Delco-Light Plants

photography — Early Commercial for Delco-Light Plant. Public Domain.

The Delco Light is a milestone of early electrification known only to Americans. It was a system which consisted of a power generator, a battery and the lamps. It was manufactured by the Dayton Engineering Laboratories Co. (Delco). It was primarily intended for use in farms.

The system was invented by Charles F. Kettering. He was born in 1876 on a farm in Loudonville, Ohio. He was mechanically gifted and a good student, and graduated from Ohio State University with a degree in electrical engineering. After starting at National Cash Register (NCR) in Dayton as an experimental engineer, he developed the first electric cash register. In 1909, he left NCR and founded the Dayton Engineering Laboratories Co. (Delco) with two others. While helping a friend build a car, he had perfected the high voltage ignition system for automobiles. This was a vast improvement over the low-voltage systems then in use, and the basis of the new company. But Kettering was a prolific inventor and went on to develop a reliable electric starter for car engines. With this invention, the 1912 Cadillac was the first car that did not need to be cranked by hand to start.

Although electric light was already widespread in cities at that time and many people already had electric light, things were different in the countryside. On farms, oil lamps and lanterns, hand water pumps and outhouse toilets were common. The Delco Light system was intended as a decentralised power supply for farms, but was also used by other businesses. In 1916, Delco introduced the system, and over time the product range was expanded to 25 models with a power output between 500 and 3,000 watts.

The electricity was generated by a motor with generator and then stored in lead batteries. When the charge level of the batteries fell below a preset value, the engine started automatically and switched off when the batteries were charged. This way, the generator only worked when it was needed and fuel consumption was minimised. Through a combination of Delco's various inventions, the system was extremely low maintenance. The owner only had to refill the fuel tank. In addition, the oil level in the engine and the acid level in the batteries had to be checked regularly. The system was largely automatic, a basic requirement for use on a farm. At that time, agriculture was not yet mechanised and the necessary know-how was not available.

The Delco Light units were very compact. An average Delco unit produced a total of 750 watts at full load, which was enough to run 15 50-watt light bulbs. The air-cooled single-cylinder engine had 1.5 hp and a 20-litre petrol tank. The large lead-acid batteries were open and contained in clear glass jars. They were arranged in banks of 16, usually in wooden boxes or on shelves along one wall. Each battery gave off 1 to 2 volts, and the 16 batteries were connected in series to give 32 volts DC. The generator was used as the starter, but there was a separate 6-volt battery for starting.

Delco salesmen visited a farm at dusk. Their vehicles were equipped with a portable Delco Light system. As consumers they had a few lamps, a water pump and a coffee machine. They lit the barn, pumped water and finally brewed coffee for those present. A good kaffee was probably more important for the sales success than the claim that the life span of the engine was 42 years.

Kettering sold Delco to General Motors in 1918 and became head of General Motors research. The invention of the radio and the Frigidaire, a refrigerator manufactured by Delco, increased demand. In 1928, General Motors informed its shareholders that more than 350,000 Delco Light units had been sold. But in 1935, President Franklin Roosevelt created the Rural Electrification Administration. The Rural Electrification Act of 1936 provided the funds. Over the next two years, $210 million was spent to lay 160,000 kilometres of power lines and provide electricity to 220,000 farms. A power connection still cost about $950, which would be about $16,000 today. Therefore, Delco continued to be run by General Motors for many years, but the end was inevitable.

We have created this detailed description because Delco-Light are completely unknown outside the USA. But in the USA they were very popular in show caves in the 1920s and 1930s. With them, even the most remote cave could be equipped with electric light at a manageable price. They were low-maintenance and durable, and there was also a second-hand market.