gmikol
Posts: 107
Joined: Thu Dec 05, 2013 5:50 pm
Location: WA State

Bad Cell in Leaf Spy: What to do about it?

Sat Sep 27, 2014 6:57 pm

So I saw something unusual on Leaf Spy this afternoon as I'm pulling into my driveway:

Image

What, exactly does the "Bad Cells" mean? Is this something I should have the dealer look at? I don't charge to 100% all that often, but it's had 3 or 4 100% charges in the last month or so, including one last night...so it should be well-balanced.

17 GIDs left at this point, and battery temps in the upper 70's.

I don't expect the dealer to necessarily know anything about Leaf Spy, so what should I tell the dealer? My 12-month battery check is not until January. Is it OK to wait on this?

Thanks--

G

ElectricEddy
Posts: 374
Joined: Tue Feb 25, 2014 1:42 pm
Delivery Date: 31 Oct 2016
Leaf Number: 313506
Location: Nanaimo, B.C.

Re: Bad Cell in Leaf Spy: What to do about it?

Sat Sep 27, 2014 8:41 pm

Any DTC's ?
Pearl White Sl
mfd date 09/16

camasleaf
Posts: 610
Joined: Sun Sep 26, 2010 5:20 am
Delivery Date: 17 Jun 2011
Location: Camas, WA

Re: Bad Cell in Leaf Spy: What to do about it?

Sat Sep 27, 2014 8:42 pm

I have seen as much as 150mV difference between the cells at verry low SOC. You are fine.
2011 SLe 06/17/11 Over 76000 miles 71%SOH 15.7kWh
2015 SV 09/02/14, Over 36000 miles soon to be returned for a 2018
5.7kW DC System

gmikol
Posts: 107
Joined: Thu Dec 05, 2013 5:50 pm
Location: WA State

Re: Bad Cell in Leaf Spy: What to do about it?

Sat Sep 27, 2014 9:19 pm

ElectricEddy wrote:Any DTC's ?

No...didn't think to check that. I forget that Leaf Spy can read those. I'll check it tomorrow AM. Will re-charging clear the DTC's (fi any)?

Turbo3 is using some criteria to decide the bad cell. What criteria, and what is that based on?

--G

Stoaty
Gold Member
Posts: 4460
Joined: Fri Jun 18, 2010 9:50 pm
Delivery Date: 12 Jun 2011
Leaf Number: 3871
Location: West Los Angeles

Re: Bad Cell in Leaf Spy: What to do about it?

Sat Sep 27, 2014 9:56 pm

gmikol wrote:Turbo3 is using some criteria to decide the bad cell. What criteria, and what is that based on?

Do a search on the forum for CVLI.
2011 Leaf with 62,000 miles given to Nephew
2013 Tesla Model S85 with 251 miles rated range at full charge
Leaf Spy Manual
Battery Aging Model Spreadsheet

TimLee
Posts: 2810
Joined: Thu Jan 20, 2011 9:40 am
Delivery Date: 17 May 2011
Leaf Number: 2026
Location: Chattanooga, TN

Re: Bad Cell in Leaf Spy: What to do about it?

Sun Sep 28, 2014 1:39 am

Detailed explanation and discussion at viewtopic.php?f=9&t=17676&p=383401&hilit=+cvli#p383401.

Service manual says test is for when customer complains of range loss.
But most dealers will not run the test unless the customer pays for it.

Unclear whether dealer will then replace the modules that have bad cells and whether Nissan would cover that under warranty.

I have yet to read any posts saying anyone has confronted Nissan on it.

Tim Lee
Chattanooga, TN

Man. Date: 03/10/11, VIN # 2026
Delivered 05-17-2011
Blue Ocean, 2011 SL-eTec

gmikol
Posts: 107
Joined: Thu Dec 05, 2013 5:50 pm
Location: WA State

Re: Bad Cell in Leaf Spy: What to do about it?

Mon Sep 29, 2014 2:12 pm

Thanks, @TimLee -- I hadn't found that thread in my search.

From what I've found, it seems like the dealer won't do anything about it unless you're showing the P33E6 error code. There also seems to be some question as to what the formula for calculating the Judgment Value really is.

It's useful as an indicator, though. A couple of days later, I looked at the battery stats while it was charging (I think it was around 50-60% at the time), and cell # 28 wasn't any higher or lower than the others. I also checked DTC's, and there were none reported for the HV pack.

Next time I get the pack down below VLBW, I'll take a look again, just to see if it is still acting funny, or if it was a transient issue. Don't know when that will be, though. It doesn't get down that low very often, with charging available at both ends of a 22-mile one-way commute.

--G

Turbo3
Gold Member
Posts: 1835
Joined: Mon Jul 19, 2010 8:34 pm
Delivery Date: 12 May 2011
Leaf Number: 002191
Location: San Jose, CA

Re: Bad Cell in Leaf Spy: What to do about it?

Mon Sep 29, 2014 6:15 pm

The formula can be found in the 2011 April version of the Leaf Service Manual on page EVB-67.

If there are any other formulas please post them and where you got them from.

The only formula I know about is Judgement = Avg - (max - avg)*1.5 and the min voltage must first be below 3.713 volts. The Leaf must be parked. So you don't make this measurement while the battery is under load.

For this example the numbers are min=3.645, avg=3.673, max=3.690. Filling in the formula gives:

3.673 - (3.690 - 3.673) *1.5 = 3.673 - (0.017)*1.5 = 3.673 - 0.0255 = 3.6475

Because the minimum cell is 3.645 we know at least one cell is judged as bad.

It is possible that after heavy use the battery needs some time to stabilize. So if you leave the battery sit for a few hours and it still reports a bad cell it would have more significance.

You should definitely keep an eye on cell #28.

gmikol
Posts: 107
Joined: Thu Dec 05, 2013 5:50 pm
Location: WA State

Re: Bad Cell in Leaf Spy: What to do about it?

Mon Sep 29, 2014 7:34 pm

I saw that, and the scans of the relevant pages from the manual.

I can't find the reference now, but I thought I had also seen a formula that used 2.0 as the factor instead of 1.5

That formula is also not in the 2013 ev powertrain manual. Apparently the consult tool calculates the value now, so the tech doesn't have to rely on a formula. No way of knowing whether it has changed for 2013 and beyond.

I was parked, but I had literally just pulled into the driveway after about 35 miles of mixed city & highway driving.

I'll definitely keep an eye on things going forward.

--G

achewt
Posts: 62
Joined: Mon Mar 31, 2014 11:45 am
Delivery Date: 09 May 2014
Location: Nelson, BC

Re: Bad Cell in Leaf Spy: What to do about it?

Wed Dec 30, 2015 10:36 pm

After doing my regular commute today, which I logged entirely in Leaf Spy Pro, on the 'battery cells' page I was given a note that I had 4 weak cells. The delta was 40 mV. Dash SOC 15%, 44 GIDs and 3.3 kWh remaining. http://kootenayevfamily.ca/img_1350/

This surprised me, as I haven't seen this message before (although I've only had the app for a few months, and have only fully logged several trips).

A few hours later, my wife took the car to the grocery store, and arrived home with 8 GIDs - I ran it down to turtle at 6 GIDs, then took a screenshot of the 'battery cells' page again - no weak cells anymore, despite the delta of 374 mV! http://kootenayevfamily.ca/img_1357/

Running the numbers through the formula up thread shows that my minimum exceeded the calculated value, so I guess that's why they didn't show up?

Anyways, my SOH has generally been quite high for how old my car is, the mileage and the reasonably hot summers, so I'm not really complaining, and will keep a watch out for more of the same. I can't help wonder though if it is somehow related to the other item I've noticed with 'clunking' sounds from my battery pack and odds 'burning' smells! :shock:

viewtopic.php?f=30&t=19883
Ocean Blue 2014 SL, 133,000km as of mid-Oct 2017, back up to 85% (from low of 83%!) SOH
1 bar lost Aug 31/17 @ 54.5Ahr 83%SOH 79.72%Hx 127,413km
Commuting 142km round-trip; level 2 at home, level 1 at work
http://kootenayEVfamily.ca

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