Before you do anything, swap the charger leads from one of the known good banks to rule out a charger issue. There is a certain threshold level of discharge where the onoard chargers wil not be able to bring a battery up to full charge. If that is the case a good automotive charger may be able to bring it back up. If you have access to one, you can try that, or take the battery to a shop that has a good one. Did you disconnect everything from that battery before you put it into storage to prevent parasitic draw? If you have an opti or Verado and have poles, higher end electronics, use the livewells, etc. then that 1500 barely exceeds minimum requirements for ccas and just meets suggested reserve capacity. If you have to replace it, get a 31 series. If you like Odyssey, get the 2150 which is a rebadged Sears PM 1.