PLT ON B734 EXPERIENCED TOTAL DC ELECTRICAL FAILURE AND DIVERTED TO AN INTERMEDIATE ARPT.

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JUST S OF MOUNT SHASTA WE WERE CONFRONTED WITH A 'DC FAIL' LIGHT ON THE #2 IRS. APPROX 2 MINS LATER; WE WERE PRESENTED WITH A 'DC FAIL' LIGHT ON THE #1 IRS. DURING TROUBLESHOOTING WITH THE ABNORMAL PROC CHKLIST; WE OBSERVED THAT THE #2 ENG REVERSER LIGHT ILLUMINATED ON THE OVERHEAD PANEL. THE ABNORMAL PROC CHKLIST FOR THE IRS 'DC FAIL' LIGHTS NOTED THAT EITHER THE SWITCHED HOT BATTERY BUSS IS NOT PWRED OR THAT THE BATTERY IS NEARLY DISCHARGED. THIS WAS CONFIRMED BY A BATTERY READING OF APPROX 18 VOLTS INITIALLY AND DROPPING TO 6 VOLTS IN SHORT ORDER. NO DEFINITIVE CREW ACTION IS DIRECTED BY THIS CHKLIST PROC. THE ABNORMAL PROC CHKLIST PROC FOR THE 'REVERSER' LIGHT ASSOCIATED WITH THE #2 ENG INDICATES THAT A FAULT IS DETECTED IN THE RELATED ENG REVERSER SYS WITH A NOTE ADDING THAT ADDITIONAL SYS FAILURES MAY CAUSE INFLT DEPLOYMENT. THE PROCS CONTINUE BY STATING 'EXPECT NORMAL REVERSER OP AFTER LNDG.' SINCE THERE ARE NO OTHER QUICK REF LISTS RELATED TO ELECTRICAL BUSSES AND WHAT SYS ARE PWRED BY EACH; WE SEARCHED FOR A SYS HANDBOOK TO TRY TO EXPLAIN OUR CONFUSION OVER SEEMINGLY UNRELATED SYS ANOMALIES. WE INITIATED A PATCH WITH MAINT CTL TO ATTEMPT TO GET DEFINITIVE GUIDANCE. I HAD ALREADY DETERMINED TO LAND SHORT OF THE PLANNED DEST. DURING THE PHONE PATCH WE DISCOVERED THAT THE BATTERY CHARGER CIRCUIT BREAKER WAS OPEN. THE CONSENSUS SOLUTION WAS TO DIVERT TO AND LAND IN EUGENE (THE CLOSEST SUITABLE ARPT TO OUR GEOGRAPHIC LOCATION) AND WE WERE ADVISED TO EXPECT NORMAL REVERSER ACTUATION. DURING ALL OF THIS WE ELECTED TO START THE APU AS A BACK-UP SOURCE OF PWR. UPON LNDG IN EUG; NEITHER THRUST REVERSER DEPLOYED AND THE BATTERY DROPPED TO ZERO VOLTS. UPON SHUTDOWN AT THE GATE WE WERE UNABLE TO PWR THE ACFT BECAUSE THE APU DIED DUE TO NO BATTERY PWR. THE CABIN MEGAPHONE WAS USED TO COMMUNICATE TO THE PAX. REMARKS: WHILE WE DID NOT DECLARE AN EMER; WE WERE HANDLED AS AN EMER ACFT BY THE ATC SYS. THE ABNORMAL PROC CHKLIST IS INADEQUATE IN ITS GUIDANCE ON THIS MATTER BECAUSE NOWHERE DOES IT CONFRONT THE REALITY THAT WITHOUT BATTERY PWR THERE IS NO FIRE DETECTION/PROTECTION CAPABILITY. AT THE VERY LEAST THE PROC SHOULD INCORPORATE REMARKS THAT DIRECT THE CREW TO 'LAND AT THE NEAREST SUITABLE ARPT.' FURTHER; THERE SHOULD BE A QUICK REF LIST INCORPORATED IN THE ELECTRICAL SECTION OF THE ABNORMAL PROC CHKLIST THAT PROVIDES A SYNOPSIS OF KEY SYS AND WHAT BUSSES THEY ARE PWRED BY (THIS ALONE WOULD HAVE RAPIDLY ENABLED THE DETERMINATION THAT THERE WAS NO FIRE DETECTION/PROTECTION AVAILABLE). THERE IS SUCH A LIST IN THE MD80.