GerryAZ
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Re: Capacity vs Hx (Health)

Sat Oct 15, 2016 9:02 am

FalconFour's observations match my experience over the years. The 2011 lost regeneration and quick charge rate as original battery deteriorated. The LBC (or BMS) limits maximum voltage during charging and regeneration so current allowed (and charging power) goes down as internal resistance increases. I first noticed loss of regeneration when weather cooled in the fall of 2012 after losing 2 bars during the summer of 2012. I eventually noticed that QC charge rate really tapered off above about 60% SOC. Regeneration and QC returned to normal when battery was replaced in fall of 2013 and started to drop when weather cooled in fall 2014 (replacement battery was down to 11 bars by the time of the crash). The 2015 has much lower internal resistance and still has maximum regeneration at high SOC. The SOH percentage seems to follow AHr and GID numbers while Hx deviates from those so I also believe Hx is a representation of internal resistance (or conductance). The 2015 has lower internal resistance (measured by observing pack voltage drop under full acceleration at low SOC) after 20 months and 29,000 miles than the replacement battery in the 2011 when it was nearly new. Therefore the Hx numbers cannot be directly compared between the old battery type and the 'lizard' battery because they both start at about 100% but 100% represents a lower internal resistance on the 2015 than on the 2011.

Gerry
Gerry
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drees
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Re: Capacity vs Hx (Health)

Sat Oct 15, 2016 9:06 am

Nissan uses a standard constant current / constant voltage charging procedure. Once the highest voltage cell gets to 4.1V the charge rate starts slowing down.

I'd love to data log a QC from LBW on a variety of different LEAFs.

I wonder if the severe lack of QC performance is something one can use to get Nissan to replace the pack under the defect warranty...
'11 LEAF SL delivered Jun '11 - 3.24 kW Enphase Solar PV
Apr '17: 60k 40.3Ah 173/142 GID
2 months too late.
9th 8/12/16 43.3Ah 186/152 GID, 10th: 10/23/15 @ 47.4Ah 203/167 GID, 11th: 11/11/14 51.6Ah 220/181 GID, 12th: 9/23/13 55.3Ah 228/194 GID

QueenBee
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Re: Capacity vs Hx (Health)

Sat Oct 15, 2016 11:16 am

FalconFour wrote:OTOH, the SOH figure precisely matched the bars on the dash - he'd just lost his 6th bar (which is what got our attention and came in to get a Leaf Spy report pulled from his car), and it showed 50% SOH, exactly half (6 of 12 bars remain, 6 of 12 bars lost).


That's just happens to be a coincidence. The SOH does NOT precisely match the bars on the dash. First of all the first bar represents 15% and each bar after that 6.25% according to a table in an original Nissan service chart. Then had you looked the day prior to bar dropping it would have showed 7 of 12 bars but still close to 50% SOH. Then lastly there is a delay in when the bar drops. For example 15+6.25*5 is 46.25 loss, so the 6th bar should drop when it gets below 53.75% SOH but as you can see it didn't happen until later at 50%.

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Re: Capacity vs Hx (Health)

Sat Oct 15, 2016 11:19 am

DaveinOlyWA wrote:
cwerdna wrote:^^^
Very interesting, esp. how crappy QCing became for that 6 BL. Those are terrible rates.

Over at viewtopic.php?p=472551#p472551, I pointed to what appears to be a 7 bar loser, assuming his car was fully booted. That poster is confused.


yep but not due to degradation so much as the charging profile Nissan used in earlier models. My 2013 with 43,500 miles with 12 bars charges at 40 amps at 50% SOC.

The other day, I was charging when a 30 kwh 2016 SV pulled up and plugged in. He wasn't that low but was going home to Bellevue and wanted to top off. We talked while the cars were charging and I happened to look over and he was charging at 97 (max is 100 amps on EVGO station) amps at 85%! At the same time, I was charging at 30 amps at 72%....

SUCKS!

Can't wait to dump this LEAF and get a one with a real fast charge option!


That's because it has a larger battery and thus can charge quicker. On top of that while you may have all 12 bars that doesn't mean your HX value hasn't dropped from 100% so you are trying to compare a car with a higher HX value and a bigger battery to support your claim that the charging profile has changed which is clearly absurd.

DaveinOlyWA
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Re: Capacity vs Hx (Health)

Sat Oct 15, 2016 11:40 am

QueenBee wrote:
DaveinOlyWA wrote:
cwerdna wrote:^^^
Very interesting, esp. how crappy QCing became for that 6 BL. Those are terrible rates.

Over at viewtopic.php?p=472551#p472551, I pointed to what appears to be a 7 bar loser, assuming his car was fully booted. That poster is confused.


yep but not due to degradation so much as the charging profile Nissan used in earlier models. My 2013 with 43,500 miles with 12 bars charges at 40 amps at 50% SOC.

The other day, I was charging when a 30 kwh 2016 SV pulled up and plugged in. He wasn't that low but was going home to Bellevue and wanted to top off. We talked while the cars were charging and I happened to look over and he was charging at 97 (max is 100 amps on EVGO station) amps at 85%! At the same time, I was charging at 30 amps at 72%....

SUCKS!

Can't wait to dump this LEAF and get a one with a real fast charge option!


That's because it has a larger battery and thus can charge quicker. On top of that while you may have all 12 bars that doesn't mean your HX value hasn't dropped from 100% so you are trying to compare a car with a higher HX value and a bigger battery to support your claim that the charging profile has changed which is clearly absurd.


not implying the charging profile had changed. it was pathetic from day one!
2011 SL; 44,598 miles. 2013 S; 44,840 miles. 2016 S30; 8341 miles. 363 GIDs, Ahr 82.34, Hx; 100% kwh 28.1
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TimLee
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Re: Capacity vs Hx (Health)

Sat Oct 15, 2016 12:39 pm

QueenBee wrote:...
That's because it has a larger battery and thus can charge quicker. On top of that while you may have all 12 bars that doesn't mean your HX value hasn't dropped from 100% so you are trying to compare a car with a higher HX value and a bigger battery to support your claim that the charging profile has changed which is clearly absurd.

Generally accurate.

I am 72 days experience on a 2011 replacement with the new 'lizard' chemistry battery.

Still at 100% SOH.

But Hx finally dropped slighty below 100% yesterday.

Tim Lee
Chattanooga, TN

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JimSouCal
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Re: Capacity vs Hx (Health)

Sat Oct 15, 2016 5:22 pm

drees wrote:I wonder if the severe lack of QC performance is something one can use to get Nissan to replace the pack under the defect warranty...
Filing that thought away.... By way of thinking... My 2011 pack is aging out, rather than wearing out under usage. I still have 10 bars (showing but LEAF spy points to a bar drop soon enough). In November I will be returning from 6500 feet elevation. In order to make it home, I need to do that will a full charge, and it will be brake pads the whole way down, and regen is nill on my battery with little discharge.

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drees
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Re: Capacity vs Hx (Health)

Sat Oct 15, 2016 6:08 pm

JimSouCal wrote:In order to make it home, I need to do that will a full charge, and it will be brake pads the whole way down, and regen is nill on my battery with little discharge.

Yeah, the speed dependent regen is what really sucks when capacity starts falling - at 20-25 mph you can still get a bit of regen, but at 45mph it's negligible unless the battery is over 90F and the SOC is low.
'11 LEAF SL delivered Jun '11 - 3.24 kW Enphase Solar PV
Apr '17: 60k 40.3Ah 173/142 GID
2 months too late.
9th 8/12/16 43.3Ah 186/152 GID, 10th: 10/23/15 @ 47.4Ah 203/167 GID, 11th: 11/11/14 51.6Ah 220/181 GID, 12th: 9/23/13 55.3Ah 228/194 GID

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FalconFour
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Re: Capacity vs Hx (Health)

Mon Oct 17, 2016 2:02 am

QueenBee wrote:The SOH does NOT precisely match the bars on the dash. First of all the first bar represents 15% and each bar after that 6.25% according to a table in an original Nissan service chart.


The more I research and experience, the less I trust Nissan official information. It stands to reason that there is a gap, or a PR filter, standing between the engineering/programming and the documentation - be it technical or otherwise. For two big examples - the VSP diagram in the 2012+ models shows pin 5 as no function (unpopulated, unlabeled) but it is still labeled and functions as the "VSP Off" button at least up to 2013 (further models still likely function the same). Second, the 12V battery charging behavior is described as "only when vehicle is running, not while charging" but obviously this isn't the case (see my thread today in the troubleshooting forum about 12V behavior).

In this case, it sounds like there's a buffer between SOH% reported on the CAN bus and the bars on the dash. Likely the same kind of buffer that keeps you from easily gaining/losing a charge bar when going over hills and using regen - once it hits "low battery", for example, it holds onto that LBW even if you regen quite a few percent back. Unless of course you power-cycle the car, in which case it'll forget the LBW until it occurs again. My point is, there's probably a buffer such that it only "loses" a bar once it's sure - over a very long time period - that the capacity truly is gone.

None the less, the capacity bars are still influenced by SOH%. I do think, however, that SOH% is merely deduced from battery AHr versus a new pack (calculated by Leaf Spy), thus there is some room for discrepancy there. Maybe there's another value floating around that directly drives the capacity bars, that we haven't found yet...
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Re: Capacity vs Hx (Health)

Mon Dec 19, 2016 7:54 am

TimLee wrote:
QueenBee wrote:...
That's because it has a larger battery and thus can charge quicker. On top of that while you may have all 12 bars that doesn't mean your HX value hasn't dropped from 100% so you are trying to compare a car with a higher HX value and a bigger battery to support your claim that the charging profile has changed which is clearly absurd.

Generally accurate.

I am 72 days experience on a 2011 replacement with the new 'lizard' chemistry battery.

Still at 100% SOH.

But Hx finally dropped slightly below 100% yesterday.


I've seen Hx on my new battery vary quite a bit both above and below 100%.

The correlating factor seems to be battery temperature. Logically one would expect a colder battery to have higher resistance. That seems to be true enough judging by the recent temperature swings and by the Hx value.

All of this to say that you may see Hx go up again, maybe back to 100% or more in the spring once battery temps revive. Of course once we go through a the 2017 summer we can expect to kiss 100% Hx goodbye forever :-(
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