Educate me on 12 volt batteries

philh wrote:
6V or even lithium generally require a charger upgrade

lithium does require a different charging profile , but any flooded cell or AGM lead acid charger doesn't care if what configuration of 12V battery you have, they all have 6 cells in series. either 6 in once case or 3 each in two cases, or 6 individual 2V cells in series. It's all the same.