Dramatic Ahr rise after quick charge?

Yes, it lived in TX until Feb 2016, when it moved to MN with 9 bars. I understand that it degraded faster in TX than it has/will in MN. Nonetheless, my Ahr trend looked promising until the recent quick charges. It dropped from 50.9Ahr to 43.7Ahr in a bit over 1 year in MN with primarily L1/L2 charges.

There is another poster here who is below 40 Ah who has not lost that last bar.

Click to expand...

Yeah, I wonder how many other cars are out there with very low Ahr that still have 9 bars. it'd be an interesting datapoint but there aren't a lot of reports like that. I suppose people are more likely to report when they did lose the bar, not when they didn't.

Anyway, I'm now on day 5 of the sustained Ahr bump and still increasing, contrary to the anecdotes about temporary 24hr blips. I'll just shut up for a while until I get a better idea where it's going to go from here. I'll follow up in a week or so, just in case anyone is interested in the data.

Que será, será
Thanks again,
-Eric

I've been pushing my Leaf harder than usual lately, and I've noticed a .2Ah increase in capacity as well, but I don't have any QCs in my area to try to push things that way... Please post new data a week from now when you have it.

Unrelated to my own car, here are some posts (translated from German) showing steady and sustained increase in the LeafSpy Ahr readings - gaining nearly 6 Ahr in the stats - with multiple, frequent quickcharges:

Oct 2013; 7 QCs, 94 L1/L2s:

Jan 2014; 43 QCs, 224 L1/L2s:


That was during a German winter. Obviously on a much fresher battery, not sure which model year.

sandeen said:

Yes, it lived in TX until Feb 2016, when it moved to MN with 9 bars. I understand that it degraded faster in TX than it has/will in MN. Nonetheless, my Ahr trend looked promising until the recent quick charges. It dropped from 50.9Ahr to 43.7Ahr in a bit over 1 year in MN with primarily L1/L2 charges.

Click to expand...

That's interesting, since my car currently shows 10 bars and reads about 47.5 Ah. I'm surprised you would be down to 9 bars with 50.9 Ah. What's also surprising is that my car was right about 50.5 Ah last year at this time and has only dropped 3 Ah in one year in VA, while your car has dropped over twice that much in about 1.5 times as long starting from the same point, but in a much colder climate.

sandeen said:

Unrelated to my own car, here are some posts (translated from German) showing steady and sustained increase in the LeafSpy Ahr readings - gaining nearly 6 Ahr in the stats - with multiple, frequent quickcharges:

Click to expand...

I have only seen instances of AHr rise that high reported on 2013+ LEAFs, never 2011-2012 LEAFs.

drees said:

I have only seen instances of AHr rise that high reported on 2013+ LEAFs, never 2011-2012 LEAFs.

Click to expand...

Same person is on these forums (xado1) and their sig does say 2013.

sandeen said:

drees said:

I have only seen instances of AHr rise that high reported on 2013+ LEAFs, never 2011-2012 LEAFs.

Click to expand...

Same person is on these forums (xado1) and their sig does say 2013.

Click to expand...

I've hesitated to respond on this topic because my report is only after a single, week-long trip. There aren't any DCQC's within 85 mi, so I've been charging via L1 or L2 for most of my six years. However, I have had two summer trips, one pre-Leaf Spy and one post-Leaf Spy, to Western WA/OR allowing use of the DCQCs. I gained about 1 AHr after about a month as described here:
http://mynissanleaf.com/viewtopic.php?f=27&t=14275&p=389721&hilit=arlington#p388565

RegGuheert said:

That's interesting, since my car currently shows 10 bars and reads about 47.5 Ah.

Click to expand...

Noticed today it is now showing only 9 bars. Ah reading is 47.40.

RegGuheert said:

That's interesting, since my car currently shows 10 bars and reads about 47.5 Ah. I'm surprised you would be down to 9 bars with 50.9 Ah.

Click to expand...

The drop to 9 bars was before I got it, and the 50Ahr reading was by the previous owner, post-drop. I suppose it's possible that Ahr reading rose again after it dropped to 9 bars, but I don't really have much history prior to my ownership.

sandeen said:

The drop to 9 bars was before I got it, and the 50Ahr reading was by the previous owner, post-drop. I suppose it's possible that Ahr reading rose again after it dropped to 9 bars, but I don't really have much history prior to my ownership.

Click to expand...

What was the highest reading you ever saw?

Highest reading I got while I owned the car was 45.9, that was a couple weeks after I bought it (took that long to get LeafSpy set up).

I only have 2 readings from the prior owner; he wasn't so analytical.
He (almost) never quick charged, FWIW.

sandeen said:

Highest reading I got while I owned the car was 45.9, that was a couple weeks after I bought it (took that long to get LeafSpy set up).

I only have 2 readings from the prior owner; he wasn't so analytical.

Code:

Date		Miles		Ahr
06/04/16	30000		50.9
10/11/16	34000		46.3
04/17/17	36671		45.91

He (almost) never quick charged, FWIW.

Click to expand...

I suppose those numbers are believable for TX. But the car certainly had 10 bars at the time it was showing 50.9 Ah. The data you showed in your spreadsheet also indicates that the third (10th) bar never drops above 47.5 Ah.

I think you should ignore that 50.9 Ah reading and just work with the 46.3 Ah last October. That should give you a better idea of the slope you will be seeing. And as the cold weather sets in, your capacity should stop dropping (or slow significantly).

I have the (MN) dealer battery check from 2/3/2016, and it does show 9 bars. But yes, I take the 50Ahr reading with a grain of salt, and I'm only looking at my own data for trends. (Incidentally, I'm still 0.56Ahr above where I was before the quick charges.) As for the colder weather, yeah. :/ If I don't see a return to my prior slope soon it looks like no chance.

sandeen said:

It's just that my experience and my data doesn't seem to bear that out.

Click to expand...

Nice spreadsheet. I can see you experienced a bump in capacity when you previously QCed your LEAF, though not as big as the current one.

sandeen said:

My own experience (QC consistently bumping Ahr up for weeks), anecdotes I've read (QC bumps, QC slowing degradation curve), and data I've collected about 4 bar losers (nobody ever loses a bar above 43.5Ahr, median reported QC count is only eight (average under 50), etc) seem to point in the other direction to some degree.

Click to expand...

Thanks for putting together this data! That's very helpful.

Can you please add my LEAF into the '3 bar drops' tab:

Miles: 46,100
Ah: 47.47
Hx: 51.60
QC: 12
L1/L2: 2768

RegGuheert said:

Can you please add my LEAF into the '3 bar drops' tab

Click to expand...

Sure thing, done. (I have not put nearly as much effort into the 3 bar drop stats, as you can see - that's water under the bridge for me, but it would be interesting to collect more data there if it's been reported).

sandeen said:

RegGuheert said:

Can you please add my LEAF into the '3 bar drops' tab

Click to expand...

Sure thing, done.

Click to expand...

Thanks!

RegGuheert said:

I think you should ignore that 50.9 Ah reading

Click to expand...

I took the car in for the annual battery check today (figured that if I hope for warranty and/or goodwill, I should be sure to follow mfgr's instructions, even though the $70 hurt). Tech said no other battery check had ever been registered with Nissan, even though I have one printed out from 2016.
Anyway, I just realized that that 50.9Ahr reading was probably due to a jump right after a P3227 update after the car was bought from auction before it got resold.

Aug 30: As promised, here's an updated graph of my Ahr readings about a week after the surprising quick charge jump on the 21st. I actually needed to quick charge a couple times on the 25th as well, to get through my travels; I noted that the battery got up to around 100F that day. I've overlaid the DCQC total energy in kWh for days when I quick-charged. There seems to have been some effect back in June as well, though not nearly as dramatic. Other quick charges seem to have had no effect at all. Speaking somewhat non-analytically, it appears that my quick charging behavior has had a tendency to "reset" the decline in readings to a certain degree; so far I don't see a quick return to the prior levels.



I'll just update/edit this post rather than adding another, after another week or so.

Edit Sep 3: And now, a "dramatic decline" over the past four days. I'm now back at levels where I started prior to the round of DCQC, though had I continued on the trajectory I'd seen prior to the latest quick charging, my reported Ahr capacity would be even lower. We'll see what the next days bring.

Edit Sep 10: Still basically hovering around where I was prior to the fateful quick charges. Certainly not hard proof, but the trendline I was on for weeks prior to the quick charge is still really knocked off course. Nothing indicates that the quick charges and relatively high heat did anything to degrade the battery (at least as reflected in the LeafSpy readings).

Readings are now finally back down below where they were prior to the quick charges:
43.65 Ahr, 45.49 Hx, 66% SOH, 40125 mi.
Trend line of Ahr decline during my ownership shows me hitting 42Ahr on my warranty end date. In February. Hoping my car might be a higher-Ahr-bar-loser, because it's doubtful that I'll see that capacity drop during the colder months.
I think we have 4 more hot days left this summer.

Here's another way I've been looking at this. I'm tracking my Ahr decline with a best fit curve by date, like this:

Now, as my Ahr readings change over time, the target date moves. If I decline more quickly than average, it moves in, and vice versa. Now, here's a graph of my projected date of hitting 42Ahr, which was my goal for reasonable chance of dropping that bar, and with quick charge & L2 charges overlaid. Days w/ no DCQC or L2 are (likely) L1 charging, or (occasionally) no charging. There are probably a couple of L2 charges that I don't have logged from public stations.

What I notice about this is that faster charging seems invariably to push my "target date" out - i.e. reduces the rate of Ahr decline. And it's not temporary. There have been some very minor moves to earlier dates, but by and large, my periods of faster charging have always reduced the rate of Ahr decline, and hence pushed out my target date. If I exclusively L1 charge, the slope stays more or less the same, and my target date remains steady. It now sits at precisely my end of warranty date.
Now, it's true that the bar drop may not be governed (solely) by Ahr values. Maybe L1 charging artificially suppresses Ahr readings, but does not hasten the bar drop. But the preponderance of evidence I've seen with my car makes me think that at least the moderate amount of quick charging I have done is a net "loss" in the race for a new battery.