SOC data: 281-based, New-Bars

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tbleakne said:
You might want to see how much variation you get on several different nights charging to 80%. At this level there should be no need to shutoff because one cell-pair is slightly ahead of the others.
For sure a 100% charge must stop when one cell-pair hits max voltage.

But for an 80% charge there's a number of ways it might be done:

1. Waits for lowest cell-pair to hit 80%.
2. Waits for highest cell-pair to hit 80%.
3. Some variation of the above - charge until either the lowest cell-pair hits 80% or the highest cell-pair hits 85%.

Wish we knew for sure!
 
garygid said:
ALERT:
Boomer's SOC Meter lash-up apparently uses 279 (instead of 281) as 100% SOC.

So, his % readings are about 1% high, but his Raw-SOC are correct, I think.

By the next Gathering, I hope to have at least one of the next-version SOC-Meter models.

Really? I saw 281 and 100% on Wednesday AM and 280 and 100% this morning.
 
tbleakne said:
Boomer23 said:
I'm seeing a full 281 and 100% SOC this morning, after a full charge last night.

So what happened yesterday? The dash showed 12 bars but the SOC meter showed only 95%.
It is hard to keep up with you guys, but I am going to jump in here. My first thought: is it possible the temperature during charge was different for the two nights ?
abasile said:
In colder weather, I have noticed that the charge time estimates are way too high, as the battery appears to be at a lower SOC than it actually is. After charging for a while, the car seems to figure out the actual SOC even though the indicated battery temperature remains low.
600+ pounds of battery represents a lot of heat capacity, so the history of battery usage in the hours before and during charge might be relevant. Even if you don't recall much temperature difference (less than abasile experiences in the mountains), the temperature dependence might well be more sensitive near the top of SOC (i.e 12th bar). The 100% charge cutoff seems likely to be determined by the first cell pair to reach a cutoff voltage. If so, very slight variations would be magnified.

You might want to see how much variation you get on several different nights charging to 80%. At this level there should be no need to shutoff because one cell-pair is slightly ahead of the others.

I'd wager that ambient temps during charging weren't significantly different for the two nights. The car was in the same garage, same doors closed, dates just two days apart.
 
Hopefully we will have people from some other places do this testing. We should see significant difference in temperature.

Why don't one of you send me the cable & a programmer. I'll paypal the money. I already have the avr-can and the led display.
 
Boomer23 said:
Yes, starting charge for night 1 (the 95% full charge night) was 25%, 1 bar.

You had a starting SOC of 25% with ONE bar? Mine is always around 8% with one bar according to CarWings. So the actual is that much different?
 
just jumping in here. what we know is that we dont have access to 100% of the pack.

full charge is not full, its probably closer to 97-98% i am guessing

zero power circles in turtle mode is not dead. probably more like 7%.

so we have access to 90% of the total of 24 kwh or about 21.6 kwh which i have verified thru extrapolation several times.


so a "full" charge is not always going to be the same which btw is true for gasoline as well. u know the rumors, get gas in the morning because the liquid is more dense, etc...(not true btw. most tanks are kept at standard 58º which is pretty much ambient temp of the Earth no matter what time of day it is)

so a bit of variance i would consider the norm
 
LEAFfan said:
You had a starting SOC of 25% with ONE bar? Mine is always around 8% with one bar according to CarWings. So the actual is that much different?
Silly boy! Carwings doesn't tell you state of charge; it only tells you how many bars you have. One bar out of twelve = 1/12 = 0.08333 = 8%. You will always see 8% if you have one bar, whether you just dropped from two or are about to drop to zero.

Ray
 
Also, the percentages in Carwings are for Old-Bars, and it assumes
that any Bar it shows is "full", which is not usually true.

Since most LEAFs have New-Bars, the zero-Bar condition no longer means that you are down to about 1%, almost to Turtle Mode.

The SOC-Meter helps us explore and understand the "hidden reserve", that is apparently not always dependably available ... innmy opinion, that's probably why the low end was hidden.
 
tbleakne said:
Andrew, months ago I found info (supported by comments in the Leaf Owner's manual) that indicated that the battery's capacity was temporarily lower at low temperatures, so that the same number of coulombs appeared to be a higher % SOC. Is this consistent or not with your direct evidence ? How low are the temperatures you are talking about ? Is it possible that under charge the battery warms up enough to return to a reasonably accurate SOC ?
It's hard to say whether that's consistent with my direct evidence. At lower temperatures (we had some nights in the 20s and 30s in May), the actual time to charge was substantially less than the time estimated by the car. (I didn't write down any figures, though.) On the other hand, on some occasions, the car gained an SOC bar as the day warmed, without any intervening driving or charging. That seems to suggest that the SOC is under-reported in low temperatures.

Given that the battery temperature did not seem to change in response to charging, at least as far as we could tell from the coarse-grained temperature gauge, it's hard to tell if the car had any better idea of its SOC after vs. before charging.
 
Boomer23 said:
New report on a freeway drive today, total distance 58.9 miles, ran the "tank" down to 2 bars. I ran at normal freeway speeds, sometimes up to 74 mph, got on and off the freeway for safe data recording at times, up and down some hills, A/C on the whole time, ambient temps around 74 F. I took SOC readings immediately as the bars dropped to the indicated bar level.

Main dash energy economy for this trip = 3.5 mi/kWh

Odo miles...Bars...SOC%...SOC #...Guessometer miles
....0...........12.....100%.....280........102
...3.3..........11.....92%......257........92
...9.3..........10.....84%......237........68
...14.4..........9.....78%......220........67
...23.0..........8.....71%......199........68
...27.2..........7.....64%......180........50
...31.7..........6.....57%......162........47
...39.0..........5.....51%......141........43
...43.0..........4.....44%......123........30
...49.1..........3.....36%......103........23
...57.3..........2.....29%.......83.........19
Car Parked, trip end
...58.9..........2.....26%.......74..........15

Edit: After several hours of sitting,

...58.9...........1....25%.......70..........14

I made another run today using the same hardware and software. This run was all fairly flat freeway, speeds in high 60s from Rt 405 in Irvine up to Rt 605 to Cerritos HTB. The return trip was partially on city streets at slower speeds, with the majority of the return trip on the same flat freeways. The day ended with some family errands.

The take-home message is that the results of the SOC% and SOC# at the point of each bar drop are almost identical to the first run that I did. The terrain and speeds were different, but the bars vs. SOC were the same. This is as we would expect, I think.

Some detail: I chose not to record Guessometer readings. They aren't much use, and I wanted to reduce the amount of data that I was recording while I drove. Secondly, after my arrival at my first destination, I got out of the car and turned it off, disconnecting the SOC gauge for a 3 hour breakfast meet up. When I started the car again, the indicated 7 bars had dropped to 6 remaining. (This has happened to me before, losing a bar just by stopping and starting the car. Gary has a theory that it has something to do with the way the bars display works, hysteresis, something.) Then I made a 9.3 mile trip at low speeds, without losing a bar. I parked the car again and when I turned it back on, it had lost one more bar, now down to 6 bars. So the SOC readings that I took were upon re-starting the car, but not upon losing a bar during continuous driving.

Also, I missed recording the drop from 5 to 4 bars. What, do you think this stuff is easy, while driving down the freeway??? :lol:

And the remaining readings were taken after numerous starts and stops on family errands. So these were also less precise readings.

All of that said, though, the readings match up darn well with the previous run.

Average mi/kWh efficiency from main dash: 4.0 mi/kWh for this run

Odo miles...Bars...SOC%...SOC#
..0.............12.....99........279
..4.4...........11.....92........257
..9.2...........10.....84........236
..13.9...........9.....78........219
..20.8...........8.....71........199
..25.8...........7.....66........186
..35.1...........6.....58........163
..40.8...........5.....51........143
..Data Missed..4....................
..51.8............3.....36........102
..56.6............2.....31.........88
..61.8............1.....26.........73
 
The top Bar certainly has less usable capacity, even though the New-Bars have about 7% each of our "SOC".

I suspect that the SOC is based upon an estimate of no-current battery pack voltage. This voltage will fall more quickly near the top end, and near the bottom end. So, the top Bar and the bottom Bars (hidden New-Bars) will tend to "contain" less usable energy.

Still, different measurements (the individual cell-pair voltages) are probably used to actually Stop Charging at the top end (the highest cell-pair voltage) and Stop Driving (and Turtle Mode?) at the low end (the lowest cell-pair voltage).

A lower "fully-charged" SOC probably indicates a greater mismatch in cell equalization, which also tends to cause "premature" Stop-Driving, at an unexpectedly-high SOC.
 
Boomer23 said:
Average mi/kWh efficiency from main dash: 4.0 mi/kWh for this run

Odo miles...Bars...SOC%...SOC#
..0.............12.....99........279
..4.4...........11.....92........257
..9.2...........10.....84........236
..13.9...........9.....78........219
..20.8...........8.....71........199
..25.8...........7.....66........186
..35.1...........6.....58........163
..40.8...........5.....51........143
..Data Missed..4....................
..51.8............3.....36........102
..56.6............2.....31.........88
..61.8............1.....26.........73

Hmmm.

This looks a lot more consistent than the last one. The top bar isn't much different from the rest, even though it is the least efficient. But that can easily be explained by initial AC draw etc.

BTW, kwh/soc-unit = 0.075 this time compared to 0.082 last time. That doesn't sound too consistent ... unlike the SOC units that are no more than 1 unit away from the last time, except for 2 & 7.

LeafSOC-u2.png


Old one for comparison ...

LeafSOC-u.png
 
Based on the above here is my estimate of the SOC bars with the upgraded firmware ...

LeafSOC2.png


This is consistent with our experience that after we hit 0 bars, we can still drive around for 15 to 20 miles (so a 3 kwh usable charge left in the battery looks reasonable).
 
evnow said:
This is consistent with our experience that after we hit 0 bars, we can still drive around for 15 to 20 miles (so a 3 kwh usable charge left in the battery looks reasonable).

But Tony's chart shows 10-11 miles left at zero bars, and that's at 38mph. With one bar (and low battery warning) it was 22 miles at 38mph. So we need to change the chart now?
 
LEAFfan said:
But Tony's chart shows 10-11 miles left at zero bars, and that's at 38mph. With one bar (and low battery warning) it was 22 miles at 38mph. So we need to change the chart now?
Tony's bar says you get 16 miles after battery low. I got battery low & zero bars before and after an off-on event.

I think battery low is a better indicator of charge remaining at low charge than # of bars (i.e. 0 or 1). In the SOC chart above 1% and below are my extrapolations. boomer reported till 2 bars.
 
Wow! Nice work guys!
This is my first post here... I've ordered a laptop based CAN analyzer but it hasn't arrived yet so I modified one of my old dashboard displays from the defunct EDrive PHEV Prius project (128x64 OLED) so I could sneak a peak at 0x5BC on the EV-CAN bus. Very cool.. My Leaf (555 miles on the odo, 3wks old) only goes up to 278 but I suspect that has more to do with the fact that I've only been to "full" about 3 or 4 times so far and less to do with my miles.. I'm guessing most balancing that needs to be done (if any) is done at or near 100% SOC.. So perhaps a few more 100% charge cycles will bump me up to 281... Anyway, looking forward to jumping into the discussion!
-Greg Hanssen, Irvine
 
evnow said:
LEAFfan said:
But Tony's chart shows 10-11 miles left at zero bars, and that's at 38mph. With one bar (and low battery warning) it was 22 miles at 38mph. So we need to change the chart now?
Tony's bar says you get 16 miles after battery low. I got battery low & zero bars before and after an off-on event.

No, that's 'Mixed City'. 38mph is 22 miles on Tony's chart.
 
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