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Discussion Starter · #21 ·
I can't say for sure that Champion is better than the rest, but they are well respected here. They also stand by their products. The QC should be better.

Someone else may correct me, but I view (portable/inverter) generator quality to go like:
  • Honda
  • Yamaha
  • Champion
  • Clones that use genuine Honda or Yamaha engines
  • Everyone else to varying degrees
My concern with Champion was that the THD rating was a little high. If I run electronics on surge protectors, I should be good?
 

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My concern with Champion was that the THD rating was a little high. If I run electronics on surge protectors, I should be good?
My little Champion inverter generator (100899) has both a better looking sinewave and lower THD than my house power. The Champion sinewave visually looks perfect and THD was 1.5% with a 1kW load (it does about 1.7kW on propane). House power is 2.4%THD. House power has to deal with all the power supplies in our house and in neighbors homes that only pull power on the sinewave peaks which distorts the waveform.

The sinewave on the traditional generator I have doesn't look too bad and I have run backup power to my home with it (power large TVs and electronics). The THD was 11.5% at 1kW, but as long as you don't have big spikes most devices won't care. Inverter generators are nice, but I wouldn't lose sleep worrying about the THD of generators.
 

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My concern with Champion was that the THD rating was a little high. If I run electronics on surge protectors, I should be good?
Surge protection and THD are like comparing apples and cats. Not even closely related as fruits/veggies. Surge protectors won't protect any against high THD. From what I know at the moment - nothing will (I could be wrong, perhaps that is "no realistic/sensible method will"). The cure for high THD is to recreate the AC power. So that would have to come from another form of power generation - such as converting to DC then from DC back to AC with a power inverter. That is the principal behind an "inverter" style generator from the get-go - the input to the "inverter" is DC, which was rectified from the alternator spun by the engine. The Inverter does the "creation of the AC wave". With a rotary generator that is producing the AC directly (no conversion from DC) you gets what you gets.

THD = Total Harmonic Distortion. This is how far off the AC waveform is from a pure sine wave. I posted this in another thread recently when looking for a comparison of example waveforms at differing amounts of THD. This waveform is at 12%:
9441
'

Power surges, conversely, are spikes in line voltage. You could say that is a deviation from a pure side wave waveform of the AC power, but it is a voltage spike that affects the voltage peaks (every 180 degrees) in the waveform, not something that affects the entirety of the waveform - all 360 degrees.

Think of THD as a "fuzzy" waveform. If you equated the image quality of the waveform to sound it would be like a crisp clear AM radio station and one that is really far away that has a lot of static and is harder to hear.

Also for example - this is the waveform from my 15kw rotary unit. It is a Mecc Alte alternator with a THD spec of <4% (pretty good - especially for a rotary). You can see its not a "perfect" sine wave and on the rise just to the right of the first redicle to the left of center there is a notch in it. I don't have a way of "measuring" THD at the moment, so I can not tell you numerically what the THD represented by the waveform on the 'scope screen is yet, but interesting to see none-the-less.

9442
 

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FWIW I just bought a Champion as a second or back up generator based on reviews, and discussions here. I also called them to ask a couple of "loaded" questions and was very impressed by the knowledge available and they weren't reading from a script!!

One last thought, buying a generator is like everything else, comes down to "what do you have more of, time or money?" If you have the time to do manual load shedding, turning off breakers turning on breakers. Only turn on well pump when needed to replenish water. e.g. It used to be SOP in Hurricane country to fill bath tubs for water to flush toilets. When your generator is connected, turn on breakers one at a time and let load stabilize before going to the next one. The determining factor in sizing would be the well pump and the generator would have to have 120/240. That's the least costly option. From there, you go up in initial installation cost, generator cost and fuel consumption, higher cost for more convenience. For me it's how often do I have to do this and duration of outage.

Champion admits that their generators have a THD of 15-25% which is considered high. Getting THD numbers on other generators is kind of ..... difficult and numbers available are suspicious. Champion has at least "bit the bullet" and published what other folks won't. I get along with "open frame" non inverter generators and have never had any issues. I'd guess we have the usual Frig, Freezer, flat screen tv's, desktops, laptops, etc. If you have super sensitive electronics, maybe that's a concern. The whole house generators which do everything for you aren't inverters and are open frame with higher THD ratings. Also, THD increases as load increases which folds back to portable generators should be run, steady state at half load. My guess is that your electronics will get along with an open frame unit, but I'm a majority of one here. :)
 

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My concern with Champion was that the THD rating was a little high. If I run electronics on surge protectors, I should be good?
Champion makes regular and inverter generators. It depends on which one you're looking at. I'd recommend inverter style generators regardless of brand.

The only thing Champion doesn't have going for them is large quiet (enclosed) inverter generators that some of the other companies offer.
 

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My thought process is to store gasoline at the beginning of season and use by the end of season.
Do your math.

For example: My 15kw unit supposedly sucks down 1.5 gallons an hour, I think that is around 1/2 load, then it goes up to about 1.8 gallons an hour closer to rated load if I recall correctly. For math purposes I've been using the 1.5 number and was comfortable with it so I'll use it for the time being until more real world testing to get a better number for the way I use it.

Think about that for a minute - 1.5 gallons every hour of operation, on average.

In 24 hours that will be (1.5 x 24) = 36 gallons per day.

If you loose power for a week, thats 7 days, or (7 x 36) = 252 gallons.

If you loose power for 2 weeks.... Thats (14 x 36) = 504 gallons.

How are you going to store all that gas?

I have the ability to hold around 80 gallons if I filled up EVERY container/tank. Thats a pain in the arse. At the moment I have about 45 gallons, or less than 2 days, and I try to cycle through it so it isn't sitting around all year.

Now - instead of storing the gas you could go to the gas station and refill a days worth of gas every day, or a couple days worth of gas every couple days, right?

WRONG.

If you are in a big power outage your gas stations are going to be closed down also. We ran in to that many years ago. The remnants of a hurricane went through the midwest and caused a big wind storm that left us out of power for close to 2 weeks. In the early days we had a lot of trouble finding gas stations that were even open. And when we got there - the lines were horrendous. We'd be in line for a couple hours just to get to a pump.

The above scenario is if you are lucky and CAN find a gas station open that can pump gas and.... has gas left to pump.

You can not rely on that.

Please keep in mind that in a disaster scenario - such as the post-hurricane back-up power situation you allude to - acquiring fuel is going to be an issue. What fuel can you get - if any? If you can not get fuel and you dont already have it then your generator is a giant paperweight.
I state again - if you can not get fuel and don't already have it on-hand your generator is a giant paperweight.

You need to have better plans than "a bunch of gasoline". That ain't gonna work too well.

Now, you could get a small inverter generator like a Honda EU2200i that sips gas and run your essentials - refrigerator, lights, fans. That will run around 8 hours on a gallon of gas, or around 12 times the run time of the 15kw example above. In that case - you could get by on gasoline because it is so fuel efficient. But - you are NOT going to run your AC on that. For that same week period of time you would go through ~21 gallons of gas instead of 252 gallons, or for 2 weeks ~42 gallons instead of 504 gallons. Big difference.

When you're talking big power and whole home back up - natural gas makes a whole lot of sense because it is piped in and "there". You CAN run long run times and big watts - as long as the fuel supply is there. And that is the kicker. If the gas gets shut off you are hosed. Then you're back to tanked forms of fuel - propane and gasoline. Trying to feed a big watt generator on tanked in fuel, as illustrated above with the gasoline numbers, is a hurdle. That is where smaller generators that are much more fuel efficient are a blessing. Yeah you might have to sacrifice some things - but you will have some power for the essentials.

Speaking of essentials - I consider refrigeration an essential. We can't eat spoiled food. Yeah, when it is 90deg and humid AC would be nice - but if we are rationing fuel it, unfortunately, has to go because the draw is so huge on the fuel. And we have generator options - 15kw rotary, 2600w rotary, and a 2200w inverter. I wish I could bridge the gap with something in the 5kw class. At some point I will - I just happened to stumble in to a deal on the 15kw so thats what I went with - and the bigger thought with it was there are some things my other units won't run so if I was in a scenario where I needed more power I could fire up the 15kw for that purpose only, then shut it off. Options.
 

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Discussion Starter · #27 ·
Do your math.

For example: My 15kw unit supposedly sucks down 1.5 gallons an hour, I think that is around 1/2 load, then it goes up to about 1.8 gallons an hour closer to rated load if I recall correctly. For math purposes I've been using the 1.5 number and was comfortable with it so I'll use it for the time being until more real world testing to get a better number for the way I use it.

Think about that for a minute - 1.5 gallons every hour of operation, on average.

In 24 hours that will be (1.5 x 24) = 36 gallons per day.

If you loose power for a week, thats 7 days, or (7 x 36) = 252 gallons.

If you loose power for 2 weeks.... Thats (14 x 36) = 504 gallons.

How are you going to store all that gas?

I have the ability to hold around 80 gallons if I filled up EVERY container/tank. Thats a pain in the arse. At the moment I have about 45 gallons, or less than 2 days, and I try to cycle through it so it isn't sitting around all year.

Now - instead of storing the gas you could go to the gas station and refill a days worth of gas every day, or a couple days worth of gas every couple days, right?

WRONG.

If you are in a big power outage your gas stations are going to be closed down also. We ran in to that many years ago. The remnants of a hurricane went through the midwest and caused a big wind storm that left us out of power for close to 2 weeks. In the early days we had a lot of trouble finding gas stations that were even open. And when we got there - the lines were horrendous. We'd be in line for a couple hours just to get to a pump.

The above scenario is if you are lucky and CAN find a gas station open that can pump gas and.... has gas left to pump.

You can not rely on that.



I state again - if you can not get fuel and don't already have it on-hand your generator is a giant paperweight.

You need to have better plans than "a bunch of gasoline". That ain't gonna work too well.

Now, you could get a small inverter generator like a Honda EU2200i that sips gas and run your essentials - refrigerator, lights, fans. That will run around 8 hours on a gallon of gas, or around 12 times the run time of the 15kw example above. In that case - you could get by on gasoline because it is so fuel efficient. But - you are NOT going to run your AC on that. For that same week period of time you would go through ~21 gallons of gas instead of 252 gallons, or for 2 weeks ~42 gallons instead of 504 gallons. Big difference.

When you're talking big power and whole home back up - natural gas makes a whole lot of sense because it is piped in and "there". You CAN run long run times and big watts - as long as the fuel supply is there. And that is the kicker. If the gas gets shut off you are hosed. Then you're back to tanked forms of fuel - propane and gasoline. Trying to feed a big watt generator on tanked in fuel, as illustrated above with the gasoline numbers, is a hurdle. That is where smaller generators that are much more fuel efficient are a blessing. Yeah you might have to sacrifice some things - but you will have some power for the essentials.

Speaking of essentials - I consider refrigeration an essential. We can't eat spoiled food. Yeah, when it is 90deg and humid AC would be nice - but if we are rationing fuel it, unfortunately, has to go because the draw is so huge on the fuel. And we have generator options - 15kw rotary, 2600w rotary, and a 2200w inverter. I wish I could bridge the gap with something in the 5kw class. At some point I will - I just happened to stumble in to a deal on the 15kw so thats what I went with - and the bigger thought with it was there are some things my other units won't run so if I was in a scenario where I needed more power I could fire up the 15kw for that purpose only, then shut it off. Options.

If I am out of power for a week...I'm going somewhere else that has electricity. I see myself using my generator for 12 hours a day for maybe 3 or 4 days. Anything more than that...I am gone! haha
 

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If I am out of power for a week...I'm going somewhere else that has electricity. I see myself using my generator for 12 hours a day for maybe 3 or 4 days. Anything more than that...I am gone! haha
(12 x4) = 48 hours

48 hours x 1.5 gal/hr* = 72 gallons

*use what ever consumption you want, the 1.5 here is just an example to illustrate.
 

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and the honda is still the best.
buy what you want.
for us here the honda works for us.
or if you are looking at larger gen sets
look at cat.
 

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FlyFisher underscores why you must determine the absolute minimum power required and then go from there.
Just tossing out there "food for thought", I realize I am complicating things but I think it is very wise to "think through". Hopefully everything I throw out there helps others in that thought process, if at the very least it gets their wheels turning.

Determining the absolute minimum power required isn't necessarily a "go from there" determination.

There is a threshold of every generator to produce power before a change in fuel consumption.

If you have a 35kw generator and draw 1kw from it you are not going to decrease the fuel consumption from if you were drawing, say, 10kw.

As to where that threshold is, I am not sure. The point I am making is there is a level of wattage that you can draw from a generator before the fuel consumption increases.

So with respect to the "minimum wattage" thought - if you only have 1 generator you are at the mercy of its fuel consumption no matter what. The only way to benefit (in terms of lower fuel consumption) from knowing the "minimum" is to start small right off the bat with a very fuel efficient inverter generator. Yes, you will have some strict limits. If you need more power than what the little inverter can - have another generator that can provide that next step up.

The idea is to get the wattage you need while making the best use of the fuel you have/can get. If you are max'ing out the wattage on a generator you need to step up. If you aren't using the wattage within the threshold of where the fuel consumption of a larger unit goes up then you have too big of a generator.

I've heard numbers between 50-75% duty cycle being where you want to plan generator sizing for. What i would say is to use the 75% figure - off of the running wattage, not the starting wattage. What this means is when you add up all the wattages of your devices that total should be no more than 75% of the running wattage of the generator you're looking at. This will give you head room for starting loads without hitting in to the starting wattage figure, or at least minimizing it. Even though the unit is spec'd for 25% more on the running wattage that 25% cushion will run the alternator cooler. And at 75% of the running wattage you are well in to the loading of the engine that will make the fuel consumption go up. So with lighter loads the fuel consumption will drop.

To get more detailed - if you can figure up the loading on each half of the split phase power system (think house breaker panel and the even vs odd numbered breakers) and match the highest load count (not the breaker amperage, but all the devices running on all the breakers on each leg and what they draw, not what the breakers are) to the 75% figure above that would be ideal. This gets in to load balancing somewhat, but that can be a bit tricky. What ever the highest power draw is on a leg take that as your 75% and the rest won't be as important.

If you are running extension cords from a portable generator then try your best to even out the loads, if it is a split phase 120/240v unit. Otherwise, if it is 120v only like a lot of the inverter units - it is all the same.
 

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New to this generator talk so take it easy on me. :)

I am looking to purchase a generator for backup power for my house. I live in the country, so sometimes it takes a few days to regain power after a hurricane. I do not have natural gas available.

I would like to run my A/C (4 ton, I believe it runs at 5kw?), lights, 2 fridges, freezer, tv, and water pump.

What size would I need? What are the brands to look at?

Thanks so much for the help. I have been driving myself crazy trying to decide on a unit.
Hello, Depending your electric consumption in your home, a 12kVA diesel generator would be perfect for you. You can check our website in the profile :)
 

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and on the older diesel generators think on wet stacking...
they like a 15 to 25% load as a min.

i guess this is why I like the idea of tri fuel gasoline, LP, NG
and right now my favorite is the NG...
at least as a priority fuel..
way less fumes.... and it is fuel on tap.... you pay for what you consume...
and the same on LP..
except you have to have a delivery truck or get your own fuel on LP...

the other thing to keep in mind you are at 25% more cost than grid power when on a gen set...
at a min...
just throwing out numbers....

now if a new gen set came on the market that would be a true all fuel generator...
Diesel, gasoline, natural gas, Liquid propane.....
and make it pass epa and all of the world standards with out any add on fuel exhaust trickery like a DPF.
now you would have an all in one gen set!
then areas where bio fuel is a BIG thing (NG and diesel renew fuels) you would be covered.

do that as a larger inverter generator maybe is the range of 30 to 60 kw to give you room.
and make it where the fuel consumption when at lower levels of power demand would be
proportional to the fuel consumed...
then you would have something!
think 2,4,6,8 CYL progression.... with electronic valves, direct CYL injection.
total electronic fuel management by octane sensor...

yup I would buy one or two right now!
and the onboard inverter would make it work with other power sources as well.
it could be selected as primary master of secondary slave for the sync step.

lol mic drop...
stay safe out there!
 

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and on the older diesel generators think on wet stacking...
they like a 15 to 25% load as a min.

i guess this is why I like the idea of tri fuel gasoline, LP, NG
and right now my favorite is the NG...
at least as a priority fuel..
way less fumes.... and it is fuel on tap.... you pay for what you consume...
and the same on LP..
except you have to have a delivery truck or get your own fuel on LP...

the other thing to keep in mind you are at 25% more cost than grid power when on a gen set...
at a min...
just throwing out numbers....

now if a new gen set came on the market that would be a true all fuel generator...
Diesel, gasoline, natural gas, Liquid propane.....
and make it pass epa and all of the world standards with out any add on fuel exhaust trickery like a DPF.
now you would have an all in one gen set!
then areas where bio fuel is a BIG thing (NG and diesel renew fuels) you would be covered.

do that as a larger inverter generator maybe is the range of 30 to 60 kw to give you room.
and make it where the fuel consumption when at lower levels of power demand would be
proportional to the fuel consumed...
then you would have something!
think 2,4,6,8 CYL progression.... with electronic valves, direct CYL injection.
total electronic fuel management by octane sensor...

yup I would buy one or two right now!
and the onboard inverter would make it work with other power sources as well.
it could be selected as primary master of secondary slave for the sync step.

lol mic drop...
stay safe out there!
Paul you make very interesting points.

Diesel is one fuel I don't have a way to burn in a generator. And my truck is diesel so I am SOL on siphoning from its large tank as backup generator fuel. I've thought of going the route of a DC generator at some point (combined with the power consumption side of an alternative energy system - the batteries and inverter side - where the DC generator charges/maintains the battery bank). Having a diesel engine for that would be awesome - and a gasoline that could be set up as tri-fuel. In that case I could cover all bases.

I am not sure I like the staging of firing cylinders idea in a larger engine. I would be surprised if there is much market for a home backup generator north of 25kw. I'm sure there are probably some mansions out there that have 6 central AC units etc etc and have 100kw generators... but that is the far exception, and at that point commercial prime units are out there to many hundreds of kw so that rare "home" market is already covered. If you have a house that big you probably don't need to ask the price of anything anyway. For the more normal folk - the vast majority - with a home that has 1 AC unit, refrigerators, the usual TV's, computers, lights - I can't see needing more than 25kw, and that still sounds awfully high unless you are trying to run at a pretty low duty cycle. If there were an inverter generator that covered that base alone I think that would be good. I am not sure how the wear would balance between cylinders if only some are firing. I know there are vehicle engines today that do something similar - run 4 cylinders of a v8 in economy mode or what ever. It just seems like it would throw off the balance on the engine - and you're dragging the other 4 cylinders along for the ride. I suppose with computer control it would be possible to do it, just seems like an odd concept.

Just the ability to throttle the engine through its' RPM range from idle to full throttle depending on the power required would be a huge help on fuel consumption on the bigger units.

I'm sure big inverter generator technology is coming - its just a matter of time. And of course it is going to be pretty expensive off the bat. Look at where Honda is today vs, say, Powerhorse in the price game for comparable units. Its a name brand that has the better product and generally is early, then other manufacturers follow after the trail has been blazed to bring down the price point and compete with the name brands.

Although - it would be interesting if a large inverter generator could be made with 2 engines. As the load surpasses what one engine can provide have the 2nd engine start and come on line. I am not sure what the response time needed would be and if the 2nd engine could start and come up to speed "in time", or if a capacitor bank could be used to stretch that time period of the capacitors providing for what the 1 engine isn't until the 2nd engine can come online and keep up, but it would be an interesting concept. Sort of like a hybrid vehicle, although you aren't concerned with voltage/frequency drop in the time lag of the engine coming online.

It would be easier to match DC power on the input to the inverter than it would be to synchronize AC power on the output. With DC the voltage doesn't matter - the base voltage of the system will balance and what ever ability which ever alternator has to push a higher voltage will simply translate in to higher current as the wattage the alternators can produce will be there, just with restricted voltage = the other variable is current will rise. Thats the same principal in a wind turbine powered off-grid system that uses batteries - the power from the turbine is converted to DC for charging and that charging restricts the voltage vs the turbine spinning free with no load.
 

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On the subject of THD here’s the sine wave from my old champion 7000w generator. Not too shabby.
View attachment 9443
View attachment 9444
The sample rate of your 'scope isn't fast enough to resolve the waveform with much detail. I agree, though, it does look decent.

On digitals you get a basic overview but the pixelation of the waveform hides the detail. Without spending a fortune on a high end digital 'scope your best bet is a CRT - the analog 'scopes do not have the pixelation. They don't have the fancy math features etc etc that the digital ones do, but you can't touch their ability to resolve waveforms with a 10ft pole

The two 'scopes here are of the same leg of my 15kw unit at the same time. If you look at the digital 'scope you can interpret some of the detail, but if you didn't have the CRT to compare to it would be impossible to see anything other than the one notch on the rise of the wave and one spot on the fall you can correlate, towards the top of the wave. The rest of the wavy'ness on the CRT is buried in the pixels of the digital.

9445


9446
 

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just keep in mind every time you convert energy from one state to another there is a % of loss....
thermal, friction etc...

yea if battery tech gets better i could see a battery storage and a inverter for each different items in a house...
idle current only till it kicks in....
and then use a gas generator for a battery charger to be on call for when the battery charge management calls for a charge.
it could work!
we just need low cost 20+ year batteries.....
i am still watching the salt water batteries...
they could be the ticket!
there is also the flywheel system out there that has low loss in the storage...

for now the little systems we have.... they work ok!
who knows where we will be in another 20 years from now!
 

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I look forward to improved battery tech. And I’m thinking of experimenting with some solar stuff. A solar shed.

On a recent YouTube rabbit hole I watched some stuff on flywheel systems. Neat enhancements have mad a niche for them.
 

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yup things have gone "full circle" for sure GRIN!
every thing out there has loss...
the trick is to get that loss as low as you can get it....

same on the fuels....
minimize the damage to the pocket book!
or get the max the bang for the buck.

and for storage of power.
get it as small as you can and the most power you can.

just think 122 years ago we were dependent on coal and steam power.
who knows where we will be in the next 50 or 100 years!
 
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