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Why Charging Your Gadgets Over 80% Is Such a Bad Idea | iFixit News
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This is a most excellent place for technology news and articles.
I just charge my phone to full when it's at like 20 and then unplug it when it's done charging. Have had this phone for like 2 and a half years and I don't have noticeable degradation, but it's a flagship samsung phone so I know they typically have pretty good cells in them.