Narrative:

Departed ZZZ airport after maintenance had been performed on the aircraft. Taxi; run-up and departure all seemed normal. In cruise flight; the ammeter needle became erratic and the charging system showed abnormally high voltage. Then the smoke started and was increasing in intensity when I shut off all electrical power. With no radios and increasing smoke; I made an emergency landing at ZZZ1 with no radio calls and against flow of traffic. Conditions were good VFR and I could see that there was no traffic conflict. Had a traffic conflict arisen; I could have flown a normal pattern but due to the emergency condition; I elected to land as soon as possible.

Google
 

Original NASA ASRS Text

Title: C182 EXPERIENCED ELECTRICAL SMOKE IN FLT. PLT SHUT OFF ELECTRICAL SYSTEMS AND DIVERTED TO UNCTLED ARPT.

Narrative: DEPARTED ZZZ ARPT AFTER MAINT HAD BEEN PERFORMED ON THE ACFT. TAXI; RUN-UP AND DEP ALL SEEMED NORMAL. IN CRUISE FLT; THE AMMETER NEEDLE BECAME ERRATIC AND THE CHARGING SYSTEM SHOWED ABNORMALLY HIGH VOLTAGE. THEN THE SMOKE STARTED AND WAS INCREASING IN INTENSITY WHEN I SHUT OFF ALL ELECTRICAL POWER. WITH NO RADIOS AND INCREASING SMOKE; I MADE AN EMER LNDG AT ZZZ1 WITH NO RADIO CALLS AND AGAINST FLOW OF TFC. CONDITIONS WERE GOOD VFR AND I COULD SEE THAT THERE WAS NO TFC CONFLICT. HAD A TFC CONFLICT ARISEN; I COULD HAVE FLOWN A NORMAL PATTERN BUT DUE TO THE EMER CONDITION; I ELECTED TO LAND AS SOON AS POSSIBLE.

Data retrieved from NASA's ASRS site as of January 2009 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.