Most commercial lawn trimmers cut grass with a spinning nylon strings, although some models use reciprocating blades. Gas trimmers are powered both by two-cycle and four-cycle engines; there are advantages and disadvantages for each. Electric lawn trimmers are both run off alternating current electricity supplied with a cord and direct current from batteries.
Two-Cycle Gasoline Trimmers
Trimmers with two-cycle gasoline engines are more powerful than electrical models and come with more attachments. Many models have spring-loaded starter systems that make them easier to start. Gasoline trimmers are more mobile than electrical models that require cords to be carried with them.
Four-Cycle Gasoline Trimmers
Trimmers with four-cycle gasoline engines are more powerful than those using a two-cycle engine. They are good for commercial use or large trimming jobs. They do not require users to mix oil and gasoline, and they get 30 percent more fuel efficiency. Four-cycle models are somewhat more quiet than trimmers powered by two-cycle engines, and they meet the emission standards of the Environmental Protection Agency and the California Air Resources Board.
Gasoline Trimmer Disadvantages
Gasoline trimmers make more noise than electrical models. They are more expensive than trimmers powered by electricity, and they require more care and maintenance. Two-stroke models are especially noisy and may pollute the air with a smelly, bluish smoke. Gasoline trimmers require the transport and storage of inflammable gasoline.
Electric lawn trimmers are quiet and so are less offensive to neighbors. They are less expensive than trimmers run by gasoline engines. They are also lighter, easier to start and generally easier to use. They require less maintenance than gas-operated trimmers.
The more powerful electrical trimmers run off alternating current from a cord. They are best for use on lawns within 100 to 150 feet of an electrical outlet. Cordless powered trimmers using direct current are good for small lawns, but they don't have as much power as those that operate from a cord. They are only good for about 45 minutes before the battery needs recharging. Battery-operated models are heavier than those that run off a cord.
Electrical Trimmer Disadvantages
Electric lawn trimmers do not have as much power as gas-operated models. Some gardeners find it annoying to drag a cord around. They are not good for large lawns or tough jobs. Having to carry a cord makes them more difficult to transport.