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We can see this simple chart in many places, however I am curious to know how the numbers work out for different starting charge levels than 40% (3.8V, ish? for li-ion).

For example, how much worse is 10% charge level than 40% charge level? Importantly, is it preferable to leave a battery charged at 100% or at 10% (as these are usually the states that we find cells charged to)?

Steven Lu
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  • Factories usually ship at 60% SoC for max room temp life – Tony Stewart EE75 Jun 23 '18 at 01:17
  • What do you mean "how much worse is ..."? Worse than what? – Ale..chenski Jun 23 '18 at 03:31
  • @AliChen worse than 40%. E.g.: 40% starting charge, after one year @ 25C, 4% is lost. *What if starting charge is 10%?* How much total capacity is lost after one year?? – Steven Lu Jun 23 '18 at 03:59
  • 100% is not good for the battery. It will last longer if stored at lower SOC. The danger with low SOC levels is that the battery may become deeply discharged. – user57037 Jun 23 '18 at 05:53
  • What I mean is, I don't think 10% is bad for the battery. But the battery protection circuit or BMS consumes some current, and there is also self-discharge. So if a battery is kept at 10%, and sits for many months, it may become deeply discharged (for example below 2.7V) which is generally considered bad. – user57037 Jun 23 '18 at 08:42
  • Actually I think factories have to go down to 40% now due to shipping regulations. I am not 100% sure, but that is what I remember from talking to our operations guys where I work. – user57037 Jun 23 '18 at 08:47

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