Battery corrosion on painted parts

A sealed battery might have a different charge voltage. Some smart chargers have settings for flooded lead acid AGM and gel VRLA. I think AGM and gel float lower, around 13.5V. Something to think about if your cars regulation is running high. Then there are smart batteries with charge and discharge management built in. Might be time to readup up battery, and use voltmeter and monitor what charger is doing.
As others suggest, some chargers are junk, unregulated. In the summer my line voltage reads up to 132V, instead of more typical 117V. An unregulated charger will run high too.