monkey44 wrote:
When I read these 'loudness' threads it reminds me of a generator I bought used from my local dealer once - used it for building homes when no power was available at the site.
It fired up off a battery (with jumpers), and ran at 1800 rpm, then you put a load on it, and it still ran at 1800 rpm and carried all the load of saws, compressor, etc on my jobs. It was VERY QUIET although I never measured it.
At the time, numerous Honda and Yamaha generator were advertised at 1800 rpm at idle, but even if you put a light bulb on it, let alone a saw load, it jumped to 3600 rpm and was very loud.
Brand name Kohler. The dealer told me it was out of a Motor Home ... It was pretty large and heavy (But I could pick it up and put in my PU), but ran on gas or propane, and put out 110v and 220v - so I imagine that was some of its weight and size.
Where am I going with this - AM curious why a mfgr can't build a quiet, idle constant 1800 rpm generator today. This one I had was used and in 1980s ... Am sure technology has improved significantly since then, with electronics and methods to create the power needed. Ran on a carb, not FI.
I'm not sure how the rpm factors into power production, I know we could run all our equipment at once (all with motors - table saw and compressor for example were half-horse each) and it never did anything but idle along quietly at 1800 rpm.
they can and some do. However, it isn't "free" HP= torque x rpm so in general it will take a bigger engine to develop the same HP at 1800rpm as one running at 3600rpm. And it takes roughly 1HP/500 watt of output power. 1HP=750 watts, but then there is conversion efficiency.
so, it's a tradeoff of engine size, weight and cost vs. longevity, noise, etc.