80% Charge only 9 bars?

[DaveEV]

It's been significantly warmer in the San Diego area this summer compared to last over the weeks in question (last two weeks) - that combined with the cars for the most part being one year older might explain why we're getting the 9/80's now? Here's a graph of maximum temperature (at Lindbergh) from July 20 to August 19 in both 2011 and 2012:

Wow, what a difference a year makes! Lindbergh field is usually cooler than most of San Diego being right on the coast, too. Still - there was no known reports of 9/80% charges last year even in much warmer climates - most of the 9/80% reports from warmer climates came much earlier this year - it must be a combination of battery degradation along with heat that can trigger it.

Our garage was undoubtedly cooler last night...but we didn't charge, so I don't know whether we'd have gone back to 10/80.

My car went back to 10 bars this morning. Was maybe a degree or two cooler in the garage, but still around 76F this morning - my garage is mostly insulated so the temperature stays fairly constant even with 4 14"x14" vents. Highs during the day are typically around 83F (with ambient being 2-4F higher). Even leaving a side door open until midnight does not help more than a couple degrees - of course at midnight lately it's still been 70F outside.

 

[GregH]

uhm.. ok. So 203 again this morning but this time 10 bars. And that 10th bar lasted all the way down to 192 gids. I'm not sure how much the 9 vs 10 bars at 80% tells us about capacity loss.

 

[LEAFfan]

I also bet that GIDs are temperature adjusted as well - TickTock in AZ has documented seasonality with his GID counts and found that his GIDs seem to hold more energy when it's warm than when it's cold.

Ya, but I'm willing to bet that the so-called seasonality gid count/% is insignificant. What is the % increase, 1-2%? I've had my BCM for some time (thru all four seasons) and I've never noticed more than a 1-2% increase in the cooler months. That's about 5 gids. To me, that's an insignificant amount to even mention. Now, maybe in your area, it makes a bigger difference.

 

[ttweed]

uhm.. ok. So 203 again this morning but this time 10 bars. And that 10th bar lasted all the way down to 192 gids. I'm not sure how much the 9 vs 10 bars at 80% tells us about capacity loss.

No gid count here, but I have also seen 10 bars again on the last two 80% charges we have done after seeing 9 bars for the first time and then doing several 100% daily charges. The 10th bar lasted less than a mile when I pulled out of the garage yesterday, though, so I do suspect that this behavior is indicative of some capacity loss, possibly combined with some temperature-related charging effect that we don't understand yet, and may be a precursor to losing a capacity bar in the future. Hope I'm wrong, but only time will tell. If our battery really is suffering from accelerated degradation even in the relatively mild conditions and use we have subjected it to here in coastal San Diego, it really is going to be a big problem for Nissan after the promises that were made in the original sales push.

TT

 

[ttweed]

Update:
Today I received my second "9 bar/75%" charge when programmed for 80%, after a couple more 100% charging days in between where we had longer trips planned. On the last 10 bar/83% charge, I drove 2 miles and shut off the car, then noticed when I turned it back on it had only 9 bars, so that 10th bar is very "shallow" even when it does show up. I also noticed that my temp bars were back down to 5 that day, for the first time in several months, but they were back up to 6 bars yesterday and again today. On the last 100% charge, my wife still drove 73 miles, half street and half freeway, and had 11 miles left on the GOM, so range does not seem to have been horribly effected yet.

TT

 

[TomT]

Back when I still had a 10th bar, I used to get about 5-6 miles out of it on my way to work on the freeway...

The 10th bar lasted less than a mile when I pulled out of the garage yesterday, though, so I do suspect that this behavior is indicative of some capacity loss, possibly combined with some temperature-related charging effect that we don't understand yet, and may be a precursor to losing a capacity bar in the future.

 

[edatoakrun]

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;

 

[ttweed]

The same "80%" charge level can show as 9 or 10 bars.
Apparently, the tenth bar disappears and reappears, as the battery temperature changes.

This may very well be true now that the battery has degraded to some extent, but it was never true on our car for the first 16 months and 18K miles of service. We charged to 80% by the Leaf timer for the majority of that time, and NEVER got a 9-bar result until just recently, including over the first summer we had the car, which had some hot weather periods similar to the ones we have recently experienced. There is definitely something else going on now, which I assume to be some amount of degradation that has taken place that has put us on the "cusp" of the 9th-10th bar when charging to 80%, allowing this small temp "fluctuation" to bounce between the two indicator levels. Like TomT, we always got 5-6 miles out of the 10th bar (post-firmware update) when charged to 80% previously, and now seem to have 1-2 mile range when (and if) it reaches the 10th bar.

I am certainly not surprised by a certain amount of degradation of the battery--we were fairly well informed by Nissan that it would take place, but the amount of capacity loss being experienced in such a short time by owners in the hot-weather states has made me nervous and concerned. We determined before buying the car that even with the predicted 30% capacity loss in 8 years, it would still serve us well, as we have no long commute to make each day, and figured we would eventually just begin to charge to 100% all the time, and depend more on opportunity charging at remote locations as necessary, until a new (hopefully improved) battery pack would be required in perhaps 10 years or so (which would easily be paid for by the gas savings achieved in that time). Needless to say, the growth of the charging infrastructure has been nowhere near what was predicted, and if capacity loss is going to be accelerating beyond what was expected, the equation changes somewhat. I do not want to be regretting my buy vs. lease decision after 3 years!

It is not clear to me yet that this "9 bar/75%" charging phenomenon is a direct precursor to a capacity bar loss, but I suspect it is. What I find confusing is that it is only reporting a 75% charge when it is programmed to charge to 80%. The people who have reported capacity bar losses still get 12 SOC bars when charging to 100%, so why don't you still get 10 SOC bars when charging to 80%, even if there has been some partial capacity loss? There is something odd/inconsistent about the Carwings programming, I guess, which does not surprise me, considering what a POS that system has proven to be.

TT

 

[davewill]

...What I find confusing is that it is only reporting a 75% charge when it is programmed to charge to 80%. The people who have reported capacity bar losses still get 12 SOC bars when charging to 100%, so why don't you still get 10 SOC bars when charging to 80%, even if there has been some partial capacity loss? There is something odd/inconsistent about the Carwings programming, I guess, which does not surprise me, considering what a POS that system has proven to be. ...

Carwings simply takes the number of bars and multiplies that out to a percentage. That's why you get numbers like 83% (10/12) and 75% (9/12). Since neither 9 bars or 10 bars exactly equals 80%, Carwings will never report 80% even though the charge timer seems to charge to it.

 

[edatoakrun]

The same "80%" charge level can show as 9 or 10 bars.
Apparently, the tenth bar disappears and reappears, as the battery temperature changes.

This may very well be true now that the battery has degraded to some extent, but it was never true on our car for the first 16 months and 18K miles of service. We charged to 80% by the Leaf timer for the majority of that time, and NEVER got a 9-bar result until just recently, including over the first summer we had the car, which had some hot weather periods similar to the ones we have recently experienced. There is definitely something else going on now, which I assume to be some amount of degradation that has taken place that has put us on the "cusp" of the 9th-10th bar when charging to 80%, allowing this small temp "fluctuation" to bounce between the two indicator levels....

Yes, and I got my first 9 bars after an "80%" charge sooner than you did, after ~11,500 miles, and 15 months, possibly due to my LEAF's greater exposure to high temperatures, than your LEAF has experienced. I posted on this thread three weeks ago, see the link below.

There are other explanations besides "degradation" for this, occurrence however. And they may also be, in part, the same explanations for heat-related capacity bar loss.

It seems likely that either "gids" are variable with temperature (short or long term), The BMS limits charging in higher temperatures, or both.

To separate these effects from the underlying battery degradation rate, we need drivers to post actual observations.

That is why I asked:

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?

If the gid count remains stable over a wide temperature range, I think we could probably rule out very short-term variability in the Wh value of each gid.

="edatoakrun"

I got my first "...nine bars..." email, and also had nine bars on the dash, both for the first time, Thursday AM, the day I brought my car in for repair as mentioned here:

http://www.mynissanleaf.com/viewtopic.php?f=30&t=9573" onclick="window.open(this.href);return false;

More observations, and/or coincidences?

This was the first timer recharge to 80%, following my hottest day of driving this year, on last Tuesday. The dash temp had topped out at 103, but the temp bar never hit 7.

As soon as I descended the ~200ft over the first 1/8 mile of my drive, the 10th bar appeared. Very odd, considering I get little regen (reported by CW as .0 kWh) on this steep, slow, gravel grade.

The 10th bar lasted for about 13 miles, close to what I usually get, with the 1500 ft net descent, on the drive towards Redding, at the same speed.

Second and third bars lasted about as long as I'd expect, had I had the normal 10 from the beginning, also.

http://www.mynissanleaf.com/viewtopic.php?f=30&t=8765&start=120" onclick="window.open(this.href);return false;

 

[ttweed]

Carwings simply takes the number of bars and multiplies that out to a percentage. That's why you get numbers like 83% (10/12) and 75% (9/12). Since neither 9 bars or 10 bars exactly equals 80%, Carwings will never report 80% even though the charge timer seems to charge to it.

Understood, but I did not say "Why doesn't Carwings report 80% when I ask for an 80% charge," I'm fully aware that the choices are 83% or 75% for Carwings. What I asked was "...why don't you still get 10 SOC bars when charging to 80%" even with diminished capacity (or higher temps)? If the SOC gauge bars still report 12 for a 100% charge to an owner who may have 11, 10, or even only 9 capacity bars left, it is adjusting for the diminished capacity and reporting that the battery is charged to 100% of what it is capable of at that point in time, not compared to what it did when it was new. Regardless of whether it is temperature variations or degradation that is causing this "9 bar/75%" phenomenon, why isn't the same adjustment being made by the SOC gauge in this 80% charging scenario, resulting in a report that the battery is still charged to 83% (or 10 bars) of what it is capable of taking at this moment in time as well? That seems inconsistent to me. The calculation of percentage vs. voltage for each bar should be made on the fly each time it starts charging, according to what represents a "full" (100%) SOC for the current battery condition. It seems to do this when told to charge to 100%, even with diminished capacity, so why is the same adjustment not being made for the 80% program as well?

TT

 

[edatoakrun]

Carwings simply takes the number of bars and multiplies that out to a percentage. That's why you get numbers like 83% (10/12) and 75% (9/12). Since neither 9 bars or 10 bars exactly equals 80%, Carwings will never report 80% even though the charge timer seems to charge to it.

Understood, but I did not say "Why doesn't Carwings report 80% when I ask for an 80% charge," I'm fully aware that the choices are 83% or 75% for Carwings. What I asked was "...why don't you still get 10 SOC bars when charging to 80%" even with diminished capacity (or higher temps)...?

AFAIK, the info at the owners site has nothing to do with carwings.

The site gives you the option to launch CW, which will be useful only if you "accept" the car's onscreen prompt.

So if you decide not to subscribe to CW after the 3 year free period ends, I think you should still have access to the %/bars info, for whatever it's worth to you...

 

[davewill]

...What I asked was "...why don't you still get 10 SOC bars when charging to 80%" even with diminished capacity (or higher temps)? If the SOC gauge bars still report 12 for a 100% charge to an owner who may have 11, 10, or even only 9 capacity bars left, it is adjusting for the diminished capacity and reporting that the battery is charged to 100% of what it is capable of at that point in time, not compared to what it did when it was new. Regardless of whether it is temperature variations or degradation that is causing this "9 bar/75%" phenomenon, why isn't the same adjustment being made by the SOC gauge in this 80% charging scenario, resulting in a report that the battery is still charged to 83% (or 10 bars) of what it is capable of taking at this moment in time as well? That seems inconsistent to me. The calculation of percentage vs. voltage for each bar should be made on the fly each time it starts charging, according to what represents a "full" (100%) SOC for the current battery condition. It seems to do this when told to charge to 100%, even with diminished capacity, so why is the same adjustment not being made for the 80% program as well?

TT

It's pretty obvious that the bar calculation has been played around with. The bars are not linear, and they are hiding capacity after all the bars are gone. The easiest way to program arbitrary algorithms like that is a table. They probably have a whole bunch of tables to account for degradation (since less capacity still has to map across 12 bars), perhaps one table for each capacity bar, perhaps more. Worse, I'm pretty sure that the charger uses true SOC to charge to 80% while the bars use a coulomb counter which accumulates errors over time (per Phil)...that's probably why we sometimes still get 10 bars. As the battery degrades, 80% SOC maps to a different coulomb count and moves down into the ninth bar. As degradation progresses, I would look for the car to switch to a different table and for 80% to jump back up into the tenth bar at some point. As far as 100% always showing 12 bars, a 100% charge isn't close to a bar boundary, so any inconsistencies would be masked for that one...besides I'm sure they were most careful to make sure a 100% charge always shows 12 bars...EVERY owner would be marching in to the dealer if their car didn't seem to be charging all the way up! The 80% mark IS close to the 9/10 bar boundary and they obviously didn't take care to make sure that 80% always landed in the tenth bar.

 

[davewill]

AFAIK, the info at the owners site has nothing to do with carwings.

The site gives you the option to launch CW, which will be useful only if you "accept" the car's onscreen prompt.

So if you decide not to subscribe to CW after the 3 year free period ends, I think you should still have access to the %/bars info, for whatever it's worth to you...

I've been hoping that's the case, since CarWings itself has been useless, and I'm unwilling to spend time and energy (much less cold, hard cash) to get it working properly. The only online features I value are the ones in the app and the owner's site.

 

[planet4ever]

So if you decide not to subscribe to CW after the 3 year free period ends, I think you should still have access to the %/bars info, for whatever it's worth to you...

I've been hoping that's the case, since CarWings itself has been useless, and I'm unwilling to spend time and energy (much less cold, hard cash) to get it working properly. The only online features I value are the ones in the app and the owner's site.

That would be nice, but I doubt it. After all, the only way the app or website can get access to the car's information is through a cell phone connection. Someone has to pay for that connection, and I suspect strongly that is buried in the cost of CarWings.

Ray

 

[planet4ever]

The calculation of percentage vs. voltage for each bar should be made on the fly each time it starts charging, according to what represents a "full" (100%) SOC for the current battery condition. It seems to do this when told to charge to 100%, even with diminished capacity, so why is the same adjustment not being made for the 80% program as well?

They probably have a whole bunch of tables to account for degradation (since less capacity still has to map across 12 bars), perhaps one table for each capacity bar, perhaps more. Worse, I'm pretty sure that the charger uses true SOC to charge to 80% while the bars use a coulomb counter which accumulates errors over time (per Phil)...that's probably why we sometimes still get 10 bars.

My theory is closer to what TT said. I suspect they get a max allowed Gid count from the BMS, calculate (present Gid) / (max Gid) and, at least logically, use that fraction to look up bar count in a single table. [In practice they would scale the values so that they were using integers rather than fractions.]

To answer TT's question, I would point out that the other thing Phil has told us about 80% is that it is not 80% of max allowed charge, but 80% of total battery capacity. As the battery degrades the BMS may well change what % of the total capacity is allowed. This would change where "80%" falls on the bar scale. (It is, of course, the BMS - or what Nissan calls the LBC - and the On Board Charger that control when charging stops at "80%", and the Combination Meter computer that controls what is displayed.)

Ray

 

[ttweed]

So if you decide not to subscribe to CW after the 3 year free period ends, I think you should still have access to the %/bars info, for whatever it's worth to you...

I've been hoping that's the case, since CarWings itself has been useless, and I'm unwilling to spend time and energy (much less cold, hard cash) to get it working properly. The only online features I value are the ones in the app and the owner's site.

That would be nice, but I doubt it. After all, the only way the app or website can get access to the car's information is through a cell phone connection. Someone has to pay for that connection, and I suspect strongly that is buried in the cost of CarWings.

That has always been my assumption, Ray--that if one doesn't subscribe to Carwings at the end of the free period, the cellular connection to the car would be terminated, and the owner's portal remote functions would be disabled (as well as the even more useless data in the window that pops up when you click on "Launch Carwings" link there). Edatoakrun, do you have some reference to a policy statement from Nissan that indicates differently--that the owner's portal will remain available to non-subscribers? I would be happy to hear that is true, as those remote functions are the only useful aspect of the system. I have always considered "Carwings" to be the entire communication system interface, not two separate modules, one of which will always be available to the owner through the portal for status checks and remote control of charging and climate control. The data on energy usage and driving habits and route planning, etc., I could definitely live without, but I have always thought the two go hand in hand.

TT

 

[Stoaty]

So if you decide not to subscribe to CW after the 3 year free period ends, I think you should still have access to the %/bars info, for whatever it's worth to you...

I am hoping that not subscribing to Carwings will make the "OK" prompt go away. That would be an outstanding solution!

 

[wsbca]

I'm probably going to jinx it by even saying anything, but after our initial flurry of 9 bar 80% charges earlier this month here in SoCal during the heat wave (which a number of other "second-summer moderate mileage mostly 80% charging" people were also suddenly getting), we've now had several consecutive 10 bar charges. It's been a little cooler, although the last few days were back into the high 80's. Anybody else seeing the same?

 

[aqn]

I'm probably going to jinx it by even saying anything, but after our initial flurry of 9 bar 80% charges earlier this month here in SoCal during the heat wave (which a number of other "second-summer moderate mileage mostly 80% charging" people were also suddenly getting), we've now had several consecutive 10 bar charges. It's been a little cooler, although the last few days were back into the high 80's. Anybody else seeing the same?

Are you sure they're 10-bar charges?! I had a few of what I thought were 10-bar 80% charges after a month or so of 9-bar-on-80% charges, but in retrospect, they immediately preceded my noticing that I've lost one capacity bar: those "10-bar charges" were really only 9-bar charges, but looked like 10-bar charges next to the 11 capacity bars!