Generators, Gen sheds, Gen fuel systems, etc.

Re: Generators, Gen sheds, Gen fuel systems, etc.

alyaz wrote: »

We tried the Honda EU6500iu generator and with less than 500 hours it was in the shop for a major repair... Not amused.

Inverter generators are best suited to camping and such at light loads. They are quite inefficient when required to run at rated load for off-grid battery charging systems and I have seen several EU3000 Honda's with failed inverters from running at or near rated load in hot weather.

We also did a recent generator upgrade. We had a Generac EcoGen and replaced it with a Honda EM4000SX. In our climate the amount of energy input required to start a diesel or LP engine at temps under -10F is too great, and the generator only auto-starts at other times during the year for peak load management. So with the primary considerations being cold weather starting, and the ability of the generator to accept rated load with a 15 second warmup for peak load managment, we went with gasoline-fueled.

Our inverters have the ability to load share with the generator for peak loads so we don't need a large kW generator. It was difficult to keep the EcoGen at full load where it runs the most efficient, even for load start amps, so we went with a smaller unit. The new generator required a new generator shed and I have photos of my gen shed project here:
https://picasaweb.google.com/110979388690716770927/HondaGenerator
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Chris

Re: Generators, Gen sheds, Gen fuel systems, etc.

BB. wrote: »

Chris, neat little setup... How did you handle autostart and control of choke (or alternative) for cold starts?

Bill, the new Honda EM-series deluxe generators now have an electronically controlled iGX engine. It has computerized ignition and the engine's ECU is directly above the carb where it also controls throttle and choke. The key switch completes two different circuits in the "ON" position - one for the ignition module and the other for the engine ECU.

As far as wiring it up, the Trace GSM has two relays. The Run relay Common and NO terminals are used to turn on 12V power from the genset battery to the ignition, and I also had to install an additional relay on the genset that uses that 12V signal to enable the ECU. The third wire is the crank signal.

It was very easy to wire up. Not quite as simple as our old EcoGen with the two-wire start. But frankly the Honda is twice the generator the Generac ever thought of being. That little EM4000SX with the iAVR system where it maintains voltage and freq at 25% overload for 10 seconds easily rivals the EcoGen's surge power for starting air compressor, well pump, etc..
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Chris

Re: Generators, Gen sheds, Gen fuel systems, etc.

The "EM-series S" are the standard units that do not have electric start. The ones with the "SX" suffix are the deluxe version with the iGX engine. The ones that have an "iS" suffix are inverter units. The inverter units and standard "S" suffix generators use the old GX-series commercial engine.

On the website they don't really cover the "S" standard units' features - the just "SX" deluxe ones. However, when I went to the dealer to get it, I had to specify that I wanted the SX because the price on the rope-start "S" models is a lot cheaper. I think they call the "S" units the "economy" generator in the dealer book.

Although there is a fair amount of market speak here, this is a YouTube video that explains a lot of the features of the new deluxe series generators
http://youtu.be/qSG7wbAOMRw

I should also mention that there is a remote control plug on the SX generators. However, that ended up not being useful for an off-grid auto-start system. The Honda remote control box has a start button, a stop button and a pilot light to show that the generator is operating. It requires that the key switch be left in the "ON" position for it to work, which places a few mA draw on the genset battery because the ECU and digital ignition module are powered up all the time.

I removed the key switch, studied the wiring diagram in the manual, ohm'd the switch out to make sure I had it figured out - then spliced into the wires coming out the switch to tie it into the GSM. By splicing into the wires at the switch, it exactly duplicates what the key switch does, so there is no draw on the genset battery in standby.

In the inverter Generator Starting Details Menu, I have pre-crank set at zero seconds, max crank time 3 seconds, post crank 20 seconds (before it attempts another starting sequence). Basically the starter just bumps the engine and it's running. The inverter senses voltage and disengages the starter. In very cold weather I may have to adjust the crank seconds - I won't know that until it gets below zero here this winter. But at -20F I suspect it will take several intake strokes with the choke closed to get the mixture rich enough to fire, so it may require more cranking time.

The auto-choke on it does not just start it and slam the choke full open. It must use temperature, time, or some other factor to determine how fast to open the choke. I took the air cleaner element out and watched it during a Load Start cycle with the engine cold. As soon as it starts it opens the choke partly, but not all the way. For Load Start I have warmup set to 15 seconds and when the inverters load the generator it doesn't miss a beat, and it takes about 30-45 seconds for the choke to open all the way.
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Chris

Re: Generators, Gen sheds, Gen fuel systems, etc.

The thing I like about it is that it puts out utility grade power without having an inverter on it. Inverter generators are very nice because they put out clean power and can idle down to save fuel at light loads, having a permanent magnet alternator instead of a conventional wound field. But for off-grid systems where the auto-start will start the generator for one of two reasons - either load amps or low battery - an inverter generator is a bad choice. Inverter generators run least efficient at full load. Conventional generators run most efficient at full load.
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Chris

Re: Generators, Gen sheds, Gen fuel systems, etc.

What he means is that (all mitigating factors being equalized) at full load conventional generators are more efficient than inverter-generators . As the loading decreases the advantage goes in favour of the inverter-generators because they don't have to maintain RPM to maintain Voltage & frequency. This fact has been proven many times by those of us with years of experience with both types of generators and has been iterated on the forum over and over.

The tricky part is equalizing 'all mitigating factors' because no two generators are alike. There aren't 3kW 'Brand A' generators available in both conventional and inverter type for a side-by-side comparison. It is possible to have two conventional or two inverter generators of the same kW rating with different fuel efficiencies because they are made by different companies and have different engines. By the same token, two identical generators (make and model) could have different efficiencies in side-by-side testing because of variations between the two (but it should be close). Some engines simply are more fuel efficient than others of the same HP/size.

It isn't really fair to compare different size gens to one another and extrapolate efficiencies of type from that data. A large generator is going to use more fuel because it has to be bigger over-all, including greater mass of the generator portion which requires more power to move it.

Re: Generators, Gen sheds, Gen fuel systems, etc.

Cariboocoot wrote: »

What he means is that (all mitigating factors being equalized) at full load conventional generators are more efficient than inverter-generators . As the loading decreases the advantage goes in favour of the inverter-generators because they don't have to maintain RPM to maintain Voltage & frequency

This is pretty much what my testing showed re: the inverter-type generators. I concluded that for an off-grid power system where the generator is used only for battery charging with an inverter-charger that an inverter generator could possibly provide higher efficiency. Initially, when the battery bank is in bulk charging it will probably run at full load and be less efficient than a conventional.

But as we all know, as the internal resistance in those batteries comes up, the amount of charging current required is reduced in absorb. This is where the inverter type can make up for what it lacks in full-load efficiency. It can start idling down as the load is reduced where a conventional has to maintain rpm.

For off-grid systems where the generator is used for Load Start Amps (auto-start where the generator takes over heavy loads to reduce load on the inverters and bank), I think an inverter type is a bad choice because it's going to spend more time off the peak of its efficiency curve. This was, in fact, one of the problems with our EcoGen - it was too big for us, even for Load Start. All the generator really has to do it take the top edge off the loads for a Load Start situation and the inverters have no problem delivering the balance of the power. It was difficult to keep the EcoGen loaded at full load, and hence it was not the most efficient generator we could use.

The Honda EU2000/EU3000 are impressive little generators. Cummins also builds the QD (Quiet Diesel) series of inverter generators in larger sizes that are quite impressive. But again, considering a Cummins QD6000 that burns 1 gallon of fuel/hr at rated load, it is pretty inefficient at full load compared to even a gasoline fueled conventional one at the same load.

It is an interesting topic - I have seen the Perkins units like shown in this thread. I don't know what the size is of the one shown here, but it would nice to collect some fuel consumption data on one of those to see how they compare.
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Chris