My Nexus 4 says it's charging but it's actually discharging I plug in my Nexus 4 to a charger cable plugged into a wall outlet each night, and each morning I disconnect it.

But sometimes during the day when it's not plugged in, like today, it says "Charging - 95%", and later, it says, "Charging - 92%", and continues to discharge normally. The battery icon also shows the little lightning bolt symbol to indicate charging.

I've seen the related/similar questions but they don't match my device or situation, as far as I can tell. Since other devices have similar issues, is it a software problem?
Either the battery is damaged or it's a software issue. You should first try to reboot the phone. If it doesn't fix it, try a factory reset.