I have a 10+ year old 6v Optima (Sealed Absorbed Glass Mat, AGM, battery) battery in my 1954 Suburban.

I do not trickle-charge/maintain it over the winter - it starts up te Suburban every Spring (up north, that is - I drive the Suburban over the winter in NC).

I have a 6v battery minder/tender, but I have never used it.