3000W Chinese Gensets Info.

SonicLogic wrote:

BORoarke wrote:

toprudder wrote:

SonicLogic wrote:
For every 1,000 feet above sea level your power output decreases by 1%.

Actually, it is worse than that. About 3% per 1000 feet. :(

Bob R.

What I was taught, reduce the power rating on the label of the generator by 1% for every 1000 feet you are above sea level, 3% for every 1000 ft. above 3000 ft. So basically, if you are at 8,000 ft, your generator's output would be reduced by 18%.

1,000 ft - 1%
2,000 ft - 1%
3,000 ft - 1%
4,000 ft - 3%
5,000 ft - 3%
6,000 ft - 3%
7,000 ft - 3%
8,000 ft - 3%
Total reduction: 18%

This is what I was taught. If this is wrong, please correct me so I know.

Thanks!

Of course, you guys are right and I stand corrected. Suffice it to say that both elevation and high ambient temperatures (anything over 77º F) will reduce the generator output. My real point was that John’s generator is not “over-rated”. It is running well within specifications and perhaps putting out more power than advertised.

These are all 'thumbnail' rules, of course. But, SonicLogic got it right--I did indeed forget to account for altitude and temperature. My particular model of the PowerPro generator is rated for 3750 watts of surge and yet I was killing my engine at a point somewhere between 2850 and 3000 watts with purely resistive loads. Later, I noticed my old Briggs & Stratton lawn mower manual had yet another thumbnail rule:

"Engine power will decrease 3-1/2% for every 1000 feet (305 m) above sea level and 1% for each 10ºF above 60ºF (16ºC)."

Working out the math for my altitude and temperature--I was at 85º F when I did my testing--it comes out to just over a 21% reduction, or a surge capacity of only 2950 watts. That's right on target, but OUCH! In Colorado, one often camps at 9000 feet and that means a power loss of over 30%. The only thing I like about this formula is the thought of mowing my lawn at 60ºF. Usually it's in the 90's when it's time to mow around here.

--John