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

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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]