what battery for trunk?

My Optima is 16 years old this year. But it didn't hold a charge over winter this year.On a $/per year basis, this is the cheapest battery I have ever owned. I mighta paid $160Can(all taxes in) for it, back in 2000.So that would be $10 per year.
The terminals have never needed freshening
Just saying.

Holy cow that a long time. I have a walmart battery going on 5 years old and i thought that was good lol