GID/capacity increases as cooler weather returns

[DaveEV]

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.

I thought we beat this horse already in the test results thread?

Phil has confirmed that battery pack voltage readings are accurate using an external high precision Fluke, so we have no reason to disbelieve those readings. For the cars that were run to turtle, they all stopped with similar voltages - definitely beyond the knee where voltage drops rapidly with little remaining charge. All the cars were charged to 100% which has been shown to vary by perhaps a volt or two at most. The results of the range test strongly correlate with bar/GID loss, though not as much as one might predict by the bar/GID loss. Andy Palmer confirmed that the capacity meter is pessimistic in his interview with Chelsea Sexton.

I don't see any reason to NOT to see Tony's results as valid - LEAFs exposed to Phoenix heat are losing capacity and range far faster than cooler climates.

 

[TonyWilliams]

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?

Yes, I want to eat pizza with drees. We absolutely know that Hall effect instruments are temperature dependent, yet folks are predicting INCREASED capacity in colder temps.

It's not; any battery powered car will have more energy with a HOT battery (obviously, there is a limit to how hot, maybe 120-130F). Also, any vehicle, bullet, arrow, rock, etc, traveling through hotter air will have LESS resistance to travel.

Folks, there is NO WAY that a colder battery is getting more power, or more range. I'll take pepperoni; what about you, Dave?

 

[TonyWilliams]

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.

We could have run the test with no instruments (external distance and speed measuring) and not disclosed anything extra. Guess, what? Same results.

The car with the least energy still went 59 miles, and the best 79.

 

[LEAFfan]

We'll have to wait a bit longer to test that theory (title) because we just had our 117th day for the year of 100F or higher yesterday. With the Low coming in Mon. night, Tuesday is supposed to be in the high 80's.

 

[DaveEV]

I'll take pepperoni; what about you, Dave?

LOL - I'm not picky.

I am simply looking forward to seeing someone running additional tests to prove it one way or the other - win-or-lose we all come out ahead. Can never have too much data!

 

[garygid]

Perhaps a cooler BMS / Hall sensor / voltage measurement
circuit simply allows the Pack to be charged more fully?

 

[nogajim]

Perhaps a cooler BMS / Hall sensor / voltage measurement
circuit simply allows the Pack to be charged more fully?

Over the past 2 days I have gotten a GID back each day. I am up to 205 for an 80% charge. Still a ways from the 220s I had this spring. I did not get any GIDS back until the morning temp bars were down to 5. Garage temp is down to the low 70s, but I was so happy to see the GID that I forgot to check it today!

 

[smkettner]

Temps dropped again last couple days. I actually got 10 bars charging to 80% pretty much the first time since I lost a capacity bar.
So is it the charge improving from lower temps or is this indicating I am on my way to the second bar loss?
Today was the first solid full day of 5 battery temperature bars since spring.

I am hoping I can hang onto 11 bars 'til first of 2013 :|

I think I have given up on the cool temps bring back #12

 

[TomT]

Not if my experience is any indication: I lost my second bar last week even after a number of days of 5 temperature bars all day......

Temps dropped again last couple days. I actually got 10 bars charging to 80% pretty much the first time since I lost a capacity bar.
So is it the charge improving from lower temps or is this indicating I am on my way to the second bar loss?
Today was the first solid full day of 5 battery temperature bars since spring.

I am hoping I can hang onto 11 bars 'til first of 2013(

 

[sparky]

My Gid readings seem to be returning to about the same levels as before the hot weather hit.
Don't know if they'll go all the way back to the May numbers.
The last two 80% charges were 227, I usually see 230. I'm guessing I'm down nearly 10% after 21 mos. My only regular long trip is LAX and back (65 mi, fwy) and the number of bars when I get home has always been about 2-3. Still is.

 

[edatoakrun]

Sparky,

How many miles on your LEAF in total, and how many driven since 5/31?

What sort of changes in ambient temperatures has your LEAF experienced since 5/31?

Do your gid readings ever change with temperature, even with no charging or discharging of the battery?

Any gid readings from before 5/31?

To all,

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.

My Gid readings seem to be returning to about the same levels as before the hot weather hit.
Don't know if they'll go all the way back to the May numbers.
The last two 80% charges were 227, I usually see 230. I'm guessing I'm down nearly 10% after 21 mos. My only regular long trip is LAX and back (65 mi, fwy) and the number of bars when I get home has always been about 2-3. Still is.

 

[mwalsh]

My only regular long trip is LAX and back (65 mi, fwy) and the number of bars when I get home has always been about 2-3. Still is.

Driving the same way? I've head to increase my efficiency to maintain the same end point result.

 

[sparky]

I know I drive more efficiently now than the early days. So, it's not a very accurate assessment. I think I used to average about 3.5 on this trip and now I seem to be able to do almost 4 mi/kWh. Also, there's now a DCQC on my way home (downtown L.A.) so, I can use that if it becomes a problem getting home.

 

[sparky]

Sparky,

How many miles on your LEAF in total, and how many driven since 5/31?

What sort of changes in ambient temperatures has your LEAF experienced since 5/31?

Do your gid readings ever change with temperature, even with no charging or discharging of the battery?

Any gid readings from before 5/31?

To all,

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.

About 18.2k mi total. ~3500 mi driven since May 31.
Measuring Gid changes with temp but without charging is difficult since the LEAF is used every day and the battery seems to have a lot of thermal mass. I'll try to get some measurements the next time the LEAF is sitting for a couple of days.
My Gid readings go all the way back to July 2011. 278 is the highest I've ever read. March 2012 was 272±2, 394 V.

 

[garygid]

I got down to about half way between LBW and VLBW
yesterday afternoon, about 13% GIDs.

Charging overnight at about 68 F by morning, GIDs were
268 (95.3% GIDs) and the "Real SOC" read 93.6%.

Still down from the values of 99% GIDs of last year,
but up form the 88.x% GIDs reported a month
or so ago in the hot weather.

The GID value dropped from 268 to 267 while I
was writing down these values.

But, what does this mean for capacity and available energy?
Still, a bit difficult to determine.

 

[TomT]

Me too. I'm now driving about 3-5 mph slower to maintain the same range...

Driving the same way? I've head to increase my efficiency to maintain the same end point result.

 

[DaveinOlyWA]

I know I drive more efficiently now than the early days. So, it's not a very accurate assessment. I think I used to average about 3.5 on this trip and now I seem to be able to do almost 4 mi/kWh. Also, there's now a DCQC on my way home (downtown L.A.) so, I can use that if it becomes a problem getting home.

Sparky; i am glad you have adjusted well to the limitations of your LEAF in order to better enjoy the overwhelming benefits EV driving has to offer.

can you assess the extra time spent on your commute? i found that the only real hurdle to my driving slower other than my own impressions of "dragging along"was the additional time and it was like 5 minutes. a really inconsequential amount of time. like the commercial (i am also a military brat) if i am not 5 minutes early i am late.

but i talk to people who seem to struggle to accept that. wondering what your experiences have been

 

[sparky]

can you assess the extra time spent on your commute? i found that the only real hurdle to my driving slower other than my own impressions of "dragging along"was the additional time and it was like 5 minutes. a really inconsequential amount of time. like the commercial (i am also a military brat) if i am not 5 minutes early i am late.

but i talk to people who seem to struggle to accept that. wondering what your experiences have been

The LAX trip is infrequent so, I don't notice any time difference since traffic is highly variable from trip to trip. I'm just easier on the throttle and keep it below 65.
My wife commutes in the LEAF less than 30 mi R/T most weekdays. Which is a good thing since she drives it like a slot car; <3.2 mi/kWh.
Of course that short distance is no problem and should allow the LEAF to continue to be our main commuter car for many years.

 

[tbleakne]

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.

I thought we beat this horse already in the test results thread?

Phil has confirmed that battery pack voltage readings are accurate using an external high precision Fluke, so we have no reason to disbelieve those readings. For the cars that were run to turtle, they all stopped with similar voltages - definitely beyond the knee where voltage drops rapidly with little remaining charge. All the cars were charged to 100% which has been shown to vary by perhaps a volt or two at most. The results of the range test strongly correlate with bar/GID loss, though not as much as one might predict by the bar/GID loss. Andy Palmer confirmed that the capacity meter is pessimistic in his interview with Chelsea Sexton.

I don't see any reason to NOT to see Tony's results as valid - LEAFs exposed to Phoenix heat are losing capacity and range far faster than cooler climates.

+1. Voltages don't lie, and the Gid variations are a 2nd-order effect. Same voltages, fewer Coulombs, means less kWh capacity.

My LEAF has seen about 5 days of cooler weather in which it gets back from 6 T-bars all the time to 5 T-bars in the morning. I have regained 2 Gids, less than 1%, from my low of 12% loss at 100% charge.

Perhaps I will regain a couple more Gids after more weeks of low 70s weather, but the predicted return of mid 90's for next few days will see my new garage A/C getting a lot of use.

 

[kmp647]

I run the a/c in the garage for my dogs, doing it for a car is just nuts, but I understand.
Nissan needs TMS in all ev's