smkettner
Well-known member
OK and how many lost miles in 26 mV?
Bad cell pair on my 2012???
- Thread starter Computerizer
- Start date
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Computerizer
Well-known member
OP here. I drove it down pretty low (25 Gids), about 0.3 miles until VLBW. LBW happened exactly when the app predicted. I was actually driving home as inefficiently as possible, but that wasn't enough so I had to drive back and forth on the road a couple times. Anyway, it's now on the trickle charger aimed at 100%. Here's what I've got at the low end:
(Full size: http://imgur.com/62K0fPl)
The difference is quite a bit more at the low end, now 67 mV. I know this isn't "out of spec" but it's significantly more different than the rest of the cells are from each other.
After it reaches 100%, how long should I leave it sit plugged in?
Thanks,
Tyrel
(Full size: http://imgur.com/62K0fPl)
The difference is quite a bit more at the low end, now 67 mV. I know this isn't "out of spec" but it's significantly more different than the rest of the cells are from each other.
After it reaches 100%, how long should I leave it sit plugged in?
Thanks,
Tyrel
Computerizer
Well-known member
Finished "100%" about 3 hours ago while I was gone. As soon as I got home (now), I took this status:
(Full size: http://imgur.com/wayzA2c)
The difference on that cell pair is much less noticeable at the higher charge levels.
When we go to town tonight we'll take this car and I'll take screenshots every 10% or so to post later.
Tyrel
(Full size: http://imgur.com/wayzA2c)
The difference on that cell pair is much less noticeable at the higher charge levels.
When we go to town tonight we'll take this car and I'll take screenshots every 10% or so to post later.
Tyrel
ebill3
Well-known member
If using the default color scheme, red denotes shunts in use. Why so many shunts active, even on low cell pairs?
smkettner
Well-known member
Looks like the low pair has a shunt at the low end of spec driving it low.ebill3 said:
Computerizer
Well-known member
ebill3 said:
I don't believe it when it says it's shunting. It does it almost all the time -- when I'm driving, etc. Which ones are red and which ones are not appears to be random. Perhaps I inherited a broken setting from a very old beta version of the app, or something, causing it to label them incorrectly?
TonyWilliams
Well-known member
gbarry42 said:
The cutoff is about 2.9 volts on the lowest cell pair.
TonyWilliams
Well-known member
Computerizer said:
You haven't yet gone past the battery "knee" yet, where the voltages drop like a rock. You'll see far greater cell pair voltage differences there.
The battery warnings are indexed to the Gid value, so it will always be "exact":
LBW = 4kWh stored / 80Wh per Gid = 50 Gids = (50 - 6 unusable Gids) * 77.5Wh usable per Gid = 3.4kWh usable
VLB = 2kWh stored / 80Wh per Gid = 25 Gids = (25 - 6 unusable Gids) * 77.5Wh usable per Gid = 1.4kWh usable
NOTE: 6 unusable Gids is merely an estimate of the low end of the battery. It can be more or less depending on many variables, however when any cell pair equals 2.9v, that's when the car stops.
RegGuheert
Well-known member
Except for the following:gbarry42 said:
Higher internal resistance will cause the terminal voltages of that cell to be higher while charging, even though the cell may be at a lower SOC. But when you make a measurement at idle, the internal resistance has little effect, since the current is near zero, and the voltage then reflects the actual SOC.gbarry42 said:
If the extra internal resistance is high enough, it can potentially cause that cell-pair to have a high voltage while charging and thus to be shunted, even though it may be at a lower SOC. When shunted, the cell-pair may then show up as having the lowest voltage. Since the prime directive for the BMS is to prevent overcharging of any cell, it has no choice but to shunt high-voltage cells, even if that then makes them low-voltage cells.ebill3 said:
Assuming the colors are correct, this agrees with what we see here (which may not be an accurate assumption).
As expected, this charge has brought all of the cell-pair voltages to within 20 mV of each other. It's possible that the BMS is incapable of achieving this level of balance on your pack when charging at L2 rates.Computerizer said:
DaveinOlyWA
Well-known member
Why min max? It should be min avg if anything.
when your cells are out of balance a deep discharge is not recommend ed I think. balancing happens all the time but generally you have to be moving to reach the delta voltage that starts it. . Now your pack always having the same cell as low is different than mine where I see deltas as large as yours but the low cells seem to be pretty random. I will gave to start paying more attention to it but I also think you have little to worry about.
when your cells are out of balance a deep discharge is not recommend ed I think. balancing happens all the time but generally you have to be moving to reach the delta voltage that starts it. . Now your pack always having the same cell as low is different than mine where I see deltas as large as yours but the low cells seem to be pretty random. I will gave to start paying more attention to it but I also think you have little to worry about.
RegGuheert
Well-known member
Max cell-pair is the one which will stop charging at the high end and min cell-pair is the one which will stop discharging on the low end.DaveinOlyWA said:
ELROY
Well-known member
Over 96% capacity with over 9600 miles is excellent! I have same mileage with 89% capacity.
essaunders said:I have one of those on my 2012 too.
<edited to add a picture I found>
never been over 6 bars temp, no QC, 80% charge normal.
I'm not holding out much hope the dealer would find much. Does anyone have guidance on how much voltage delta would warrant action by Nissan? This is only 25mV from average to low.
bowthom
Well-known member
Hello,
My #16 cell was low by 30 mV for months. I tried the usual balance inducing methods mentioned but it remained in the low pole position.
THEN
I took my leaf in for reprogramming and #16 looked normal. In fact all the cells were within 14 mV. The car was not charged while at the dealership and the whole service took only an hour. Now a few days later #16 is still up with the others.
Very curious.
I'll post the pics when I'm not on my phone.
My #16 cell was low by 30 mV for months. I tried the usual balance inducing methods mentioned but it remained in the low pole position.
THEN
I took my leaf in for reprogramming and #16 looked normal. In fact all the cells were within 14 mV. The car was not charged while at the dealership and the whole service took only an hour. Now a few days later #16 is still up with the others.
Very curious.
I'll post the pics when I'm not on my phone.
Computerizer
Well-known member
My assumption was that this low cell was what is responsible for my lowered capacity, but maybe it's something else. Last Winter and Spring I could always charge to 22.5 kWh according to the app, and now I can't get it past 19.5. A loss of 3 kWh over about 4000 miles of driving does not sound right at all.
Tyrel
Tyrel
- Joined
- Jun 13, 2011
- Messages
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Computerizer said:
Are you observing this on the 2012 or 2013 LEAF?
Computerizer
Well-known member
surfingslovak said:Computerizer said:
Are you observing this on the 2012 or 2013 LEAF?
The 2012. The '13 is still working fantastically -- it only has about 3,500 miles on it (1,300 of which was a single roadtrip) and it as 99.6% capacity.
EV1
Active member
Discovered my bad cellpair in july this year, it was even 339mV off at 4,5% SOC, see this post:
http://www.mynissanleaf.com/viewtopic.php?p=308374#p308374
After 2 weeks waiting and still seeing this cellpair as clearly lower as the rest, every day, I went to the dealer and yes, it was not visible when i arrived there with about 70% SOC. The last 2 or 3 nights charging at 100% must have balanced it out. They checked it anyway, but not more unbalance as 20mV @ 70% SOC. They did not do the discharge to 2 bars, but I drove the car until it was at about 15% SOC and went back, still no unbalance enough to worry.
However the cellpair now and then shows clearly lower voltages. So although it may fall "within specs" as far my dealer or Nissan is concerned its definatly in worse shape then the rest of the cellpairs.
btw, the capacity showed always 101% with battery app v0.25 until recently.
Computerizer, be sure to read the part below my post, about the shunt order. even with the "right" shuntorder (8421) the readings make no sense, imho. I stopped taking notice of the shunts, as the readings just seem very, very unlogical.
http://www.mynissanleaf.com/viewtopic.php?p=308374#p308374
After 2 weeks waiting and still seeing this cellpair as clearly lower as the rest, every day, I went to the dealer and yes, it was not visible when i arrived there with about 70% SOC. The last 2 or 3 nights charging at 100% must have balanced it out. They checked it anyway, but not more unbalance as 20mV @ 70% SOC. They did not do the discharge to 2 bars, but I drove the car until it was at about 15% SOC and went back, still no unbalance enough to worry.
However the cellpair now and then shows clearly lower voltages. So although it may fall "within specs" as far my dealer or Nissan is concerned its definatly in worse shape then the rest of the cellpairs.
btw, the capacity showed always 101% with battery app v0.25 until recently.
Computerizer, be sure to read the part below my post, about the shunt order. even with the "right" shuntorder (8421) the readings make no sense, imho. I stopped taking notice of the shunts, as the readings just seem very, very unlogical.
Computerizer
Well-known member
As requested (sorry I forgot to post this), here are screenshots of the battery graphs roughly every 10% from full charge down to 30%.
http://imgur.com/a/1qS7F
That one cell pair is the lowest at almost all times, but I guess it's not really THAT low.
Why is my capacity so low (93%) given that this cell isn't actually so bad, the car only has 8,000 miles on it, and battery temperature is in the 60s?
http://imgur.com/a/1qS7F
That one cell pair is the lowest at almost all times, but I guess it's not really THAT low.
Why is my capacity so low (93%) given that this cell isn't actually so bad, the car only has 8,000 miles on it, and battery temperature is in the 60s?
DaveinOlyWA
Well-known member
Computerizer said:
i have been paying attention to my cell pairs as well especially when there is active balancing going on and I have at least a 33 mV range (for some reason I am at that range a lot...) and my low cells are pretty random unlike yours where it always seems to be #47.
have you tried to "force a balance?" like turn the car on with a low power drain to see if the low cell does any moving? beginning to think that maybe its not really doing much because the BMS simply thinks there is not a problem. your delta at full (18 mV) is actually much better than what I see most of the time
now your pix show a lot of balancing going on most of the time which is something I have only seen once and that scenario did last a day and a half but have not seen it since. this would go a long way towards explaining your low SOC at full charge
Yeah, looks pretty normal. About 20mV all the way down to 30% SOC. Things won't really get interesting until you get down to ~20% (LBW) or lower.Computerizer said:
What I find really interesting is that the display indicates that the lowest CP is being shunted - this is especially apparent in your first picture - what it should be doing is shuting all the CPs except that one. I suspect there is an off-by-one error in the display or that 4812 is definitely not right.
Here's a pic for everyone to see:
