LEAF CANbus decoding. (Open discussion)

[TickTock]

I am fairly certain that 55b is the actual SOC in D1&D2:

55b1[7:0]<<2+D2[7:6]>>6 = SOC % X 10.

I get exactly 80.0 on an 80% charge and 95.1-95.6 on a 100% charge. This suggests that this is actually what is used to dtermine the stop point on an 80% charge. I was wondering if anyone who hasn't seen the southwest loss impact could take a look. I'm curious if it shows > 95% for a new battery or if 95% is the target. Since 80% scales with the battery capacity degradation I would expect the 95% too as well but maybe less precisely since they use pack volts to stop instead of SOC.

OK, I'll play. My LEAF is not so young ~ 18kmi and 20 mos old. Still have 12 bars. I'm in Southern Cal foothills.
I checked the CAN bus data (55B) with your scale factor for "SOC" above when it had 9 bars; then charged to 80% then charged to 100%

Began at 9 bars; "Gids" = 189; "SOC" = 72.1%
Charged to "80%"; 10 bars; "Gids" = 219; "SOC" = 80.0%
Charged to "100%"; 12 bars; "Gids" = 252; "SOC" = 94.2%

Sorry, guess I can't tell you if > 95% is likely with newer pack. But, results seem reasonable to me.
I'll be interested in trying this when the weather cools down.

Thanks. This corroborates with my data supporting that this is, in fact, SOC and independent to present battery condition (my gid counts are much lower for the same SOC).

 

[TickTock]

I only remember the percent. I will charge to 100% tonight and post the gid reading.

Thanks, I really just wanted to confirm that these *were not* the readings you get from the 55b message. I'm predicting *everyone* will read 80.0% for a successful 80% charge for that message.

 

[TickTock]

I was looking at this on some old logs and found one old log from 2/25/2012 labeled "balanced" that reached 98% for a 100% charge. My more recent capture of a charge with a "balance" only reached 95.8. Keep in mind I am only assuming a balance took place because the EVSE turned on a second time automatically later in the night - not sure that balancing is the only thing that can cause this (or even *if* balancing causes this behavior really - just speculation).

 

[lincomatic]

TickTock,
I think you're really onto something, great work!

Last night, for 80% charge, I got 205 gids / 79.9 "SOC"
I'm guessing "SOC" dropped .1 overnight... I charge at midnight, and I checked it a 7am.

Last year, my car was charging to 221 gids for an 80% charge.
So your "SOC" number isn't directly tied to gids
I noticed that when I when I went out for a short drive this morning,
the "SOC" has a bit higher resolution than gids, dropping ~.2-.3 per gid.
When I did a short regen going towards a traffic light, "SOC" increased by .1
while the gids were unchanged.

I will test tonight with 100% charge.

 

[lincomatic]

Just looked at Gary's old 100% charge log, ChgLoBatt.evc, and it has
"SOC" = 95.1, 273 gids, which correlates well with your data.
I guess 100% charge really means ~95%?

 

[sparky]

This all seems consistent with Ingineer's assessment from awhile ago.
Nice find TickTock.

http://www.mynissanleaf.com/viewtopic.php?f=30&t=8802&p=204880&hilit=SOC#p204880

For an 80% charge the Leaf always stops when SoC=80%, but keep in mind this is dependent on the accuracy of the battery ECU's calculation during charging, so there could be some error from charge to charge and/or Leaf to Leaf. (I would imagine temperature as well)

However a "full" charge seems to be usually somewhere from 94-95%, with the Gids varying appropriately. I don't often do many full charges, but I'll begin paying closer attention to my numbers.

Something also to note is that Gids seem to have significant hysteresis. Sometimes they won't "tick" when it seems when they should. I have observed sometimes they won't drop during use for some time even after a few gid's worth of SoC has clearly been consumed, then all the sudden they will play catch up. It is unknown why this is.

SoC always seems to keep up, even when the Gids don't, so I don't trust Gids as much. But conversely, when SoC is corrected, such as on power up, sometimes the Gids will stay the same.

Many mysteries!

-Phil

 

[chris1howell]

I just loaded test code from lincomatic, a full charge my new SOC displays 95.1% at 223 gid (~80% based 223g/281).

I am driving from Lancaster to Santa Monica (80 miles and back today). I should get a good idea how this new value behaves...

 

[lincomatic]

I just loaded test code from lincomatic, a full charge my new SOC displays 95.1% at 223 gid (~80% based 223g/281).

I am driving from Lancaster to Santa Monica (80 miles and back today). I should get a good idea how this new value behaves...

Ouch. My car was getting 221 gids @ 80% when it was new.
How can you make it all the way to Santa Monica on a charge?

 

[garygid]

I will try to add this "Real SOC" value to the GID-Meter as Mode 3,
showing "SOC " and the 0x55B value (as " 92.3"), in an F1.09 version
of the firmware.

Soon I expect to have an F1.10 version that will do a better job of
Logging ALL of the CAN messages, instead of just "most" of them.

Most of the messages that we are using are repeated multiple or
many times per second, so missing a few too closely-spaced
messages is not a problem for most applications.

Cheers, Gary

 

[chris1howell]

I just loaded test code from lincomatic, a full charge my new SOC displays 95.1% at 223 gid (~80% based 223g/281).

I am driving from Lancaster to Santa Monica (80 miles and back today). I should get a good idea how this new value behaves...

Ouch. My car was getting 221 gids @ 80% when it was new.
How can you make it all the way to Santa Monica on a charge?

I made it with 3 bars to spare... Only beacuse it is down hill. Starting elevation 2500 ending 0, well maybe 10 (I did charge on the pier). On the way home I need a couple hours charge in valencia.

 

[garygid]

Please reserve this thread to discuss the decoding of CAN bus data.

There are other threads that discuss Range, use of GIDs, etc.

Thanks, Gary

 

[chris1howell]

Please reserve this thread to discuss the decoding of CAN bus data.

There are other threads that discuss Range, use of GIDs, etc.

Thanks, Gary

Not you too, Gary... The forum police take away all the fun... Maybe I start a new thread, but I am sure there is already another similar one out there...

 

[garygid]

Thanks for your understanding.

 

[chris1howell]

I just loaded test code from lincomatic, a full charge my new SOC displays 95.1% at 223 gid (~80% based 223g/281).

I am driving from Lancaster to Santa Monica (80 miles and back today). I should get a good idea how% this new value behaves...

Yesterday, I was able to watch the 55b value over a almost full cycle and two partial cycles. It appears to be a bit optimistic on the low end. At 2 bars it still shows 30%. I did not take it down to LBW or VLBW. I am guessing a charge full does not equal %100 so turtle may not equal 0%.

55b behaves much better than gids. During regen the value smoothly increases. .1% at a time. It takes a very long time to add a gid during regen. I really think 55b is a great find, we just need to verify the low end...

 

[TonyWilliams]

2 bars it still shows 30%. I did not take it down to LBW or VLBW. I am guessing a charge full does not equal %100 so turtle may not equal 0%.

55b behaves much better than gids. During regen the value smoothly increases. .1% at a time. It takes a very long time to add a gid during regen. I really think 55b is a great find, we just need to verify the low end...

The low end will be 2-3%, just as the top end was 95%. With SOC, you're measuring the % of the 24kWh battery. Only 22.48kWh is store for use, with no energy at the top 5%, and 2-3% left at the bottom what the contacts open to disconnect the battery from further discharge.

So, 300 Gid equals 24kWh, but 0 Gid equals about 0.5kWh left in the bottom. We, of course, only use 4.1 volts per cell, so unless you want to jack up your cells to 4.2 or 4.3, you won't see more than 281 Gid.

LEAF battery capacities

New 70F/20C fully charged battery:


-------------------KWH-------Gid------SOC%
Rated capacity: --24 ------- 300 ---- 100
Stored energy: --22.5 ----- 281 ----- 95
Usable energy: --21.0 ----- 281 ----- 95
Depleted cutoff: --0.5 ------ 5 -------- 2


Battery at 70F/20C fully charged, 50% depleted battery:


-------------------KWH-------Gid------SOC%
Rated capacity: --24 ------- 300 ---- (not possible)
Max possible. : -- 12 ------ 150 ----- 100%
Stored energy: --11.2 ----- 140 ----- 95
Usable energy: --10.5 ----- 140 ----- 95
Depleted cutoff: --0.5 ------ 5 -------- 2

 

[garygid]

When the Pack is at half capacity, the SOC is still
likely to show 95% to 5% or some such, much like
the Fuel-Bars, which only show how full the "tank" is.
So, a "full" (roughly 95% True SOC) tank will show 12 fuel
bars even when the tank is down to 50% capacity.
Thus, neither the True SOC nor the "Fuel" Bars are very
useful unless one also has pack capacity inforation.

GIDs, on the other hand, should show rougly 50%,
indicating something closer to the percentage of "new"
e-fuel that is currently in the battery.
Thus, generally GIDs are a much more useful indicator.

 

[palmermd]

I just loaded test code from lincomatic, a full charge my new SOC displays 95.1% at 223 gid (~80% based 223g/281).

I am driving from Lancaster to Santa Monica (80 miles and back today). I should get a good idea how% this new value behaves...

Yesterday, I was able to watch the 55b value over a almost full cycle and two partial cycles. It appears to be a bit optimistic on the low end. At 2 bars it still shows 30%. I did not take it down to LBW or VLBW. I am guessing a charge full does not equal %100 so turtle may not equal 0%.

55b behaves much better than gids. During regen the value smoothly increases. .1% at a time. It takes a very long time to add a gid during regen. I really think 55b is a great find, we just need to verify the low end...

That makes sense. If you have been following along with the other thread regarding the range test in Arizona. According to Nissan's tech bulletin ntb11-076a there is 21% capacity remaining when you start the last bar. If you look at Tony's range chart you can also see that his empirical data matches. No official document from Nissan, but according to the data from the AZ folks, the LBW remains at the same place even as capacity drops, so as you lose capacity essentially more and more range is "buried" in the last bar and below. Tony has put this in his second range chart for folks who have lost a bar.

 

[lincomatic]

According to Nissan's tech bulletin ntb11-076a there is 21% capacity remaining when you start the last bar. If you look at Tony's range chart you can also see that his empirical data matches. No official document from Nissan, but according to the data from the AZ folks, the LBW remains at the same place even as capacity drops, so as you lose capacity essentially more and more range is "buried" in the last bar and below. Tony has put this in his second range chart for folks who have lost a bar.

That's interesting. But I just looked at NTB11-076A, and can find no reference to 21% capacity and the start of the last bar. The only thing I see is a chart of estimated range to 1 segment and no bars, based on average energy economy. Could you point me to the relevant text?

 

[palmermd]

According to Nissan's tech bulletin ntb11-076a there is 21% capacity remaining when you start the last bar. If you look at Tony's range chart you can also see that his empirical data matches. No official document from Nissan, but according to the data from the AZ folks, the LBW remains at the same place even as capacity drops, so as you lose capacity essentially more and more range is "buried" in the last bar and below. Tony has put this in his second range chart for folks who have lost a bar.

That's interesting. But I just looked at NTB11-076A, and can find no reference to 21% capacity and the start of the last bar. The only thing I see is a chart of estimated range to 1 segment and no bars, based on average energy economy. Could you point me to the relevant text?

the table on page 2 that shows ranges. range to 1 bar is 79% in all cases and 21% remaining to turtle.

 

[lincomatic]

Average
Energy
Economy
Estimated Range
to 1 segment
remaining
(miles)*
Am I looking at the wrong document? This is the only table I see on page 2:

Average Estimated Estimated
Energy Range Range to no
Economy to 1 segment remaining remaining
power *(miles) (miles)
2.5 38 - 42 47 - 52
3.0 45 - 51 57 - 63
3.5 52 - 60 66 - 73
4.0 60 - 68 76 - 84
4.5 67 - 76 85 - 94
5.0 75 - 85 95 - 105
5.5 82 - 94 104 - 115
6.0 90 - 102 114 - 126

* From fully charged (100% setting) to one remaining segment