Page 14 of 16

Re: Capacity vs Hx (Health)

Posted: Wed Dec 21, 2016 9:56 am
by DaveinOlyWA
JPWhite wrote:
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 :-(
not true... in theory. Li has a sweet spot for temperature just like we do. IOW; there is too hot and there is too cold. You can maintain high Hx with battery temperature management. now how to do this is the real question. If faced with fun Sun parking in the front row or back row parking with shade? well, that is up to you...

Re: Capacity vs Hx (Health)

Posted: Wed Dec 21, 2016 2:50 pm
by ZOMGVTEK
.

Re: Capacity vs Hx (Health)

Posted: Wed Dec 21, 2016 4:16 pm
by JPWhite
DaveinOlyWA wrote: You can maintain high Hx with battery temperature management. now how to do this is the real question. If faced with fun Sun parking in the front row or back row parking with shade? well, that is up to you...
That might be a reasonable approach in the PNW, in Tennessee 99 in the shade is 99 in the shade.

At least I can keep the car garaged most of the time now my employer has moved us into a new building. I park in the basement at work now :-)

Re: Capacity vs Hx (Health)

Posted: Wed Dec 21, 2016 9:54 pm
by DaveinOlyWA
JPWhite wrote:
DaveinOlyWA wrote: You can maintain high Hx with battery temperature management. now how to do this is the real question. If faced with fun Sun parking in the front row or back row parking with shade? well, that is up to you...
That might be a reasonable approach in the PNW, in Tennessee 99 in the shade is 99 in the shade.

At least I can keep the car garaged most of the time now my employer has moved us into a new building. I park in the basement at work now :-)
that does not change the fact that 99 in the shade is 120 on the asphalt

Re: Capacity vs Hx (Health)

Posted: Wed Jul 18, 2018 2:15 pm
by dwl
Bumping an old thread to see if any more insight into exact meaning of Hx. The 30kWh update doesn't change Hx so it seems independent of the Ah/SoH calculation. There is scepticism about how a lot more Ah can be found for same Hx http://www.mynissanleaf.com/viewtopic.p ... 80#p532480

Re: Capacity vs Hx (Health)

Posted: Wed Jul 18, 2018 9:02 pm
by lorenfb
An explanation I've read is that health represents the battery's internal resistance - but not much to explain what that represents. The internal resistance is how much the voltage drops under load - how much effort the battery has to put forth to deliver the amount of power being consumed. This is what makes or breaks a battery, and why lithium has such a huge advantage over lead and earlier batteries: it has a very low internal resistance. As this resistance rises, health gets lower. I'd imagine the Leaf's computer uses this information to protect the battery as much as it can, by setting limits as needed regarding regen and acceleration.

In other words, health is actually very important. This explanation of internal resistance goes in line with all the trends I'd seen in posts I've read so far, and my own car's experience. It could spell an early decay for a strained battery. It seems very much dependent on how much strain is put on the battery during its use.
From here; http://mynissanleaf.com/viewtopic.php?f ... 50#p319070

Getting close to an understanding/definition. Actual internal resistance calculations (delta V/ delta I) should have been done with a varying
battery temperature. Hx highly correlates with the ratio of degraded battery conductance to the new battery conductance, just as SOH
relates the degraded Ahrs to the new battery Ahrs.

Re: Capacity vs Hx (Health)

Posted: Thu Jul 19, 2018 4:18 am
by DaveinOlyWA
dwl wrote:Bumping an old thread to see if any more insight into exact meaning of Hx. The 30kWh update doesn't change Hx so it seems independent of the Ah/SoH calculation. There is scepticism about how a lot more Ah can be found for same Hx http://www.mynissanleaf.com/viewtopic.p ... 80#p532480
LOL!! Lucky you don't have a 2018. My Hx is currently hovering at 115%!

Re: Capacity vs Hx (Health)

Posted: Thu Jul 19, 2018 4:15 pm
by Turbo3
DaveinOlyWA wrote:
dwl wrote:Bumping an old thread to see if any more insight into exact meaning of Hx. The 30kWh update doesn't change Hx so it seems independent of the Ah/SoH calculation. There is scepticism about how a lot more Ah can be found for same Hx http://www.mynissanleaf.com/viewtopic.p ... 80#p532480
LOL!! Lucky you don't have a 2018. My Hx is currently hovering at 115%!
Perhaps I should take off the "%" sign and just leave it as a number.

Re: Capacity vs Hx (Health)

Posted: Thu Jul 19, 2018 9:59 pm
by dwl
Turbo3 wrote:Perhaps I should take off the "%" sign and just leave it as a number.
Help please over at http://www.mynissanleaf.com/viewtopic.p ... 11#p532611. Any new insights into accuracy of Hx ? Can anyone confirm how accurately it might be measuring resistance?

Re: Capacity vs Hx (Health)

Posted: Fri Jul 20, 2018 10:18 am
by lorenfb
dwl wrote: Can anyone confirm how accurately it might be measuring resistance?
"measuring resistance" ?????????????