80% Charge only 9 bars?

[planet4ever]

Anyway - I'd like to think we're just still on the threshold between 9 ("75%") and 10 ("83%") bars. In that, at the beginning, when we asked for 80%, it rounded to 10 bars because whatever internal value that is was closer to 83% of nominal full, and maybe now the internal value is more like 78-79% of nominal full, which is closer to 75, hence 9 bars. Rather than an entire bar being gone. Which fits with the 9th bar being pretty sturdy if it's the first bar of the day.

I agree with your conclusion, but that seems like a very strange way to arrive at it. "75%" and "83% are totally bogus numbers calculated by the website or ap and never used inside the car itself. They are based on the completely false assumptions that: a) you have 0% of the battery left when the last bar disappears; b) every bar displayed is 100% full; and c) every bar represents the same amount of energy.

We don't know what algorithm the dash computer is using to convert values it gets from the CAN into number of bars, though we are pretty sure it uses a combination of at least two such values. What we do know is that the website has nothing to go on except the number of bars. See "bogus" and "false" above. What we also know is that the decision to stop charging is made by the battery controller, which has access to much information that never gets onto the CAN, and way better data than gets to us mere mortals.

Ray

 

[Stoaty]

I am the service director at a leaf certified dealer nissan dealer in Jacksonville, FL. We have a couple employees driving leafs and I have one coming in. I think that many of you are overthinking this issue. charge it, drive it, and use the heck out of it. The battery is guaranteed by Nissan to retain 80% capacity at 5 years. Drive the car and if it loses capacity, take it in and have your dealer cover it. That's what we do.

This is either a sly commentary on Nissan's lack of a capacity warranty, a dumber than dirt service director, or a troll. Hard to know which. :lol:

 

[theaveng]

I am the service director at a leaf certified dealer..... The battery is guaranteed by Nissan to retain 80% capacity at 5 years. Drive the car and if it loses capacity, take it in and have your dealer cover it. That's what we do.

What dealer are you? I want to buy my car there.
I'm guessing this one:
http://nissanattheavenues.com/" onclick="window.open(this.href);return false;

 

[smkettner]

I am the service director at a leaf certified dealer..... The battery is guaranteed by Nissan to retain 80% capacity at 5 years. Drive the car and if it loses capacity, take it in and have your dealer cover it. That's what we do.

Assuming that is true, you are going to be swamped starting in 2016 with battery swaps.

 

[edatoakrun]

On the afternoon of 9/6 my 6th temp bar appeared, but for the first time in a few weeks, the 10th charge bar did not disappear. And I have had 10 bars when charging to 80% and they all stayed there, even after the 6th temp bar came on (every day I checked) ever since. So I know that 9/10 bar display change point does not represent an actual fixed amount of kWh charge. I still don't know if the gid count is also non-representative of kWh charge, since no one with a gid meter (AFAIK) has looked at and posted their results.

My 9/1 summary on this thread below:

My tenth capacity bar at "80%" charge continues to disappear, about the same time the 6th temperature bar appears, and vice versa.

As I asked on P 17 of this thread, it would be very useful for those with gid meters to report whether the gid count varied with temperature, like the 9/10 capacity bar does.

The same "80%" charge level can show as 9 or 10 bars.

Apparently, the tenth bar disappears and reappears, as the battery temperature changes.

As I posted below on the "Gid sensitivity to temperature" thread:



"Has anyone with considerable variability in their daily ambient temperatures watched the gid count following a charge, while remaining parked, and neither charging nor discharging the battery, to see if the gid count changes (declines, presumably) as the ambient temperature warms during the day?

I've had my car parked at following a "80%" timer charge for a few days, with nighttime lows around 60 F, and daytime highs around 90 F.

The charge bars increase from 9 to 10 in the early morning, and decline back to 9 late in the afternoon, shortly after the battery temp bars increase from 5 to 6.

(8/28 edit- On the last test cycle, it went back up to 10 bars by one AM the next morning, completing a 10 bar to 9 bar to 10 bar cycle, without any charging or significant battery discharge.)

Just wondering if this charge bar variability by temperature, is reflecting gid count variability, or if something else is causing it.


http://www.mynissanleaf.com/viewtopic.php?f=30&t=9776&start=20" onclick="window.open(this.href);return false;

Until recently, I would have been pretty sure 9 bars at "80%" charge indicated my battery had loss of capacity of ~10%.

But recent range tests, which seem to show no loss of range in my LEAF over the last 12 months, might indicate otherwise.


http://www.mynissanleaf.com/viewtopic.php?f=31&t=9064&start=20" onclick="window.open(this.href);return false;

 

[planet4ever]

On the afternoon of 9/6 my 6th temp bar appeared, but for the first time in a few weeks, the 10th charge bar did not disappear. And I have had 10 bars when charging to 80% and they all stayed there, even after the 6th temp bar came on (every day I checked) ever since. So I know that 9/10 bar display change point does not represent an actual fixed amount of kWh charge.

I'm afraid I don't follow your argument as to why the change point is not a fixed amount of kWh, but I have no doubt as to the accuracy of the conclusion. Consider a battery so degraded that it now has only 50% of its original capacity. You will still see 12 bars if you charge it completely, but obviously 10 bars will represent far less energy that it did when the battery was new.

Ray

 

[edatoakrun]

On the afternoon of 9/6 my 6th temp bar appeared, but for the first time in a few weeks, the 10th charge bar did not disappear. And I have had 10 bars when charging to 80% and they all stayed there, even after the 6th temp bar came on (every day I checked) ever since. So I know that 9/10 bar display change point does not represent an actual fixed amount of kWh charge.

I'm afraid I don't follow your argument as to why the change point is not a fixed amount of kWh, but I have no doubt as to the accuracy of the conclusion. Consider a battery so degraded that it now has only 50% of its original capacity. You will still see 12 bars if you charge it completely, but obviously 10 bars will represent far less energy that it did when the battery was new.

Ray

Because the same amount of kWh, was represented by a variable number of capacity bars, apparently dependent on the battery temperature.

There are multiple possible explanations for this. Two of them (which are not mutually exclusive BTW) are:

This could be because as warmer battery warms it now has a larger capacity (as expected) and each one of the bars in the display now represents the same amount of kWh, but rounded to the nearest ~12th of the total capacity available (or maybe more like ~14th, taking into account the kWh available after the last bar disappears?) it now displays one less bar.

It also could be because the gid count which is (apparently) expressed by the bar display, itself is variable for temperature, and so each gid contains more Wh as the battery warms.

That is why I think those who rely on gid counts for Wh values, could eliminate Wh/gid variability for the same charge (but not for longer term changes in Wh/gid) by watching the gid count of a constant charge level, of a fixed kWh amount, as the battery warms and cools significantly.

 

[planet4ever]

Because the same amount of kWh, was represented by a variable number of capacity bars, apparently dependent on the battery temperature.

There are multiple possible explanations for this. Two of them (which are not mutually exclusive BTW) are:

This could be because as warmer battery warms it now has a larger capacity (as expected) and each one of the bars in the display now represents the same amount of kWh, but rounded to the nearest ~12th of the total capacity available (or maybe more like ~14th, taking into account the kWh available after the last bar disappears?) it now displays one less bar.

It also could be because the gid count which is (apparently) expressed by the bar display, itself is variable for temperature, and so each gid contains more Wh as the battery warms.

First, you do not know that you had the same number of kWh. None of the data available to you is precise enough to guarantee that. Second, you seem to be ignoring a pair of known facts:

1. GID count goes down as the battery ages.
2. Number of bars displayed does not go down as the battery ages.

Yes, as the battery warms it has a larger capacity, and that, independent of GID count, is why you can lose a bar. No fancy arithmetic in twelfths of fourteenths is needed. The number of bars shown is derived from (current capacity) / (maximum allowed capacity). If current capacity is held constant and maximum allowed capacity increases, the ratio decreases, and that may push you over the edge of a bar count. End of story.

Ray

 

[edatoakrun]

Because the same amount of kWh, was represented by a variable number of capacity bars, apparently dependent on the battery temperature.

There are multiple possible explanations for this. Two of them (which are not mutually exclusive BTW) are:

This could be because as warmer battery warms it now has a larger capacity (as expected) and each one of the bars in the display now represents the same amount of kWh, but rounded to the nearest ~12th of the total capacity available (or maybe more like ~14th, taking into account the kWh available after the last bar disappears?) it now displays one less bar.

It also could be because the gid count which is (apparently) expressed by the bar display, itself is variable for temperature, and so each gid contains more Wh as the battery warms.

First, you do not know that you had the same number of kWh. None of the data available to you is precise enough to guarantee that...

I didn't derive that the kWh charge was constant from from any "data".

I was observing a battery that was not charged, or (significantly) discharged, and watched the 10th bar appear and disappear as it correlated to ambient temperatures.

There is a slight rate of discharge even when turned off, but whatever that was, it did not stop the 10th bar from reappearing over several days, and over several longer periods.

"planet4ever"...GID count goes down as the battery ages...

Yes it does. However, for unexplained reasons, gid count reportedly also sometimes goes up...

"planet4ever"...Yes, as the battery warms it has a larger capacity, and that, independent of GID count, is why you can lose a bar. No fancy arithmetic in twelfths of fourteenths is needed. The number of bars shown is derived from (current capacity) / (maximum allowed capacity). If current capacity is held constant and maximum allowed capacity increases, the ratio decreases, and that may push you over the edge of a bar count. End of story.

You have restated one of the possible explanations that I mentioned above, the one that seems to be commonly accepted.

However, you have not produced any evidence for your contention that this one possible explanation is the "End of the story".

Until you actually observe the gid count while the battery heats and cools, there is no way to know if the bar disappearance and reappearance correlates to a falling and rising gid count, or not.

 

[planet4ever]

First, you do not know that you had the same number of kWh. None of the data available to you is precise enough to guarantee that...

I didn't derive that the kWh charge was constant from from any "data". I was observing a battery that was not charged, or (significantly) discharged, and watched the 10th bar appear and disappear as it correlated to ambient temperatures.

OK, I missed that. I withdraw my first point.

This could be because as warmer battery warms it now has a larger capacity (as expected) and each one of the bars in the display now represents the same amount of kWh, but rounded to the nearest ~12th ...

Here is where you and I part ways. I insist that the bars in the display do not represent the same number of kWh as the capacity changes, so I have not, as you claim, "restated one of the possible explanations that I mentioned above."

The key point that I must repeat is that a charge bar is not a constant number of kWh. It is a variable amount depending on both battery temperature and battery age. It is a constant fraction of the maximum allowed charge at that instant in time. (Note: I am not saying that all charge bars are the same constant fraction. I believe some bars may "hold more" than others.) Perhaps you need evidence of this assertion. Pages MWI-26 and MWI-27 in the service manual (April 2011 edition) spell this out in excruciating pictorial detail. Here is one of several examples:

Ray

 

[edatoakrun]

First, you do not know that you had the same number of kWh. None of the data available to you is precise enough to guarantee that...

I didn't derive that the kWh charge was constant from from any "data". I was observing a battery that was not charged, or (significantly) discharged, and watched the 10th bar appear and disappear as it correlated to ambient temperatures.

OK, I missed that. I withdraw my first point.

This could be because as warmer battery warms it now has a larger capacity (as expected) and each one of the bars in the display now represents the same amount of kWh, but rounded to the nearest ~12th ...

Here is where you and I part ways. I insist that the bars in the display do not represent the same number of kWh as the capacity changes, so I have not, as you claim, "restated one of the possible explanations that I mentioned above."

The key point that I must repeat is that a charge bar is not a constant number of kWh. It is a variable amount depending on both battery temperature and battery age. It is a constant fraction of the maximum allowed charge at that instant in time. (Note: I am not saying that all charge bars are the same constant fraction. I believe some bars may "hold more" than others.) Perhaps you need evidence of this assertion. Pages MWI-26 and MWI-27 in the service manual (April 2011 edition) spell this out in excruciating pictorial detail. Here is one of several examples:

Ray

OK, I can see why my attempt to explain bar variability was poorly worded, and I misled you.

Obviously, each bar does not represent an equal amount of kWh, whether of a twelfth of fourteenth of total capacity. My use of "~" was intended to convey this variance of kWh content of the different charge bars, from one to twelve, but I realize now my statement would be understood as you have stated.

My error.

However, I don't (entirely) accept your statement:

"...The key point that I must repeat is that a charge bar is not a constant number of kWh. It is a variable amount depending on both battery temperature and battery age. It is a constant fraction of the maximum allowed charge at that instant in time... "

I think we both agree that whatever that "maximum allowed charge" is, the total kWh of that charge will be constant, and the bar display will vary with temperature, as illustrated in the manual.

But I do not agree that your statement that "...It is a constant fraction of the maximum allowed charge at that instant in time..." has been proven to be correct.

The total charge is a constant, but the fraction represented by each bar may not be.

In fact, I think that if gid count varies with temperature changes on a battery that is neither charged or discharged over the course of observation, that would tend to indicate very strongly that any bar is not a constant fraction, over varying temperatures.

It would also provide additional data on the subject of gid variability with temperature, which could be very useful for answering other questions, accuracy of the capacity bar display, being the most, significant, IMO.

Which is why I think this would be a very useful observation for those with gid meters to make, and report the results from.

 

[planet4ever]

But I do not agree that your statement that "...It is a constant fraction of the maximum allowed charge at that instant in time..." has been proven to be correct.

You are right. That statement has not been proven. I contend that it is correct, but I have no proof of that. The two statements I claimed to be proven are:

1. GID count goes down as the battery ages.
2. Number of bars displayed does not go down as the battery ages.

The business about bars not representing a constant amount of energy is a corollary of the second statement. GIDs not being directly related to charge bars is an unavoidable conclusion from the two statements. At a logical level, this frees GIDs to represent a constant amount of energy, as Phil has told us, but it does not prove that they do.

Ray

 

[edatoakrun]

But I do not agree that your statement that "...It is a constant fraction of the maximum allowed charge at that instant in time..." has been proven to be correct.

You are right. That statement has not been proven. I contend that it is correct, but I have no proof of that. The two statements I claimed to be proven are:

1. GID count goes down as the battery ages.
2. Number of bars displayed does not go down as the battery ages.

The business about bars not representing a constant amount of energy is a corollary of the second statement. GIDs not being directly related to charge bars is an unavoidable conclusion from the two statements. At a logical level, this frees GIDs to represent a constant amount of energy, as Phil has told us, but it does not prove that they do.

Ray

Directly is the key word. I think it very possible that charge bars are reflecting changes in gid count, periodically recalculated as fractional representations of the reduced battery capacity over time, and also of the reduced and increased capacity induced by changes in battery temperature.

With all due respect to Phil, I think it possible that gids do not represent a constant 80 Wh, which (IIRC) Phil himself attributed to another source...Nissan.

And again, constant Wh values of gids should be proven to be incorrect (if other assessments of gid count inaccuracy from other threads haven't indicated this already) if observations of a stable kWh charge showed variable gid counts over time, and perhaps varying with temperature (as the charge bars evidently do) correct?

 

[DaveinOlyWA]

i think the 80 watts = GID is true but for a specific temperature condition.

its apparent that the measurements are very much an estimate with too many outside variables to measure.

Phil, about that LEAFSCAN... how much and when??

 

[planet4ever]

GIDs not being directly related to charge bars is an unavoidable conclusion from the two statements.

Directly is the key word. I think it very possible that charge bars are reflecting changes in gid count, periodically recalculated as fractional representations of the reduced battery capacity over time, and also of the reduced and increased capacity induced by changes in battery temperature.

I'm not sure whether you are saying "charge bars recalculated as fractional" or "gid count recalculated as fractional". If the former, I agree.

Page LAN-38 of the service manual shows three key CAN signals that the Li-ion battery controller sends (through the Vehicle Control Module) to the Combination Meter computer:

1. Li-ion battery available charge
2. Li-ion battery capacity
3. Li-ion battery gradual capacity loss

Clearly battery temperature information is also being transmitted, since it is shown elsewhere in the manual as read by the battery controller, and as sent by CAN from the VCM to the Combination Meter, even though I didn't spot a reference to CAN signals from the battery controller to the VCM for that.

Obviously #1 is what we call the GID value. I don't see any way to interpret the diagrams in the service manual in any way other than that the Combination Meter computer is dividing #1 by #2 and scaling the result in some way to display charge bars. (I suspect strongly that it is doing a table lookup to decide how many bars to light up.) #2 is already affected by battery temperature, so there is no need for the meter computer to factor in temperature for this.

And again, constant Wh values of gids should be proven to be incorrect (if other assessments of gid count inaccuracy from other threads haven't indicated this already) if observations of a stable kWh charge showed variable gid counts over time, and perhaps varying with temperature (as the charge bars evidently do) correct?

I can't argue with that IF, assuming the variations are large enough to exceed possible sampling errors. But of course both aging and temperature changes mean that multiple measurements must be made. It is quite possible that cumulative coulomb count discrepancies, erratic voltages, or other sensor inaccuracies could result in quite large sampling errors.

Personally, I'll stick with Occam's razor for now. Everything seems to fit together neatly without hypothesizing epicycles of GID variation.

Ray

 

[edatoakrun]

GIDs not being directly related to charge bars is an unavoidable conclusion from the two statements.

Directly is the key word. I think it very possible that charge bars are reflecting changes in gid count, periodically recalculated as fractional representations of the reduced battery capacity over time, and also of the reduced and increased capacity induced by changes in battery temperature.

I'm not sure whether you are saying "charge bars recalculated as fractional" or "gid count recalculated as fractional". If the former, I agree.

Page LAN-38 of the service manual shows three key CAN signals that the Li-ion battery controller sends (through the Vehicle Control Module) to the Combination Meter computer:

1. Li-ion battery available charge
2. Li-ion battery capacity
3. Li-ion battery gradual capacity loss

Clearly battery temperature information is also being transmitted, since it is shown elsewhere in the manual as read by the battery controller, and as sent by CAN from the VCM to the Combination Meter, even though I didn't spot a reference to CAN signals from the battery controller to the VCM for that.

Obviously #1 is what we call the GID value. I don't see any way to interpret the diagrams in the service manual in any way other than that the Combination Meter computer is dividing #1 by #2 and scaling the result in some way to display charge bars. (I suspect strongly that it is doing a table lookup to decide how many bars to light up.) #2 is already affected by battery temperature, so there is no need for the meter computer to factor in temperature for this.

And again, constant Wh values of gids should be proven to be incorrect (if other assessments of gid count inaccuracy from other threads haven't indicated this already) if observations of a stable kWh charge showed variable gid counts over time, and perhaps varying with temperature (as the charge bars evidently do) correct?

I can't argue with that IF, assuming the variations are large enough to exceed possible sampling errors. But of course both aging and temperature changes mean that multiple measurements must be made. It is quite possible that cumulative coulomb count discrepancies, erratic voltages, or other sensor inaccuracies could result in quite large sampling errors.

Personally, I'll stick with Occam's razor for now. without hypothesizing epicycles of GID variation.

Ray

I think you are misapplying Occam's razor.

It only works to explain observed behavior.

Not to rationalize the avoidance of any and all observations, that could disprove your beliefs.

Your contention that "Everything seems to fit together neatly" re the ability of gid counts to reflect constant Wh values is bordering on the ridiculous at this point, in light of actual observation of gid Wh variability, such as Ticktock's.

I think we will be able to see some pretty good data on gid Wh content variability soon, albeit only for batteries at at near-constant temperatures from the Phoenix range test thread:

...Surfingslovak described the gid behavior as strange (I used the word squirrelly, to which he concurred) on degraded cars once you get low on battery, at least from the 3-bar loser he drove...

http://www.mynissanleaf.com/viewtopic.php?f=30&t=9917&start=370" onclick="window.open(this.href);return false;

It sounds like the gid observations before the drive began, as evidenced by their failure to accurately report kWh, as tested by driving range, may also have been a bit "squirrelly" (sp)...

 

[wishboneash]

I am seeing charging to 9 bars(@80% charge) due to the somewhat colder weather for last couple of days. Night temps are near 2C, but garage temps are around 10C. I still have 12 bars of capacity left, but the range has dropped 5 miles or so due to the colder temps. I may try to do an 80% charge right after a long drive to see if the warmer battery will take more charge and go back up to 10 bars.

 

[Stanton]

I am seeing charging to 9 bars(@80% charge) due to the somewhat colder weather for last couple of days. Night temps are near 2C, but garage temps are around 10C. I still have 12 bars of capacity left, but the range has dropped 5 miles or so due to the colder temps. I may try to do an 80% charge right after a long drive to see if the warmer battery will take more charge and go back up to 10 bars.

Since it's obviously cold, my advice is do a 100% charge, let it sit for at least 6 hours, and see if the pack does a "balance". I experienced the REVERSE: that is, after several weeks of 9 bars @80% charges, I finally did a 100% balance charge when temps cooled (received double "charge complete" messages) and--low and behold--got my 10 bars @80% back. Good luck.

 

[Valdemar]

I am seeing charging to 9 bars(@80% charge) due to the somewhat colder weather for last couple of days. Night temps are near 2C, but garage temps are around 10C. I still have 12 bars of capacity left, but the range has dropped 5 miles or so due to the colder temps. I may try to do an 80% charge right after a long drive to see if the warmer battery will take more charge and go back up to 10 bars.

Interesting, in my case I haven't experienced 9 bars on 80% since temperatures dropped here a month or so ago. I was getting 9 bars 1 out of 4 charges during August/September heat.

 

[wishboneash]

I am seeing charging to 9 bars(@80% charge) due to the somewhat colder weather for last couple of days. Night temps are near 2C, but garage temps are around 10C. I still have 12 bars of capacity left, but the range has dropped 5 miles or so due to the colder temps. I may try to do an 80% charge right after a long drive to see if the warmer battery will take more charge and go back up to 10 bars.

Since it's obviously cold, my advice is do a 100% charge, let it sit for at least 6 hours, and see if the pack does a "balance". I experienced the REVERSE: that is, after several weeks of 9 bars @80% charges, I finally did a 100% balance charge when temps cooled (received double "charge complete" messages) and--low and behold--got my 10 bars @80% back. Good luck.

It's been a while since I did a 100% charge, I will try that. My commute is 60 miles +/-2 miles and I am right on the edge of LBW. By the way this morning, the LEAF Android application said I had 10 bars (83%). When I went to the car, I saw 9 bars. So, I don't get the discrepancy.