JasonA
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Location: Sylmar, CA

Re: Capacity vs Hx (Health)

Wed Nov 06, 2013 9:03 pm

I believe you are actually seeing two effects.

First, the battery is an electro-chemical device. Lower temperatures actually cause a slow down in the chemical to electrical conversion process within the battery. When batteries are cold they can give the appearance of a high internal resistance because of the slower ability to convert chemical energy into electrical energy. So most types will show higher IR.. no way to get around this except fancy Nissan gimmicky programming... it just happens..

On the other side of the equation, heat has a different effect. Heat will typically increase the internal resistance of a battery therefore limiting the current the battery can provide. If you continue raising the temperature of the battery the chemical process works better however the higher resistance limits the current the battery can supply. This is NOT "C" rating..

Ideally, you want to use the battery in it's sweet spot or recommended operating temperature, not too cold or not too hot. Also the reason you should let your batteries cool down after you use them prior to recharging. This is also why on very cold days, a battery will actually start to perform better as you drive because the heat created from the discharge process warms up the chemicals and the conversion process improves.

I've noticed now on mine that the sweet spot is 22-28*c and they are kicking!

I hope that makes sense....
2012 10kw Dual LQ cooled Brusa powered Leaf "Astro"
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adspguy
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Leaf Number: 018978
Location: Newton, MA

Re: Capacity vs Hx (Health)

Fri Oct 17, 2014 1:15 pm

Image
I figured it would be time to post some data here again after a bit of a hiatus.
Above is a plot of CAP (and HX) vs time for my 2012 LEAF. The P3227 update was done on 4/26/14.
It seems that pre-update there were some roller coaster hills, and post update not so much.

The green line is just a line I put in to see how the CAP data fits a linear decay vs time.

Ignoring the tetons sticking up, it looks like a fairly linear decay of capacity. HX does seem to mostly follow the CAP if you scale it right.

Comments?

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TickTock
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Re: Capacity vs Hx (Health)

Fri Oct 17, 2014 4:00 pm

Yeah. Looks like they track more closely post update. I am curious what scalars you applied. Here is a graph from my 2011 - all post-update. For Hx, all I did was add 21. For Ah, all I did was multiply by 1.52. Also, is what you are calling CAP the same thing as SOH?
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adspguy
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Re: Capacity vs Hx (Health)

Sat Oct 18, 2014 7:19 am

CAP in this case is the raw AmpHour capacity group 79b index 5, bytes 2-4. Same as your Ah I suspect. I didn't do any math, I just plotted the raw data on their own axis and lined them up. Ah scale on left, hx scale on right.

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TickTock
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Re: Capacity vs Hx (Health)

Wed Mar 04, 2015 9:55 am

A data point from my new battery (after a week of "settling in")

SOH: 100%
Hx: 100.1
Ah: 66.14

DaveinOlyWA
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Re: Capacity vs Hx (Health)

Wed Mar 04, 2015 10:26 am

TickTock wrote:A data point from my new battery (after a week of "settling in")

SOH: 100%
Hx: 100.1
Ah: 66.14


nice. what are your plans for monitoring degradation? I think you would be a great benchmark for acid test on new Lizard pack
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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Turbo3
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Leaf Number: 002191
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Re: Capacity vs Hx (Health)

Wed Mar 04, 2015 10:29 am

TickTock wrote:A data point from my new battery (after a week of "settling in")

SOH: 100%
Hx: 100.1
Ah: 66.14

Do you happen to have the same data on the old battery just before you had it replaced?

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TickTock
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Re: Capacity vs Hx (Health)

Wed Mar 04, 2015 10:41 am

Turbo3 wrote:
TickTock wrote:A data point from my new battery (after a week of "settling in")

SOH: 100%
Hx: 100.1
Ah: 66.14

Do you happen to have the same data on the old battery just before you had it replaced?


yup :-)

SOH: 54%
Hx: 33.4
Ah: 35.88

plieshout
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Leaf Number: 013505

Re: Capacity vs Hx (Health)

Fri Jan 01, 2016 3:41 am

Not sure if this is the right place to post this, correct me if i'm wrong please.

With regards to hx value: I have noticed that if i drive my Leaf in B-mode arround 50-60 mph on the highway, and i drive the car for 2 seconds with full throttle, then 2 seconds no throttle, again 2 seconds full throttle, then 2 seconds no throttle and so on for half a 'tank' of power, the hx value increases a lot (from 97% to 102,5%).

Anybody knows what that means?

DaveinOlyWA
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Re: Capacity vs Hx (Health)

Fri Jan 01, 2016 8:35 am

plieshout wrote:Not sure if this is the right place to post this, correct me if i'm wrong please.

With regards to hx value: I have noticed that if i drive my Leaf in B-mode arround 50-60 mph on the highway, and i drive the car for 2 seconds with full throttle, then 2 seconds no throttle, again 2 seconds full throttle, then 2 seconds no throttle and so on for half a 'tank' of power, the hx value increases a lot (from 97% to 102,5%).

Anybody knows what that means?


what you are doing is simply running a lot of current thru your pack in a very short period of time. no different than the boost in numbers seen when you fast charge... not sure I would recommend your actions on a regular basis.

in the general scheme of things; there is only ONE guaranteed way of insuring greater longevity of your pack and this driving efficiently.

Image

no saying that anyone else can match me but if I am averaging 4.8 miles per kwh and someone else is averaging 3.8 miles per kwh, then it stands to reason that my pack will last longer due to less cycling but that is only the beginning. Gentler driving means a less stressful battery life. now how extreme is the damage done from this type of driving? minimal I think but in your case, you are artificially increasing your cycle count for no real benefit.

This is another reason I am a fan of neutral driving. it is stress free miles
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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