Using a generator to power a washing machine

Re: Using a generator to power a washing machine

I have a pair of ~6 year old Fisher/Paykel washer + drier machines. Standard top load washer (and a top load drier--which I do like) that both use poly phase Permanent magnet motors in them. I can not measure any surge power usage (kill-a-watt) and they both use around 0.250 kWH per load (drier is natural gas).

Power is on grid--so I cannot say how they will do off-grid, but they should be OK.

The pair does draw about 9 watts "turned off"--Which is about equal to the power needed to run them a couple times a week--So I turn them off with a power bar when I am not using them.

I am not thrilled with the mold/mildew problems that I have seen and read about with front loaders (plus other issues)--So I stayed with the top loading washer.

-Bill

Re: Using a generator to power a washing machine

An Inverter/Generator consists of:

• "wild frequency" 3 phase alternator
• Inverter which takes in "wild AC", turns it into high voltage DC, which is then "inverted" into 120 VAC 60 Hz (or 230 50Hz, etc.).
• "ECO" throttle control which allows the engine to slow way down and use less fuel while powering "small" AC loads. ECO Throttle may be turned off (full engine RPM) when running loads with heavy starting current (such as an A/C system).

So, the inverter generators are really nice for running smaller loads (lights, TV, refrigerator) which don't use 50% or more of the generator's rated load. They save a fair amount of fuel for most of us when we just need to run a few appliances during power outages.

Also, it is difficult (and expensive) to maintain 3,600/1,800 RPM +/- 1% for 60Hz power. Inverter generators are electronic so it is very easy for them to keep the frequency and voltage more stable.

The inverter can be a good TSW version, or it may be a cheap MSW... Most inverter gensets are not really clear if they are TSW or MSW.

And, while the definition of the Sine Wave should be the output of a standard AC genset--There are lots of design issues/cost trade-offs (amount of iron, copper, voltage regulation circuitry, etc.) that some AC generators have worse waveforms than a MSW inverter (and the waveform can vary greatly depending on loads and load types).

-Bill

Re: Using a generator to power a washing machine

Robert took some nice pictures of sine wave, modified sign wave, and square wave output from various devices:

-Bill

2manytoyz wrote: »

I've been using a scope on my inverters & generator for a while also. I have a Yamaha EF2400iS inverter type generator. Very clean power, cleaner than the grid power at my house.

Grid:


Generator:


Other tests of this generator here (along with a look at the DC output): http://www.2manytoyz.com/yamaha2400.html

A pic of the waveform from a Vector MSW (400W) inverter:


From a Xantrex 1800W Prosine inverter:


From an old Tripplite squarewave inverter:

Re: Using a generator to power a washing machine

I am a big believer in basic measurements... So, measuring the kWH total each time you run time it--And the amount of fuel used. Get something like kWH/Gallons (or liter) of fuel used...

More or less, you are pretty efficient if you are getting 4kWH per gallon (or ~1kW per liter)... And not doing too well if less than 2kWH per gallon (or ~0.5kWH per liter).

For example, the inexpensive generator that Chris Olson likes (the Champion 46539) is a 3.5kW unit with a 3.8 gallon gas tank that will (per specs) run about 12 hours at 1/2 load, or:

• 3.5 kW * 0.50 loading * 12 hours * 1/3.8 gallons = 5.5 kWHh per gallon

That is not too bad... The non-inverter generators tend to be more efficient at >50% load and the inverter generators tend to be more efficient (than non-inverter types) at less than 50% load--But that still does not mean that inverter generators are "that" fuel efficient--They just tend to be more fuel efficient running small loads than the big guys.

And, I would suggest, that having two gensets--one large (perhaps purchased at a good price) for the larger loads, and a small genset for emergency/small loads is not a bad thing.

The Honda eu2000i ratings are 1,600 watt full load, 4 hours at 100% and 9.6 hours at 25% on 1.1 gallons of fuel:

• 1.6 kW * 4 hours * 1/1.1 gallons of fuel = 5.8 kWH per gallon
• 1.6 kW * 0.25 loading * 9.6 hours * 1/1.1 gallons of fuel = 3.5 kWH per gallon

Note, the above numbers are based on factor specifications--Chris Olson has posted some fuel usage numbers before. Anyone that different/better numbers, please feel free to post. These numbers are intended as a starting point for discussion. Here is one post from Chris (I did not find the others yet):

ChrisOlson wrote: »

That's assuming those fuel consumption numbers are even accurate. I did a measured fuel consumption test on my new EM4000SX and it burned 57 ounces of 91 octane gasoline with no ethanol in it in one hour @ 3.8 kVA continuous output, driving water heater elements.

If you look on Honda's website it shows rated load for that generator at 3500 watts, max 4000 watts, iAVR 5000 watts. On the data tag on my generator it shows rated load 3800 watts, max 4000, iAVR 5000. On Honda's website it only shows a generic run time, which doesn't really mean much. But for rated load it says it will run for 10.1 hours. It also says the fuel tank holds 6.2 gallons.

The tank was bone empty when I got it and the most gas I could get in it, filled up at the pump at the gas station when it was in the back of my truck, was 6.06 gallons, not 6.2. And according to my fuel consumption test it will run for 13.6 hours at 3.8 kVA output on that 6 gallons of gas. And that's assuming it could get every drop of fuel out of the tank, which it can't. There's a standpipe in the tank that draws the fuel at about 1/2" off the bottom of the tank, so I estimate that there will be about 1 quart left in it when it quits due to being out of fuel.

Actual field test data is the only thing you can rely on. Taking figures off a manufacturer's website, from their sales propaganda, is a little "iffy".

Also, reading the operator's manual for my new generator, not a single mention, chart or anything, relating to fuel consumption in it.
--
Chris

• 13.6 hours * 3.8 kVA / 5.75 gallons of gas = 8.9 kVA per gallon of gasoline

The big question here is what is the kW of the load--For a typical motor load it is not unusual for PF to ge in the 0.67 range--But for resistance heating for it to be in the 0.95 to 1.00 range... That will affect the kWH per gallon ratings... For example using 0.67 PF:

• 8.9 kVA per gallon * 0.67 = 6.0 kWH per gallon of fuel

Still not bad--But "different". But since I don't know Chris' loads--The above is just an excessive in math.

There have been a few folks that have been running large genset with relatively small battery chargers--And that can get down towards 1kWH/gallon of fuel--And that gets real expensive real fast (running a genset at less than 25% loading can be really inefficient). If you are stuck trying to bulk/absorb the battery bank during bad weather--Sometimes it is just the cost of living off grid.

If you have to do a lot of "low power" generator runtime, a smaller genset can easily save its costs in fuel usage alone over a couple years of operation.

But the downside with thermodynamics is that smaller engines are almost always be less efficient than a similar engine type in a larger size...

-Bill