On July 15, 1994, about 1130 central daylight time, a Cessna 180, N333QB, sustained substantial damage in a forced landing near Battle Lake, Minnesota. The pilot reported a total loss of engine power. There were no injuries to the commercial pilot or the two passengers aboard the airplane. The personal flight originated at Forest Lake, Minnesota, at 1015, with an intended destination of Battle Lake. No flight plan was filed, and visual meteorological conditions prevailed at the time. The mechanic who examined the airplane stated he drained about 1.5 to 2 gallons of fuel from the left wing, and no fuel from the right wing. Each fuel tank has 2.5 gallons of unusable fuel. Both fuel tanks were placarded 32.5 gallon capacity, but were actually 30 gallon tanks. The pilot stated he made his fuel calculations based on the 32.5 gallon capacity placarded on each tank. The engine started and ran normally when fuel was supplied.