At 1414hr a 7m boat with 4 POB reported that it had a battery problem and required a jump start or tow. The boat was positioned between Tasman Reef and Matata. Sea conditions were good with a 7-10kt wind from NE and a calm sea. An all stations alert was transmitted and later Whakatane Rescue was called out.  However, before Whakatane Rescue was launched, a good samaritan who had a spare battery and was leaving Thornton, offered to assist. At 1501hr the good samaritan was alongside the boat and transferred the spare battery. Many thanks to the good samaritan.