# Idle Management, Honda powered generators and throttling?



## FlyFisher (Jun 30, 2018)

I've seen references to some non-inverter style generators that have a form of "idle management" on them that, I assume, is to adjust the throttle of the engine so it runs slower with little to no load.


I have been looking in to the Northstar generators that Northern Tool offers. They run Honda engines. From the research I've done on the Honda engines used in generator applications - they are fixed RPM, no throttle. The Northstar 13,000w version is the main one I am interested in (13,000w peak, 10,500w continuous). It uses a GX630 Honda engine. According to the manuals for the GX630 - the non-generator versions have a throttle control that is to the right of the choke lever. On the generator version there is no throttle lever, just a cover plate over the slot. However, the throttle lever on the back side of the engine is there next to the choke lever along with the governor spring etc. 



So my main specific question is - on this specific engine (GX630 meant for generators) - can one fashion their own throttle cable to the linkage/lever that is already on the engine to control the throttle of the engine? Or has Honda incorporated some type of electronic control over the throttle where the throttle linkage doesn't mechanically adjust the throttle, rather it is an electronic input to a computer - that is locked out from operation on this model? 



A more broad question - on a conventional alternator generator - the RPM of the alternator determines the output voltage. So I can see where the "fixed RPM" is desired - so as to keep the voltage where it should be. How do some manufacturers get away with "idle management" on this style generator and others do not? (alternator style vs inverter style) Does the idle management stop throttling back on "any" load? Or just above a certain threshold of current/wattage detected?


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## FlyFisher (Jun 30, 2018)

Well I can't figure out how to edit my own thread... Maybe there is a post count limit to do that which I haven't hit yet? 



In any event, I know the Northstar generator I referenced DOES NOT have idle management - which is the root of my questions for the theory of this and the throttling of the Honda engine... 



For what it is worth, what draws me to the Northstar generators is namely the Honda engine. I would put the "bar" on where the Honda engines stack well above most other small engines. I just think Honda generators (the whole bit - engine and generator) the size I am looking for are over-priced. I bought an EU2200i because of the low noise, low fuel consumption, and reliability, but admittedly it is was very expensive. I justified it with my experience using them and from others' experiences with owning them. I'm sure I could do the same for a bigger one, but when the price differences are thousands of dollars it becomes harder to justify!!


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## Osviur (Sep 7, 2015)

Hi FlyFisher,

I would like to clarify about your question: "A more broad question - on a conventional alternator generator - the RPM of the alternator determines the output voltage". This is partially true, the output voltage produced by a "conventional" generator, depends on three factors:

1.- The rotational speed of the magnetic rotating field (rotor RPM-engine RPM)
2.- The intensity of this magnetic field
3.- The number of turns in each stator coil.

The #1 factor is controlled by the engine RPM
The #2 factor is controlled by the voltage regulator (AVR)
The #3 factor is fixed by design value.

The #1 factor, engine RPM, not only affects the output voltage value, but the frequency (Hz) too, and in this kind of generators, this factor is which determines the output frequency, only this, so it is not possible to control the output voltage varying the engine RPMs maintaining a fixed frequency.

The solution is to maintain fixed RPMs and to vary the magnetic rotating field,via the Automatic Voltage Regulator, adjusting the voltage applied to the rotor as a response to the output voltage value. The RPMs are controlled, and maintained fixed, by a governor, electronic or mechanical, which controls the throttle lever, in accordance with the mechanical load imposed to the engine by the generator head. This load increases as the load current circulate in the stator windings increases the mechanical resistance presented by the generator shaft to the engine shaft.

The stator windings are grouped in poles and due to this characteristic, most common generators are designed as two or four poles. 

Two pole generators produce 1 cycle for each shaft revolution
Four pole generators produce 2 cycles per revolution.
One cycle per second is named 1 Hertz (Hz), so 60 cycles per second will be 60 Hz. This means that a two-pole generator will need to turn at 60 revs per second, 3600 RPM, to generate 60 Hz. A four-pole generator will produce the same frequency at 1800 RPM. Said this, is evident that with this type of generators it is not possible to generate the nominal frequency at a speed different from the synchronous speed (1800- 3600 RPM for 60Hz or 1500-3000 RPM for 50 Hz) 

Inverter generators function in a different way, they can produce fixed voltage and frequency at varying RPMs but this is another theme.

Hope this help.


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## RedOctobyr (Aug 8, 2018)

FlyFisher said:


> A more broad question - on a conventional alternator generator - the RPM of the alternator determines the output voltage. So I can see where the "fixed RPM" is desired - so as to keep the voltage where it should be. How do some manufacturers get away with "idle management" on this style generator and others do not? (alternator style vs inverter style) Does the idle management stop throttling back on "any" load? Or just above a certain threshold of current/wattage detected?


Osviur's answer was excellent, and much better-informed than anything I could offer. But I'll try to reiterate his points, relative to your questions:

- The fixed 3600 RPM is required to produce the 60 Hz power that we use here in the US (in Europe, it would be 3000 RPM to make 50 Hz). 
- Within the conventional, alternator-style generators, as soon as there is *any* electrical load (even charging a single cell phone), they need to go from idle RPM, to the full 3600 RPM. Otherwise it would be producing, say, 40 Hz, which would be bad for any connected devices, even if the voltage could be made acceptable via the AVR. 

A generator that can auto-idle is nice. But the usefulness depends on how you're using it. If it's to run tools on a jobsite, it may be in idle a lot, if a saw isn't always cutting, etc. 

But if it's to run your house during an outage, the only times it might idle are during startup and shutdown. To let the engine gradually warm up before connecting a load, and to let it cool down after disconnecting the loads, before shutting it off. The rest of the time, you'll be powering *something* in the house, so it needs to be at 3600 RPM, even for a single LED light. 

I liked auto-idle for startup and shutdown. But I don't think I'd make big changes to a new machine, just to try and "fake" an auto-idle system. You probably could rig up something if you really wanted to. But you don't want to jeopardize the governor's behavior, and mess with the electrical output (dropping lower than 60 Hz, for instance). I'd probably keep up with oil changes, use synthetic after the engine was broken-in, and deal with it going straight to full-RPM as soon as it starts. While it's not my preference, more and more engines run like this (mowers, pressure washers, some snowblowers etc). 

If you really want to reduce noise, and fuel consumption, an inverter generator will offer much greater benefits than just having auto-idle on a conventional generator. Which you know from your EU2200i. But you'd have to increase your budget, and deal with reduced output, vs a conventional unit.


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## FlyFisher (Jun 30, 2018)

Thanks for the replies. 



I understand the theory that has been explained. I can see where the drop in frequency would be an issue. 



The biggest inverter generator I can find is the Honda EU7000is, but at around $4500 stock it is very pricey for what it is. The generator I mentioned earlier - Northstar 13000 - is around $2700 in comparison - $1800 less and 5000 watts more continuous power (10,500 on the northstar vs 5,500 on the honda). 



I have 2 other generators - the EU2200i and an open frame 2600 or 2800w conventional. So for smaller power needs I am plenty covered, but the small generators have their limits. That is where I would like a larger generator to fill in. I'd rather have some overhead in power than to cut things too short. I know the 5000-7000w generators are quite popular, but I think for the times I would need more power than what I can run on the 2 generators I use now (intermittent use) going a lot bigger won't matter much as it won't be running much. The conventional generator I have now is a pretty cheap generator, so I am not sure what it's lifespan is going to be. If it bites the dust I'm not out much - I got it for free. Maybe at that point I can look in to something in the 4000-5000w range as a mid-range generator. We'll see what the future holds.


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