DaveinOlyWA
Posts: 13224
Joined: Sat Apr 24, 2010 7:43 pm
Delivery Date: 16 Feb 2018
Leaf Number: 314199
Location: Olympia, WA
Contact: Website

Re: OK To Short Charge (30 min) To Assure Range

Thu Dec 14, 2017 8:20 am

alozzy wrote:FWIW, if you take the data from table 2 and assume that 100% DoD is equivalent to 80 miles (range of a new 24 kWh Leaf), then below are the number of miles one could travel until the battery degraded by 30% of its original capacity:

  • 100% DoD cycling - 48,000 miles (600 cycles x 80 x 100%)
  • 80% DoD cycling - 57,600 miles
  • 60% DoD cycling - 72,000 miles
  • 40% DoD cycling - 96,000 miles (3000 cycles x 80 x 40%)
  • 20% DoD cycling - 144,000 miles
  • 10% DoD cycling - 120,000 miles

Obviously, the range diminishes as the battery degrades but the numbers above are really just for relative comparison. Interesting that when comparing 40% DoD cycling to 100% cycling, the miles travelled doubles.

If you believe that source, then daily charging based on a 50% DoD cycle should result in a loss of 30% capacity after roughly 85K miles. These numbers seem too pessimistic to me, since I'm guessing my Leaf will have gone 120K miles by the time the SOH drops to 70% - I don't think I've averaged roughly 30% DoD charging cycles, it would likely be more like 50% DoD on average...

Perhaps the data was based on testing at hotter temperatures, with no TMS. Or it's just a bunch of BS ;)


the cycling chart is not valid unless a "heat" factor is applied. The issue we have (that most here seem to ignore) is that there is a degradation curve that varies with temperature and that curve starts at a shockingly low temperature.

The other question is what 40% DoD means? Is that 40-80% SOC? Because if it is, that only means that issues with heat are magnified.

Finally I love Battery U for the legwork they have done but they have only recently started concentrating on the specific issues EVs face. So a realistic picture requires stitching several studies together with leaps of logic to make sense of them.

This last part is something that most refuse to accept.
2011 SL; 44,598 miles. 2013 S; 44,840 miles.2016 S30 deceased. 29,413 miles. 2018 S40; 11,987 miles, 485 GIDs, 37.6 kwh 110.89 Ahr , SOH 96.00, Hx 115.22
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alozzy
Posts: 1116
Joined: Fri Jan 20, 2017 4:25 pm
Delivery Date: 18 Jan 2017
Location: Vancouver, BC
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Re: OK To Short Charge (30 min) To Assure Range

Thu Dec 14, 2017 11:10 am

The takeaway is the relative comparison between different depths of discharge (DoD) for charge cycling, and how that impacts battery degredation.

Limiting the DoD to less than 50% makes intuitive sense to me, assuming it does in turn slow down battery degredation. I choose to believe that it does, based on several sources of "evidence". Of course, that doesn't mean I obsess about it and never discharge more than 50%, but I do try to "top up" when the opportunity arises.
Vancouver, CA owner of a 2013 Ocean Blue SV + QC, purchased 01/2017 in WA
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LeftieBiker
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Joined: Wed May 22, 2013 3:17 am
Delivery Date: 31 May 2013
Location: Upstate New York, US

Re: OK To Short Charge (30 min) To Assure Range

Thu Dec 14, 2017 11:16 am

Limiting the DoD to less than 50% makes intuitive sense to me, assuming it does in turn slow down battery degredation. I choose to believe that it does, based on several sources of "evidence". Of course, that doesn't mean I obsess about it and never discharge more than 50%, but I do try to "top up" when the opportunity arises.posting.php?mode=reply&f=9&t=25002


It seems to me, based on experiences by many, many people with lithium batteries, that 20% is the best "floor" for DOD, with 50% being more like a compromise storage charge, and 30% or so being optimum. "Top up" implies charging to full, and that definitely isn't the way to maximize lithium pack longevity, as lithium batteries don't seem to "like" being at 100%.
Scarlet Ember 2018 Leaf SL W/ Pro Pilot
2009 Vectrix VX-1 W/18 Leaf modules, & 3 EZIP E-bicycles.
PLEASE don't PM me with Leaf questions. Just post in the topic that seems most appropriate.

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