Capacity Loss on 2011-2012 LEAFs

[Herm]

This chart shows you how risky (cell voltage reversal) it is to continue driving past VLBW, not something you want to do on a routine basis.

 

[DaveEV]

This chart shows you how risky (cell voltage reversal) it is to continue driving past VLBW, not something you want to do on a routine basis.

I very highly doubt it's risky if you are inferring that it might significantly damage a cell - in which case I ask you to stop spreading FUD as you are often inclined to do.

If the BMS allowed you do reverse a cell's voltage you'd quickly have a car-b-que simmering under your car. Lithium batteries do not tolerate that kind of abuse which is why the BMS monitors each cell-pair's voltage to prevent bad things from happening.

Now please - stay on topic - this thread is long enough as it is!

 

[RegGuheert]

To my knowledge we don't have any data like this, but this would identify if the BMS is hiding any additional capacity at the bottom of the pack.

TickTock has recorded voltages at a bunch of low GID values over time. They don't correspond to LBW or VLBW, but a plot of GIDs versus voltage might tell us something about how these are related, particularly if we could tag the temperature at each point.

Here is a scatter plot of TickTock's Battery Voltage versus GIDs:

(Sorry about the Y-Axis label! Excel munged it when I exported the chart as a picture. It says "Battery Voltage (V)".)

I don't see anything going on at the bottom end of this chart. At the top end, it looks like normal capacity variation that one would expect due to temperature variations or cell imbalance followed by balancing at the very top.

It might be interesting to go through a few of those points and see which direction temperature tends to move the voltage.

FWIW, I attempted to throw temperature in on the right axis, but I couldn't figure how to do that in this version of Excel. It might not have displayed well, anyway, since a lot of the temperature data was missing and there would be multiple temperatures per GID, so it would not really be possible to interpret what it means.

(BTW, the outlier in the graph is found on row 263 of TickTock's spreadsheet. It's probably just a typo.)

 

[DesertDenizen]

I have 12 bars but the telltale signs do not bode well. My 80% charge will sometimes fill only 9 bars, my GOM shows 75 miles after always showing 83 miles after a 80% charge. And on my computer when the charging ended it always showed an 80% SOC, now it stops charging and shows 75% charged.

That's two signs, not three. The owners website always and only reports #bars/12, expressed as a percentage. I'm quite positive you used to see "83%", not 80%, because 10/12 = 0.8333...

Not saying that two signs is good , just that the "percentage" reported by the website is content-free and misleading. It tells you nothing more than what the bars there show, and it is not "SOC" by any stretch of the imagination.

Ray

Got it, thanks Ray!

 

[RegGuheert]

Here is a scatter plot of TickTock's Battery Voltage versus GIDs:

Here is another cut at this chart. This time I have split the data into two sets: One set before April 15, 2012 and one set after. That gives us a kind of image of how things have changed as the temperatures got hotter in Phoenix:

(Again, sorry about the Y-Axis label! Excel munged it when I exported the chart as a picture. It says "Battery Voltage (V)".)

I will say it is quite difficult to say whether the movement in the curve is due to time or temperature, since both changed between those two data sets. In winter 2013 when we have more data we should be able to get some separation between the effects of time and temperature by plotting three sets of data.

Thanks for collecting and sharing the data, TickTock!

 

[DaveinOlyWA]

he is actually seeing 395 V? wow. i occasionally get 394 v if i check right after charge is complete, but if i let it sit a few hours its never more than 393

 

[RegGuheert]

he is actually seeing 395 V?

Almost. 394.5V.

 

[Herm]

I very highly doubt it's risky if you are inferring that it might significantly damage a cell - in which case I ask you to stop spreading FUD as you are often inclined to do.

Clean the FUD from your eyes so you stop seeing it everywhere you look. At VLBW you are depending on your BMS to not glitch and allow a cell to go negative.. yes its risky, plus it abuses the cell for little gain.

 

[EdmondLeaf]

I very highly doubt it's risky if you are inferring that it might significantly damage a cell - in which case I ask you to stop spreading FUD as you are often inclined to do.

Clean the FUD from your eyes so you stop seeing it everywhere you look. At VLBW you are depending on your BMS to not glitch and allow a cell to go negative.. yes its risky, plus it abuses the cell for little gain.

How nice it will be if Nissan will provide all that info for us (but in reliable form). During my recent chat with CS I was told that as long as battery temp is in white area battery will not suffer degradation, however 120F is dangerous for the battery

 

[DaveinOlyWA]

he is actually seeing 395 V?

Almost. 394.5V.

i finished charge this morning at 5:45 AM. checked it at 6 am and it was 279 GID and 393.5 by the time i leave (about 8) it will be at 393. temps 74F in car, 20.3 C air temp in garage.

many state the storage charge does not change with temps which i thought to be true as well. but have had cases when i parked car in morning before heat of the day for example

scenario 1 on Mon
parked 8 am 204 GID, 383.5 V, temps 58F
left 1 pm 199 GID, 381.5 V temps 75F


#2 yesterday

parked about 8 160 GID, 377 V temp 57F
left 11:30 159 GID 378 V temp 72 F

have several examples of both. in scenario one, lost "significant" charge (5 GID) and voltage. 17º temp diff. in #2, lost only one GID, but "gained" voltage temp diff about the same

still collecting data, guessing some variances, random conditions are at play here.

 

[TickTock]

This chart shows you how risky (cell voltage reversal) it is to continue driving past VLBW, not something you want to do on a routine basis.

When I got my CVLI test done, the difference between the max and min cell at VLBW was less than 100mV so there is no chance of cell reversal - even at dead.

 

[JPWhite]

Now this is interesting

http://www.plugincars.com/nissan-an...hy-wattstation-damages-some-leafs-123471.html

How has the GE/LEAF investigation got ANYTHING to do with this thread?

Here's me hoping against hope.

If a software glitch can fry a vehicle charger under certain conditions, maybe a software glitch can fry a battery pack under certain conditions.

I really really hope it is bad software that has caused accelerated battery degradation. The fix is easy. Fix the software and replace the affected batteries and all will be well.

Here's hoping, fingers crossed.

 

[JRP3]

Highly unlikely, and that it would only damage packs in warm areas makes it even less likely.

 

[AZMerf]

How can I get my name on the first page of this thread? I just lost my first bar on Tuesday, July 24th at 14,100. I've had it 16 months. Live in Phoenix, Arizona. At this rate I'll only be down 3 bars by the time the lease is up but it's worrisome.

 

[vrwl]

How can I get my name on the first page of this thread? I just lost my first bar on Tuesday, July 24th at 14,100. I've had it 16 months. Live in Phoenix, Arizona. At this rate I'll only be down 3 bars by the time the lease is up but it's worrisome.

Your information has been added to the forum Wiki.

Be sure to post and let us know when you've reported the issue to Nissan and received a Case number from them so we can update the wiki with that additional info.

 

[Volusiano]

The count continues...

I've now officially fallen victim to a 2nd bar loss today at 19,345 miles, almost 14 months into my ownership. My first bar loss was at 16.5K miles back in 5/28/2012, only 2 months ago. I've called Nissan and reported my 2nd bar loss today. I'm already on the Wiki list for 1st bar loss. I've asked Stoaty to add me to the Wiki list for my 2nd bar loss in the other thread.

I don't take the LEAF to work, so it doesn't sit baked in the sun all day at work. It sits in the garage during the day unless a family member takes it on trips around town.

 

[Volusiano]

How can I get my name on the first page of this thread? I just lost my first bar on Tuesday, July 24th at 14,100. I've had it 16 months. Live in Phoenix, Arizona. At this rate I'll only be down 3 bars by the time the lease is up but it's worrisome.

Many people lost their 2nd bar shortly a month or two after they lost their 1st bar (myself included). So it's more likely that you'll lose your 2nd bar sooner rather than later.

 

[vrwl]

The count continues...

I've now officially fallen victim to a 2nd bar loss today at 19,345 miles, almost 14 months into my ownership. My first bar loss was at 16.5K miles back in 5/28/2012, only 2 months ago. I've called Nissan and reported my 2nd bar loss today. I'm already on the Wiki list for 1st bar loss. I've asked Stoaty to add me to the Wiki list for my 2nd bar loss in the other thread.

I don't take the LEAF to work, so it doesn't sit baked in the sun all day at work. It sits in the garage during the day unless a family member takes it on trips around town.

Wiki updated.

 

[DaveinOlyWA]

Highly unlikely, and that it would only damage packs in warm areas makes it even less likely.

unlikely yes. impossible? ooooh no. any computer novice will tell you that heat is a killer. what protects the Nissan pack? computers do. how do computers protect the pack? they monitor various parameters of the pack and provide operations to keep those parameters within predesigned guidelines.

excessive heat can mess up the computer's circuitry to the point that it may no longer measure accurately or respond accurately.

your blanket statement needs a much closer examination

 

[AZMerf]

Be sure to post and let us know when you've reported the issue to Nissan and received a Case number from them so we can update the wiki with that additional info.

Are people just calling their Nissan sales rep? Or is there some place else?