# Starting Watts vs. Running Watts Portable Generators



## jasonjax (Mar 15, 2020)

Hi folks,

I'm wondering what these ratings really denote. 

Say you had a running load of 10,000 watts on a generator rated for 12,000 starting watts and 9,500 running watts. Would the generator be able to sustain the 10,000 provided nothing tripped over 12,000 total. 

Just curious to understand the real-world correlation between these values.

Thanks


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## jasonjax (Mar 15, 2020)

Was this just a really dumb question?


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## drmerdp (Apr 10, 2018)

lol, not at all. Starting watts is an interesting and not terribly applicable value placed on generators. Its almost best to disregard starting or surge numbers entirely. Focus on the rated watts and assume that if the brand name isnt honda, yamaha, onan... etc that the numbers should be taken with a grain of salt.

The problem stems from a lack of a standards and practices in properly rating a generators output. Ever wonder why a $3,000 genuine honda generator with 389cc engine is rated for 5000-5500 watts but a $1000 knock off touting the same 389cc engine is rated at 7000watts with a surge rating of 9000watts. Maybe the engine would keep chugging but it will lose RPMs and the power would get very very dirty.






Blackmax | 7000 Watt Electric Start Generator Powered by Honda







www.blackmaxtools.com





To answer your specific question, yeah maybe for a very short time if the engine is large enough to overcome all the electromagnetic forces of the alternator. But keep that much load applied continously and something will give way... and it wont take long.

My old champion 439cc 7000 running 9000 surge was actually capable of sustaining 9000 on a load test but the voltage and frequency was drooping. Something would have over heated or broke if I left it 

Its best to judge output potential by engine size. And never run bargain generators continuously at their rated load.


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## iowagold (Jan 22, 2020)

jasonjax said:


> Hi folks,
> 
> I'm wondering what these ratings really denote.
> 
> ...


well,
it all depends on the generator!!
the Jina gens run way lower on the real power output than what is on the tag..

so if you are looking at a real generator like Honda eu7000is series.
the posted surge of 7000 is a real number and the rated of 5500 watts yes it is all that!!
they are truly designed for 5500 watts as a 24/7 output..

but if you choose a jina unit that set of ratings is in the real world much less..
most are 40% less or worse as a 24/7 run time..
there is no extra power!

before choosing a low cost gen set, find some one who has done real world testing..
and look at the real world numbers..

and remember you get what you pay for!!

and here is the rub!!
as a design engineer of systems you really want another 20 % to 30 % buffer over the honda ratings as well as a min.
I prefer 50% more gen set than you need...
that is why I like the idea of several gens in parallel so you can ramp up the power for summer demands and ramp down to the low number for winter power demands..
the generators run cooler and last way longer if they are at 50% of the rated power as a running watts.
less chance of failure during summer 100 deg + high heat days!!

and make sure your gen set is clean and dust free for a cooler run as well.
inlet air filters on quiet boxes is a real good idea!!


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## jasonjax (Mar 15, 2020)

Thanks for the responses. My application is standby generator with manual transfer switch to the breaker box in the event of an extended hurricane related outage. This gives me food for thought, and definitely explains why those honda engine based generators are so much more expensive.


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## speedy2019 (Jan 29, 2019)

iowagold said:


> and here is the rub!!
> as a design engineer of systems you really want another 20 % to 30 % buffer over the honda ratings as well as a min.
> I prefer 50% more gen set than you need...
> that is why I like the idea of several gens in parallel so you can ramp up the power for summer demands and ramp down to the low number for winter power demands..
> ...


Its like anything, buy stuff thats over the top and then they last longer,, like I bought a 275watt subwoofer about 10yrs ago now and I paired it up with 2 100watt speakers, and to this day the subwoofer still sounds as good now as when I bought it, because its never at full throttle.


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## iowagold (Jan 22, 2020)

yea... pretty much you have to spend good money to get good power..
so save up for the good generator!! it is worth it!!

the heck of it is
it takes 4-5 times the bucks right now with a generator to make the same power as the grid in most usa city's..
that is on the 5 year plan.. cost per kwh thing!!

by the time you spend in the design, setup, cost of materials and just on and on... and fuel cost too!

but here is the deal why a gen is a good idea!!
do you want to live like a person in the 1800's?? think amish..
these days we are all about comfort... and food storage.
and we are wired to the digital world too...
so a bad storm, earth quake, fire, or just a basic grid failure can put us back
220 years..

so plan a system that is good for you!!
and plan for several sources of energy with expansion in mind...
start small, but leave room for expansion!! some clean power is better than none.
think a single eu2200i for a basic system..
the cool thing on the portable gen set. you can take it with you if you move... or go camping.
or sell it to the next owner if the price is right!! and buy a new setup!! lol

I am always updating my system, planning the next update right now!
I did a bit of more work on it today.
and working on the next generation of meter panel this weekend.

more on that in the honda gen group.

right now a mfg could do well if they had an inverter generator that would produce up to 200 amps..
or 50kw running watts @ 240 vac
but ramp down to 20 amps or 4.8 kw @ 240 vac and sip fuel like the little eu2200i gens..
they have those 4 6 8 motors for the cars... if they could get those to do gen sets with inverter output..
I could use 3 of those right now for a client..
there has to be a way to do it on the cheap...


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## iowagold (Jan 22, 2020)

speedy2019 said:


> Its like anything, buy stuff thats over the top and then they last longer,, like I bought a 275watt subwoofer about 10yrs ago now and I paired it up with 2 100watt speakers, and to this day the subwoofer still sounds as good now as when I bought it, because its never at full throttle.


hey speed, run 2 of those subs!! and run them as left right..
then you get stereo on the sub parts of the music..
yea they have a blend ckt on board of most of the powered subs... but that cancels out part of the music at times..

I always say at 100 watts per channel on your main amp you need 1000 watts of sub amp to match it or 500 per side as left right sub... and 4 times that for the sub speaker rating. or 2000 watts rated like car audio on the sub rating..

now if you are using the GOOD STUFF like sound reinforcement stuff like for band gear..
that is rated totally different from home stereo gear..
there is a lot more head room..
and depending on your main room or home theater room size etc.
in a small 14x20 room 1000 watts at .001 dist sounds great at 10% volume.
I use
4) 12" drivers front
1) 10" driver middle
2) 10" drivers rear
and 2) 18" velodyne subs for the sub portion..
and plenty of mids and tweeters spread around..
and a rack of amps...


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