In article ,
says...

I've always been told that short run times creates condensation and acid in the motor oil from incomplete warmup - get her good and hot to drive off moisture. I realize the OP was asking about charging times, but he'd be better served by letting that old Buick idle for a good half an hour every few weeks, or better yet, have OP
take the old girl for a blast.


OTH, Harbor Freight has cheap little float chargers but 120v power
will be needed. A friend uses one of these when out of the country:
https://www.harborfreight.com/automa...ger-42292.html




I am using one of those HF float chargers to hold up a lawn mower
battery over the winter. I really use that battery to power a sprayer
instead of the lawn mower.

My mower is in a shed with out power. I have a small solar cell about
the size of a mouse pad to keep it charged over the winter months.

If starting the mower, I would run it long enough to get the motor and
exhaust system hot. Maybe a 5 ot 10 mile trip to the store and back
once every 2 weeks or so. It will probably do the other parts of the
car some good also.