I have a Genesis setup with dual Odysseys. In my blissful ignorance, I thought that because they were deep cycle batteries that I could leave them connected and unattended for 2 months this past winter... parasitic draw be damned. After failing to start my JK I was able to bring them back to 12.8V, however they would both drop back to 12.2V overnight. Thankfully my point of purchase replaced both batteries under warranty NQA. I have since learned that "Whenever any lead-acid batteries (including AGM batteries) are discharged below 12.4 volts, sulfation will begin to form, which diminishes both capacity and lifespan," (optimabatteries.com, Basic Information on Battery Voltage). Now if my JK stays parked for more than a few days, I connect the batteries to a multi-step charger and/or disconnect them from the vehicle.