O.E. battery lasted just short of 11 years. Because all places I called wanted to "dumb down" the battery for our C70 Convertible to a group 47 instead of the larger (original) group 48, I succumbed to buying a group 48 Exide Classic 48-60 @ a local BJ's Wholesale Club because they had brand new, clean, fresh stock in this size and easy self-service.

Less than 1 year later, Car won't start w/o help from a portable jump starter. My charger shows battery is fully charged out of the car. I'm going to reinstall in a day or so, but
1) could it be this battery can't take the load?
2) how do I convince them @ the store if I go to one further away that has a tire/battery center?
3) should I just call it quits on Exide and call around until someone has an Interstate in Group 48?
4) other ideas? I'm not expecting anything other than perfect if I check the charging system (13V running) since battery shows fully charged even 2 months later.

Thanks all!