Feature #1: Electric Start
This feature enables a generator to be easily started without having to pull a starter rope.
Feature #2: Low Oil Shutdown
I would classify this feature as MANDATORY on any portable generator. It shuts the engine down if the oil level drops below a safe operating level.
Feature #3: Idle Control
Automatically throttles down engine when no power is being drawn from alternator. This feature saves fuel, cuts down on noise and reduces engine wear.
Feature #4: Hour Meter
This feature helps with maintenance by keeping a record of how long engine has run. Now you can automatically schedule oil changes.
Feature #5: Large Fuel Tank
If your generator is used for providing backup power during power outages, get a fuel tank with a capacity of five gallons or more. These units can run on average, seven to ten hours before refueling.
Feature #6: Ball Bearing Alternator
This simply amounts to a cheap generator versus a quality generator. The alternators with the ball bearing costs more than the ones with the needle bearings but they last longer.
Feature #7: Brushless Alternator Design
This feature boils down to common sense and pure economics; brushless alternators require less maintenance and produce cleaner power, which is more suitable for today's sensitive electronic equipment. Brush-type generators have brushes that are wear items, requiring replacement.
Feature #8: All-Metal Alternator
How many times have we seen portable generators go clunk because of cheap manufacturing? More than you ever want to know! Stay away from generators that have alternators with plastic housing because they are known to warp over time and cause moving parts within the alternator to come out of alignment, wear excessively and eventually break. Get an all-metal alternator.
Feature #9: Cast Iron Sleeve
If you expect to utilize your generator often or for long periods of time, this feature is absolutely crucial! Hidden in the cylinder of some engines is a cast iron sleeve liner that reduces wear, which makes the engine last longer, which saves you money. The added cost of a generator with a cast iron sleeve in the engine is small and well worth it.
Feature #10: OHV (Overhead Valve) Engine
This technology is suited for portable generators because it produces fewer emissions than side-valve (pushrod) engines, OHV engines start easier, run quieter, and they have proven to last longer.
Feature #11: Full Power Switch
This allows you to switch off the 240 Volt output to get more 120 Volt power from the generator. This feature is useful for starting 120 volt electric motors on air compressors and water pumps.
Feature #12: Portability Kit
Some generators, although portable, seem like they weigh a ton. With a portability kit, (wheels and handles specifically made for that generator) you can move the heavy units around with relative ease.
Feature #13: Total Harmonic Distortion (THD)
Total Harmonic Distortion is a means to measure the quality of the output electricity of a generator. Six percent THD is considered the upper limit for "clean" electricity. Go above 6% THD and the electricity will most likely reduce the life of electrical circuits, cause microprocessors to malfunction and cause furnace controllers to operate incorrectly. A good generator has less a THD of less than 6%. Be warned, some generators produce a THD greater than 15%. Make sure you know what your THD is before you buy.
Feature #13: Brand Name
For some items, brand names won't make that much of a difference, but when it comes to portable generators, brand names such as Honda, Briggs & Stratton, Cummins, etc., are worlds apart from the cheap generator knock offs. You'll save up front money when buying a cheap generator, but on the back end (terrible fuel efficiency, loud noise, breakdowns, high maintenance, etc,) they will cost you much more than a brand name when it's all told.