A Generator Worthy of the Leisure Era

Around 1963, the development of the E300 portable generator began in response to the spread of electrical appliances in the home and the arrival of the leisure age. Based on the technology cultivated in developing the E40, output was set at 300 W, which could be used for everything from TV power sources to various power tools. As with the E40, the E300 was developed as a compact, lightweight, and easy to carry generator that was quiet and easy for anyone to use, with styling that looks like a household appliance, and not like a machine.
Although based on E40 technology, the E300’s output was nearly 10 times greater. The first task was to make the engine smaller. This led to designing a 55.2 cc 4-stroke side-valve engine specifically for this purpose. One of the problems that plagued development was that the output side of the crankshaft was occupied by the power generator, so all engine control functions had to be housed on the other side. The magnetic rotor, engine-rotation governor used to maintain constant revs. and the recoil starter, all had to be mounted on the same axis. Furthermore, the key was to position everything, including the muffler, ignition coil, and cooling fan within a small space.

Soichiro Honda’s Key Project

Around the time the drawings were complete, Soichiro Honda suddenly appeared, tossed them into the waste basket, and said the crankcase fastening bolts were in the wrong position, he wanted a smaller case, and the crankshaft was too long. And, split the crankshaft.
This idea of a cantilever split crankshaft was effective in terms of productivity and cost, and had the advantage of integrating the connecting rod. However, the actual prototype could not solve the tapping noise until the end, and the shaft had to be changed to a single-piece type for mass production.
Soichiro had a strong attachment to the portable generator, and in his enthusiasm for the project, he showered the development team with requests: “Don’t ignore the bottom section. You must pay equal attention to areas that are not exposed.” “Give it a warm, accessible look, so that everyone will have a sense of ease.” “Reduce the operating sound and minimize vibration.” Soichiro “wanted to compete with Honda’s rivals by creating something that was new and original.”
As for the design, consideration was given to small details in order to emphasize the product's “gentle image and ease of use.” For example, a round knob design was adopted for all switches. The integrated control that served as both a switch and fuel cock looked exactly like the volume knob of a radio. As for the screws, ideas were incorporated to conceal the head section as much as possible. Throughout its design the team faithfully reflected the advice given by Soichiro, who wanted to minimize mechanical elements and convey an easy-to-use image.

E300 layout in the early stages of development with split crankshaft.

Switches designed to look like a radio’s volume knob.

The Big Hit Defining Portable Generators

Overcoming many difficulties, the revolutionary E300, a portable power generator that could be carried in one hand, was launched in January 1965, and the response was even greater than initially expected. Demand for the E300 for use in lighting night stalls at festivals and fairs spread nationwide at a dizzying pace.
The E300’s compact design and ease of use led to its widespread use in a variety of settings around the world. Initially intended for leisure use, it was also in demand for commercial use, such as construction sites due to its ease of use, and became a big hit, selling a cumulative total of 500,000 units (as of 1980). In addition, with the cooperation of the Electrical Appliance and Material Testing Laboratory at the time, Honda provided a great deal of data for the enactment of laws regarding portable generators with safety in mind, and contributed to improving the safety of portable generators that appeared in subsequent years.

The E300 was not only used for leisure activities as originally envisaged, but also for lighting night stalls, construction sites, and other commercial applications.

Honda Generator catalog showing portable generators that can be carried in one hand.

Lineup Expanded to Meet Diverse Needs

Honda expanded its lineup of generators, while improving output and quietness, as a convenient power source for everything from business use to disaster relief and leisure.
In the 1970s, riding the wave of rapid economic growth, generators were widely used at construction sites. In addition, Quiet operation was required not only for nighttime construction work, which was increasing in urban areas, but also for backup power supplies for hospitals and private use. To meet these social needs, Honda began sales of the high-output, low-noise, soundproofed EM5000, powered by the Life k-car’s water-cooled 4-stroke engine. The EM5000 was so quiet that when it was tested in the middle of the night in front of the development manager’s home, nobody noticed it being operated. With its quiet operation was highly regarded, the EM5000 was widely used not only at construction sites but also at movie and TV production sites. In 1979, Honda launched the EX400 / ED400 which inherited the E300’s basic concept, but was equipped with an automatic voltage regulator (AVR) that increased output and maintained a constant voltage. The EX400, with improved usability, sold more than 100,000 units a year, including overseas, and was nicknamed “Denta” in Japan. In 1987 Honda launched the EX300, based on the concept of a “pochette generator that anyone can easily carry around.” While most portable generators at the time weighed around 20 kg, the EX300 was significantly lighter, with a dry weight of 8.5 kg (J and N models) and a low noise level of 50 decibels despite its 2-stroke engine.

EM5000 soundproofed generator uses Life k-car’s engine.

EX400 also known as “Denta” sold over 100,000 units worldwide.

EX4.5D-ATS developed for use in emergency power outages.

Since Japan is a country prone to natural disasters, the effectiveness of generators as emergency power sources had been attracting attention. Honda launched the E2010 generator for traffic signals in 1987, and was steadily taking initiatives with emergency generators, with 1,000 units installed throughout Japan. Honda also developed the EX4.5D-ATS auto-starting generator in response to the Great Hanshin-Awaji Earthquake of 1995, which paralyzed traffic due to widespread power outages rendering traffic signals useless and greatly hampering emergency services and the transportation of relief supplies. The EX4.5D-ATS was an outdoor stationary generator that automatically started up when it sensed a power outage, and automatically stopped supplying electricity when power was restored. In addition to waterproof specifications that allow for extended operation even in the rain, it was also coated for 20 years of use even when placed outdoors. Subsequently, space-saving and large-discharge models were added, and the “generators not for ordinary use” have been delivered to more than 500 locations throughout Japan, including not only traffic signals but also municipalities and private financial institutions.

Higher Quality for Portable Electricity:
The Sine Wave Inverter Challenge

EX300 with Honda’s first inverter circuit

The EX500, which solved the EX300’s problems and realized a sine wave equivalent to a commercial power source.

Sine wave inverter output

Portable generators are characterized by their small size and simple mechanism, which means that their voltage and frequency are affected by the condition of the engine and the load generated when supplying electricity. However, many electrical appliances are designed for accurate, low-distortion electricity supplied by a large power generator, such as the household power supply, and early generators sometimes caused lights to flicker and equipment to fail.
To solve these problems, Honda took on the challenge of inverter technology. Honda continued to work on evolving the quality of electricity in portable generators. Inverters use electronic control technology to produce a stable frequency and voltage comparable to commercial power sources, and when combined with a multi-pole alternator, can reduce noise and fuel consumption in addition to being lightweight and compact.
Honda’s first generator with an inverter circuit was the EX300 released in 1987, which adopted a three-phase, multi-pole, high-speed power generation system in which a high-speed rotor generated three-phase alternating current in order to stabilize unstable frequencies and improve power generation efficiency. This method did in fact improve power generation efficiency by increasing generation efficiency, producing direct current through a rectifier, and then converting the current to single-phase alternating current with a stable frequency by an inverter circuit. On the other hand, a problem remained that some equipment was incompatible with the “square wave” waveform generated.
The EX500, launched in 1996, realized a sinusoidal waveform equivalent to a commercial power source by incorporating integrated custom integrated circuits (ICs). This sine wave inverter power generation system solved the problem of home appliances not functioning properly due to waveform distortion.

Higher Quality Electricity at the Outlet Level

Since around the end of 1995, precision electronic devices such as personal computers had rapidly spread, and higher quality electricity was required for these products. In addition, in order to respond to the world’s growing environmental problems, generators with lower fuel consumption, noise, and vibration were needed. Against this backdrop, Honda began development of the GENE21 series, a new generation of portable generators featuring a stable frequency, a sine wave comparable to that of commercial power sources, and ease of use such as small size and light weight.
GENE21 series development aimed to achieve many technological breakthrough, to “catch and surpass the wall outlet.”

Establishing a High Quality Generator Brand

GENE21 series EU9i developed for household outlet
level high-quality power generation.

Compact and lightweight due to use of an
ultra-miniaturized high-speed multi-pole alternator

Fuel consumption reduced by the eco-throttle
mechanism. Noise levels have been reduced to
meet European noise regulations thanks to
cube-shaped double layer structure.

In 1998, Honda launched the GENE21 series models EU9i, EU24i and EU28is. Equipped with a high-speed multi-pole alternator and the world’s first microcomputer-controlled sine wave inverter mechanism in its class, the supply of clean waveform power was achieved. In addition, the 1kVA class EU9i achieved the lightest weight in its class at 13 kg by minimizing the alternator and reducing its weight. Honda’s unique cube-shaped double soundproofing structure complied with Europe’s strict noise regulations (EN). Furthermore, adoption of the eco-throttle mechanism that automatically controls engine speed succeeded in reducing fuel consumption by 20% to 40% compared to conventional 1kVA-class products.
The GENE21 series, designed for the 21st century, also features an enriched lineup including models with increased output, ultra-low noise models, and models with electronically controlled fuel injection (PGM-FI). Honda’s “Red Generator,” which continues to mature and evolve, has become synonymous with high-quality in North America, Europe, and other parts of the world where large power output is required for outdoor recreation and air conditioning. Cumulative production of the GENE21 series exceeded 1 million units in 2006.

More Accessible and Useful Generators
With More Readily Available Fuel

Butane-powered ENEPO generator developed to use gas canisters that are readily available and easy to store.

Honda also focused on the fuel used in its generators. In 2010, Honda launched the ENEPO EU9iGB generator, powered by butane canisters, as its second gas-powered product following the Pianta FV200 mini-tiller introduced in 2009. Compared to gasoline, gas canisters are easier to purchase and store. In addition, the foldable handle and large wheels made it easy to move around, and the package design allowed for easy storage, winning the praise of customers new to generators. The EU9iGB succeeded in broadening the user base of small generators as a power source for familiar outdoor leisure activities, and as a backup power source in the event of power outages.
In addition, the effectiveness of portable power generators was established in areas where infrastructure was destroyed in the 2011 Great East Japan Earthquake, to which Honda donated 1,000 ENEPO EU9iGB units. In addition, taking advantage of the lessons learned from the difficulty of obtaining gasoline due to the earthquake, Honda developed the EU9iGP and EU15iGP disaster-recovery generators that run on propane gas, which is relatively easy to obtain, and began supplying them to LP gas companies in June 2014.

The Concept of “Power Source”
Based on Generator Technology

The concept went beyond the small, portable generators Honda had created, and evolved and developed over a half-century as “portable electricity.”
Once a year, the design department at Honda’s Power Products division held an advanced study meeting led by its designers to freely propose their product ideas, regardless of marketability or needs or technological constraints. At this meeting, a “Power Source” concept model based on the E300 portable generator’s design was displayed.
The idea was inspired by news that the Self-Defense Forces had installed generators at evacuation centers and opened them to victims of the power outage caused by the Great East Japan Earthquake. The designers saw many people charging their cell phones in front of a large generator and thought, if only there was one battery in the home that a family of five, for example, could use for about a week to charge their communication devices. They were convinced that Honda had the technology, such as its unique sine wave inverter, improved over many years through generator development, and could create something useful for many people.
It was also around the time when Honda would celebrate its 50th anniversary since launching its first generator, Honda decided to modernize the E300 design, aiming for the size of the prototype E40 partly in homage, with an emphasis on ease of use in the home.

Battling with Weight Reduction

Design sketch during the 2015 Tokyo Motor Show

Bathtub resin monocoque frame houses the
electronic components, and provides high rigidity
and shock resistance.

Initially, the power source was planned with a maximum output of 300 W, and the concept model was given the model name E300, the same as the portable generator released in 1965, but the rapid technological evolution of batteries made it possible to achieve a maximum output of 500 W in the same product size during the development process. While the battery size remained the same, the need for a cooling system catering to the higher output resulted in difficulties in maintaining size and weight.
In 2015, a prototype was exhibited at the Tokyo Motor Show, as a reference model for production. Honda aimed to test the reaction of show visitors. Visitors said the size was just right, but some, especially women, felt it was a bit heavy.
The prototype weighed 6 kg, most of which was occupied by the battery, so there was not much room for weight reduction. In response, the engineers came up with a bathtub-shaped resin monocoque frame, which served as a framework covering the electronic components, achieving high rigidity and impact resistance. Furthermore, the battery, inverter, control panel, and side panels were secured without bolts, and the wiring was laid out so that each component was gathered in the center, eliminating the need for securing mounts. The inverter was also specially designed to be compact and lightweight, achieving a weight of 5.3 kg for the production model, which was more than 10% lighter than the prototype.

“Portable Electricity” with Unlimited Applications

In 2017, the handheld LiB-AID E500 portable power source was complete. The built-in lithium-ion battery could be charged from a household outlet or car accessory socket, maximum output was 500 W and the rated output is 300 W for about 1 hour of continuous operation. Since there are no emissions, it could be used indoors, in cars, even in tents, and was also very quiet, despite it being equipped with an inverter and electric fans for internal cooling. Operation was as simple as connecting an appliance to one of the sockets or USB port and pushing a button. The sine wave inverter enabled use of precision devices such as PCs and smartphones.
Since its launch, the E500 has been used for a variety of purposes. It has been used for outdoor activities such as camping, for example, but it is also used by audiophiles to improve sound quality because of its ability to output electricity with a clean waveform, and by electrical contractors as a power source for checking current leakage in buildings, among other uses beyond what was expected. In response, Honda added LiB-AID E500 for Music, optimized for use with audio equipment (limited to 200 units), and LiB-AID E500 for Work, optimized for various tasks such as electrical equipment inspection, to the LiB-AID lineup, further expanding its possibilities. Honda's generators and power sources supply electricity when and where it is needed. “Portable Electricity” meets a wide variety of needs around the world, and continues to enrich and expand people’s lives.

The LiB-AID E500 power source is expanding its possibilities with models optimized for audio equipment and commercial applications.