House DC on AC Shore Power?

[clearsea]

Our last boat had a shore power battery charger that seemed to have no problem both charging the batteries and supplying enough DC house electricity. Not so the new shore power charger I just installed in our 20s' foot sailboat. The charger, I found out too late, is the type that can only charge the batteries, but not keep up with DC house loads at the dock on shore power. I did not know about this issue until after the install, clarified when I called the company.

So, instead of buying a more expensive batter charger and wasting the one I have, can I just add an AC-powered device in addition to the battery chager that will allow the battery charger to do its thing with the batteries, but separately supply DC house loads from AC shore power directly to the DC distribution panel independantly of battery charging, preventing the batteries from being discharged to supply house loads? Am I looking for a recitfier or swithchable power supply?