Hello, I know this seems a silly question, but is it possible to add a charging kit to a 1975 Evinrude 6HP model#6504? I believe there are charging options for these later in the 70s. I love my 6hp, my Yacht has an outboard well and this was the original engine, tried others, but nothing works as well as the old 6hp Evinrude. I am a bit sick off hauling out my battery for charging.