Section 8(1) in The Merchant shipping (Radio Direction Finders) Rules, 1968.
(1)If Batteries are provided as a source of electrical energy for the radio direction-finder, means shall be provided on every ship for the charging of such batteries from the ship's main source of electrical energy. The master of the ship shall cause to such batteries to be tested once a day by Voltmeter and once a month by Hydrometer, and shall cause any battery which is found not to be fully charged to be brought up to that condition as soon as possible.
