I might charge the battery and do a load test on it before trying to use it the first time next spring. You might also consider turning the engine over by hand when you stop using it. In the late fall.

Then before anything else see if it can be turned over manually as easily as it was next spring. . For example you could have even the alternator sticking after a winters vacation. Usually in my experience it take a longer period on average for engines to stick. Especially diesels. There are of course exceptions.

Another concern is some coolant might be leaking into a cylinder very slowly and rusting up a cylinder making it tight. You could drain the coolant each fall to avoid that possibility. It would not take much internal leakage to cause an issue.

Also the modern battery or most of them really do not tolerate non use that well. At least in my experience. Still all things considered I do not suspect your battery especially. Yet it still could easily be the candidate.

There may be climate issues in my region that make my experience with batteries not that great. This year was exceptional in that our lawn tractor batteries were still good. Both are a few years old now.

Actually other members will probably have more realistic ideals.

I should include a word of warning. In my experience letting the newer cars sit unused. Too many of them will seize their alternators. I think the clearance between the rotor and stator has been reduced over the years. Increases efficiency but adds an issue.

Probably not an issue in a dry climate. It is a very real one on the east coast of Canada. With certain brands of cars you can almost count on this occurring beyond a couple of months of non use.

Perhaps I should also add. A fully charged battery may read 12.75 volts. That is just a confirmation that the battery is fully charged. It in no way gives you any indication of what amount of current is stored. For example a badly sulfated battery could read 12.75 volts. Yet could not crank and engine. It just is unable to deliver enough current.

Absolutly nothing is written in stone. I had a parts lawn tractor sitting around for about five years. I do not know why I tested the battery after that much time. It was not too bright to think it might still be good.

Suprisingly it was. I just went and looked at it. It is a workaholic by interstate. Two hundred and thirty cold cranking amps. I posted this information because there is a very slight chance it might be a better battery. It should have on average again been bad.