Something is about to happen

Something about to happen: If something is about to happen, it will happen very soon.

• https://www.collinsdictionary.com/us/dictionary/english/be-about-to

"My phones about to die. Luckily, I have a charger. I’ll be right back."

Shouldn’t we not use "about to" if we are going to not let it happen very soon? According to the definition, you use it when you think it will happen very soon. Can someone explain?