SD knows what he is talking about. The answer is yes, an echo charger will do what you want. Keep doing your homework and sometimes you will find that you spent some money that could have been better spent, just ask me
Fortunately I have not bought the AC charger yet, so I am only out the $80 I spent on the Flexcharge unit. I am glad I sought the advice of this forum before getting any deeper into this project.
Right now my outboard is connected to the starter battery. I am assuming that if I go with the echo charger arrangement that I should connect the outboard to the house bank and let the echo charger handle this arrangement to. Or maybe this is too complicated an approach to handle the occasional 6 or 8 amp output of the outboard generator.