Mine is a 535 CCA 6V from a farm supply store, 3 years old, I keep it on a battery tender over the winter, put it on a charger for a few minutes in the spring, and make sure to check the electrolyte with a bulb tester in fall and winter.
Here is an inexpensive battery load tester.
https://www.harborfreight.com/100-am...ter-61747.html