Albert,
You might want to try an old drag racing trick with your battery cables, and add a battery kill switch in the trunk. You can shut down the battery when you park the car in your garage. It will not let you use the alarm system though, as all battery power will be gone, but your battery should last longer. Another thing, do you drive in 5th or 6th gear at all? If you do, you are not charging the battery enough, unless you go on longer trips. Just a thought. You also may want to add a trickle charger and plug it in whenever the car is in the garage, then you can leave the alarm on if you want to, or just let it keep the battery charged up all the time. Some can mount permanently next to the battery. Hope you solve the problem, sounds like you are keeping Optima in business!