There are a lot of different opinions on how low to let your battery get. I've used lithium ion batteries for a lot of tools, devices and such and believe not letting it go dead is key. I think it can go below 30 easily and still be fine. I usually throw it on the charger when it gets to about 15. And also now a days lithium ion batteries can stay on the charged pay the point if when it says fully charged. I heard it will not affect them in any way. I have a lot of tools I leave on over night and phones, tablets that when doing so they have lasted years with it damage to the battery.
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