I can't remember ever seeing the battery icon on the glance screen except when it's plugged in. On the lock screen, you mean you turn on the phone and the very top bar of the phone doesn't have a battery icon - where the cellular, wifi etc. icons are on the left? I think the battery icon only shows on the lock screen in Windows 10 Mobile on the very top.
I have an app ("Battery" by Enless Soft Ltd.) which I add to the lock screen (Personalization... Lock Screen... Choose apps to show quick status):
The battery app shows below the clock and has a percentage next to it, while the system battery shows at the very top of the screen.