A 12 volt automotive wet cell battery is fully charged at 12.5-12.6 volts. 12.2 volts is less than 25% charged. A battery showing 12.5 volts should not drop below 9.6 volts after a load of 50% of the cold cranking amps (CCA) applied at 70 degrees F. for 15 seconds. This load test is probably the best to discern your true battery condition. That said, I found the correct replacement batteries at NAPA without freight. About $160 each with my discount. They had been stored a while, not a high turnover item. I spent another $9 to add electrolyte. As to the smaller battery recommendation, I live in Montana; 9 months of winter, 3 months of poor skiing so I went with the OE replacements.