I had the same problem with my Optima Red Top. I just brought it in out of the car and hooked it up to a trickle charger and it wouldn't charge. I contacted Optima and they said they would replace it under warranty. But, I found on their website that they recommend you charge the battery hard if they get completely discharged. So, I took it to a friends who had a starter/charger and we charged it at 10 amps and it came back to life. It's holding a full charge for me now. I'm going to put it back in the car and see if it continues to work the rest of the summer. Something for you to try.