[Video + Article] Strategies to reduce Li-ion Battery Degredation

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Well-known member
Aug 20, 2020
Burnaby, BC
A couple of weeks ago, there was this Engineering Explained YouTube video that took some excerpts from a couple of sources to discuss some of the worst things you could do to an EV battery.

Eng Exp vid:

source 1: https://pubs.rsc.org/en/content/articlehtml/2021/cp/d1cp00359c (Lithium-ion battery degradation: what you need to know)
source 2: https://www.sciencedirect.com/science/article/abs/pii/S0378775313016510 (Calendar and cycle life study of Li(NiMnCo)O2-based 18650 lithium-ion batteries)

source 2 [webinar] EV Battery Health with Dr Jeff Dahn Dalhousie U:

I preferred the webinar and paper because the whiteboard engineer is condensing the info to cover the essentials, but the gist was that

  1. Calendar aging: Parking in Higher Temperatures and 100% SOC Degrades the battery more quickly, but at 30% SOC this is cut by an order of magnitude. And like you would expect, cold temperatures slow aging even moreso, to the point where even storing at 100% would be comparable to storing at a lower SOC in the heat.
  2. Author Madeleine Ecker and the professor from the webinar argue that small Depth of Discharge cycle use between 40% and 60% presents the least amount of battery volume change which would otherwise cause microcracking in the electrode material and generation of more SEI/CEI electrolyte solvation in those cracks, leading to capacity degradation and performance loss too.
Despite the data presented, I have a big problem with the depth of discharge interpretation and believe the conclusion is faulty and lacks rigor, so I can only vouch for the recommendation to store cars in cooler areas at low SOC.

Oh I should also point out that 100% = 4.2V traditionally, but in the Spark EV 100% is 4.08-4.1V depending on cell balance and temperature, at least from my own OBD II readings. By comparison, Tesla usually sets their EVs' 100% SOC = 4.15V and only recommends it for non-daily trip use. So the Spark does offer a slight reduction in wear when you use the whole battery, but it's still fairly high, obviously because the cells require higher energy density to compensate for their small size.