You say you checked the charge level using your charger? How does that work? Have you checked the battery's resting voltage? If it's 12.6 or 12.7 it should be fine.
In my opinion Optima batteries are overpriced for what they are. I've installed hundreds of Deka batteries over the years along with lots of Rolls and Lifeline. I've had very good results form all of them.
You have just one battery but use it to power an inverter running a coffee maker? That is very hard on that battery. If you have a 1,200 watt coffee maker I would think you would want at least 600 AH of battery hooked to the inverter.