, JISMs, etc are not real data values?

These are artificially created and calculated values based upon some numbers found by CAN buss sniffing--they are not found in the Factory Service Manual and a dealer service tech with the Consult Tool would have no idea what you are talking about.

In an attempt at technical rigor for this forum, this is information from the FSM:
https://www.mynissanleaf.com/viewtopic.php?f=8&t=30599&p=572835#p572835

nlspace said:

You do realize that GIDS, SOH, HX, JISMs, etc are not real data values?

These are artificially created and calculated values based upon some numbers found by CAN buss sniffing--they are not found in the Factory Service Manual and a dealer service tech with the Consult Tool would have no idea what you are talking about.

In an attempt at technical rigor for this forum, this is information from the FSM:
https://www.mynissanleaf.com/viewtopic.php?f=8&t=30599&p=572835#p572835

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They are real. The technical documentation refers to them as LB_CAPR (gids). LB_SOH (soh), LB_Historical_Data_Degradation_ Internal_Resistance_Coeff (HX)

Just because the FSM doesn't mention them doesn't mean they are irrelevant.

Indeed. The readings were there from the start, programmed by Nissan. Gary Gid and the LeafSpy developer just renamed them.

Dala said:

They are real. The technical documentation refers to them as LB_CAPR (gids). LB_SOH (soh), LB_Historical_Data_Degradation_ Internal_Resistance_Coeff (HX)

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Which document is this?

nlspace said:

Dala said:

They are real. The technical documentation refers to them as LB_CAPR (gids). LB_SOH (soh), LB_Historical_Data_Degradation_ Internal_Resistance_Coeff (HX)

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Which document is this?

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One I cannot share since I was asked not to. Stamped Nissan Confidential. But all the good stuff I've put into the database files here https://github.com/dalathegreat/leaf_can_bus_messages

Dala said:

They are real. The technical documentation refers to them as LB_CAPR (gids). LB_SOH (soh), LB_Historical_Data_Degradation_ Internal_Resistance_Coeff (HX)

Just because the FSM doesn't mention them doesn't mean they are irrelevant.

Click to expand...

Good. So if we have 90% of people agreeing that GIDS represents the available energy, and that GIDS after a 100% charge is total capacity available for you to use, I would re-ask for opinions:
A: This acceptable behavior.. Don't sweat it.
B: This is slightly abnormal behavior-but not yet worth your time to investigate...Don't sweat it yet.
C: This is abnormal behavior-time to investigate... Have a double Rum & Coke.

It's at least somewhat unusual.

Virtuallydead said:

Good. So if we have 90% of people agreeing that GIDS represents the available energy, and that GIDS after a 100% charge is total capacity available for you to use, I would re-ask for opinions:

Click to expand...

GIDs are an ESTIMATE of the available energy.


B: This is slightly abnormal behavior-but not yet worth your time to investigate...Don't sweat it yet.

Would make more sense if you had changed your driving pattern, new job or new hours or adding a trip to drop the kids off at soccer or something...

OP,

do you know the temperature at the times that you made those measurements? Temperature is an important variable for calculation of the charge available and remaining capacity values.

nlspace said:

OP,

do you know the temperature at the times that you made those measurements? Temperature is an important variable for calculation of the charge available and remaining capacity values.

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Not really. Winter IS coming, but they weren't the first of the cold mornings. Also, this effect didn't occur last autumn.

Another change that I think is related to the (artificially) increased capacity estimate:

The charge timer seems to finish more ahead of time than it used to (when the capacity & SOH estimates were as expected).

I had to set the finishing time a few hours later (noon or 1pm), to end up about 80% when the car gets unplugged about 6:30 am. Previously I think I had set it to 10am to accomplish the same result. I suspect the car starts charging sooner because there's more Ahrs it needs to fill up by the finish time. But there's really no extra capacity to fill.