Just a followup, in case anyone is interested...
I replaced the batteries with 2 EGC2's. Batteries Plus had a fantastic price.. I ended up getting the two batteries for $99 each before tax.
Tried them out again this weekend... and had almost the same result. The lights would get dimmer and dimmer for about 5 minutes, then the converter fan would run and they would get bright again, 5 minutes later they would be dim.
So I checked the voltage at my batteries: 12.47v. Checked it at the converter terminals: 12.47v. Started the engine and checked the battery again: 13.20v.
So pretty obviously I have a converter problem. Ordered a Progressive Dynamics 60 Amp RV Converter Charger W/Charge Wizard PD9260CV. Expected to arrive next Wednesday, should be a simple remove and replace as my current converter is already a deck mount.
