Notification that disappears so fast that I can't see what it is

I started getting a notification on my phone recently, it usually pops up when I unlock my phone or when I slide down the notification bar. It appears on the whole screen but disappears after one second which is too fast for me to see anything.All I can see is a big battery icon colored orange on the bottom, kinda looks like an almost empty battery. But I'm not sure since I can't actually see what it is. There's definitely some text written on it.  This is the best I could describe it. I would really appreciate your help. Thank you.