Electric Generators

Brooke Clarke 2001 - 2020

My Generator
    Generator Interlock Kit
    L14-30 Extension Cord
    Power Back Alarm
    Ramps for Honda Van
    Gas Cans
    Fuel Stabilizer
    Honda EU7000iS
Solar AA Charger & USB Power Source
Solar USB Phone Charger
Generator Modes of Operation
Fuel Choice
Fuel Consumption
Honda Generator Codes

My Generator

2019 December 20

Since the highest load I've seen on the Honda EU7000iS has been a little over 4kW I've been looking into using a smaller generator to power the house.  The NEMA 5-15P to L14-30R adapter looked like an easy way to use a couple of the EU2200i generators to power my house.  BUT, the adapter is rated for only 1875 Watts, i.e. the rating for the NEMA 5-15 plug.

NEMA 5-15P
                  to L14-30R adapter
This adapter will NOT work to combine a pair of Honda EU2200i generators since the power is limited to that of the 5-15 plug, i.e. 1800 Watts.  See 1-Phase below.

It can be used with a single phase 120 Volt generator to power both phases of a house by shorting them together.  This would be an excellent way to power a house using the EU2200i generator where the total load of the house is within the capability of the generator.  This requires using an interlock or transfer switch.  For example to power the refrigerator and some lights and internet devices.  But not heavy 120 VAC loads like motors and no 220 VAC loads.

In order to get 4400 Watts it would take three of the EU2200i generators, i.e. two generators will provide 2 * 1800 = 3600 Watts.

AC Works - AD515L1430 -

The Honda EU2000i turned off the fuel and ignition at the same time preventing you from running the carburetor dry.  An aftermarket kit is available (Hutch Mountain) to add a separate ignition switch so that the main Honda control can be turned to off (with the kit it  only turns off the gas leaving the carburetor dry).  Note you can get the benefit of running out of fuel by bypassing the ignition electric circuit without the add on kit, but then there's no way to turn off the engine quickly, not a good idea.  But Honda fixed that problem with the introduction of the EU2200i (Run, Fuel Off, Off).  This is the gold standard in this power level generator.  There are many generators trying to compete, but in my opinion none have come close. 

Leaving gas in the carburetor and then storing for months allows the volatile components of the gasoline to evaporate leaving behind "gummy" residue that can block the small holes in the carbureator preventing it from starting.  The easy fix is to just let the engine run out of gas before storage.  But that can take some time if the gas tank is near full.  Shutting of the gas between the tank and carburetor is an excellent approach and was easy to do on motorcycles where this problem was understood decades ago.  The fuel injection system in the Honda EU7000iS is another way to avoid this problem.

Make & Model
On Line
Dec 2019
Hours @ 25%
(Rated Load)
Honda EU2200i
8.1 (450W)
Generac SP220i
10.75 (425W)
HF Predator 2000 500
12  (400W)

In many racing events the vehicles are classified by engine displacement which drives up the HP/cu in numbers, but that degrades the reliability (Low BMEP).  How you build and run an engine allows for trading off power and longevity.  A drag race engine that only needs to run for a minute can produce much more power than the same engine used in a street legal car.  There's a similar effect with filament light bulbs where you can trade life and brightness by how much voltage you apply (Wiki).  In the case of these generators the Honda is using a larger displacement engine which is under stressed compared to the others where the engine is running under more stress.  I expect the other generators to have a much shorter life.

Note so far generators do not have features that would allow them to operate over a broad range of power levels.  Such measures as being able to turn off cylinders that are not needed so that a minimum of fuel would be used at times of low power demand.  These features probably would no allow the generator to be cost effective.  Honda has a plethora of generator patents most of which go to getting more performance for the cost of a generator.

1-Phase Power

I'm thinking of getting the Honda EU2200i to carry on the Polaris Ranger EV as sort of a gas can, i.e. a way to recharge the batteries if stranded.  A better solution would be a gas powered 48V battery charger, but that's probably too specific to be a commercial product.  Note this generator will power the Ranger's built-in battery charger as well as would plugging it into a standard wall outlet.

NEMA5-15 U.S. Wall Outlet
Note that the standard U.S. A.C. Mains outlet (Wiki: NEMA5-15) is rated for 15 Amps.
Since the nominal line voltage (at my house) is 120 VAC RMS the maximum power available is 15 * 120 = 1800 Watts.

Note that the Honda EU2200i is rated for 1800 Watts continuous.  That's to say it's rating matches the maximum output from a normal outlet.

A Horsepower (Wiki) is 746 Watts, so the maximum input power to an electric motor is 2.4 HP.
But the mechanical output is going to be less than that.
For an induction motor the efficiency can be as good as 85% to 97%.
For a BrushLess DC motor (Wiki: BLDC) the Wiki page does not have any actual numbers.

So, if a vacuum cleaner that plugs into this socket says it's a 5 HP model, that's just sales hype.

It's common practice to wire a number of these sockets in parallel on a single 15 Amp breaker.  That means that you probably can not draw the full 15 Amps from most sockets because the breaker circuit may already have other loads.

My house has some wiring errors related to GFI (Wiki) confusion.  When a GFI outlet is at the end of a circuit it's operation is straight forward.  The outlet connections (Wiki: Typ Config "2") are connected to all downstream outlets and they are treated the same as the output terminals "2".  That's to say that any imbalance in the Hot and Neutral lines will trip the GFI.  This is commonly used in kitchens and bathrooms where there's more than one outlet on the same circuit and all the outlets need GFI protection.  It saves the expense of using multiple GFI outlets when one can do the job.

Whoever wired my house did not understand how they worked, so I have a bathroom where there's multiple GFI type outlets all wired on the same breaker.  But worse, one bathroom wired on the same circuit as the garage where both have GFI outlets.  I've had the garage GFI trip (don't know why) and that cut off power to the bathroom.  It took some time to figure out that the garage GFI needed to be reset to restore the bathroom power.

2-Phase Power

While Honda offers a kit to parallel two EU2200i generators it's intended to double the single phase power.  It is not designed to offer 120/240 power like is available from the EU7000iS.  I think that a pair of EU2200i generators (with or without the pairing kit) that are wired to supply 240 VAC with a center tap the two 120 VAC circuits would properly power the two phases of my home electrical needs.  But, I expect that none of the 240 VAC loads would be properly powered.  This may be a non problem since I would not be using the electric oven, close-dryer or air conditioner during a power outage.

2019 October 9

Last night after 1:06 am (last email received) PG&E shut down the power in Northern California because of the danger of a fire.  So this morning around 8:00am I started the generator and after a minute or so turned on ECO mode.  After turning off the house and turning on the generator input breaker and turning on the AC power on the generator the power was slightly over 3000VA, but when I checked again at 10:00am the power was around 1,000VA and when switching out of ECO mode the generator ran faster, i.e. it is in ECO mode.

The problem is my new wireless point-to-point broadband service died because the neighbor's house where the relay is located ran out of battery.  My AT&T DSL comes from a DSLAM box that also has a small battery and it too has died. It came back in an hour or so after at&t added a generator.

After turning on a floor heater, rated at 1500 Watts, the generator now reads 2200VA, i.e. the heater rating is higher than the actual performance.

Generator Interlock Kit (less expense than full transfer switch and just as safe)

If a an automatic transfer switch turns on the generator when the power fails, that might not be what I want.  For example I turn off the generator at night since it does not do much, makes a little noise, and burns fuel.

Sliding plate prevents main breaker and adjacent generator breaker from being on at same time.

YouTube: How to Connect a Full Size Portable Generator To Your House Safely - Storm Ready - using Honda EU7000iS Generator, burning 5 gal gas per day.
YouTube: How to Install a Generator Interlock Switch  - notice different style than above interlock switch.

Interlock Kit - carries various configurations to match entrance electrical panel as well as the Inlet Box and 30 or 50 Amp generator cable.
My entrance panel may be the Challenger, Interlock Kit 2210.

Installed on July 17, 2019
Fig 1 Interlock fitted to main breaker panel.
                  Interlock Kit
Fig 2 New Generator Twist Lock Feed + new duplex outlet both outlet on new breakers.
                  Interlock Kit
Fig 3 Male twist-lock plug
Important for safety.
Extension cord will have male and female connectors.
This way there is no male connector with live AC power.
The house is the load, hence male plug, not socket.
                  Interlock Kit
Fig 4 - 2019 October 8 - standing by . . . .
PG&E threatening to shut off power in Northern California. 
The number of people trying to get to their web,
shut down pge.com.
                  Interlock Kit
Fig 5 a backup generator keeping the at&t DSL service going.
There are also much larger backup generators at the pumping
stations for my water service to keep the tanks full. 
This is for fire fighting, not homeowners convenience.
                  Interlock Kit
Fig 6 When PG&E is shut down the Smart Meter LCD is blank since there's no power.
                  Installation of electric SmartMeter
N168BH PG&E Line Inspection helicopter 2019 October 10 15:30. Flight path from FlightRadar24. N402PJ is also in the air.
N168BH PG&E Line Inspection helicopter 2019
                  October 10 15:30

 N168BH Line PG&E Inspection helicopter.
As of 5pm 2019 October 10 power is still off.
N168BH Line
                  PG&E Inspection helicopter

Fig 7 2019 October 24 There are at least 3 fires nearby and PG&E is talking about
another shutdown.  Just topped up the gas and charged the internal
starting battery (meter shows 4: 14.5 Volts).  Note light inside
clear end of extension cord.
                  Interlock Kit

Honda recommends storing the generator with a full tank of gas.  Part of this is common sense, i.e. you want gas in the generator when it's needed.  But also by filling the tank there's less oxygen available to react with the gasoline, thus minimizing fuel degradation.

L14-30 Extension Cord

This connects the generator to the house.  There is a safety standard that says the load is on a plug that mates with a socket (receptacle) that has the power.  This way the exposed pins of the male plug are NOT carrying live voltage that would be a shock hazard.

Reliance makes this cable in lengths of 10' (PC3010M), 20' (PC3020M) and 40' (PC3040M).  These are on eBay, Amazon, &Etc.
The shortest cable will have the lowest resistance and so the lowest power loss.  But the generator should be positioned at least 3 feet away from the house (further is better) so that carbon monoxide does not get into the house.

Box marked:
Reliance Cat. No.: PC3010M Cord Set
Type: 10-4
Length: 10 Foot
Max Capacity: 30A
Plug & Connector: L14-30
UPC: 851890000126

Fig 1 Extension Cord
House Generator
                  Extension Cord L14-30
Fig 2 New In Box.  Note mating male and female connectors.  The clear female end contains lights that are on when there is power present.
House Generator
                  Extension Cord L14-30
Fig 3 socket:
PC30XX NEMA L14-30R  30A 125/250V~  E234684NL
House Generator
                  Extension Cord L14-30

Power Back Alarm

2019 October 10 - Update.  This alarm is not needed because when PG&E is shut down the Smart Meter LCD is blank.  The only advantage of the Power Back Alarm is the audio alarm feature.

I should have got this for installation while the electricians were here.  From HomeDepot: PowerBack Utility Power Return Alert - use Energizer Alkaline 9V battery so that the Low Battery Indicator works properly. (The Lithium 9V battery has a higher voltage and so not good because of the low battery function).
Talked to PG&E about installation. 1- (800) 743-0011 press 4 for "other". Schedule a "Disconnect & Reconnect".
Have Power Back Alarm on order 2019 July 18.  arrived 2019 July 25.
The TPH108 PowerBack is made by  Reliance Controls Corp.  - Brochure - Instructions -
Fig 1 The threaded part at the bottom is intended for mounting in a 1/2" knockout.
But that requires a surface mount electrical box, but mine is flush mounted.
Instead a cable clamp that fits a 1/2" knockout will be used on the black cable and green wire.
PowerBack Utility
                  Mains Power Return Alert
Smart Meter when PG&E is shut off.
To check that power has been restored it is important that  you
look at meter face for 15 seconds or more. 

With no load connected to meter the face shows blank for a
number of seconds as part of its normal cycle. 

So it may look like the photo below in a quick glance
even though the power is on.

                  Installation of electric SmartMeter

Ramps for Honda Van

These would be required if I wanted to move the generator.
2000 Honda Odyssey EX Van -
YouTube: Dandy DJ Harbor Freight 6 ft ATV Ramp Mod -
Harbor Freight Item 44649 1000 Lbs. Capacity 9" x 6' Steel Loading Ramps, Set of 2.
Have a pair of ramps on order 2019 July 18.
These should also work for my Addmotor  M-360 eTrike.

Gas Cans

2019 October 28 - Two more of the Justrite 7250130 on order.  The tank in the Honda EU7000iS holds 5 gallons and for my load seems to run for 3 hours/gallon.  I turn it off at night, so the consumption is about 5 gal/day.
The cans have arrived.  An empty can weighs very close to 8 pounds when empty.

Type I gas cans have a combined fill and pour opening.  Type II gas cans have separate fill and pour openings.

So far I'm leaning towards the Justrite 7250130 (shop around the sticker price is way above market) which is a Type II can with the 1" x 9" hose.  Ordered 26 July 2019.

The 5/8" x 9" hose is available as a spare part No. 11078.  This fits into the hole in a car gas tank, i.e. be the same size as a gas station filler nozzle.
The gas station automobile filler nozzles are 13/16" for gas (15/16" for diesel).  So the 1" hose on the gas can will not fit into either of them, but is great for a low fill time.  This is important since it minimizes the time you are holding 40 pounds of gasoline.  Within seconds the can gets lighter.  I suspect the capacity of the Jerrycan (wiki) was set at 5 Gallons because it's about as much weight as you can easily lift and pour.  The three handles allow carrying by one person (center handle) or two people (the two outside handles) (Wiki).  This Justrite can only has one handle.
The 5/8" hose will fit either gas or diesel filler holes in cars, but at the cost of a slower fill time.

If the can has been sitting for some time there may be pressure.  If the chrome handle is pulled it will be expelled.  A better idea is to position the can for filling then pull the handle.  That way the pressure helps to get a higher flow rate, i.e. faster emptying of the can.

Justrite 7250130
Fig 1 Notice valve just inside opening
                    7250130 5 Gal gas can 1" spout
Fig 2 Overall view
                    7250130 5 Gal gas can 1" spout
Fig 3 Flame Arrester
(see Koehler Miners Lamp Fig 3)

                    7250130 5 Gal gas can 1" spout


Note there is a flame arrester (Wiki) just inside the fill opening.  This is not a filter as some have said.  The idea is to cool a flame front and so stop the flame from crossing the arrester.  The Davy Miner's Lamp (Wiki, ) is the first example of this I'm aware of.  See Miners' Safety Lamp for more on flame arresters.
2335195 Gasoline
                    safety can, Charles S Packer, 1943-11-23
2335195 Gasoline safety can, Charles S Packer, Justrite Manufacturing Co, App:1940-12-09, Pub: 1943-11-23 -
  3729122 Safety container for inflammables, F Flider, Justrite Manufacturing Co, 1973-04-24 - applied to plastic can

3811605 Safety container for inflammable fluids, F Flider, Justrite Manufacturing Co, 1974-05-21 - plastic can

3851791 Plastic safety can for containing fires burning inflammable fluid inside the can, , F Flider, Justrite Manufacturing Co, 1974-12-03 - addresses the problem of a fire inside a plastic gas can where the plastic allows the gasoline to pour out spreading the fire.

PS all the Justrite Type I and Type II gas cans are steel.  This may be the reason, even though they have a number of patents on plastic gas cans.  They do sell Polyethylene safety cans for flammable corrosives see: 4597504 for the "conductive current-carrying carbon insert is embedded into the rib of containers, completing a ground path between the cover assembly and the ground arrester."

4597504 Non-metallic container for flammable fluid and method, Edward H. Witt, Justrite Manufacturing Co, 1986-07-01 - "In accordance with this invention, an insert is sealed within the plastic container body in contact with both the structural handle member parts and the screen flame arrestor."

6390153 Valve body for safety cans, Frank S Flider, Ted E Holmes, Justrite Manufacturing Co, 2002-05-21 - integrates fill, pour and vent
8602273 Safety
                    can, Glen A. Carter, Mark T. Goddard, Justrite
                    Manufacturing Co, 2013-12-10 -
8602273 Safety can, Glen A. Carter, Mark T. Goddard, Justrite Manufacturing Co, 2013-12-10 -
"...includes a valve assembly with a pour spout, a fill spout, and a venting system."
Note the centerline of the pour spout is offset from the centerline of the fill port.

There are two types of venting:
1. In hot conditions the pressure inside the can goes up and when it gets between 3 and 5 PSI spring 218 allows the filler cap to open relieving the positive pressure.
2. When pouring there is negative pressure inside the can that hinders the flow.  The pour valve assembly (202) contains a passage (226) that allows air to enter the main chamber.  PS in a YouTube comparison with other gas cans this model was twice as fast to pour 5 Gal. as the slowest can.  i.e. for professionals who pour a lot of gas this is the can to have.

The Justrite Mfg Co. has a number of innovative patents for flashlights.
This patent covers models 7250120 or 7250130 which only differ in the diameter of the fill hose.


eBay: 25kg*5g Pocket Electronic Digital Hanging Hook Travel Luggage Weight Scale - under $5
0 - 25 kg or 0 - 55 lbs.

While scale is weighing the red LED flashes.  Once the weight is determined the red LED stays on (hold function).

The gas can at the generator weighs 12.31 lbs, or contains between 1/2 and 1 gallon.

25kg Scale
25kg Scale
Fig 2 tank with some gas
25kg Scale

The idea is an easy way to know how much gas in left in the can.  Weighting with a 25kg (55 lb) hanging scale with 5 gram resolution should work.  eBay title "25kg*5g Pocket Electronic Digital Hanging Hook Travel Luggage Weight Scale" is under $5 including delivery from china.  I'm guessing it uses a 2032 coin cell battery and I have between 50 and 100 of them.
density of gasoline is 6.30 pounds per gallon, or 2.857632 kg per gallon.  5 gallons would be 14.288 kg (31.5 pounds) plus the weight of the empty gas can.


eBay: Car Hand Manual Siphon Syphon Transfer Hose-Pump Fluid Liquid Water Gas Gasoline - under $10

1/4" ID x 3/8" OD.
Two tubes each about 3' long for a total of over 6'.

The bulb has no valves so
the open end of the tube needs to be blocked
after squezing the bulb to draw a vacuum.

In the PG&E outage just over a week ago the local town of Ukiah was not turned off and so the gas stations were all opened.  My single 5 gallon Justrite gas can could easily be filled.  But this time Ukiah was shut down, meaning that almost all businesses are closed including all but 2 gas stations.  Both of those have very long lines.

The gas tank in a car holds much more than 5 gallons and is a much safer way to move gasoline than in any gas can.  In an accident a gas can in a car is a very dangerous thing.  So, after waiting in line to get gas be sure to fill your car's tank and a gas can.  Then you can use the siphon to remove some gas from the car to the gas can.

Fuel Stabilizer

2019 October 9 - If you plan on using the generator in the near future do not bother to use fuel stabilizer.  During an outage there's no need to use fuel stabilizer, so after the outage, and if another is not expected soon, you can add the stabilizer to full gas cans.

Putting 1 ounce of Sea Foam per gallon of gas may stabilize the fuel.
YouTube: How to store gasoline & fuel long term - Stabilizer DIY for 1 week of Fuel - Sea Foam motor treatment - [1 oz/Gal] - Stabilizes gas & diesel fuels up to 2 years

Gas can go bad if allowed to set for long periods and especially if exposed to air. 

Honda EU7000iS

This model was rumored in 2012 and released in 2013, here are some comments on the SmokStak forum.
This Honda generator gets a lot of good reviews. Excellent fuel economy (ECO mode) and ability to parallel with other Honda "i" Inverter generators.
The ECO mode (turned on after starting and running for a few minutes) saves gas by allowing the engine to throttle down if less than full load.  This only will work with an inverter type system.  Conventional AC generators must run at a fixed RPM (typically 1800 for high end units and 3600 RPM for less expensive units) in order to maintain the 50 Hz output frequency.

The EU7000iS has fuel injection rather than a carburetor.  Since carburetor fouling from sitting gas is the number one problem starting after a year of storage this is an excellent idea.
The solution to the problem for small gas engines with
carburetors is to keep the engine running until the gas tank is empty just prior to storing the engine.  If you store a gas engine with gasoline in the carburetor there's a good change you will plug some of the orifices and it will not start next year.  I've seen a new Yamaha small inverter generator with a carburetor drain feature and another way around this problem.

In stock at Motorsports of Ukiah.  Note this weighs 261 pounds, so not at all a one man lift.  Comes with wheels and handlebars so easy to roll around once delivered.  Ask about delivery.

The gas tank holds 5.1 gallons.

See Extension Cord above - this was written during the search phase.
I have not found the cable to connect between the generator and the house, so will either make it from scratch or from an extension cord.  TBD
The Generator end is a L14-30 "California" twist-lock socket.
30A L14-30P 125/250V Twist Lock Electrical Male Plug (Wiki: NEMA 14)  is needed to mate with the generator.

The NEMA 14 devices are four-wire grounding devices (hot-hot-neutral-ground) available in ratings from 15 to 60 A. The voltage rating is 250 V. Of the straight-blade NEMA 14 devices, only the 14-30 and 14-50 are in common use. The 14-30 is used for electric clothes dryers, the 14-50 is used for electric cooking ranges, and either may also be used for home charging of electric vehicles. The NEMA 14 connectors are essentially the replacements for the older NEMA 10 connectors described above, but with the addition of a dedicated grounding connection.

All NEMA 14 devices offer two hots, a neutral, and a ground, allowing for both 120 and 240 V when supplied by split-phase power, or 120 and 208 V if the supply is three-phase. The 14-30 has a rating of 30 A, and an L-shaped neutral blade. The 14-50 has a rating of 50 A, and a straight neutral blade sized so that it does not mate with 14-30 connectors.

The Honda EU7000iS uses the L14-30 Twist Lock connector, not the one with straight blades.  See Fig. 3 below.
Note that when the 4-wire 240 VAC cable is used to connect the generator to a house, one of those wires connects to the house Earth ground.  But if the generator is used in a field application where there's no Earth ground there may a shock hazard.  See the article: Portable Generators in Motion Picture Production -

More on the connecting cable later.

YouTube: Honda displays the first electronically fuel injected inverted generator 2014 - (0:19) "Our customers have asked us for ease of maintenance and simplicity of use and the electronic fuel injection brings both of those benefits to the customer.  Eliminates fuel storage issues that are very prevalent with carburetor type generators or any small equipment." 
as of 2012:
the injector itself is Honda Part Number 16450-Z1C-C01, $74.33
YouTube: Pull starting the EU7000iS with the battery disconnected.

Fig 1 2019 June 28 As delivered Controls
Fig 2 2019 June 28 As delivered exhaust
Fig 3 Control Panel
Fig 4 Connected to house.
                    Interlock Kit
Fig 7 Topping up battery and demonstration of light in
extension cord.
                    Interlock Kit

Solar AA Charger (Wiki) & USB Power Source

Discovered this after learning about amorphous silicon solar cells (Wiki) like used on the Flip-Flap Solar wig-wag type toys, Solar Lighthouse, Solar Showcase 360 Turntable and Mova Globe which all work indoors on just room light.  This Solar panel has can charge two AA batteries and/or serve as a USB-A power source.  Note that the solar panel must first charge the Ni-MH AA cells, then they power the USB charging port.

Made by PowerFilm - USB+AA Foldable Solar Charger spec Sheet.pdf -

It came with a couple of eneloop HR-3UTGA 1.2V 1.900mAh cells.  This brand is renown for very long shelf life, which is not at all typical for rechargeable Ni-MH cells.
In my battery drawer I have eneloop BK-3MCCA4BA cells rated at 1900mAh and BK-3HCCA4BA cells rated at 2450mAh.
New sticker price about $140.

Fig 1 Note red LED is blinking even though the panel is
on the North side of the house in total shade.
                    AA Charger & USB Power Source
Fig 2 Can charge 2 AA cells then provide USB-A power.
Shown folded up.
                    AA Charger & USB Power Source

Solar USB Phone Charger

This is just a solar panel with a USB 5Volt output.  No on board batteries like the PowerFilm unit above.
The literature talks about "Full Sun" so expect this is not an amorphous silicon panel like the one above, but rather Monocrystalline silicon (Wiki) which has higher efficiency in direct sunlight.  Under $40 new on eBay.

Fig 1
Choetech 14W
                    Solar USB Phone Charger
Fig 2
Choetech 14W
                    Solar USB Phone Charger
Fig 3
Choetech 14W
                    Solar USB Phone Charger

Generator Modes of Operation

This Honda EU7000iS is an inverter type generator.


A classical AC generator determines the output frequency by regulating the RPM.   Lower cost 60 Hz generators run at 3600 RPM and the better ones run at 1800 RPM.  As the generator is loaded the RPM falls and the regulator opens and sends more fuel to the engine to speed it up.  Running at a slower speed translates to quieter and half the wear or twice the life.  The regulator mechanism to do this dates back to steam engine times and can be as simple as a fly ball governor (Wiki).


This is where the engine turns an alternator with AC output that varies in frequency with the engine speed.  The AC output is rectified into DC which in turn is converted back into AC at the desired output frequency which is typically 50 or 60 Hertz.  In this case when there's no load the engine is throttled down to an idle RPM and as the load increases the engine speed is raised to supply the needed power.  Honda has a version of this called ECO mode and there's a switch on the EU7000iS to implement it, but the switch needs to be off when the generator is started since it does not yet know what load it will be supplying.

Parallel Operation

It seems to be easier to connect the outputs of these generators in parallel so that they share the load.  This is very difficult to do with a classical generator where any slight electrical phase difference will cause them to fight each other.

Fuel Economy

Since the RPM of the engine depends on the power delivered the engine slows down for light loads thus greatly reducing fuel consumption.  This also lowers the noise.


The inverter mode makes for a more expensive generator, but I expect that's going to be paid back by the benefits listed above.

The below was written while investigating generators in general.

Fuel Choice

Gasoline contains varnish (coloring) and hydrocarbons that can cause it to go stale after sitting for many months or years.  This may lead to problems starting due to the carburetor fouling.

The solution to the problem for small gas engines with carburetors is to keep the engine running until the gas tank is empty just prior to storing the engine.  If you store a gas engine with gasoline in the carburetor there's a good change you will plug some of the orifices and it will not start next year.  Putting 1 ounce of Sea Foam per gallon of gas may stabilize the fuel.
YouTube: How to store gasoline & fuel long term - Stabilizer DIY for 1 week of Fuel - Sea Foam motor treatment - [1 oz/Gal] - Stabilizes gas & diesel fuels up to 2 years

Propane does not have that problem, but as explained in the Fuel Consumption paragraph below, may take more gallons for a given number of kW hours.
Modern diesel also has additives that may degrade it's ability to be stored.

Wiki Gasoline gallon equivalent:  1 Gal Gasoline = 0.88 Gal Diesel #2 = 1.54 Gal Natural Gas = 1.25 Gal Propane = 33.4 kW hours of electricity

So let's see if there's data on fuel consumption for propane generators.
Champion - 8000-Watt Dual Fuel Generator - gasoline or propane - no on line fuel consumption data.

Key Point


For this to be viable you need a huge tank in order to have 4 days worth of fuel (see Fuel Consumption) or use another fuel.  A 200 Gal tank dedicated to the generator is too small.

There is also a safety concern with propane or natural gas in that a generator consumes a lot of it.  If the piping is not done correctly (a large pipe between the pressure regulator and the generator) it's possible the generator will suck the gas from the house which can cause pilot flames to be extinguished.


In terms of a fuel is a good choice.  But as far as I know modern inverter generators, like the Honda EU7000iS are not available in diesel.  Which leaves old fashion 3600 or 1800 RPM type generators which are not as economical as the inverter and more modern types.


Should not have a fouling problem with fuel injection, that's the reason Honda used FI on the EU7000iS. Gas can be stored for a couple of years by using a fuel stabilizer.
This is one of the reasons for choosing the EU7000iS.  There is a new Yamaha EF2000iSv2 generator that has a valve on the carburetor that allows draining it to avoid the clogging problem (Yamaha Easy Carburetor Drain).

Fuel Consumption

2019: Thinking about house backup generator considering the lesson learned from the fires the past couple of years (2017 Redwood/Potter, 2018 Ranch & River) that the ionized air above a fire is conductive and will short out the AC power lines.  This blows a system wide fuse resulting in power loss.  Or . . .  if the firemen see that a fire is about to blow a fuse then notify PG&E and they shut down the grid.  In either case the power is out for a few hours.  But in cases where wooden power poles burn and the lines fall to the ground there will be no power for days.  If that happens then a generator that uses propane from a 250 gallon tank will require refilling from a truck, it is not something you can refill yourself.  Gasoline as a fuel is a poor choice for a standby generator because it goes bad when sitting for long periods of time.  The optimum fuel choice in this case seems to be diesel since you can go to any working gas station (might need to be out of the area) and get it in 5 gallon cans.

Diesel fuel consumption Gallons per hour & [Gallons per kW hour varies between 0.7 and 1.4 Gal/kWhr at full load]

No Load
Cummings Onan
RV QD 12500




Kubota GL7000

Kubota GL9000

DA7000SSA3 6

Note to get Gal of propane per kW hour multiply by 1.42.  So at full load a propane generator will need about 0.1 Gal Diesel/kWh or .142 Gal Propane.



Generators with "Whole House" in the title are normally mounted on a foundation where the wiring and fuel supply are also fixed.  This makes sense when a transfer switch (Wiki) is used and offers more convince than a portable generator.


These vary from small units that can be lifted with one hand up to units that weigh thousands of pounds and require a heavy truck to move.  The portability is the key benefit.  In exchange it takes more work to connect the output and keep a portable generator supplied than a fixed model.

The Honda EU7000iS is way too heavy to lift.  But it comes with wheels and a handlebar so is easy to roll around on level ground.

Honda Generator Codes

The "i" suffix seems to indicate Inverter, as described for the EU. Quiet & efficient operation.  [EU1000i, EU2200i, EU3000i, EG2800i, EB2200i, EB2800i]
The "S" suffix seems to indicate the 10 second high power Starting capability for motors. [EM4000S, EM5000S, EM6500S] or maybe Self Start?
The "iS" suffix seems to be for both of these. [EU3000iS, EU7000iS]
The "c" suffix seems to be for CycloConverter technology [similar to inverter by there's no DC in between the input high frequency AC and the output low frequency AC]

EU Recreational

These make use of an AC generator running at whatever the engine speed needs to be to supply the load.  That AC is rectified into DC and drives an inverter running at 60 Hz in the U.S..
Very efficient and quiet.  Two generators can be connected in parallel with a special cable to double the capacity.  Typically only have 120 VAC and 12 VDC output, not 240 VAC.
EU1000i - 2019
EU2200i - 2019
EU3000i - 2019
EU3000iS - 2019
EU7000iS - 2019 (retail: $5,000, )

EG Home Backup & Construction

120/240 VAC outputs, HD frame.
EG2800i - 2019
EG4000 - 2019
EG5000 - 2019
EG5000CL - 2019 Home Depot  $1749
EG6500 - 2019

EM Emergency Home Backup

Electric starting, 10 second high power output to start motors, wheel and lifting kit, 120/240 VAC outputs
EM4000S - 2019
EM6500S - 2019

EB Commercial Industrial

Inverter technology similar to the EU series. GFCI and Wheel & Lift Kit.
EB2200i -  2019
EB2800i - 2019
EB3000c - 2019
EB4000 - 2019
EB5000 - 2019
EB10000 - 2019


Capstone MicroTurbine -
This company sells a 20 kW model with a stated efficiency of 27%, in versions for low and high pressure gas feed. The large fridge-sized cabinet of this system received the "Good Design" award from the Chicago Athenaeum Museum of Architecture and Design", the oldest industrial design prize in the world.
Elliott Energy Systems - Unison Alternators
Elliott is the only manufacturer to provide systems of different power output: in addition to 45 kW and 80 kW models, a 200 kW model is in the pipeline. The systems produced by the UK packager Bowman are also based on the Elliott microturbines.
Exide Technologies - GNB Technologies -

Foster Wheeler Corporation - for powering a city

GE Power Systems - GE Micro Gen -

Honda - Manes a number of generators that are much lighter than the competition.

CycloConverter Generators
2523090 Parallel Operation of Converters, Westinghouse, Sep 19, 1950, 307/47 - oldest patent with the word CycloConverter (named in this patent)
7952230 Cycloconverter generator, Honda, May 31, 2011, 307/47 - Honda model EB3000c

Honeywell Power Systems Inc.

Previously known as AlliedSignal, this is the only major turbine manufacturer engaged  in producing microturbine systems. Honeywell systems are sold under the name Parallon 75 and have a 75 kW output with 28% efficiency.
Hpower - Fuel Cells

Ingersol-Rand Energy Systems - micro turbine

International Fuel Cells -

K-tronik International Corp. -

Kohler - Generators -

Marathon Electric, Inc -

Turbec AB

Turbec is a Swedish company created in 1998 by Volvo and ABB to complete the development, and market, the 100 kW VT 100, previously developed by Volvo Aero turbines. The company claims an efficiency of 30%. This is the only microturbine produced which from the start has had a thermal recuperation system for cogeneration applications.


6707170 Inverter type generator, Yamaha Motor Power Products Co Ltd, 2004-03-16 - uses two alternators, one for normal loads and another for high loads.


5426578 Generator having automatic parallel operation function, Honda, Priority: 1992-02-10, Pub: 1995-06-20 -
5943221 Portable power unit, Honda, 1999-08-24, - includes output voltage detecting circuit
6344988 Power unit, Honda, 2002-02-05, - includes output voltage detecting circuit
8232777 Inverter generator, Honda Motor Co Ltd, Priority: 2008-07-25, Pub: 2012-07-31 - includes harmonic distortion minimization to give clean sine wave output
9077207 Parallel running control apparatus for inverter generators, Honda Motor Co Ltd, Priority: 2011-05-17, Pub: 2015-07-07 - 3 phase, 4 wire system.
9086044 Start control apparatus for engine generator, Honda Motor Co Ltd, Priority: 2011-05-17, Pub: 2015-07-21 - for starting piston engine; uses more starter current just prior to TDC.
2010/0019508 Inverter generator, Honda, 2012-01-24, - "Then a desired speed of the engine is determined based on the estimated power of the load, and the actuator is controlled such that an engine speed becomes equal to the desired engine speed, thereby improving the response of engine speed control."

Thermal Generators (see Heat Batteries, Wiki: RTG)

Thermo Electron Engineering Corp
2915652 Conversion of thermal energy into electrical energy, George N Hatsopoulos, Kaye Joseph, Thermo Electron Engineering Corp, App: 1956-04-18, Pub: 1959-12-01
3054914 Process and apparatus for converting thermal energy into electrical energy, George N Hatsopoulos, Kaye Joseph, Thermo Electron Engineering Corp, App:
3075030 Thermoelectric generator, Robert A Elm, William G Krawczak, Delmar D Schley, Evert J Levin, 3M, App: 1959-12-22, Pub: 1963-01-22 -
3304445 Semiconductor battery, James B Weddell, Precht Walter, Martin Marietta Corp, Pub: 1967-02-14, - radioactive source activates semiconductor to act as battery.


MEP-25A 28VDC Military Generator (Gasoline) - to power the GRC-206 Pacer Speak radio system
Weeden-El-Mtr  Weeden DC Electromagnetic Machine
ArCo Demonstration AC DC Generator
Permanent Magnet DC Motors, Testing Small DC PM Motors - these also work as DC generators - Kv (RPM/Volt) with a unit conversion is the inverse of Ki (Newtons/Amp).


American Power Systems -
DOE - Summary of Micro Turbine Technology.pdf - Advanced Micro Turbine ystems.pdf -

Makelim Power Systems is Stockton, CA Kohler dealer

Natural Gas, Italy - Microturbines for cogeneration -
SMP Electric - Microturbine -

Back to Brooke's home page

This is the [an error occurred while processing this directive] time this page has been accessed since 6 Feb. 2001