Terry : I believe that I'd spend the money for a new charger, specifically a Xantrex True Charge 20 or 40 amp. (Look in Defender for the best price)
See what you get back in other equipment from the company that you bought the refurbished chargers from. I doubt they will refund money, but might give you a credit toward another equipment item that you might need for the boat.
I wouldn't leave any charger plugged in while I was away and not on the boat. Good luck.
