The word "chargings" is spelled with the letter "s" at the end because it is a verb in the present participle form, which always ends in "-ing." The spelling of this word can be explained using IPA phonetic transcription as /ˈtʃɑːrdʒɪŋz/ with a stressed first syllable "chah-rj-ings" and a voiced "z" sound at the end. This word refers to the act of charging, as in "The battery is chargings" or "His charging of the enemy’s position was incredibly brave."
The word "chargings" is the present participle form of the verb "charge". The etymology of "charge" can be traced back to the Old French word "charger" which meant "to load, burden". It has further origins in the Late Latin word "carricare", which carried the same meaning. From there, it can be traced back even earlier to the Latin word "carrus", meaning "cart" or "wagon". The word eventually made its way into Middle English and took on the sense of "to command" or "to entrust with responsibility". The present participle form "chargings" continues this lineage and refers to the act of charging or the process of entrusting someone with a task or responsibility.