Well fixed the gas problem, and here we are back to the boat and charger problem

It looks like the original item. Never had any issues. Today when we got there had couple lights on, and blower in engine bay running. about an hour or two later I went back in and noticed all lights were out. checked and there was power to the boat from dock, so all outlets were on. And banks selector normally I keep on "BOTH" but was left on house battery (2) luckily. So battery was dead, as it was not charging (Batteries are new, got them earlier in the season. So I am no electrician, but assumption is charger is not charging. I switch to main battery, all lights get back on. But did not want to drain that battery and not be able to charge it back up. So I let it be. Started looking for the replacement battery Charger "121805eg c-charger 5000 series 20 amp". I am sure it is no longer made and do not want one from eBay that may or may not work, or worst yet may have electrical problems. So question for you all is anyone replaced this exact same charger with another? what is recommended, for easy swap of old and new for a non-electrician as me. Granted, I have done many electrical work around the house. Appreciate any inputs anyone may have on this, thanks in advance.