## Active EV-CAN sampling: cell voltages, pack temperatures...

TonyWilliams
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### Re: Active EV-CAN sampling: cell voltages, pack temperatures

GregH wrote:When I was looking at vehicles on the dealer lot I was trying to figure out an equation that could give a consistent battery health number.. Ideally something on the order of Gids/SOC...
I know I've brought this up before, but I don't remember why you didn't like a simple comparison of SOC% (adjusted to 2013 LEAF readout, where 95.4% SOC = 100%) and Gid2%?

When new, the two equal 100% at full charge, and as the battery degrades, the delta between the two will suggest the % degradation (but not temperature related losses).

TonyWilliams wrote:
vegastar wrote:I am used to the gids percentage, but I think that it would be good to have usable kW.h before turtle, like (gids - 7) x 0.08.
100 ((281 -7) / (281 - 7)) = 100% * 21 = 21kWh

100 ((144 -7) / (281 - 7)) = 50% * 21 = 10.5kWh

100 ((7 -7) / (281 - 7)) = 0% * 21 = 0kWh

The new 2013 will show 100% regardless of capacity, when fully charged, and show the following:

kWh----------Gid----Gid%---Gid2%---2013 dash % (2013 dash % data based on SOC %, not Gids)
21.0--Full----281---100%---100%----100% (non-degraded at 70F; 21kWh usable)
10.5--Half----144--51.2%----50%----50% (non-degraded at 70F; 10.5kWh usable)
10.5--Full***--144--51.2%----50%----100% (***used 50% degraded at 70F; 10.5kWh usable)
3.2---LBW----49---17.4%---15.3%----15%
1.3---VLB----24----8.6%-----6.2%----5%
0.0---Turtle --7-----2.5%-----0%-----0%

NOTE: LBW and VLB are indexed to Gids, therefore those values won't match the SOC derived data of the 2013 dash % with a degraded battery.

Turtle is not indexed to Gids, therefore under a high load, like freeway speed, expect turtle at 7 or 8 Gids, and at extremely low power, as low as 4 Gids to Turtle.

garygid
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### Re: Active EV-CAN sampling: cell voltages, pack temperatures

GregH,
Notice that 281 / 300 = 93.67%

(not a response to Tony's post just above)
Last edited by garygid on Sun Feb 24, 2013 12:31 am, edited 1 time in total.
See SOC/GID-Meter and CAN-Do Info
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TonyWilliams
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### Re: Active EV-CAN sampling: cell voltages, pack temperatures

garygid wrote:Notice that 281 / 300 = 93.67%
I don't expect the two to magically be identical since they are measuring by two different methods, which is why I want them equalized to 100% at the highest Gid2% and highest SOC%, and to use 7 Gid on the bottom as zero, which should closely match the 2013 LEAF "0%".

If 281 is 95.4% SOC, then I want that at 100% (just like the 2013 LEAF already has available to the driver).

GregH
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### Re: Active EV-CAN sampling: cell voltages, pack temperatures

TonyWilliams wrote:
GregH wrote:When I was looking at vehicles on the dealer lot I was trying to figure out an equation that could give a consistent battery health number.. Ideally something on the order of Gids/SOC...
I know I've brought this up before, but I don't remember why you didn't like a simple comparison of SOC% (adjusted to 2013 LEAF readout, where 95.4% SOC = 100%) and Gid2%?

When new, the two equal 100% at full charge, and as the battery degrades, the delta between the two will suggest the % degradation (but not temperature related losses).
I'm not considering the 2013 SOC% display.. I don't have a 2013. Soon enough we'll know the conversion between CAN SOC% and the 2013 display for those who care..

Also I don't use GID% as I always found it confusing, especially now that we have actual SOC% in the CAN data. I have no problem thinking of raw Gids.
It's not important to me that I see "100%" at a full charge especially now that we know that the car doesn't always charge to the same final estimate of remaining energy.
281 Gids is NOT 95.4%. It was in my car that one time but the fact that on that charge, "full" was 281 and 95.4% does not mean they are related. I wouldn't be surprised if some people can get 281 Gids at 96% or for that matter at 94%.. Some people on this list have reported seeing 282 or 283 Gids as well which is not surprising (and all the more reason not to divide by 2.81).
TickTock has seen the CAN SOC% as high as 98.6% !! (@265Gids) But I'd bet he hasn't seen 281 Gids.. actually he has a most excellent public spreadsheet showing all his data..

I realize many on this list using Gary's meter are accustomed to seeing Gids/2.81, but for me it's just confusing. As I noted, you could use the same equation using Gid%, it would just be off by a factor of 2.81..

The problem with a straight comparison (or normalizing at the top to 100%) is that it may not be consistent at lower SOCs.. I want something that will return the same basic number regardless of what SOC the vehicle happens to be at when measured. When I watched a friend's Leaf charge and noted the SOC% and Gid#, simply dividing them didn't give consistent results over all SOCs.. yet Gid/(SOC-3) came a lot closer (still some error as the Gids are roughly 1/3 the precision of the SOC%)
I imagine (Gid-7)/SOC could work similarly well but I haven't tested it... but here goes:

From my personal log on the new car 2/5/13 Tuesday
............................GID/(SOC-3).......(GID-7)/SOC
0mi. 278Gid 94.5%........3.04.........2.87
34.3mi 160Gid 56.4%....3.00.........2.71
43.3mi 130Gid 45.9%....3.03.........2.68
78.4mi 49Gid 19.1%......3.04.........2.20
82.7mi 33Gid 12.8%......3.37.........2.03

Guess not..

2/10/12 258Gids, 96.0%.. so "health Gid/(SOC-3) = 2.77
2/25/12 265Gids, 98.6%.... 2.77
3/27/12 246Gids, 94.7%.... 2.68
fast forward..
8/11/12 232Gids, 95.8%... 2.50
9/16/12 213Gids, 95.3...2.31 (Lost 12th capacity bar)
9/24/12 215Gids, 96.4%... 2.30
11/20/12 219Gids, 95.7%... 2.36
1/3/13 217Gids, 94.7%... 2.36
2/21/13 219Gids, 95.0%... 2.38
garygid wrote:Notice that 281 / 300 = 93.67%
????
Last edited by GregH on Sun Feb 24, 2013 1:47 pm, edited 2 times in total.
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GregH
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### Re: Active EV-CAN sampling: cell voltages, pack temperatures

<deleted> Moved to edit in initial post.
Last edited by GregH on Tue Feb 26, 2013 10:45 am, edited 1 time in total.
'17 blue Volt Premier w/ACC
'12 SL black Leaf
'11 SL blue Leaf
RAV4-EV 2002-2005
Gen1 & Gen2 EV1 1997-2003
PV 2.4Kw, 10kWh lithium battery SCE TOU-DA

garygid
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### Re: Active EV-CAN sampling: cell voltages, pack temperatures

One long set of data from the BMS should be the estimated
cell (pair) resistances, derived from noting how much the
cell-pair's voltage sags when current is being withdrawn.

There might be another set of data indicating charging
resistances, derived from how much the voltage rises
when charging.

Perhaps use F (x 10, so in tenths) = (C x 18) + 320
to display the battery temperatures?
See SOC/GID-Meter and CAN-Do Info
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2011 LEAF, sold in 2015
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GregH
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### Re: Active EV-CAN sampling: cell voltages, pack temperatures

garygid wrote:One long set of data from the BMS should be the estimated
cell (pair) resistances, derived from noting how much the
cell-pair's voltage sags when current is being withdrawn.

There might be another set of data indicating charging
resistances, derived from how much the voltage rises
when charging.
Yes!
There are some odd sets of 10 x 16bit data in group 5.. no clue yet.
Also I'm guessing we might find some sort of counters in there for charge events so that the Nissan battery report can tell how often you've been plugging in at high states of charge or how often you've used QCs..
garygid wrote:Perhaps use F (x 10, so in tenths) = (C x 18) + 320
to display the battery temperatures?
It is increasingly looking like Nissan is NOT using a look up table for the non-linear NTC values but rather a set of linear approximations.. (edit-maybe)
So yes in the range of 18-24 degrees it looks like 10 steps per degree C.. but in looks like in the 12-17 degree range it's closer to 10.5 steps. I'm still filling in my temperature data table.. so far I have the following for temp transitions..

13 degrees starts at 589
14 degrees starts at 579
15 degrees starts at 569
16 degrees starts at 558
17 degrees starts at 548
18 degrees starts at 537
19 degrees starts at 527
20 degrees starts at 517
21 degrees starts at 507
22 degrees starts at 497
23 degrees starts at 487
24 degrees starts at 477
25 degrees starts at 467
26 degrees starts at 457
27 degrees starts at 447
28 degrees starts at 438
29 degrees starts at 428
30 degrees starts at 419
31 degrees starts at 410

<edit> If anyone has data below 13 or over 30, please share!
(btw as soon as the highest temp clicked over from 468 to 467, the 6th temp bar on the dash lit up. After resting it has gone down to 468 (24.9deg) and the 6th bar went away..)
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JeremyW
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### Re: Active EV-CAN sampling: cell voltages, pack temperatures

Does the Nissan Consult have the ability to turn on the pack heater? Even though we are heading into spring, this is something I'd like to play around with next winter. I know the heaters are pretty abysmal but it's better than nothing!
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Now driving Spark EV and Model 3.

garygid
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### Re: Active EV-CAN sampling: cell voltages, pack temperatures

GregH,
So, it looks like the raw temp data will indicate
a precision of very near a tenth of a degree C,
even if we do not know much yet about the accuracy.

Akso, it seems that tell Pack temperature Bar display
operates on the highest temperature, and there is
essentially no hysteresis.

So, using the raw values, we might try to display the
extended-precision temperatures, like "C20. 3".

In the CANary, scrolling plots of the 4 high-precision
temperatures on one graph would be very interesting.
See SOC/GID-Meter and CAN-Do Info
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2011 LEAF, sold in 2015
2018 Tesla Model 3
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PU: SDG&E
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GregH
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### Re: Active EV-CAN sampling: cell voltages, pack temperatures

JeremyW wrote:Does the Nissan Consult have the ability to turn on the pack heater? Even though we are heading into spring, this is something I'd like to play around with next winter. I know the heaters are pretty abysmal but it's better than nothing!
Hmmm.. good question. I bet there is a way, although we'd have to watch a Consult transaction very carefully to figure out how it's done! Those of us in the warmer climates are doing all we can to keep our packs from getting warm..
'17 blue Volt Premier w/ACC
'12 SL black Leaf
'11 SL blue Leaf
RAV4-EV 2002-2005
Gen1 & Gen2 EV1 1997-2003
PV 2.4Kw, 10kWh lithium battery SCE TOU-DA