[rohrmann]

Assuming you have two batteries paralleled if 12 volts or series if 6 volts. I think the prevailing thinking is any time you have a bad battery, you replace both at the same, because the batteries should be the same to avoid damaging the weaker one. Before you replace a converter, you should check it for operation, so you don't replace a perfectly good converter. If your converter has the smart technology, if there is a need to replace it, the new one should also have that same technology which really does maintain your batteries much better than a standard single mode charger. Many times, if a battery was replaced, and the converter no longer charges properly, there is a possibility that the new battery may have been connected backwards, which will blow the reverse polarity fuses, and just replacing the fuses, along with the battery being connected properly, will solve the problem.