Charging, Charge State and Battery Longevity

[neal adkins]

Unfortunately what we saw from Honda's documentation is that the battery (combined Pack A and B) would have to fall to 25% of original capacity before Honda would declare it defective - that is a fully charged battery would have to provide less than 12 miles of range.
https://insideevsforum.com/community/index.php?attachments/p144a-battery-pack-deteriation-pdf.1359/
in
https://insideevsforum.com/communit...rge-strategy-for-max-battery-life.1154/page-2

I think this section explains the nessacary deteriation for the system to log a code of severe deteriation. I remember reading that the ev battery has an expected rate of deteriation. If the battery exceeds that amount then honda will replace it. Also Honda can say anything they wish in thier manual but that does not nessacarily exempt them from liability in the event of a failure or material deteriation. As you know honda will sometimes do things under warranty even after it expires.

 

[neal adkins]

Unfortunately what we saw from Honda's documentation is that the battery (combined Pack A and B) would have to fall to 25% of original capacity before Honda would declare it defective - that is a fully charged battery would have to provide less than 12 miles of range.
https://insideevsforum.com/community/index.php?attachments/p144a-battery-pack-deteriation-pdf.1359/
in
https://insideevsforum.com/communit...rge-strategy-for-max-battery-life.1154/page-2

Sorry for the delay. I had replied afew days ago but apparently something went wrong and it didn't post.
When i checked the link it appeared that a code will log for severe deteriation at this point wich is about 25 percent capacity remaining. Honda can say anything they wish in thier manual but that does not excuse them from legal liability in the event of material deteriation. I read that the battery has an expected normal rate of deteriation so i would think that if the battery falls below that it would be replaced. I would appreciate any opinions.

 

[bpratt]

This is something I ran into at batteryuniversity.com:

 

[Steven B]

This is something I ran into at batteryuniversity.com:
View attachment 1680

So, again, the question we all have that Honda won't answer, is: Will this happen automatically by decision of the onboard control system or would this require visiting the dealer, the dealer performing a battery test (per the previously posted Honda documentation), and then the dealer sending a command to the battery management system to expand the bandwidth?

 

[neal adkins]

I call all ev's and hybrids smile now cry later cars. I was allways smiling in my camry hybrid unti the battery failed at 140k miles. Then the frown came on my face. I was able to get an excellent dorman rebuilt pac for 1800. I had saved about 5k$ in fuel so not too bad. This is inevitable with all batteries. Thats why i will not own a tesla at thier current high price.Be sure to moniter the 12 volt battery because when it fails the charging system diverts more current to compensate. Hence the service indicator device on the 12 volt. This can strain the system and cause premature main battery failure.

 

[bpratt]

If LI battery makers can figure out how to prevent resistive buildups on the anode and cathode of the battery then the battery would last forever. Until then, (or at least until LI battery life is 20 years) I sold my Toyota Hybrid after 4 1/2 years and will probably only keep my Clarity about that long.

 

[weave]

would have to fall to 25% of original capacity before Honda would declare it defective

OMG -- Here I have been thinking it is a 25% loss (ie, 75% of original capacity). 25% capacity (~12 miles) would be horrible.

 

[AnthonyW]

AHA!! I have found it. The answers to all our questions! See screenshot and attached document. The screenshot seems to confirm that around 12.5kWh of the pack is usable (red dash line to red dash line). CD stands for "charge depleting" operation. Also it confirms the observation and assertion that I made over in the Scangauge thread, that Honda leaves very little battery buffer at the top and a whole lot at the bottom. https://www.insideevsforum.com/comm...ended-pids-capacity-and-specific-energy.2633/

Now, if we only knew why they set the extra buffer/capacity zones that way.

 

[KentuckyKen]

AnthonyW that makes perfect sense.
Based on other posts:
14.4 is max kW for a charge and at an assumed 86% efficiency would be about 12.4 kW added to the battery for the usable power out of 17 kW total capacity.
12.4 or 12.5 is about 73% of 17 kW
So 27% is reserved for battery preservation but until now we had no clue as to how much was reserved at the top and bottom.

Your research would then lend credence to those who advocate not charging all the way up to 100% since the buffer up there is rather low. It also informs me that I should continue using scheduled charge for early morning hours to charge when battery temp is lower and there is less time spent at full charge before being driven. And the buffer at the bottom is so large that we don’t have to worry about how low or how often we discharge the battery.
Great find!!
I’m adding Honda Grand Master to your slew of titles.

 

[PHEV Newbie]

AHA!! I have found it. The answers to all our questions! See screenshot and attached document. The screenshot seems to confirm that around 12.5kWh of the pack is usable (red dash line to red dash line). CD stands for "charge depleting" operation. Also it confirms the observation and assertion that I made over in the Scangauge thread, that Honda leaves very little battery buffer at the top and a whole lot at the bottom. https://www.insideevsforum.com/comm...ended-pids-capacity-and-specific-energy.2633/

Now, if we only knew why they set the extra buffer/capacity zones that way.

View attachment 1684

This helps explain why the Clarity won't allow regen when fully charged, even modestly. So if possible, follow Tesla's advice for their cars and charge to 80% for everyday use to maximize battery longevity.

 

[AnthonyW]

AnthonyW that makes perfect sense.
Based on other posts:
14.4 is max kW for a charge and at an assumed 86% efficiency would be about 12.4 kW added to the battery for the usable power out of 17 kW total capacity.
12.4 or 12.5 is about 73% of 17 kW
So 27% is reserved for battery preservation but until now we had no clue as to how much was reserved at the top and bottom.

Your research would then lend credence to those who advocate not charging all the way up to 100% since the buffer up there is rather low. It also informs me that I should continue using scheduled charge for early morning hours to charge when battery temp is lower and there is less time spent at full charge before being driven. And the buffer at the bottom is so large that we don’t have to worry about how low or how often we discharge the battery.
Great find!!
I’m adding Honda Grand Master to your slew of titles.

Yes I agree. It takes me about 50% charge to get to work each day. I would previously charge to 90% but now I think I will stop charging at 65 or 70% and take it much further down and closer to the automatic ICE turn on point. That way I will be operating much more in the “middle” of the pack. Seeing that the low end voltage of our battery type is 3.0v but the the automatic ICE turn on point is 3.40v, it makes sense to operate closer to fully “depleted” SOC as opposed to a fully “charged” SOC.


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[Heather]

This has been a helpful thread. I have a 2017 Audi Etron and am looking for battery longevity strategies. The quote on battery replacement for this vehicle is $12K (Canadian) installed.

 

[PHEV Newbie]

This has been a helpful thread. I have a 2017 Audi Etron and am looking for battery longevity strategies. The quote on battery replacement for this vehicle is $12K (Canadian) installed.

The car is still pretty new. Are you already experiencing battery degradation? It wouldn't be too surprising because the e tron's EV range is 17 miles so I imagine everyone who owns one will fully charge and discharge once or twice a day, which is pretty hard on the battery.

$12,000? Yowch! The A3 e tron battery is half the size of the Clarity's. I'd hate to learn how much it would cost to replace the Clarity's. Another reason to maximize battery longevity.

 

[Ray B]

FYI - Honda just released a new paper on modeling of lithium ion battery longevity as a function of temperature and SOC% during storage (lower generally better in both cases).

https://www.hondarandd.jp/point.php?pid=1305&lang=en

 

[Mowcowbell]

Makes me think Honda planned the buffer much higher on the bottom end as they knew dealers would let Clarity's sit on lots for months at 2 bars!