Years ago I had a Optima red top in my Pantera and it ran down. I tried charging it with my home charger and I couldn't hold a charge. I went back to a lead acid battery. I didn't know that typical home battery charger could not charge a run down Optima. Go to Optima's web site. There's very specific charging instructions. It's not the same as a lead acid battery and the typical home chargers can't do it. I accidentally ran down my 6 year old red top that's in my hot rod and took it to an Interstate shop. The shop manager was familiar with them and charged the battery at no cost.