Dramatic Ahr rise after quick charge?

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sandeen

Well-known member
Joined
May 12, 2017
Messages
126
Location
Minnesota
I've seen a few references to this effect, but wondering if people can share what they've seen in detail.

I'm tracking my 2012 leaf, hoping I get a 4 bar drop by the end of Jan 2018. Last week, I felt like I was getting within striking distance - I had dropped to 43.66Ahr, and was feeling pretty good about my chances. I hadn't quick charged for over a month.

Then yesterday I quick-charged to nearly full after hitting LBW. My Ahr jumped to 43.83. Then my wife drove the car for 30 miles today ... 43.87Ahr. A 0.2Ahr jump in a day seems very large. Is this a normal effect? How long have people seen it last? Is this a temporary blip or does it reset the curve, so to speak?

Here's what Ahr did as compared to SOC over the last 2 days; the rapid increase in SOC is the quick charge, of course:
dZbKSi8.png


After one quick charge session back in June I saw my Ahr jump and not drop back to the prior values for almost 2 weeks. I hope that doesn't happen this time, as I'm getting awfully close to missing my warranty expiration. :( Sigh.

Anecdote or not, I think I'm done with quick charging until my warranty period is over. :(
 
Another 30 miles, now it's 43.94 Ahr.

I know what you mean about noise, but I've never seen a gain like this so quickly, based on the last 4-5 months of driving. This is well outside the norm as far as I can tell.
 
Eric, what were your charging habits before your recent QC?

I've logged some 0.7 AHr jumps after QC, but it quickly goes back down. 80% charges and shallow discharges seem to suppress AHr readings, QCs and/or full discharge/charge cycles seem to help pump them up temporarily.

You're still on track to lose that bar in time, I wouldn't stress about it that much. Just keep on driving it - you have plenty of miles left.

BTW, did your Hx value jump, too? The times I saw AHr jump, HX remained the same.
 
you should QC more often, as much as possible to be realistic. Keep in mind; losing that last capacity bar is your prompt to get the battery tested. its that test that determines whether you get a replacement. generally you are good but if your numbers are depressed then you might not fail (to qualify) the test. I am fairly certain you would not be the first.

The ahr is not jumping, the counter is simply off. you can do the same thing by doing several full charges and deep discharges over several days. Realize if you want degradation, heat is what you need so QC in Summer is the fastest way to get that heat buildup
 
DaveinOlyWA said:
you should QC more often, as much as possible to be realistic. Keep in mind; losing that last capacity bar is your prompt to get the battery tested. its that test that determines whether you get a replacement. generally you are good but if your numbers are depressed then you might not fail (to qualify) the test. I am fairly certain you would not be the first.

The ahr is not jumping, the counter is simply off. you can do the same thing by doing several full charges and deep discharges over several days. Realize if you want degradation, heat is what you need so QC in Summer is the fastest way to get that heat buildup
1+
 
drees - I had been charging almost exclusively on L1 for over a month, last DCQC was mid-July. (2 reasons: The L1 charger cord is the one that reaches past my wife's van to my parking spot, and I only drive about 20 miles/day, so quick charge doesn't make a ton of sense). And yes, both Ahr & Hx went up, they stayed in their otherwise linear relationship. As for plenty of time - well, I have plenty of miles, not so much time. :)

DaveinOlyWA - are there really any established reports of a 4 bar loss that was not warrantied due to "not bad enough?" I think I've seen one denial in these forums because Nissan somehow determined the battery had been abused, but I don't remember any other such denial.

And yes, I agree it's more likely an accounting/measurement change than an actual battery health change, but on the other hand, there have been no reports of 4th bar loss above 43.5 Ahr, so I certainly don't want to take a long excursion back up above 44, for example. :)

Thanks,
-Eric
 
Hm. Of those who reported QC counts at 4th bar loss, the mean was 46 QCs and the median was 8 QCs. It doesn't seem like too many people quick-charged their battery to death.
OTOH, the average miles per L1/L2 charge at 4 bar loss is 16.
 
Time to start driving more if miles are not close. The battery needs to be cycled and hold the battery at full as much as you can. If you drove the battery low then brought it high that will get a better AH reading. Park the car at work with the heater on pull the pack low then fast charge at lunch? Drive the battery low then fast charge as much as you can. it worked for me.
 
sandeen said:
DaveinOlyWA - are there really any established reports of a 4 bar loss that was not warrantied due to "not bad enough?" I think I've seen one denial in these forums because Nissan somehow determined the battery had been abused, but I don't remember any other such denial.

And yes, I agree it's more likely an accounting/measurement change than an actual battery health change, but on the other hand, there have been no reports of 4th bar loss above 43.5 Ahr, so I certainly don't want to take a long excursion back up above 44, for example. :)

Thanks,
-Eric

yeah there has but due to Nissan "bar slop" than anything else. bars go and sometimes bars come back. When the last bar disappears, you are very close to the warranty exchange level but not always guaranteed to be there. IIRC there have been a few that took theirs down right away to fail the battery test but were able to pass it (to qualify) a month later.

But that is not the main concern. I would be more concerned about the time and mileage you have to work with. Cutting it close is probably not the way I would play it. As is typical, I don't know where you stand on that?
 
I have 20,000 miles left, but only 5 months. And cold months at that.

Anyway, thanks for all the suggestions; I guess I was looking more for some hard data, hoping people had been keeping track of battery stats as I have and might be able to provide some insight into how their battery had actually behaved after quick charges.

Looking back over 10 or so quick charges since March, there were times when there was no strong effect in either direction, but 3 or 4 times it resulted in Ahr jumps of 0.15 to 0.25 in a day, an amount which is outside of the normal daily jitter that I see.

Thanks,
-Eric
 
I'm in Minnesota, so Winter is Coming! Yeah, a road trip might be interesting.

But again, I was hoping for more data analysis & less anecdote. ;)

I hear everyone's advice about QC, and given that Nissan dings you for "too many" and the heat involved, it certainly seems like it would move the numbers down. It's just that my experience and my data doesn't seem to bear that out.

My biggest Ahr upswings have come on the day of, or after, a quick charge, and it takes weeks to return to where they were before. I can't explain it. I'm just wondering what other people have seen in practice (in, you know, numbers :) ).
 
Turn your winter into a hot summer with quick charging from a low SoC
And if possible, run the heater at full blast during the quick charge. Get that battery temp HOT
 
ok we can go back and forth on this all day (why not? its been going on for years!) but the reality is nothing "puts back" capacity. LEAF Spy only parrots back what the car tells it and its method of measuring the battery is... well, lets just say it could be better.

As far as the dramatic rise? We have all seen it, posted hundreds of articles, testaments, pix, etc. about it but none of that matters.

you are in position to get a new pack and you REALLY need to get serious about this. you have plenty of miles and time but you need to get busy with it. I think you have a great chance of getting the warranty no matter what barring any long term storage situations or very very light driving. But at the same time you are taking more of a risk than I would take and most people consider me more than a bit crazy...
 
I apologize - It was not my intent to go back and forth. Because sure, I've read all the advice before, etc. But my first post had specific questions:

  • Is this large bump in AHr a normal effect of QC?
    How long have people seen it last?
    Is this a temporary blip or does it reset the curve?
What I was really hoping to see was some actual data about short & long term effects of quick charging. And people helpfully offered advice on battery degradation methods, which is great, but sure, it's all been covered before. I know the common wisdom is to QC and QC a lot. I have searched these forums a lot for this kind of thing; I know there are a few prior threads. And they help, but they're just short snapshots without much of a timeline.

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. With all the LeafSpy data out there, I figured somebody would have actual datasets on QC effects in the longer term.

I'm sorry if I sound argumentative, I'm not trying to be. I was just looking for more real-world hard data. Maybe it's just not there.
I really do appreciate all the responses, and the fantastic amount of information and community that's in these forums.
I just like data, is all. :)

p.s. drees provided his long term Ahr data, thanks - I'll chew on that.
 
sandeen said:
  • Is this large bump in AHr a normal effect of QC?
    How long have people seen it last?
    Is this a temporary blip or does it reset the curve?


very

as little as 24 hours

again, does nothing. If you are regularly charging to full and using most of that charge on a daily basis the effects would be lessened.
 
sandeen said:
I'm in Minnesota, so Winter is Coming!
Personally, I think you will NOT be able to get your fourth bar to disappear in the next five months.

Do you know where your car spent most of its life? I'm going to guess that it was in the southern part of the US. I own a MY2011 LEAF with 46,000 miles (versus 40,000 on yours) and it still has about 47.5 Ah of capacity (versus 43.5 on yours). My point is that your car degraded faster than my car for most of its life, but it is virtually impossible to get a LEAF to lose capacity at temperatures below about 40F. There is another poster here who is below 40 Ah who has not lost that last bar.

Your only option to lose that bar would be to ship it into the desert and pay someone to drive it for the next few months.

My suggestion is that you take care of your car to try to preserve the capacity which you have left.
 
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