Sec.  80.915   Main power supply.

   (a) There must be readily available for use under normal load conditions a
   main power supply sufficient to simultaneously energize the radiotelephone
   transmitter at its required antenna power, and the required receiver. Under
   this load condition the potential of the main power supply at the power
   input terminals of the radiotelephone installation must not deviate from its
   rated potential by more than 10 percent on vessels completed on or after
   March 1, 1957, nor by more than 15 percent on vessels completed before that
   date.

   (b) When the main power supply consists of batteries, they must be installed
   as high above the bilge as practicable, secured against shifting with motion
   of the vessel, and accessible with not less than 26 cm (10 in.) head room.

   (c) Means must be provided for adequately charging any batteries used as a
   main power supply. There must be a device which gives a continuous
   indication of the rate and polarity of the charging current during charging.

   [ 51 FR 31213 , Sept. 2, 1986, as amended at  58 FR 44953 , Aug. 25, 1993]