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Why Charging Your Gadgets Over 80% Is Such a Bad Idea | iFixit News
(www.ifixit.com)
This is a most excellent place for technology news and articles.
For android users, we can easily set notifications if battery level reach certain range by using apps like Tasker. Before this I set it for full charge. Change it to above 80% just now.
EDIT: tasker proj file in case anyone is interested. Link.