Ok, gang. Firstwave's question got into my head like a bad BeeGees tune. I decided not to wait until I was loaded for our upcoming trip (or forced to flee approaching hurricane Danny... whichever comes first).
I pulled the Hondas out of the garage, grabbed two 20 lb LP bottles and the digtal bathroom scale and started my test.
I weighed each tank using the scale (also weighed a case of water as a "control" to assure reasonable consistency of the scale from start to finish of the test), plugged a hair dryer into each generator to simulate a load, turned the EcoThrottles "off", and fired them up (since they've never seen gasoline, they started on the third pull even after sitting in a hot garage for over a month) and started the stop watch.
After 30 minutes I switched hair dryers between the generators just in case they were not the same wattage (I was trained as a scientist... I couldn't help myself... one variable neutralized). After an hour I turned off the gas to each, unhooked and reweighed both the water (which was precisely the same as before to the 1/10 th of a pound) and the two bottles.
The answer I got was that each bottle was 2.0 pounds lighter than at the start.
Since a 20 lb LP bottle doesn't actually hold 20 lbs of LP (typically a full cylinder delivers 17 to 19 lbs before its exhausted... and blue rhino and Amerigas reportedly only put 15 in theirs) that says a generator running flat out will empty a full 20 lb cylinder in about 9 hours of operation.
Since a propane refill costs about $15-20, propane costs about $2/hour per generator at full load. Since the same load reportedly runs an EU2000 for 3.4 hours on one gallon of gas which at $2.50 per gallon is about 75 cents per hour, propane is way more expensive. Like others have reported, I chose propane because it seems safer to transport under my black tonneau, I can use the 30 lb bottles on the AS or carry 20s on the generator platform and I believe LP saves me from the reliability issues of gas left in carbs (or the need to manage that problem with additives, carb draining, etc). Other folks make the choice for gas for equally compelling and valid reasons that suit their needs. However, if fuel cost is driving your choice, GO GAS!
Now, on to the question of "what can I run with one, or two Honda EU2000s?". I mentioned yesterday that I cannot run my factory installed AC (a Dometic Penguin II 15,000 BTU AC/heat pump which Dometic says draws 13.4 amps for the compressor plus 2.6 for the fan or 16.0 amps total) and microwave (Sharp carousel micro/convection at 12.5 amps as a microwave, more in convection mode) at the same time with the two EU2000s in parallel. I did not mention that there are other loads on the system. The other biggie is my aftermarket Progressive Dynamics 4655v converter/charger. The 55amp (DC) model draws up to 950 watts or 7.9 amps of AC.
When I fire up the generators and connect them to the trailer and want AC I assume that the converter usually wants all the power it can draw to charge batteries and handle the 12v
load. Let's do the math...
16.0 amps of AC plus 7.9 amps of converter (23.9 amps total) at 120 volts is 2,868 watts. The Hondas are rated at 1,600 each continuous.... 3,200 for the pair. 2,868 is under their capacity. All is good. Now, GammaDog wants a frozen burrito to become a mouth burner and kicks in 12.5 amps of microwave and the total is 36.4 amps or at 120 volts 4,368 watts. That exceeds both the sustained 3,200 watt and max 4,000 watt output of the pair of Hondas and nasty things happen since the resulting voltage drop is bad for the burrito and any device on the system. (Has your "30 Amp" Airstream ever tripped a 30 amp breaker on a campsite pedestal? Mine has. Now you see how that happens. The breaker was likely working as designed. Thank you Square-D!). If the converter happened to be asleep at the time I hit the microwave "go" button the AC and micro would have worked. I know that it's a "smart charger". It might be smart enough to take a break now and again. If you had a similar experience and said "gee... that wasn't a problem last time I ran the micro and AC at the same time" it could be that "last time" your converter was not drawing full power to charge low batteries when you asked the microwave to cook your dinner.
The solution is to turn off any one of those loads so the other two don't overload the generator pair.
One final thought... To answer the "can I pleeeeeease run my AC on just one Honda 2000?" question. If your one AC is a Dometic Penguin II 13,500 BTU model (for which my Dometic manual lists power needs) it uses 12.7 amps at 120 volts for the compressor and 2.6 for the fan. That's 15.3 total. At 120 volts that's 1,836 total. That's over the sustained rated power of the Honda EU2000 but under the max. I'm not sure how the Honda responds to that. Maybe someone with actual EE training (I said I was trained as a scientist... and I chucked that for a business career anyway... I never would have made it as an actual engineer) can tell us. If it responds with a voltage drop, 15.3 amps at 1,600 watts would have to deliver 104 volts. Hard on the compressor? I don't know. I wouldn't do it. In any case, adding any other load - even "just the converter" - would easily exceed the Honda's capability. The even smaller 11,000 BTU penguin II is 1,572 watts for compressor plus fan and would fit as the only load on a single Honda 2000 rated for 1,600 watts continuous.
There... I'm glad I got that off my chest. Now let's hear from people with actual knowledge in how this stuff works. I'm either going camping (heading to western New York then Maryland then the outer banks including two times with the truck and trailer on the NC ferry system!) or running like a scalded dog from Danny.
My next test will answer an earlier question... Since I sometimes run my generators using a tee fitting from the LP port on the AS, is there sufficient gas flow in the trailer to deliver 3,200 watts of electricity and run the fridge, stove and hot water heater? Stay tuned....