Does a generator consume less fuel if less power is used?

Question

I was told that when I use a generator, you might as well put on all lights because consumption is the same regardless of number of lights and appliances connected to it. Is that correct? Can I save fuel by lessening use?

Answer 1

Yes, less load will require less fuel. Engine efficiency will be higher at full load however. With no load, fuel is still being consumed so efficiency is essentially zero percent. As load increases, fuel consumption will increase as well. Check the ratings on your generator, it often gives run time at half load. Under less than this load, run time will be considerably longer.

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Answer 2

Sounds like a whole lot of uninformed opinion. The short answer is this, no matter what, if you apply more electrical load, the generator will use more fuel. Here is why. By the law of "conservation of energy", Energy can neither be created or destroyed. This means that the energy stored in fuel must equal the electric energy being consumed by your house, with some losses in effciency along the way associated with engine driven generators. The efficiency, or lack there of, at very light loads or at excessive loads will become more noticable, but never the less, if you use more energy in electricity, you will definitely use more fuel.
As for some of the other answers given. Just becuase an engine runs at a constant speed, does not mean that it is using a constant amount of fuel. In the case of a generator using a wound 2 pole alternator to produce power, it must run at 3600 RPM in order to produce 60 cycle current. But as the load on the generator (electrical) increases, the engine responds by opening the throttle to keep turning at 3600 RPM. When the throttle opens, it will allow more fuel to be consumed. This action is caused by a governor. All generator sets, big or small have some sort of governor. If they did not have some type of governor it would be imposible to maintain 60 cycle current under varying load conditions. There are some generators which will run at variable speed using a permanent magnet generator and an electronic device to simulate a 60 cycle syne wave, but they are still governed, and they will still use more fuel if more load is applied.
In conclusion, More power out means more fuel in. Buy a generator that will supply your needs at about 60% load and turn off the AC if you want to save money.

Doctor Ratz

Answer 3

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Answer 4

Generator Fuel Consumption

Answer 5

This Site Might Help You.

RE:
Does a generator consume less fuel if less power is used?
I was told that when I use a generator, you might as well put on all lights because consumption is the same regardless of number of lights and appliances connected to it. Is that correct? Can I save fuel by lessening use?

Answer 6

In theory the less load the less fuel consumption. However, many small engine/generators designed for home use do not have fuel control systems of sufficient quality to properly control the fuel supply. The result is they tend to run a fuel rich mixture at lower loads.

You could run a couple of tests if you are really interested.

Top off the fuel tank and run the generator at maximum load for a hour. Top off the tank and measure the amount of fuel added.

Then run the generator at minimum or no load for an hour and top off the tank again. Measure the amount of fuel added. The difference, if any, should give you an idea about the variation in fuel consumption versus load.

Answer 7

Short Answer: Yes, less power = less fuel if your is not doing that throw it out and get new one

Long Answer: Generators are basically Engine + Alternator combination, Engine turns the Alternator to produce electricity, Engine efficiency depends on a lot of things like RPM, Load, Temperature, Fuel Quality, Fuel System Quality etc etc. Our electrical equipment require current at specific voltage and frequency, 220V 50Hz or 110V 60Hz, to maintain freq. all generators are equipped with mechanical or electrical governess which basically control how much air or fuel or both goes into engine to keep it running at constant speed, and for voltage they are equipped with AVR, Auto Voltage Regulator Circuit, but they work upto a limit and respond between a certain RPM range for a given generator within a given load. So for a given load say 500Watt, your generator throttle is half open, and engine running at steady RPM, when u put more load say 750Watt, if throttle don't open it will result in decrease in engine speed (which actually happens) and the governor sense that and open throttle more, around 3/4 till engine reaches the RPM governor is set for, its same as you going in car with same speed but when come across a bridge, you push race paddle more to keep going at same speed while climbing and vice versa, same happens on generator, as load reduces the excess fuel will cause engine to speed up which will cause governor to slow the generator to same fix rpm, this happens fast so we usually don't feel it, but you can feel the engine sound changing when there is more load on generator. If more throttle is open it will such more fuel from carburetor, for diesel it's the fuel injectors governor control and in some throttle too, so basically load does effect fuel consumption.

Answer 8

That's true for a small portable generator, but larger generators that can power the whole house will have a governor on them and will modulate with load, so you will burn less fuel with a smaller load.
You should be able to run a short test on yours and vary the load attached. If the engine speed changes with the load, you'll save some by applying less load.

Answer 9

A gas engine on a generator will run at a constant speed but when you put a heavy load on it the engine will change in speed for a moment as the electric generator engages. So it will use more gas under a load than when it is not under a load. The more you have connected the more gas it will use.

Answer 10

Yes.
You start of with a minimum consumption, that powers the cooling fan, internal friction, generator friction.
After that, all electrical load uses more fuel