Are your batteries made in Mexico
Dickeymoore, the fact that they are made in Mexico has nothing to do with it. The PPM data shows that the quality of product coming from Mexico is better than those produced in the USA. In years past I worked for Johnson Controls and still regularly visit the Mexico plant there. Most Optima failures are caused by consumer mistakes (allowing the battery to drain completely, rapid charging, repeated drains, etc)
As many have already said, you must use a battery tender if you want an AGM battery to last. I have 5 Optimas in my vehicles. 2 of them have 7 years plus and show no signs of failure
Read this
https://www.optimabatteries.com/en-us/support/charging/charging-agm-battery