User avatar
FalconFour
Posts: 324
Joined: Wed Sep 19, 2012 12:07 pm
Delivery Date: 14 Sep 2012
Leaf Number: 008681
Location: San Jose, CA
Contact: Website Facebook

Re: Capacity vs Health

Mon Aug 19, 2013 9:09 pm

(bah! Top of the page blues. See my last post first: http://www.mynissanleaf.com/viewtopic.p ... 70#p319070" onclick="window.open(this.href);return false;)

Voltages on the battery page also seem to coincide with this health figure - knowing the battery is only "feeling" 70% of its former perkiness, I observe the graph dipping under load pretty clearly. (BTW, a pack voltage readout and histogram, made from a sum of the bar graph values, would be very useful. :) ) The drop in voltage also represents a higher amp load to extract the same number of watts from the pack, versus a healthier battery that has less of a voltage drop at the same load.

That means health also influences drive efficiency (miles/kWh or kWh/KM). When you accelerate, the voltage drops less in a healthy battery. As long as I've got my math straight regarding watts and amps...
100% gas-free since September 2012
2011 LEAF SL - Sep 2012~Sep 2014 - 35,737 miles
2013 LEAF S+Charge - Jan 2014-Feb 2017 - 68,065 miles
2014 LEAF SV+Premium+QC - Feb 2017-present

User avatar
TomT
Posts: 10648
Joined: Sun Aug 08, 2010 12:09 pm
Delivery Date: 01 Mar 2011
Leaf Number: 000360
Location: California, now Georgia
Contact: Website

Re: Capacity vs Health

Tue Aug 20, 2013 7:50 am

Health appears to be - and this is only my opinion - a formula that takes in to account, and is substantially biased toward, internal resistance of the pack...
FalconFour wrote:Voltages on the battery page also seem to coincide with this health figure - knowing the battery is only "feeling" 70% of its former perkiness, I observe the graph dipping under load pretty clearly. (BTW, a pack voltage readout and histogram, made from a sum of the bar graph values, would be very useful. :) ) The drop in voltage also represents a higher amp load to extract the same number of watts from the pack, versus a healthier battery that has less of a voltage drop at the same load.
Leaf SL 2011 to 2016, Volt Premier 2016 to 2019, and now:
2019 Model 3; LR, RWD, FSD, 19" Sport Wheels, silver/black; built 3/17/19, delivered 3/29/19.

GregH
Posts: 860
Joined: Fri Jul 01, 2011 4:16 pm
Delivery Date: 13 Jun 2011
Leaf Number: 26967
Location: Irvine, CA

Re: Capacity vs Health

Tue Aug 20, 2013 8:36 am

We just don't know.. And I guess that was my point in starting this thread. When we figured out how to actively ping the car's lithium battery controller for additional information we found different "groups" of data. Initially we found 5 groups but then Sam found a few more including the 6th which had the cell "shunt" balancing info. Group 2 was clearly the cell voltages and Group 4 was clearly the 4 (or 3 for 2013) battery temperatures. But what were all the numbers in Groups 1, 3, and 5? Jim, Luke and I started poking around to see if we could figure any of it out. Group 1 has almost 40 bytes of data. Using an early version of the ELM app as well as Luke's CANary and some old EDrive DDs loaned to folks in SoCal I looked for differences in the data from a half dozen different cars. We soon discovered the high precision (20 bit) SOC which matched the lower precision number on the regular EV-CAN passive data. Another 20 bit value seemed to be a number ranging from 600000 and 670000 which correlated with max Gids on a full charge and seemed to be a good capacity number given the Leaf's supposed 66Ah battery capacity. This is the Ah Capacity number reported on ELM and LeafDD. Another 16 bit number also seemed to track capacity but was in the (initially observed) range of 7000 to 10200.. Taken as a percentage with two digits of precision I decided to call this "health" for lack of a better term. On the old software and especially for cars with only moderate capacity loss (still 12 bars) it seemed to track the Ah Capacity fairly close. Now that health is reported on LeafDD and the ELM battery app we've been able to track it over a much larger number of cars and seen some strange stuff.. like REALLY low numbers for cars with more capacity loss.. or 105-111% for some 2013 packs with Ah Capacity pegged at 67.3620Ah. What does it all mean? I don't know.

Here's a snapshot of the raw Group 1 data from the 2013 rental I had a few weeks back.. taken from the old 8 line EDrive DD.
Image
The SOC is on the 5th line 0x0B05F1 (722417) and the Ah Capacity is on the 6th (last) line 0x0a4754 (673620) and the Health is earlier on the 5th line 0x2b96 (11158) 111.58%!! This was the new 2013 rental I had with barely 1000 miles on it. Over the course of the 3 weeks I had it the Health dropped to about 108% but Ah Capacity never budged from 67.3620Ah.
My trusty 2012 which just passed 10,000 miles has 60.4897Ah capacity and 90.45% Health (old software).. Back in early April while it was still relatively cool it was at 66.0198Ah and 100.79% Health!
'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

User avatar
ttweed
Posts: 1090
Joined: Tue Sep 07, 2010 8:31 am
Delivery Date: 01 Apr 2011
Leaf Number: 1317
Location: La Jolla, CA
Contact: Website

Re: Capacity vs Health

Tue Aug 20, 2013 12:25 pm

TomT wrote:Health appears to be - and this is only my opinion - a formula that takes in to account, and is substantially biased toward, internal resistance of the pack...
If this is true, why did my health number drop 1% after the 3227 firmware update? Did the internal resistance of the battery increase that much in the one hour it took to update the software? I took readings with the LBA immediately before and immediately after the update. Something else must be involved.

TT
Tom Tweed
La Jolla, CA
Plowshare Media
2011 SLe #1317 del. 4/1/11
1st bar lost at 31,953 miles
2nd bar lost at 38,685 miles
3rd bar lost at 50,711 miles
4th bar lost at 59,758 miles after 64 months
Battery replaced at 61,307 miles.

dm33
Posts: 690
Joined: Sat May 18, 2013 4:43 am
Delivery Date: 31 May 2013
Location: Raleigh, NC

Re: Capacity vs Health

Tue Aug 20, 2013 6:35 pm

ttweed wrote:
TomT wrote:Health appears to be - and this is only my opinion - a formula that takes in to account, and is substantially biased toward, internal resistance of the pack...
If this is true, why did my health number drop 1% after the 3227 firmware update? Did the internal resistance of the battery increase that much in the one hour it took to update the software? I took readings with the LBA immediately before and immediately after the update. Something else must be involved.

TT
Because the formula used to calculate the health value changed with the firmware update.

QueenBee
Posts: 1564
Joined: Sun Aug 08, 2010 5:14 pm
Delivery Date: 20 Jun 2011
Leaf Number: 2062
Location: Bellevue (Seattle), WA

Re: Capacity vs Health

Tue Aug 20, 2013 8:28 pm

ttweed wrote:
TomT wrote:Health appears to be - and this is only my opinion - a formula that takes in to account, and is substantially biased toward, internal resistance of the pack...
If this is true, why did my health number drop 1% after the 3227 firmware update? Did the internal resistance of the battery increase that much in the one hour it took to update the software? I took readings with the LBA immediately before and immediately after the update. Something else must be involved.

TT
In a few weeks disconnect your battery and see if anything changes.

User avatar
DaveEV
Posts: 6245
Joined: Fri Apr 23, 2010 3:51 pm
Location: San Diego

Re: Capacity vs Health

Tue Aug 20, 2013 11:54 pm

ttweed wrote:
TomT wrote:Health appears to be - and this is only my opinion - a formula that takes in to account, and is substantially biased toward, internal resistance of the pack...
If this is true, why did my health number drop 1% after the 3227 firmware update? Did the internal resistance of the battery increase that much in the one hour it took to update the software? I took readings with the LBA immediately before and immediately after the update. Something else must be involved.
I don't think you can read anything into such small changes in the value, you need to look at long-term trends...

User avatar
TomT
Posts: 10648
Joined: Sun Aug 08, 2010 12:09 pm
Delivery Date: 01 Mar 2011
Leaf Number: 000360
Location: California, now Georgia
Contact: Website

Re: Capacity vs Health

Wed Aug 21, 2013 7:57 am

Perhaps the 1% change - which is really not that statistically significant - came about for the same reason that many saw a temporary increase in range and/or GIDs after the reprogram: The BMS was relearning the battery. It may also be that the algorithm was updated...
ttweed wrote:
TomT wrote:Health appears to be - and this is only my opinion - a formula that takes in to account, and is substantially biased toward, internal resistance of the pack...
If this is true, why did my health number drop 1% after the 3227 firmware update? Did the internal resistance of the battery increase that much in the one hour it took to update the software? I took readings with the LBA immediately before and immediately after the update. Something else must be involved.
Leaf SL 2011 to 2016, Volt Premier 2016 to 2019, and now:
2019 Model 3; LR, RWD, FSD, 19" Sport Wheels, silver/black; built 3/17/19, delivered 3/29/19.

User avatar
dgpcolorado
Posts: 3140
Joined: Sat Aug 20, 2011 1:56 pm
Delivery Date: 15 Dec 2011
Location: The Western Slope, Colorado

Re: Capacity vs Health

Wed Aug 21, 2013 9:06 am

dm33 wrote:Because the formula used to calculate the health value changed with the firmware update.
This. Mine is down more than 8% since P3227. I doubt that it is a real change in the battery: the Ah capacity has dropped only a small amount, similar to the decline before the update.
Blue 2012 SV Dec 2011 to Feb 2016
CPO 2014 Tesla S60 Mar 2016
One car, no ICE, at last!
Tesla Referral Code

User avatar
TickTock
Posts: 1701
Joined: Sat Jun 04, 2011 10:30 pm
Delivery Date: 31 May 2011
Leaf Number: 3626
Location: Queen Creek, Arizona
Contact: Website

Re: Capacity vs Health

Wed Aug 21, 2013 9:23 am

It is unfortunate we are calling this "health" at this point. We really don't have a clue what it is and I fear calling it health will cause heart-burn with the folk who are not paying full attention to every post on the forum (like me :-)). All we know is it starts near 100% and reduces with age but at a much faster rate than capacity. Series conductance ratio is a valid theory, but only a theory right now. My leaf is reporting 51.7% for this parameter and I am confident there is nothing I can detect that has degraded 50%. Can I propose until we know more that we call this something else. Perhaps Xfactor, or paramA, or, if we feel we need continuity, maybe "health???" instead.

Return to “LEAF CANBus”