Here that means it's time to plug in the charger. If you don't it may not make it through the night.
I may have missed where you did or knew that.
As to the last paragraph, I'm sorry to write that no smart phone may fit your request. That is, when it gets say under 50%, I plug it in.
Hello,
To me a phone is an MP3 player with an alarm...that can also make phone calls once a week.
After my Sony Ericsson finally gave up after about 7 years of loyal service, I have been forced to switch to a smartphone and I have been late to work twice already because my new Motorola G3, despite having 1/3 of its battery life left in the evening, could not stay alive until morning and the alarm does not ring when the phone is off. My old phone would sound the alarm despite a dead battery. Also, the music quality and controlls seem worse regardless of the equaliser and expensive headphones.
I’ve read that the problem of the alarm and the music quality applies to most android phones because they are all more or less the same.
Can someone knowledgeable recommend me a modern phone that is capable of waking up like my old phone did and, ideally, specializes in music?
Or alternatively, maybe a phone that has an extremely long standby time is the solution? I thought about getting an iPhone because my iPad seems to last for weeks when locked, but if I look at the specs of an iPhone, the standby time is much shorter than other phones so I guess not all Apple products are similar in that aspect.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic