There are a few questions marked as charging that relate to capacitor and inductor charging, but all of the others refer to battery chargers.
The charger and battery-charging tags should be merged anyway, there is no way they can refer to something different.
There of course are questions that are related to capacitor charging, but they can have the tag charge instead. In common sense, the word charging refers to battery charging, and the few questions about capacitor charging can be re-tagged manually. In my opinion, it's just useless to have the battery-charging and charging tag, while almost everyone adds both to their posts, or only battery-charging since it's more specific.
So I'd say we merge battery-charging and charger anyway, and, but that's more debatable, merge them to charging as well.