How many hours will a 7000 watt generator run....

zackyboy3rs wrote:
It ran 12 hours last night. Thanks. Manual states put to 14 hours at 1/2 load.

1/2 load is 3500 Watts... your 500 watt load is 1/7 of that. Would seem your generator could run like 7 * 14 hrs = 98 hours or ~ four days on a tank of gasoline.

SaltiDawg wrote:

zackyboy3rs wrote:
It ran 12 hours last night. Thanks. Manual states put to 14 hours at 1/2 load.

1/2 load is 3500 Watts... your 500 watt load is 1/7 of that. Would seem your generator could run like 7 * 14 hrs = 98 hours or ~ four days on a tank of gasoline.

Doesn't work like that at all..

Fuel consumption is more about the displacement (CID or CCs/liters) and RPMs so there is basically a point where there is no decrease in fuel under light or no loads..

Bigger displacement engine = more fuel consumption per hr vs a smaller displacement.

Higher RPMs = more fuel needed for proper air/fuel mix..

Generator engine is pegged at 3600 RPM whether it has a load or not..

OP most likely could get perhaps 16hrs per tank perhaps but not 98 hrs..

A smaller more appropriate sized gen to the load would use much less fuel.. That 7Kw gen in 12hr used about 5 gallon of fuel.. a 2Kw gen would use maybe 2 gallons for the same time..

There is a trade off for picking a larger gen and that is the amount of fuel it will use per hr..

Oh, I understand the principle of hotel loads on a generator... including its own mechanical losses at low load.

That said, I believe the run time at 500 Watts will be much closer to the idealistic four days than your 16 hours.

However, my experience was on steam turbine generators, motor-generator battery/450Volt AC, and Diesel generators.... all operated in parallel. (
and occasionally A/C Shore Power.

Not much experience with small gasoline powered generators, so my intuition may be severely off, probably shouldn't have posted.

Be interested if the OP noted how much fuel he actually used overnight???

PS. Yes, I realize that my post would make the argument that were there no electrical load that it would run forever on a tankful. lol

SaltiDawg wrote:
Oh, I understand the principle of hotel loads on a generator... including its own mechanical losses at low load.

That said, I believe the run time at 500 Watts will be much closer to the idealistic four days than your 16 hours.

However, my experience was on steam turbine generators, motor-generator battery/450Volt AC, and Diesel generators.... all operated in parallel. (
and occasionally A/C Shore Power.

Not much experience with small gasoline powered generators, so my intuition may be severely off, probably shouldn't have posted.

Be interested if the OP noted how much fuel he actually used overnight???

PS. Yes, I realize that my post would make the argument that were there no electrical load that it would run forever on a tankful. lol

Diesel and gas.. two different birds..

Example, my old 8hp Kohler in a 1966 Jacobsen tractor uses about 2 gallons of gas per hr mowing. Contrast that to my 26HP diesel tractor using 3/4 gallon of fuel per hr..

The Kohler 8HP had to run at 3600 RPM to do the same work as my 26HP diesel tractor running at 2200 RPM..

Diesel contains considerably more energy than gasoline and a diesel engine has considerably more compression to squeeze out more efficiency..

So, displacement, energy in fuel and RPM all make a difference in how much fuel will be used..

My 4Kw gas gen has a 4 gallon fuel tank, runs about 12hrs per tank and that is with than less half load.. More than half load that is about 11 hrs per tank full..

OP will never see anywhere near 96hrs of run time per tank with a 7Kw gen which has at least 13HP engine..

Pretty familiar with gas gen run times..

I'll stand on my, "Be interested if the OP noted how much fuel he actually used overnight???"

pianotuna wrote:
X2. I won't even run mine when sleeping.

greenrvgreen wrote:
If you run any gas generator underneath or near your trailer (as pictured), the fuel supply is unlikely to expire before the occupants do.

Nice comment. The gen is under the tool box, not the trailer. And no, it was not run past 10 pm as a courtesy to our neighbors. Unless your trailer floor is made of swiss cheese, there is *zero* chance of CO getting up into the TT...especially with the 20 mph winds we had when this pic was taken.

Class A's and C's and toy haulers have gen sets installed in their units...they are not supposed to run them when the RV is occupied? Put brain in gear before engaging keyboard....

pianotuna wrote:
X2. I won't even run mine when sleeping.

If you ever have to run a generator built into, or near, your RV into the night there's a simple way to do it very safely.

Close up the motorhome tight - everything ... except for one thing. Leave one roof vent open (with a Maxxair over it in case it rains) that has a reversible 12 volt fan built into it. Run the fan on just a low speed, set to the AIR IN direction, the full time that the generator is running.

This creates and maintains a small but absolutely effective small air pressure inside the RV. This small bit of air pressure will push outward through any small crack or opening anywhere in the RV's floors and walls down low and up high. No generator fumes can enter anywhere while this positive air pressure is being maintained in the interior by the roof vent fan.

Of course you have to get over any concerns that generator fumes are going to be strong enough to be sucked in way up high where the roof vent fan is. This fan will be drawing only a very, very small amount of clean up-high air into the RV's interior to compensate for any air pushed out the RV's small cracks and out through the cooktop's hood vent. Any air pushed out any small openings down low in the RV will absolutely prevent any generator fumes from entering down low where generators are.

We use this technique all the time when running the built-in Onan - even into the night if necessary for air conditioning in hot/humid conditions. Our little portable generator has so far not required use of this air pressure technique.

By the way, we also use this technique to keep dust out of the RV when traveling offroad in the desert.

A portable gasoline generator (such as pictured) produces on the order of fifty times (50X) the CO that your car does, assuming you have a gasoline engine (a diesel generator--and of course LP--puts out much much less CO). Not only does a small gennie lack a catalytic converter, but the tune on these small carb engines is rudimentary by comparision.

Is there anybody here who would run their truck for hours still hitched to the TT? Perhaps to stay warm from the exhaust? Of course not. We know better with our cars, and yet our cars are much safer than our gennies.

CO poisoning just from generators kills 50 to 60 people each year in America--this from the CPSC. More disturbingly still, the trend for these accidents is not among first-timers, but among "experienced" operators who had been accustomed to the same hazardous practices without ill effect--until the wind changed, or the temperature inverted, or snow fell around their RV, etc. All of these real possibilites fall under the category of *zero*.

If you suffer CO poisoning while awake your primary symptom is a crushing headache--as if you had a hat on way too tight. Remember, you can't smell it. If you suffer CO poisoning while sleeping, you simply descend into a deeper and deeper and deeper sleep. Do you think Darwin's going to come tap you on the shoulder before it's too late?

Thank you for that valuable information. Hopefully the CO detector in the camper does its job as well. Again, there is *zero* chance of CO killing us in our sleep because we don't run the generator while sleeping. We do leave the furnace on, however, and a faulty heat exchanger could cause CO to come into the camper there. Again, the CO detector is supposed to beep if that happens.

As an aside, how far away from the camper does the generator have to be to be considered safe? That pic was taken boondocking in a church parking lot for 10 days with temps in the 20's. Ran the generator 6-8 hours/day to keep the batteries charged. Most of the time it was running we weren't even in the camper.

I wouldn't recommend relying solely on an RV's CO detector, either. That's why we also keep air pressure in the interior of the coach as much as possible whenever the built-in or portable generator is running.