Capacity Loss on 2011-2012 LEAFs

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LEAFfan said:
I believe thats what happen to me ..2 days after perfect battery check I lose a bar :eek:
TonyWilliams said:
cdub said:
Got my 1 year checkup today... capacity has dropped 100%.

No I'm kidding... everything is fine. 12,500 miles all capacity bars. Battery check all 5 stars. I didn't get a percentage though.
Click to expand...

None of that will identify capacity loss less than 15%

You could be 14% down on capacity and still get five stars and have all 12 capacity bars.
Click to expand...

+ 1!
Click to expand...
 
Boomer23 said:
TonyWilliams said:
You dont need a LEAFSCAN to check the count of wattHours with a Gidmeter. There are dozens and dozens of these out there, and I'm sure you can find somebody who will loan you one in a major California city (I have no idea where you are).
Click to expand...

xtreme and I are friends. Perhaps I can stop by your place one Saturday morning before a breakfast meetup and check your Gids after a full charge. Our Santa Ana meet isn't until June 23, though. We can PM to set something up.
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Yea, I was talking about Boomer not Ingineer. Most days I can plug into a 120v plug at work for a couple of hours in the afternoon, but not always. Unfortunately I don't know until that afternoon if it'll be available. (the only plug in the parking lot is for the car wash guys vacuum. Sometimes he's done at 1pm, sometimes he's done at 4pm. I've asked for another plug, but the building owners won't budge.
 
TonyWilliams said:
You dont need a LEAFSCAN to check the count of wattHours with a Gidmeter. There are dozens and dozens of these out there, and I'm sure you can find somebody who will loan you one in a major California city (I have no idea where you are).
Click to expand...
While you can get an approximation with a full charge, Since Gids at full charge are variable, you can't get a very accurate number, in addition, factors such as a hot/cold pack or a imbalance can cause an artificially low gid reading temporarily. You also have to perform a full charge in order to check.

LEAFSCAN can read the battery ECU's internal capacity loss numbers, including internal resistance, and can also tell if it's only one or 2 modules, or just a general loss across the whole pack. The capacity loss coefficient that can only be read by LEAFSCAN is what the capacity bars are based on. This can be done at any SoC and any temperature. No need to charge to check, it takes only seconds.

-Phil
 
EdmondLeaf said:
leafkabob said:
Mon-Fri my car is parked in a large parking structure that is very open to breezes and airflow. I'm not sure what the temperature difference would be from being in the full sun on hot pavement, but I would think it would be significant. In the evenings and weekends my car is parked in my detached garage (uninsulated, but gets partial shade from large trees).

I also cleverly (I thought) timed my 80% charges to begin at 3 am. In hindsight I'm not sure that made any difference.
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I really feel for you:
charging to 80%, late at night did not protect you
parking in perfect condition did not protect you
low mileage did not protect you
Click to expand...
More suggestions, which may or may not be practical for your situation:
The data at the Battery University site link posted by JPWhite, while not specific for our Li-Mn chemistry, suggests that storing at charge levels below 80% yields additional benefit. Any change you can do to minimize time spent at high charge and high temperature will help. Perhaps you could add a fan to your garage to reduce how much time the car spends at elevated temperatures on the weekend. Perhaps you can sometimes top-off your charge just before you head-out.

Charging at 3 am probably does not help too much, but the charging process adds some heat of its own.

BTW, over a year ago, when I posted some other battery data from the Battery University, some comments in this forum suggested their data was obsolete and our wonderful Nissan batteries would perform much better. With real experience, we are learning.
 
Ingineer said:
LEAFSCAN can read the battery ECU's internal capacity loss numbers, including internal resistance, and can also tell if it's only one or 2 modules, or just a general loss across the whole pack. The capacity loss coefficient that can only be read by LEAFSCAN is what the capacity bars are based on. This can be done at any SoC and any temperature. No need to charge to check, it takes only seconds.
Click to expand...
I am drooling at the thought of getting the LEAFSCAN! :D
 
Ingineer said:
TonyWilliams said:
You dont need a LEAFSCAN to check the count of wattHours with a Gidmeter. There are dozens and dozens of these out there, and I'm sure you can find somebody who will loan you one in a major California city (I have no idea where you are).
Click to expand...
While you can get an approximation with a full charge, Since Gids at full charge are variable, you can't get a very accurate number, in addition, factors such as a hot/cold pack or a imbalance can cause an artificially low gid reading temporarily. You also have to perform a full charge in order to check.

LEAFSCAN can read the battery ECU's internal capacity loss numbers, including internal resistance, and can also tell if it's only one or 2 modules, or just a general loss across the whole pack. The capacity loss coefficient that can only be read by LEAFSCAN is what the capacity bars are based on. This can be done at any SoC and any temperature. No need to charge to check, it takes only seconds.

-Phil
Click to expand...

Phil, I think we are all going to be thrilled with the final product. Get back to work so I can have a LEAFSCAN before I drive to Canada!
 
Ingineer said:
TonyWilliams said:
You dont need a LEAFSCAN to check the count of wattHours with a Gidmeter. There are dozens and dozens of these out there, and I'm sure you can find somebody who will loan you one in a major California city (I have no idea where you are).
Click to expand...
While you can get an approximation with a full charge, Since Gids at full charge are variable, you can't get a very accurate number, in addition, factors such as a hot/cold pack or a imbalance can cause an artificially low gid reading temporarily. You also have to perform a full charge in order to check.
-Phil
Click to expand...

I disagree that you can't get an accurate number/% using a Gid meter/ raw number, or my BCM. I checked a guy's car after a 100% charge with my BCM and I told him it was 13-14% down, and that he would be losing a capacity bar very soon. He lost it the next day. The lowest loss so far that I've tested is about -5%.
 
all the new cars that you test come up to 281? .. Im sure its not 100% exact

You need a baseline to determine actual degradation.
 
RegGuheert said:
LEAFfan said:
The lowest loss so far that I've tested is about -5%.
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How old was that car?
Click to expand...

All of the cars I've tested so far are about one year old and have anywhere from 9000 to 12000 miles. Today, I'm going down to a dealer who has two new LEAFs for sale, one a 2011 and the other a 2012 and will take a reading if they are at 100%.
 
TonyWilliams said:
What do you base your assumption on?
Click to expand...

Measuring battery capacity with any accuracy requires lots of work and expensive hardware.. I doubt Nissan spent the money on that for each Leaf. My WAG is you are lucky to get 5% accuracy.
 
Herm said:
TonyWilliams said:
What do you base your assumption on?
Click to expand...

Measuring battery capacity with any accuracy requires lots of work and expensive hardware.. I doubt Nissan spent the money on that for each Leaf. My WAG is you are lucky to get 5% accuracy.
Click to expand...

We actually do get quite close to 281 consistently with new cars. That's 22.5kWh, and with losses, about 21kWh available at 70F.
 
TonyWilliams said:
We actually do get quite close to 281 consistently with new cars. That's 22.5kWh, and with losses, about 21kWh available at 70F.
Click to expand...
I don't get the impression Herm is arguing that point.

Rather, it seems entirely reasonable that when you attach a new battery to a controller and tell it it now has a new battery that it will *assume* the battery has a capacity of *exactly* 24 kWh and assign 300 GiDs to that full capacity. Then when we request 100% charge, it goes to a predefined voltage, balances the cells and then defines that to be 281 GIDs. It can then make calibrations based around this assumption of initial battery capacity. Then, as the battery degrades, the number of GiDs will go down. It's just a guess, but it's reasonable that some assumptions are made so that there is a consistent measurement that can be made between cars.
 
LEAFfan said:
All of the cars I've tested so far are about one year old and have anywhere from 9000 to 12000 miles.
Click to expand...
That's interesting...is there anything noteworthy that might set the one(s) with higher capacity readings apart from the others?
LEAFfan said:
Today, I'm going down to a dealer who has two new LEAFs for sale, one a 2011 and the other a 2012 and will take a reading if they are at 100%.
Click to expand...
That should be interesting. I don't know that anyone has done this on a new LEAF before.
 
RegGuheert said:
Rather, it seems entirely reasonable that when you attach a new battery to a controller and tell it it now has a new battery that it will *assume* the battery has a capacity of *exactly* 24 kWh and assign 300 GiDs to that full capacity. Then when we request 100% charge, it goes to a predefined voltage, balances the cells and then defines that to be 281 GIDs. It can then make calibrations based around this assumption of initial battery capacity. Then, as the battery degrades, the number of GiDs will go down. It's just a guess, but it's reasonable that some assumptions are made so that there is a consistent measurement that can be made between cars.
Click to expand...
Interesting idea, but I don't believe that this is how it works. Phil told us that each Gid corresponded to 80 Wh of energy stored in the battery. The raw inbound coulomb count is adjusted periodically by looking at the OCV, and by subtracting the outbound coulomb count. The resulting number are our "Gids".

Both the 80% and 100% voltages are preset and fixed. The battery holds, what it can hold at those potentials. As it ages, and its storage capacity deteriorates, the maximum Gid count will decline. I believe that we are beginning to see that. The only open question is seasonality. You would think that the battery will hold more energy at 394V when it's warm out, not less. Consequently, the Gid count should be higher in the summer, but that seems to be the opposite of what we are observing.
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