2 AHr loss in 15 days - is this unusual?

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dashamstyr

New member
Joined
Apr 1, 2017
Messages
2
Location
Vancouver, BC
Greetings,

I have recently become the proud owner of a used 2013 SV. I first plugged LeafSpy Pro into the vehicle prior to buying it approximately two weeks ago. The car has 55,000 km on it. At this time the readings were:

10 QC
2112 L1/L2

SOH: 88%
AHr: 58.167
Hx: 88.02%
12 bars

The most recent readings show:

10 QC
2122 L1/L2

SOH: 86%
AHr: 56.75
Hx: 84.94%
11 bars

I'm wondering if this is typical variation to be expected or if this is indicative of a malfunctioning or possibly damaged battery.

Thanks for any help or insight anyone can provide!
 
Can you update your location info via your user name in the upper right > User Control Panel > Profile tab? That way, we don't need to ask in future posts/threads or do sleuthing to deduce it.
dashamstyr said:
I have recently become the proud owner of a used 2013 SV. I first plugged LeafSpy Pro into the vehicle prior to buying it approximately ...
The most recent readings show:

10 QC
2122 L1/L2

SOH: 86%
AHr: 56.75
Hx: 84.94%
11 bars
That is weird. Make sure you are reading the bars right. http://www.electricvehiclewiki.com/File:Scott_3_bars_s.jpg is an example of a 3 bar loser.

I'm currently at
AHr: 56.53
SOH: 86%
Hx: 84.56%

But I still have all 12 bars, on my 5/2013 built '13 SV at 42.7K miles (so that's about 68.7K km). I've been hovering around readings like this for weeks if not a few months. I've had my used Leaf since July 2015. Of course, my 3 readings have declined since I bought it.

What was the build month on your car? It's on the driver's side door sticker. Any idea where the car resided before? Does Carfax/Autocheck work wherever you?

It is possible the car's a victim of a BMS reset.
 
I have also seen a ~ 2 Ahr drop in capacity reported by LeafSpy over 2-3 months since I bought my '13 car. I think this is too slow to be a BMS reset, so I'm hoping it is just the car getting "used" to a new climate and driving/charging routine and the battery capacity will soon plateau.
 
cwerdna:

I've updated my location: Vancouver BC. Thanks for the tip! Also thanks for the not about which bars to read. I'm reading the outside ones.

The car came from the US. I checked it out on CarFAX and here is what I found out:

Manufactured in 03/2013
Operated by one owner (lease) in Fremont , CA (near San Francisco)
No serious issues and seems to have had regular checkups, including a battery and charging system check at 30,000 miles.

As for the number of bars vs. SOH. I know this is a little odd, as the first bar is supposed to drop at 85%. As near as I can figure it's right on the edge of where that bar goes out because it has dropped and come back and then dropped again.

I have very little data to go on as I've only been driving for a week, but as far as I can tell the AHr reading seems to be holding steady between charges and then drops about 0.3 AHr with each charge.

I'm charging it at home off of a 110v circuit using the charging cable that came with the car. I have it set to only charge up to 80%, but there is no timer set so each time it has been plugged in for roughly 10 hours.
 
I doubt that your car's BMS (Nissan calls it the Lithium Battery Controller or LBC) was reset because the AHr readings are reasonable for the age and mileage.

The AHr (and SOH and Hx) numbers for my 2015 vary as much as 2 AHr day-to-day and even during the day depending upon charge level, driving conditions, and charging method. DCQC will always increase the numbers and 120-volt (or low rate 240-volt) charging will tend to reduce the numbers temporarily. Gentle driving and shallow discharge levels also tend to reduce the numbers while highway driving with deep discharging and higher-rate 240-volt charging tend to stabilize the numbers.

I suggest you watch the numbers over a few more weeks before becoming too concerned. I suspect you will see the numbers stabilize.
 
Manufactured in 03/2013


Bingo. We have another "winner." Leafs made January through March of 2013 appear to use the older battery chemistry, and lose capacity much faster than those made after March. I wouldn't rule out a BMS reset yet - this car may have three bars actually gone, and the BMS is possibly "relearning" that.
 
dashamstyr said:
cwerdna:

I've updated my location: Vancouver BC. Thanks for the tip! Also thanks for the not about which bars to read. I'm reading the outside ones.
Yay! Cool. No prob.

dashamstyr said:
The car came from the US. I checked it out on CarFAX and here is what I found out:

Manufactured in 03/2013
Operated by one owner (lease) in Fremont , CA (near San Francisco)
No serious issues and seems to have had regular checkups, including a battery and charging system check at 30,000 miles.
Fremont is I'd say medium-ish in terms of temps. It's definitely not one of the cooler spots (e.g. city of SF, Pacifica, Half Moon Bay) but not the hottest either (e.g. Walnut Creek, Concord).

dashamstyr said:
As for the number of bars vs. SOH. I know this is a little odd, as the first bar is supposed to drop at 85%. As near as I can figure it's right on the edge of where that bar goes out because it has dropped and come back and then dropped again.
I don't know that it's supposed to drop at 85% SOH. I haven't compiled stats, but one of the moderators looks only at AHr and compiled the table at http://www.mynissanleaf.com/viewtopic.php?p=487979#p487979, which doesn't seem quite right for 2013 Leafs.

But Leftie's right re: our observations about build month. I too am unsure yet if you're the victim of a reset. Definitely keep us posted if any of the 3 stats keeps declining rather rapidly.
 
GerryAZ said:
Gentle driving and shallow discharge levels also tend to reduce the numbers while highway driving with deep discharging and higher-rate 240-volt charging tend to stabilize the numbers.
We fit the gentle driving, shallow discharges and drop in Ah profile to a tee.

Any ideas why this happens, and whether it implies a more stressful life on the battery ? After all, I could discharge further before charging; I was avoiding that behaviour as a presumed way to improve battery longevity.
 
SageBrush said:
GerryAZ said:
Gentle driving and shallow discharge levels also tend to reduce the numbers while highway driving with deep discharging and higher-rate 240-volt charging tend to stabilize the numbers.
We fit the gentle driving, shallow discharges and drop in Ah profile to a tee.

Any ideas why this happens, and whether it implies a more stressful life on the battery ? After all, I could discharge further before charging; I was avoiding that behaviour as a presumed way to improve battery longevity.

It's probably the opposite of "stressful." The pack isn't seeing high enough discharges and charges to get a strong reaction going, and so may not be charging as thoroughly as designed. That condition shouldn't be permanent, unless maybe the pattern continues for years. Just accelerate briskly once in a while, and if you aren't charging to 100%, do that once every week or two. Sort of an EV version of what we used to call "an Italian Tuneup", which consisted of running the engine flat out to burn out carbon deposits.
 
SageBrush said:
GerryAZ said:
Gentle driving and shallow discharge levels also tend to reduce the numbers while highway driving with deep discharging and higher-rate 240-volt charging tend to stabilize the numbers.
We fit the gentle driving, shallow discharges and drop in Ah profile to a tee.

Any ideas why this happens, and whether it implies a more stressful life on the battery ? After all, I could discharge further before charging; I was avoiding that behaviour as a presumed way to improve battery longevity.

I suspect your usage pattern is no more stressful or even less stressful for the battery than mine, but the LBC has trouble measuring or estimating the actual battery capacity under those gentle use and shallow discharge conditions. If you are concerned about numbers, you could run it down to VLBW and charge to 100% once a month. An occasional QC from VLBW to full charge if you have any stations nearby would also help your numbers. Since my Leaf Spy numbers improve after every QC, I try to use a QC from VLBW to full at least once every couple of months now that I no longer have 30 minutes of free QC.

One theory I have is that the higher sustained reverse current flow from either high-rate (6kW) L2 charging or especially DCQC breaks down the buildup on the electrodes in each cell. I have attached a link to an article about battery deterioration that you might find interesting.

http://batteryuniversity.com/learn/article/bu_808b_what_causes_li_ion_to_die
 
GerryAZ said:
I suspect your usage pattern is no more stressful or even less stressful for the battery than mine, but the LBC has trouble measuring or estimating the actual battery capacity under those gentle use and shallow discharge conditions. If you are concerned about numbers, you could run it down to VLBW and charge to 100% once a month. An occasional QC from VLBW to full charge if you have any stations nearby would also help your numbers. Since my Leaf Spy numbers improve after every QC, I try to use a QC from VLBW to full at least once every couple of months now that I no longer have 30 minutes of free QC.

One theory I have is that the higher sustained reverse current flow from either high-rate (6kW) L2 charging or especially DCQC breaks down the buildup on the electrodes in each cell. I have attached a link to an article about battery deterioration that you might find interesting.

http://batteryuniversity.com/learn/article/bu_808b_what_causes_li_ion_to_die
Thanks for chiming in. I'm going to follow my own advice to others and stop worrying about a number I cannot reliably interpret. I'll just keep trending LEAFspy once a month and hope to see the line plateau. As it is, I have no problem driving 100 miles on a full charge so I have nothing practical to complain about.
 
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