I was wondering about how expensive it is to generate electricity with my pickup truck to power my accessories in the evening compared to the 16 cents a killowatt hour electricity I have at home from National Grid (including the 1.8 cent a killowatt hour surcharge for wind-hydro power).

Figuring…

The inverter and wiring has a maximum output of 800 watts. In an hour, it can produce up to 0.8 a kilowatt hours of electricty.

The truck battery has a reserve capacity of 120 minutes at 50 amps draw at 12 volts.

Gas is $2.75 a gallon. A Ford Ranger uses approximently 1/2 oz of gasoline per minute idle, and it takes 256 minutes or 4 hours, sixteen minutes idling per gallon.

Idle the truck 20 minutes an hour to keep the battery charged. That means each hour it uses 10 oz of gasoline, or 1/12 a gallon of gasoline.

Adds up to…

About $1.50 a kWh for electricity. While it takes more then hour to produce that killowatt hour energy, that’s what the net cost is. It’s 10 times the cost of utility plant, but that’s to be expected.

A pickup truck’s engine and alternator is not designed as a dynamo to efficently generate electricity. The primary goal of the alternator is keep the battery charged up, and the battery is designed mostly to provide a high amperage output to the starter, to quickly spin a cold engine with significant resistance from congealed oil in the winter.

Alternators are at best 50-60% efficent at converting engine power to electricity, and that’s on top of an engine that is probably about 20% efficent at putting power to drive line. That means the entire system is about 10% efficent, far below the 30-40% that most utilities can create electricity at.