What percentage to charge?

[joeldf]

Below 20% is where internal damage can really accelerate, but 30-40% is the usual recommended point at which to charge. In general, Li-ion batteries like a happy medium.

That, I do agree with.

 

[mustang7757]

What's "too low" though?

They say once in a while 5% to 100% to calibrate it, usually 10 -15% I start charging mine then to either 90 or 100% , these phone batteries are usually set to get 2 to 3 years out of them then replace it or move to next phone , if your looking to get 5 years be pretty lucky then follow strict 40 to 80 formula. My iPhone x is the longest I currently have active over 2 years at 86% capacity doing what I mentioned.

 

[jlangner]

Put it on charger when go to bed, unplug when get up. It charges while on android auto on way to and from work. Don't pay attention to levels generally.