RedactedNarrative: Owner and his wife were operating there all powered electric boat with large battery packs in the stern of the vessel when they smelled burning electrical wires and noticed smoke emanating from underneath the stern hatch leading covering the battery packs.  They opened the rear hatch and saw that the battery packs were on fire about 6 in flames.  They extinguished fire by onboard fire extinguisher and vessel was towed to to shore.  No injuries property damage only.