A C210 pilot reported a total electrical failure while in IMC in the vicinity of btr.

Attributes
ACN	570238
Time
Date	200212
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	navaid : btr.vortac
State Reference	LA
Altitude	msl bound lower : 4000 msl bound upper : 6000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : btr.tracon
Operator	general aviation : personal
Make Model Name	Cessna 120
Operating Under FAR Part	Part 91
Navigation In Use	other
Flight Phase	cruise : level
Route In Use	enroute airway : v70.airway
Flight Plan	IFR
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : multi engine pilot : commercial pilot : instrument
Experience	flight time last 90 days : 20 flight time total : 3000 flight time type : 50
ASRS Report	570238
Person 2
Affiliation	government : faa
Function	controller : approach
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	aircraft equipment other aircraft equipment : ammeter other flight crewa
Resolutory Action	flight crew : overcame equipment problem other
Consequence	other
Supplementary
Problem Areas	Aircraft Maintenance Human Performance
Primary Problem	Aircraft

Narrative:

The alternator failed in IMC while on an IFR flight plan from btr to dwh which caused an electrical failure. There was an undercast and low ceilings along the route with clearing WX expected from the west at the ETA. A handheld radio was on board for use during such sits, so radio contact was re-established with ATC. However, the range was limited, so there were some periods when contact was lost momentarily. A battery pwred GPS was also on board for such sits, so navigation along the airways proceeded without difficulty once the situation was assessed and under control. ATC called houston approach for permission to enter the mode C perimeter and class B airspace without a transponder and the flight continued without further incident. As I approached dwh, I had been told to expect runway 17, so was momentarily confused when instructed by the tower to enter a downwind for runway 35. A jet had been cleared for takeoff, so the tower controller was rather firm in reiterating 'turn south now for runway 35,' but the jet had just started its roll and I turned to downwind well before reaching the runway. I used to fly this plane as a rental 6-7 yrs ago before the FBO sold it to a local pilot. I bought it several months ago and had been flying it without incident until the week before when the alternator needle stuck to the side of the case making it appear that the alternator had failed. It checked out ok and the local mechanic who has flown and maintained the plane for about 10 yrs reported that he changed the alternator a few weeks ago and there had been some ongoing problems with the indicator, but the alternator and regulator worked fine. The remedy was to tap the case which would free the needle from the side of the case. On this occasion, the needle stuck to the side of the case, but came free when the instrument was tapped after leveling off. The needle was close to the zero indication, then power was lost. The remedy was to replace the voltage regulator at dwh. A voltmeter and improved ammeter will be installed during the next annual, or before. An external antenna for the backup radio will also be installed.

Original NASA ASRS Text

Title: A C210 PLT RPTED A TOTAL ELECTRICAL FAILURE WHILE IN IMC IN THE VICINITY OF BTR.

Narrative: THE ALTERNATOR FAILED IN IMC WHILE ON AN IFR FLT PLAN FROM BTR TO DWH WHICH CAUSED AN ELECTRICAL FAILURE. THERE WAS AN UNDERCAST AND LOW CEILINGS ALONG THE RTE WITH CLRING WX EXPECTED FROM THE W AT THE ETA. A HANDHELD RADIO WAS ON BOARD FOR USE DURING SUCH SITS, SO RADIO CONTACT WAS RE-ESTABLISHED WITH ATC. HOWEVER, THE RANGE WAS LIMITED, SO THERE WERE SOME PERIODS WHEN CONTACT WAS LOST MOMENTARILY. A BATTERY PWRED GPS WAS ALSO ON BOARD FOR SUCH SITS, SO NAV ALONG THE AIRWAYS PROCEEDED WITHOUT DIFFICULTY ONCE THE SIT WAS ASSESSED AND UNDER CTL. ATC CALLED HOUSTON APCH FOR PERMISSION TO ENTER THE MODE C PERIMETER AND CLASS B AIRSPACE WITHOUT A XPONDER AND THE FLT CONTINUED WITHOUT FURTHER INCIDENT. AS I APCHED DWH, I HAD BEEN TOLD TO EXPECT RWY 17, SO WAS MOMENTARILY CONFUSED WHEN INSTRUCTED BY THE TWR TO ENTER A DOWNWIND FOR RWY 35. A JET HAD BEEN CLRED FOR TKOF, SO THE TWR CTLR WAS RATHER FIRM IN REITERATING 'TURN S NOW FOR RWY 35,' BUT THE JET HAD JUST STARTED ITS ROLL AND I TURNED TO DOWNWIND WELL BEFORE REACHING THE RWY. I USED TO FLY THIS PLANE AS A RENTAL 6-7 YRS AGO BEFORE THE FBO SOLD IT TO A LCL PLT. I BOUGHT IT SEVERAL MONTHS AGO AND HAD BEEN FLYING IT WITHOUT INCIDENT UNTIL THE WK BEFORE WHEN THE ALTERNATOR NEEDLE STUCK TO THE SIDE OF THE CASE MAKING IT APPEAR THAT THE ALTERNATOR HAD FAILED. IT CHKED OUT OK AND THE LCL MECH WHO HAS FLOWN AND MAINTAINED THE PLANE FOR ABOUT 10 YRS RPTED THAT HE CHANGED THE ALTERNATOR A FEW WKS AGO AND THERE HAD BEEN SOME ONGOING PROBS WITH THE INDICATOR, BUT THE ALTERNATOR AND REGULATOR WORKED FINE. THE REMEDY WAS TO TAP THE CASE WHICH WOULD FREE THE NEEDLE FROM THE SIDE OF THE CASE. ON THIS OCCASION, THE NEEDLE STUCK TO THE SIDE OF THE CASE, BUT CAME FREE WHEN THE INST WAS TAPPED AFTER LEVELING OFF. THE NEEDLE WAS CLOSE TO THE ZERO INDICATION, THEN PWR WAS LOST. THE REMEDY WAS TO REPLACE THE VOLTAGE REGULATOR AT DWH. A VOLTMETER AND IMPROVED AMMETER WILL BE INSTALLED DURING THE NEXT ANNUAL, OR BEFORE. AN EXTERNAL ANTENNA FOR THE BACKUP RADIO WILL ALSO BE INSTALLED.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.