An exemplary charging method includes charging a storage battery of a mule vehicle as a tow vehicle tows the mule vehicle to a stranded vehicle. The storage battery configured to be electrically coupled to a traction battery of an electrified vehicle to charge the traction battery. An exemplary charging assembly includes a mule vehicle. A storage battery of the mule vehicle charges as the mule vehicle is towed to a stranded vehicle. The storage battery is configured to be electrically coupled to a traction battery of the electrified vehicle to charge the traction battery.