GID/capacity increases as cooler weather returns

[garygid]

My GID readings, after a full/100% charge, have been increasing
as cooler weather returns.

Dropping from about 98% GIDs last spring to about 89% in mid september,
the GID readings (throughout a more-frequent series of full-charging
sessions) have steadily risen, back up to 93.2% yesterday.

Although not a full recovery by any means, it is an interesting turn
of events that might mean that the BMS does not fill the Battery Pack
as full during hot weather.

Sure, it looked like rapid capacity loss, and I do not expect a full
recovery to last February's levels, but this is a new (and welcome)
"bump" in the charging "capacity" curve, at least for me.

In this thread let's discuss the return of this "usable capacity" as
other users experience it.

 

[edatoakrun]

My GID readings, after a full/100% charge, have been increasing
as cooler weather returns.

Dropping from about 98% GIDs last spring to about 89% in mid september,
the GID readings (throughout a more-frequent series of full-charging
sessions) have steadily risen, back up to 93.2% yesterday...

In this thread let's discuss the return of this "usable capacity" as
other users experience it.

Please also include reports of data indicating actual increase in available battery capacity, as evidenced by increasing range results or higher recharge capacity (metered or timed), which would indicate you are actually getting a higher kWh charge, rather than only seeing Wh variability per gid.


See TickTock's record of recharge reports indicating seasonal Wh/gid variability here:

https://docs.google.com/spreadsheet/ccc?key=0An7gtcYL2Oy0dHNwVmRkNkFnaEVOQTVENW5mOTZlb0E&pli=1#gid=3" onclick="window.open(this.href);return false;

 

[Bassman]

I don't have a GID meter, but I've definitely noticed that charging at work in the hot parking lot to 100% doesn't give me as much charge as in the evening charging to 100% at home in a cool garage. After work, I almost always see the first regen bubble just driving out of the parking lot. This has been happening a lot this summer. In the morning, it usually takes a 2-3 miles before I get the first regen bubble. At 28.600 miles and almost 18 months of ownership, I haven't dropped a bar yet, but at 80% charge I only get 9 bars now, so I have lost about 9-10% of my battery capacity. This probably also causes the regen bubble to appear earlier than it use to.

 

[garygid]

Getting 9 Fullness Bars instead of 10 on an 80% charge can happen
If the 10th Bar is only 49% full instead of 51% full. It does not
indicate capacity loss. These Bars are NOT a "fuel" gauge.

Even after 25% capacity loss, which should show up as the loss
of two of the small Capacity Bars, a full charge should still
display 12 Fullness Bars, indicating that the smaller e-fuel tank
is "full".

Without some other instrumentation, the car "hides" capacity loss
until at least 15% is lost, then one capacity bar disappears.

I noticed that I was arriving home with less battery remaining
after a 75 trip (to HTB) that I take the same way, on cruise control,
once each month.

I have the original March 2011 firmware, and I have a GID-Meter.

 

[smkettner]

I am still holding out hope for getting my 12th capacity bar back by November

 

[DaveinOlyWA]

My GID readings, after a full/100% charge, have been increasing
as cooler weather returns.

i predicted that would happen. another thing to discuss is what is the "real" sweet temperature spot because i am seeing to distinct issues.

1) the sweet spot for driving range. the best temp seems to be the low 80's. reason i feel this. i have several oft driven routes in my life. obviously, there is always a day to day variance that affects performance but one route is driven up to 2 times a week and has been over a year thru all seasons and there is a trend i noticed that i cannot get 6 miles/K unless the temp is 80. if the temp is 75, then i get 5.6 or 5.4 or 5. something.

2) at the same time. when charging for GID count, the best temp seems to be the upper 60's. granted, this one is a much tougher cookie to swallow simply because ambient temps can be much different than pack temps so i tried this on very cold nights with garage door open later and skipped charging a day here and there to make the pack as cool as possible.

as far as what i see coming back? my hot weather charging experiment had GID as low as 263/93.5% of which all came back later the next week. it did take a good 3 days to cool off from that upper 90's "charging during the middle of the afternoon" session which tells me that pack retains heat too well which also means it heats up rather slowly as well. not a good thing in Phoenix but good for me in winter.

so, i predicted that people in Southern Ca would get 4-6% capacity back come winter, Phoenix 5-8% or more

 

[Nubo]

I haven't been tracking GIDS, or wall-power at all, but I have noticed the last couple of times when charging to 100%, an apparent battery-balancing where I get another charge-complete message about 2 hours after the first one. I had seen this back in the Spring, none during the Summer. I can only speculate that it has something to do with temperature change.

 

[smkettner]

I haven't been tracking GIDS, or wall-power at all, but I have noticed the last couple of times when charging to 100%, an apparent battery-balancing where I get another charge-complete message about 2 hours after the first one. I had seen this back in the Spring, none during the Summer. I can only speculate that it has something to do with temperature change.

I have always wondered if the extra charge is actually balancing the cells or I am inclined to think the BMS is topping up a battery that has cooled. Might seem like more energy from "balancing" but I keep thinking it is just the BMS adjusting for a temperature drop and posssibly a voltage drop as the battery rests.

 

[timhebb]

No GID-meter here. So, as a poor substitute, the readings that I view with the most significance are the GOM range prediction numbers at the end of a charging session. Although they are virtually useless for predicting range, I believe they have a clear relationship to SOC, although that relationship (algorithm) must be complex beyond the understanding of mortal beings.

When my Leaf was new (18 months ago), a 100% charge always resulted in GOM range readings of well over 100, up to 120 or 122ish. This summer, they never exceeded 100, sometimes sinking to the 80s.

With the cooler ambient temps of the last few days, I saw the first reading again of exactly 100 at 100% charge (I commonly charge to 100% because: a) I often use public charging and want to maximize the opportunity, and b) I'm leasing, so I can afford to lose the range).

I'm hoping that continued cool weather will result in more frequent/higher GOM range predictions again, bouncing back a bit from the summer doldrums. We'll see...

 

[DaveinOlyWA]

I haven't been tracking GIDS, or wall-power at all, but I have noticed the last couple of times when charging to 100%, an apparent battery-balancing where I get another charge-complete message about 2 hours after the first one. I had seen this back in the Spring, none during the Summer. I can only speculate that it has something to do with temperature change.

how are these messages delivered? is it from Carwings via text/email or is it from your charger's alert system?

 

[Nubo]

I haven't been tracking GIDS, or wall-power at all, but I have noticed the last couple of times when charging to 100%, an apparent battery-balancing where I get another charge-complete message about 2 hours after the first one. I had seen this back in the Spring, none during the Summer. I can only speculate that it has something to do with temperature change.

how are these messages delivered? is it from Carwings via text/email or is it from your charger's alert system?

Carwings sends a text message to my phone.

 

[DaveinOlyWA]

I haven't been tracking GIDS, or wall-power at all, but I have noticed the last couple of times when charging to 100%, an apparent battery-balancing where I get another charge-complete message about 2 hours after the first one. I had seen this back in the Spring, none during the Summer. I can only speculate that it has something to do with temperature change.

how are these messages delivered? is it from Carwings via text/email or is it from your charger's alert system?

Carwings sends a text message to my phone.

maybe this is something that needs some further illumination. in the 20+ months of ownership, i have never once had this happen to me.

now, granted up until this Spring, i did not charge to 100%$ very often, but since then, i am doing it 3-5 times a week so i potentially could have seen this probably a few hundred times.

i guess we will see how this Winter goes since it would seem this phenomena would happen more in a colder condition?

 

[vegastar]

My gids at 80% charge are also recovering. 215 today vs 210 all time low. My log:

https://docs.google.com/spreadsheet/ccc?key=0AvuZhK4s7poqdEJfYTBCb3lwakZDNGI1cGNJUlFIUmc&pli=1#gid=4

 

[mksE55]

My gids at 80% charge are also recovering. 215 today vs 210 all time low. My log:

https://docs.google.com/spreadsheet/ccc?key=0AvuZhK4s7poqdEJfYTBCb3lwakZDNGI1cGNJUlFIUmc&pli=1#gid=4

Thanks, very helpful. I dont know why the car could not post a piece of information like this from its own data on screen and we could follow our degradation over time. and possible see what could be accelerating that process on our own. Wish I had a gidmeter .

 

[planet4ever]

I haven't been tracking GIDS, or wall-power at all, but I have noticed the last couple of times when charging to 100%, an apparent battery-balancing where I get another charge-complete message about 2 hours after the first one. I had seen this back in the Spring, none during the Summer. I can only speculate that it has something to do with temperature change.

Interesting theory, since I have seen something similar. The three times I saw an extra charge-complete message were 2011-09-10 0330, 2012-02-08 0300, and 2012-02-19 0130.

One thing that seems curious/suspicious about my instances is that in all three cases the message time was exactly on the hour or half hour. (Not that it should matter, but I always have a 80% end-only timer set for 0700, and only get charge-complete if I override that with either the dash button or website command.)

My battery would likely have been cooling in all three cases, since I park outdoors, but I'm not sure why that would trigger a top off. Doesn't the battery actually lose capacity as it cools (except perhaps at high temperatures, which wouldn't have been my case)? I might also mention that I charge at 240v 12A, using Phil's original EVSEupgrade.

Ray

 

[DaveEV]

Although not a full recovery by any means, it is an interesting turn
of events that might mean that the BMS does not fill the Battery Pack
as full during hot weather.

In this thread let's discuss the return of this "usable capacity" as
other users experience it.

Tony's range test shows that the capacity loss is real. GIDs may go back up, but as TickTock documented, GIDs are affected by temperature.

There's two ways you might show a return of "usable capacity".

1. Perform a range test. Tony has well documented procedures to follow to minimize variance.
2. Measure from-the-wall energy when charging from turtle to 100%. I would suggest at a minimum recording charge time/energy from turtle to 80%, 80% to 100%, then waiting a set period of time 1-4 hours and then topping off (unplug it while you're waiting so it doesn't try to top-off automatically) to see if/how much more energy is able to be squeezed in due to balancing.

Pizza bet?

 

[DaveinOlyWA]

Although not a full recovery by any means, it is an interesting turn
of events that might mean that the BMS does not fill the Battery Pack
as full during hot weather.

In this thread let's discuss the return of this "usable capacity" as
other users experience it.

Tony's range test shows that the capacity loss is real. GIDs may go back up, but as TickTock documented, GIDs are affected by temperature.

There's two ways you might show a return of "usable capacity".

1. Perform a range test. Tony has well documented procedures to follow to minimize variance.
2. Measure from-the-wall energy when charging from turtle to 100%. I would suggest at a minimum recording charge time/energy from turtle to 80%, 80% to 100%, then waiting a set period of time 1-4 hours and then topping off (unplug it while you're waiting so it doesn't try to top-off automatically) to see if/how much more energy is able to be squeezed in due to balancing.

Pizza bet?

it is not possible to NOT have loss. that is how batteries work. they lose capacity from day one. however, many are using bars and GIDs to extrapolate loss into next year and they are using temperature adjusted #'s. now, is the return of these GIDs giving them some range back?

no, its not (unless the temperature is DROPPING to about 80º) it is simply revealing range they already had and along with that; revealing how truly difficult it is to quantify that loss. driving around aint really gonna cut it unless you can do it 20 times and average it out. problem with that is most dont have a baseline to compare when the LEAF was new because we ALL thought that a trip or two was enough to know what we needed to know.

now some are lucky enough that their commute is close enough to their maximum range to where they can see an indication of how much less range they have when parking the LEAF at night.

the other thing is what ambient temp allows best range? i doubt that even that answer is as simple as we want it to be.

for me its about 80º ambient. but batteries heat up when being used, being charged or just sitting in parking lots and that radiant heat can and does vary widely from area to area so i have to guess that my 80º is best but for those in lower latitudes and more radiant heat and more concrete, etc you might want to test your range at 70º instead.

 

[Stanton]

More data to support this premise (which I agree with): after a couple of months of 9 bars @80% charges, I'm back to 10 bars @80%!! The temps have definitely moderated here in Dallas (<90F), especially at night when I do my charging. In fact, we're going to get down-right cold this weekend (for this time of year) with lows in the 50's; I even saw 5TB's a couple of days this week. I don't have a GID meter, but I can tell I'm getting a few miles (and even a bar on long trips) back in my range.

 

[DaveinOlyWA]

More data to support this premise (which I agree with): after a couple of months of 9 bars @80% charges, I'm back to 10 bars @80%!! The temps have definitely moderated here in Dallas (<90F), especially at night when I do my charging. In fact, we're going to get down-right cold this weekend (for this time of year) with lows in the 50's; I even saw 5TB's a couple of days this week. I don't have a GID meter, but I can tell I'm getting a few miles (and even a bar on long trips) back in my range.

lows in the 50's is cold?? :?

hmmm, that is what i hope for just about all Summer long for night time. ya, we huddle around that campfire!!

 

[evnow]

Tony's range test shows that the capacity loss is real. GIDs may go back up, but as TickTock documented, GIDs are affected by temperature.

Range is heavily affected by temperature as well.

I appreciate the test Tony and others did - but it gave us no results apart from the well know fact that both GOM & capacity bars are unreliable. We can't separate instrumentation error from actual range, since the range Leaf allows depends on instrumentation. So we don't know whether the loss of range is because of capacity loss or instrumentation problem.