So here it is 6 years later, and this thread helped me out! I added an Isotherm 2501 cold plate to the icebox on my O'Day 322, which is kept on a mooring. I added 2 100watt solar panels and an MPPT controller, and it's been working great keeping water, beer, gatoraid and some condiments cold 24/7 for 2 seasons. At Rod's suggestion (Maine Sail) I went with a Trojan T1275 house battery. great!
Then we had a big front roll through a few weeks ago, and one of my solar cables came loose from the connections outside. 3 days later I was at the boat, and of course, cold plate running for 3 days with no charging. Battery was down to 10 v and change, pretty much dead. My ACR saved my start battery. So, I was researching adding a resistor to the coldplate circuit as shown by Isotherm.
But, I'm ordering me a Blue Sea m-LVD as soon as I'm done posting this, and leaving it at its factory 12.1 VDC. Although I've secured the cables better, I'd rather come out to the boat to warm water and beer than a $350 battery that I need to replace.
Thanks, all!