A B737-300 EXPERIENCED TOTAL LOSS OF MAIN SHIP'S BATTERY PWR.

Narrative

AFTER 1.5 HR DELAY FOR STARTER AND THEN START VALVE CHANGE; WE HAD RECENTLY LEVELED OFF AT CRUISE; WHEN THE #1 IRU DC FAIL LIGHT ILLUMINATED; FOLLOWED SHORTLY BY THE R IRU (INERTIAL REF UNIT) DC FAIL. COMPLIED WITH QRH. DC SYS APPEARED NORMAL. AFTER 1 HR OR SO THE CLOCKS BOTH FAILED AND MORE CHKS REVEALED THE BATTERY WAS DOWN TO 6 VOLTS. MAINT WAS CONSULTED TWICE BY AIR PHONE DURING THIS EVENT. AFTER LNDG SEVERAL SYS WERE INOP; WE HAD NO PA AFTER ENG SHUTDOWN AND THE EXTERNAL PWR WAS NOT ACCEPTED. WE WERE NOT PARTICULARLY CONCERNED BECAUSE EVERYTHING EXCEPT THE IRC 'DC FAIL' AND CLOCKS WERE OPERATING NORMALLY. HAD WE REMEMBERED THAT WE HAD NO FIRE PROTECTION; ONLY 1 REVERSER WOULD DEPLOY AFTER LNDG; THE AUTOPLT DISENGAGE LIGHT AND ALARM COULD NOT BE SILENCED UNTIL LNDG; GND PWR WOULD NOT CONNECT TO THE ACFT AND NO PA WAS AVAILABLE OR VHF RADIO AFTER SHUTDOWN WE'D HAVE BEEN A LITTLE BETTER PREPARED. A NOTE IN THE QRH TO THE EFFECT OF 'IF THESE LIGHTS COME ON YOUR BATTERY IS GOING DEAD -- HERE'S A LIST OF WHAT YOU DON'T HAVE AND WON'T HAVE AFTER LNDG' WOULD BE USEFUL. ALSO; I WOULD BE EXPECTING A LITTLE MORE EXPERTISE AND HELP FROM MAINT. I AM ALSO HOPING THAT THE MAINT TECHNICIAN DIDN'T KNOW THAT WE WERE WITHOUT FIRE PROTECTION OR DIDN'T MENTION IT FOR CONCERN THAT WE MIGHT DIVERT AND LAND SHORT OF OUR DEST.