Deka DC31DT battery? Deep Cycle?

MrWizard wrote:
The problem is numbers and the way they are expressed.

For comparison purposes between different makes / models of batteries the 20 HR rate is the most commonly used and as valid as any. However, anyone who takes that 20 HR rate and automatically assumes that simple math will tell them exactly how long the battery will last when drawn down to 50% SOC will be sorely disappointed as no battery will deplete in a linear manner but will vary considerably as the total load varies. Interestingly, while the OP has been agonizing over which batteries to purchase he hasn't said a word about what charger he's using to maintain those batteries, which is critical if he expects to maximize the life of any battery he may invest in, particularly if he opts for AGMs or Gels instead of flooded. :R