Open Frame Vs Inverter With Heavy Loads

In audio doubling output power is worth 3 decibels more volume. A 100 watt amplifier has 3 db more output than a 50 watt amplifier.

Carrying it to generators, I would assume two running inverter generators would add 3 db over one running inverter generator. Of course that would vary if the inverter generators were not identical.

If the open frame numbers come out close maybe you could mitigate it some with a sand berm, depression, or unused chairs around it to attempt to deflect sound upward. Safely of course.

DB meters are reasonable on Amazon.

2oldman wrote:

mrekim wrote:
If the inverter at full load has the same noise level as the open frame generator then the only advantage of the open frame one seems to be weight.

I'm not sure you said that the way you meant to. The only advantage I've ever seen is price.

I already own a single open frame generator and a single inverter generator. The only reason to buy a 2nd inverter generator would be in order to be a good citizen when running the AC, probably infrequently. The only other possible reason for a 2nd inverter gen would be that it's somewhat more portable. I was really surprised to find out that running a pair of inverters in the 50-75% load was the same as an open frame generator - at least with the units I have.

2oldman wrote:

Many folks try to 'justify' the cheaper, louder gens by saying that the inverters are just as loud at full load - and that may well be true. But, what's ignored in that argument is that you don't (and shouldn't) run full load very often.

Agreed. I had the open frame unit first and have no regrets getting the inverter. If I only had the inverter, I wouldn't hesitate to get a 2nd inverter. Given what I already have, justifying a 2nd inverter for loads in the 16-20 amp range seems difficult.

2oldman wrote:

I can run air on my 2 Hondas, but it's not a common occurrence. 96% of my generator running is for battery charging, and that's a varying load. That's where inverter gens really shine.

I've tested charging and agree here too. I'm not anticipating needed to run A/C often but want that ability.

2oldman wrote:
I rarely see anyone using portable gens for running air. It's way more prevalent in MHs with built-ins.

I'm prepping for dry camping on the beach on the east coast in August. I want to prep for a few hours of AC time per day, if only to cool things down for lunch and dinner as a escape from the heat.

Here in Texas, when boondocking at a gathering or festival, it is very common to see (and hear) generators powering A/C units.

One rule of thumb I have read is that generators work the best at about half a load. So, my inverter gen running my A/C is using about 1500-2000 watts (starting is a different beast altogether.)

I compared the noise level of my generator to a camper down the road with a similar A/C and a twin set of Hondas handling the load. The Hondas were louder than my single 3000 watt generator when handling the A/C. However, earlier in the year, when the other person had the generator on for battery charging, one of his 2000 watt Hondas on Eco-Throttle was quieter than my 3000 watt Yamaha on econ mode.

It is all about trade-offs. At the level of red/blue inverters, it becomes a matter of positioning. I lowered the dB of my Yamaha generator by putting it on the ground, exhaust positioned away from my TT and other people, and rolling it on a rubber mat so vibrations wouldn't be transmitted into the ground.

mrekim wrote:
If the inverter at full load has the same noise level as the open frame generator then the only advantage of the open frame one seems to be weight.

I'm not sure you said that the way you meant to. The only advantage I've ever seen is price.

Many folks try to 'justify' the cheaper, louder gens by saying that the inverters are just as loud at full load - and that may well be true. But, what's ignored in that argument is that you don't (and shouldn't) run full load very often. I can run air on my 2 Hondas, but it's not a common occurrence. 96% of my generator running is for battery charging, and that's a varying load. That's where inverter gens really shine.

I rarely see anyone using portable gens for running air. It's way more prevalent in MHs with built-ins.

I found a chart from Champion:

Champion Global Power Equipment 2000W Inverter


Percent Load.......Noise Level
0....................53
25...................54
50...................59
75...................65
100..................65

My measurements are a little noisier than that but I'm not testing with their conditions either:

The Champion 2000W inverter noise level (shown in Table 1) is measured under the following conditions:
• Distance of 7 meters (23 feet) from inverter
• Inverter placed on concrete surface
• 30.4 meters (100 feet) from reflective surfaces (walls)
• Ambient noise level 45 dB

Great video. The summary starting at 2:39 shows my point. The 2KW Champion inverter that I measured is nothing like the Honda 2KW inverter in the video. The Honda in the video is 59 db at full load. The champion is 68 db. If the inverter at full load has the same noise level as the open frame generator then the only advantage of the open frame one seems to be weight.

I'm still waiting for Champion to get back to me for the Db rating at full load to see if this particular inverter generator may have a problem.

Generator sound video

This compares various 'open frame' and inverter generators and their sound levels. Very instructional and short.

The plot thickens.

Yamaha and Honda both claim a rated load noise level close to 60 db for their 2KW units. I have not found a rated load noise level published for the Champion 2KW units, but I would expect a number in the same ballpark. It's possible that either my test was bad or the generator has a problem. I 'll test more when I can and I've sent an email to Champion asking if the the noise level should be much more that 60 db under a heavy load.

If one of these runs close to 60Db at full load then a pair of 2KW inverters is a no brainer....

2oldman wrote:
The most annoying noise doesn't come from the engine, it comes from the whirring of the generator rotor. A big muffler doesn't make much difference.

Just get the 2 inverters. You'll be much happier.

X 2, else a bad ca$e of morning after sickness....

I did a quick test. Load is an electric heater that draws 12 amps. Measurements are at 21`. Units placed at same location with exhaust pointing in same direction.



Unit....Eco...NonEco...Loaded
46514....n/a....69db....70db
73537i...55db...60db....68db


Consider the 55 ballpark. It was at the bottom of the scale of the meter and it was hard to get a good reading.


The above is a SINGLE 73537i. I'm not sure this test is fair when trying to compare paralleled unit though....