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Re: Capacity vs Health

Posted: Tue Jul 09, 2013 4:23 pm
by barsad22
Sorry if this has been covered before, but I just want to make sure... this "Health" is on the .25b Beta version of the Android app that isn't available in the Dropbox yet, right? And what is the Health number (all I can find is a "16-bit number I'm playing with" earlier in this thread)?
Again, sorry if I missed it in earlier posts.

JG

Re: Capacity vs Health

Posted: Thu Jul 18, 2013 4:28 pm
by LEAFer
With one tiny exception (7/16/2013 13:49) ... my Ahr and SOH have been monotonically decreasing. See http://www.mynissanleaf.com/viewtopic.p ... 3&start=37" onclick="window.open(this.href);return false;

Re: Capacity vs Health

Posted: Thu Jul 18, 2013 4:49 pm
by barsad22
Interesting data... but do you think the drop is a good indication of reality? It seems strange that your capacity would drop 6 points in one month (89 to 83), when in the previous 27 months you only dropped 11 points (100 to 89). This makes me wonder about the accuracy of the capacity reading (and what is the math behind "Health") on the Leaf Batt App.

JG
LEAFer wrote:With one tiny exception (7/16/2013 13:49) ... my Ahr and SOH have been monotonically decreasing. See http://www.mynissanleaf.com/viewtopic.p ... 3&start=37" onclick="window.open(this.href);return false;

Re: Capacity vs Health

Posted: Thu Jul 18, 2013 5:38 pm
by lincomatic
GregH wrote:What are the numbers in the first photo (other than Vpack)? If the 2nd photo is Ah Capacity and Health that seems odd.. 85.67% Health sounds really low for a 61.35Ah pack. Just the other day I was at 93.57% Health with 62.1166Ah Capacity in my car.
I'm seeing the same thing as GlennD ... the health dropped by ~15% when I got it back from the dealer, but the Ah didn't change much.

Re: Capacity vs Health

Posted: Thu Jul 18, 2013 6:39 pm
by LEAFer
The drop so far is just the adjustment to Pre-P3227 levels. Look at the summary table at the bottom of this post: http://www.mynissanleaf.com/viewtopic.p ... 3&start=34" onclick="window.open(this.href);return false;

Before the P3227 I was at 54.85Ahr (now "still" 55.29), and that was about (only) 800 miles and one month ago.

When I said "monotonically decreasing" I was referring only to the slow drop since the strong (fake) jump (increase) cause by P3227.
barsad22 wrote:Interesting data... but do you think the drop is a good indication of reality? It seems strange that your capacity would drop 6 points in one month (89 to 83), when in the previous 27 months you only dropped 11 points (100 to 89). This makes me wonder about the accuracy of the capacity reading (and what is the math behind "Health") on the Leaf Batt App.

JG
LEAFer wrote:With one tiny exception (7/16/2013 13:49) ... my Ahr and SOH have been monotonically decreasing. See http://www.mynissanleaf.com/viewtopic.p ... 3&start=37" onclick="window.open(this.href);return false;

Re: Capacity vs Health

Posted: Thu Jul 18, 2013 11:06 pm
by GregH
Ah capacity (in Ah) and health (in %) are the raw numbers direct from the car... No math involved.
The 2013 I've been driving for 12 days now has had Ah capacity pegged at 67.3620Ah but Health has jumbled around between 109% and 111%. The car charges consistently to 284 Gids and 97.2999% SOC on a full charge. At some point I'm guessing if the health drops below 105 to 108% then I might see the Ah capacity nudge downward.. If that happens in the next 9 days while I still have the car I'll let you know...

Re: Capacity vs Health

Posted: Fri Jul 19, 2013 7:39 pm
by LEAFfan
Greg, since you have a '13 to use could you please use Jim's App and see if you have true GIDs displayed correctly? Thanks! Mine changes drastically constantly (goes from 300 GIDs to 0 in a short time/ten minutes/5 miles) so it would be interesting to see if it happens on other '13s.

Re: Capacity vs Health

Posted: Fri Jul 19, 2013 9:25 pm
by GregH
LEAFfan wrote:Greg, since you have a '13 to use could you please use Jim's App and see if you have true GIDs displayed correctly? Thanks! Mine changes drastically constantly (goes from 300 GIDs to 0 in a short time/ten minutes/5 miles) so it would be interesting to see if it happens on other '13s.
I have a 2013 for the next week or so but no ELM nor any android devices..

Re: Capacity vs Health

Posted: Sat Jul 20, 2013 11:44 am
by LEAFfan
GregH wrote:
LEAFfan wrote:Greg, since you have a '13 to use could you please use Jim's App and see if you have true GIDs displayed correctly? Thanks! Mine changes drastically constantly (goes from 300 GIDs to 0 in a short time/ten minutes/5 miles) so it would be interesting to see if it happens on other '13s.
I have a 2013 for the next week or so but no ELM nor any android devices..
That's okay, it may have been fixed with v.k which I just dl today.

Re: Capacity vs Health

Posted: Mon Aug 19, 2013 9:00 pm
by FalconFour
barsad22 wrote:And what is the Health number (all I can find is a "16-bit number I'm playing with" earlier in this thread)?
Again, sorry if I missed it in earlier posts.

JG
I'm interested in the same thing right now as well. I recently updated to the latest version, and have been unnerved by the "health" figure ever since I first saw it. Mine's lingering around the 68% area, apparently dropping. I believe it started at around 72% or so when I first discovered it a few weeks ago. I've since started changing driving habits a bit, and it seems to have stopped the downward trend, now fluctuating around this (last night while charging):
2013-08-19 01.00.23.png
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. Some folks are posting pretty decent health, and low health seems somewhat rare. I've driven the past 9 months of my Leaf like a racecar for the most part - but with zero quick-chargers to abuse in my area. Just over a thousand L2 charges, three quick charges. It's also a 2011 model that sat unused on a lot for over a year. The sudden racecar abuse of a battery that sat for a year might not be the best thing in the world...

The big question I've got now is... what can be done to improve health, not just stop killing it?