Best converter?

RJfishin: I'm just over the hill and need a new converter. Do you install??? Just kidding, but I am going to need to get on with it and get a new converter. Right now I am using a battery charger that my late husband wired in, but I am having problems with the batteries under the hood as well as the battery for the housing part of the RV. Since I don't use it a lot I would like to find a good used one. I bought a used one just like the one that my hubby took out only to do a little research on the internet (isn't the internet wonderful, thank you Mr. Gore) and found that it kills batteries. Now I am back to looking for another one. Any thoughts would be great. I do shop on eBay. Next time you head to the dunes, wave as you go by!!!