The former Eastbourne Borough, Dover Athletic and Staines Town striker joins the squad after impressing on a trial period.
Charles has twice played for his country, in two qualifiers for the 2014 World Cup, against Belize and Saint Vincent and the Grenadines.
Manager Alan Dowson was pleased to be able to add the striker to his squad.
"We have had a number of lads down on trial but Elliott has stood out," Dowse said.
"We're on a great run of form and I don't want to sign someone for the sake of it, but he has earned it and I look forward to seeing him play."
Charles is available for selection on Saturday for the visit of East Thurrock, and we hope he enjoys his time at the Bev.