Peri, My thinking on the degradation has to do with the fact that most people do not actually discharge the cells below 50 or 60 percent. I learned from some of the people involved with the lithium cells that it is best to think of them as a "sponge". That is, if you leave a sponge soaking in a bucket, it rots very quickly (always plugged in or charged), and if you leave it on a shelf all the time, it becomes very hard, and takes a very long time to re-hydrate (prolonged low charge). However is you wring it out on a regular basis, lasts for a very long time (regular full charges and discharges). This is why it was recommended to fully discharge ie. wring out (according to the instrumentation) once per month. I know that it worked well for me.
-Tom On Wed, Oct 5, 2016 at 7:10 AM, Peri Hartman via EV <[email protected]> wrote: > Something doesn't make sense, here. No doubt you prolonged the battery > capacity by not charging and discharging fully, per the engineer's advice. > > But according to what others have said, if you consistently charge to 80% > and discharge to 20%, you should see very little or no capacity degradation > with LiFePos. Yet the vast majority of Leaf owners do see significant > degradation and never see thermal runaway. > > So, either LiFePos need even a smaller margin of operation, say 35% to > 65%, or what the engineer told you isn't completely true. Or there's some > other significant factor in the situation. > > Peri > > ------ Original Message ------ > From: "Thos True via EV" <[email protected]> > To: "Cor van de Water" <[email protected]>; "Electric Vehicle Discussion > List" <[email protected]> > Sent: 05-Oct-16 7:00:20 AM > Subject: Re: [EVDL] To fully charge or not to fully charge that > isthequestion > > I'm not sure why this keeps coming back to roost. Some people on this list >> may recall the same conversation back in the spring of 2011, where I >> contacted Nissan about the 80% issue. I received a phone call from one of >> the engineers in Tennessee. He understood my confusion and expressed some >> frustration at their end, explaining that they designed the on board >> battery management system to protect the batteries. Doing so by never >> letting the batteries charge above 80% (which shows as the full 100% on >> the >> instrumentation), and never discharging below 20% (which shows as 0%). >> Explaining that if you let the battery pack get below 10%, it would >> typically brick (not allow a charge), and above 90%, that your could >> experience a thermal even ( Thermal runaway & fire). >> The final recommendation from him was to discharge the pack to 10 miles or >> so in range (according to the instrumentation), and fully recharge about >> once a month to "refresh" the battery. I followed his advice, and after 39 >> months and 56,000 miles, (the end of the lease), the pack was still above >> 98% capacity, which seemed to surprise the service department at the >> dealership where we turned it in at. >> I suspect that some of the degradation that we experienced may have been >> due to some of the fast chargers that we used toward the end of the lease, >> but have no way to be sure of that. >> >> Tom True >> >> On Tue, Oct 4, 2016 at 11:39 PM, Cor van de Water via EV < >> [email protected]> >> wrote: >> >> Let's try that *with* the link: >>> https://techcrunch.com/2016/09/29/tales-from-a-tesla-model- >>> s-at-200k-mil >>> es/ >>> >>> >>> Cor van de Water >>> Chief Scientist >>> Proxim Wireless >>> >>> office +1 408 383 7626 Skype: cor_van_de_water >>> XoIP +31 87 784 1130 private: cvandewater.info >>> >>> http://www.proxim.com >>> >>> This email message (including any attachments) contains confidential and >>> proprietary information of Proxim Wireless Corporation. If you received >>> this message in error, please delete it and notify the sender. Any >>> unauthorized use, disclosure, distribution, or copying of any part of >>> this message is prohibited. >>> >>> >>> -----Original Message----- >>> From: EV [mailto:[email protected]] On Behalf Of Cor van de >>> Water via EV >>> Sent: Tuesday, October 04, 2016 11:28 PM >>> To: Electric Vehicle Discussion List >>> Subject: Re: [EVDL] To fully charge or not to fully charge that >>> isthequestion >>> >>> Here is the article about the 200k mi Tesla (in 1 year) Note that >>> Tesloop is actually aiming at putting 400k mi on their cars each year, >>> so the 8 year warranty on battery and drivetrain would give them ~3 >>> million miles under warranty... >>> Their website has a blog with a few of the details, including an early >>> front motor replacement under warranty. >>> >>> Cor van de Water >>> Chief Scientist >>> Proxim Wireless >>> >>> office +1 408 383 7626 Skype: cor_van_de_water >>> XoIP +31 87 784 1130 private: cvandewater.info >>> >>> http://www.proxim.com >>> >>> This email message (including any attachments) contains confidential and >>> proprietary information of Proxim Wireless Corporation. If you received >>> this message in error, please delete it and notify the sender. Any >>> unauthorized use, disclosure, distribution, or copying of any part of >>> this message is prohibited. >>> >>> >>> -----Original Message----- >>> From: EV [mailto:[email protected]] On Behalf Of Cor van de >>> Water via EV >>> Sent: Tuesday, October 04, 2016 2:06 PM >>> To: Willie2; Electric Vehicle Discussion List >>> Subject: Re: [EVDL] To fully charge or not to fully charge that is >>> thequestion >>> >>> Willie, >>> Not dynamically, just a one-time upgrade (dealer visit required). >>> Many Leaf owners who lost the 4th bar and thought they qualified for the >>> warranty battery replacement were miffed to see the dealer really >>> enforcing the Nissan requirement that the warranty will only be honored >>> after the mandatory re-calibration of the 12 battery bar gauge. Most >>> owners found out that after re-calibration their earlier 4 bar loser no >>> longer showed 4 bars lost so they no longer qualified unless they would >>> again see 4 bars lost on the re-calibrated gauge. The first bar does not >>> disappear until 15% is lost and each subsequent bar should stand for >>> 6.25% so in theory you need a battery degraded to just over 66% of >>> nominal capacity to qualify if the gauge will indeed drop to 4 bars >>> right at that point. But reports I have seen of Ah capacity degradation >>> suggest that the loss of the 4th bar happens later. >>> I found it significant that Leafs can lose more than 40% capacity in >>> about 50k mi while some Tesla drops only 6% in 200k mi. >>> >>> Of course this is only one sample with a specific usage pattern, but I >>> highly doubt an expansion of the samples will give different results, >>> we'll see. >>> >>> Cor van de Water >>> Chief Scientist >>> Proxim Wireless >>> >>> office +1 408 383 7626 Skype: cor_van_de_water >>> XoIP +31 87 784 1130 private: cvandewater.info >>> >>> http://www.proxim.com >>> >>> This email message (including any attachments) contains confidential and >>> proprietary information of Proxim Wireless Corporation. If you received >>> this message in error, please delete it and notify the sender. Any >>> unauthorized use, disclosure, distribution, or copying of any part of >>> this message is prohibited. >>> >>> >>> -----Original Message----- >>> From: EV [mailto:[email protected]] On Behalf Of Willie2 via EV >>> Sent: Tuesday, October 04, 2016 11:18 AM >>> To: Electric Vehicle Discussion List >>> Subject: Re: [EVDL] To fully charge or not to fully charge that is the >>> question >>> >>> On 10/04/2016 12:29 PM, Cor van de Water via EV wrote: >>> > on the battery as the Leaf *does* degrade its battery by 40% to approx >>> >>> > 60% capacity in approx 50k mi in warmer climates (that is the point >>> > where Nissan gives a warranty battery replacement, even though they >>> > promised 70% but re-calibated the battery to lose the 4th bar around >>> 60% >>> > capacity and triggering the warranty if it occurs within the warranty >>> > limits for time and mileage.) >>> When I first got my Leaf, I was astonished at how crappy the >>> instrumentation is/was. Coming from the conversion world, I expected to >>> >>> see, or find out, how much energy went into the battery and how much >>> came out. Instead, I had these twelve "bars". Unacceptable granularity. >>> Later, I found the "bars" were not even of equal value. >>> After some pondering, I came to the conclusion that Nissan did things in >>> >>> that way to hide information from their customers. What other >>> explanation could there be? >>> >>> Even more astonishing is how Leaf owners accept the situation and speak >>> of almost meaningless "bars". I'm not surprised to learn that Nissan >>> dynamically recalibrates "bars" to manage their warranty threshold. >>> >>> _______________________________________________ >>> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub >>> http://lists.evdl.org/listinfo.cgi/ev-evdl.org >>> Read EVAngel's EV News at http://evdl.org/evln/ Please discuss EV drag >>> racing at NEDRA >>> (http://groups.yahoo.com/group/NEDRA) >>> >>> _______________________________________________ >>> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub >>> http://lists.evdl.org/listinfo.cgi/ev-evdl.org >>> Read EVAngel's EV News at http://evdl.org/evln/ Please discuss EV drag >>> racing at NEDRA (http://groups.yahoo.com/group/NEDRA) >>> >>> _______________________________________________ >>> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub >>> http://lists.evdl.org/listinfo.cgi/ev-evdl.org >>> Read EVAngel's EV News at http://evdl.org/evln/ Please discuss EV drag >>> racing at NEDRA (http://groups.yahoo.com/group/NEDRA) >>> >>> _______________________________________________ >>> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub >>> http://lists.evdl.org/listinfo.cgi/ev-evdl.org >>> Read EVAngel's EV News at http://evdl.org/evln/ >>> Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/ >>> group/NEDRA) >>> >>> >>> >> >> -- >> Remember, it is not that the glass is half empty, in reality, the glass is >> merely twice the size that it needs to be! -TNT'82 >> -------------- next part -------------- >> An HTML attachment was scrubbed... >> URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/ >> 20161005/594baeca/attachment.htm> >> _______________________________________________ >> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub >> http://lists.evdl.org/listinfo.cgi/ev-evdl.org >> Read EVAngel's EV News at http://evdl.org/evln/ >> Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group >> /NEDRA) >> >> >> > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > Read EVAngel's EV News at http://evdl.org/evln/ > Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group > /NEDRA) > > -- Remember, it is not that the glass is half empty, in reality, the glass is merely twice the size that it needs to be! -TNT'82 -------------- next part -------------- An HTML attachment was scrubbed... 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