# Generator Run Time Intervals During Outages



## Bluwolf (Nov 8, 2020)

This may be a stupid question but I'm always good for those. I understand that you shouldn't run portable generators non-stop during an outage. But there's also the consideration of conserving fuel (gas, propane, whatever).

What other things besides the fridge and freezer do you take into consideration? How long can the gennie be off before it's time to re-cool the fridge and freezer? How long after heating up a water heater before it would be time to heat it again if you needed hot water? What other things do you take into consideration for conservation of fuel vs. reasons to run it?

I'm interested in all of it. But I'm particularly interested in warm weather outages because I'm in SW Florida. We're in the dead of winter and it's 85 degrees and very humid right now.

Thanks,
Mike


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## Browse Deweb (Jan 16, 2021)

Bluwolf said:


> This may be a stupid question but I'm always good for those. I understand that you shouldn't run portable generators non-stop during an outage. But there's also the consideration of conserving fuel (gas, propane, whatever).
> 
> What other things besides the fridge and freezer do you take into consideration? How long can the gennie be off before it's time to re-cool the fridge and freezer? How long after heating up a water heater before it would be time to heat it again if you needed hot water? What other things do you take into consideration for conservation of fuel vs. reasons to run it?
> 
> ...


This is a good question. I believe freezers will keep food from thawing for about at least 12-24 hours if kept closed and refrigerators may not keep food at the proper temperature for as long...maybe a few hours. 









Food Safety During Power Outage


Find out from FoodSafety.gov how to keep food safe before, during, and after emergencies, such as floods, fires, natural disasters, or the loss of power.




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A hot water tank should keep water hot enough for a day or two. Air conditioning and heating that is turned off will depend on weather conditions and how good the home's insulation is.

When I lost power this past summer for 3 days, we ran the generator pretty much the whole time, though I did stop it after the first day to change the oil since it was a new unit and Honda recommends the first oil change at 20 hours, then every 100 hours of use. After we got power back, I changed the oil anyway just to keep everything fresh and clean for storage. It only takes a quart.

If you have a good portable generator like the Honda, it probably makes sense to shut it down once per day for at least a few hours, but mine ran a full two days non-stop with no issues. For a generator with more questionable build quality, it may make sense to run it in smaller cycles of 8-12 hours with a few hours in between cycles to allow the engine to cool. Also, changing the oil more frequently than recommended can't hurt the unit. If you had an outage lasting a week and you ran the generator 8 hours on and 4 hours off, you'd reach 100 hours by the end of the week, but I'd be tempted to change it every 50 instead of every 100 just to be safe.


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## aandpdan (Oct 8, 2012)

Not knowing how long the power might be out, I'm careful to conserve fuel. I'll run it at least every 3-4 hours to keep the refrigerator cold and the house warm. My practice with that is to run it until the house reaches a comfortable temp AND the refrigerator compressor shuts off. It may run for an hour or two but usually not much longer.

I'm not running it just to keep the lights or tv on. I don't have a well or need to run a/c. I've been without power for 5 days in the past and still had enough hot water, you just limit your use.

Cold showers and sweaters help.


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## exmar (Jun 29, 2015)

We basically run the generator from noon to midnight, that keeps frig and freezer cool provided you minimize opening them. I keep a couple of gallon jugs of ice in the freezer which are transferred to the Frig during "off" times, then back to refreeze. That cycle let's cell phones, tablets, etc. be charged, everyone can watch TV, catch up computer time, etc. Heat and cooking are independent of electricity and that cycle covers the hottest part of the day if it's summer to run an AC unit.


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## Airstreamer67 (Oct 3, 2020)

I have a 25-year-old Yanmar-Gillette 6000W diesel genset and a 15-year-old Honda 4500W gasoline genset. I've owned them since new. I run one or the other 24-hours-a-day when the power is off. I can't see how this hurts the generators, since they reach a certain operating temperature and stabilize there as long as they are running. Shutting them down just to cool off and let them rest seems counterintuitive to me.

So, as long as I've got fuel, I have a generator operating day and night during outages. I usually start with 35 gallons of gasoline and 35 gallons of diesel in the generator building, with more that can be accessed in my vehicles. That's been enough for outages around here. My gensets use about a half-gallon-per-hour with my normal household outage loads. It's one of the reasons why I don't want larger generators: they use proportionally more fuel.

I'm in Louisiana. The heat and humidity in the summertime can be terrible, so I have an 8000BTU window air conditioner that I accommodate with my generators during outages for cooling one bedroom. I could get a larger one, but it would just "eat" more fuel. So I don't.

Choices...choices...all the choices that need to be made.


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## Browse Deweb (Jan 16, 2021)

I don't think air cooled units are meant to run continuously. I guess it depends on hot it gets and how well it is made. Prolonged high temperatures can break down the oil, which can then cause other issues with rings and seals. High quality liquid cooled diesel generators like those the military uses can and probably do run continuously for very long periods at high loads and they don't skip a beat if they're well maintained.


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## Bluwolf (Nov 8, 2020)

I read that a full freezer could go 48 hours. But that strikes me as a little optimistic. I think the 12 to 24 hours seems reasonable if kept closed. And I read 4 hours for the fridge which sounds about right. I have no problem with shutting down to give the gen set a break as well as conserve fuel (in my case propane if I can keep from using gas in it). But my wife wants the portable A/C I bought for these ordeals to sleep at night so there's 7 hours straight. I'm good with that. Then leave it running long enough to make coffee in the morning and I'm good

I didn't realize a water heater would stay hot that long. Good to know. Especially here, during these outages, the days are 95 degrees and 80 to 85 at night. A lot of the water heaters here are in the garage so those kind of temps won't hurt towards keeping the water hot.


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## Browse Deweb (Jan 16, 2021)

Bluwolf said:


> I didn't realize a water heater would stay hot that long. Good to know. Especially here, during these outages, the days are 95 degrees and 80 to 85 at night. A lot of the water heaters here are in the garage so those kind of temps won't hurt towards keeping the water hot.


If it's used, it will cool down as fresh cold water is pulled in. One long shower and that hot water is gone.


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## Ground Fault (Jun 9, 2020)

I've had to run a generator for extended periods quite regularly since the early 80's. Air cooled all of them. They run from the time the power goes off until the power comes on, save for gas refills and oil/air filter changes. I've read all the owner's manuals. None of then stated less than 100% duty cycle. In Texas, and I'm sure in Florida, there is no such thing as turning a temporarily-installed window air conditioner off and it'll be able to "catch up" later after you have "rested" the generator. Hurricane season is BRUTAL around here with temps and humidity. That thing is going to be running 24/7. (Buy one of those $50 pools at Academy, the second absolutely necessary piece of equipment for surviving after a hurricane.)

Start it, then turn on the A/C, the frige and freezer. That's what you bought it for. If you have to rest your generator, sell it and buy one you don't.

Conserve gas? At the expense of not running the A/C? Surely you jest. Go ahead and use that gas. When it runs out, buy more.


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## exmar (Jun 29, 2015)

Ground Fault, conserving fuel is due to possibly not being able to replenish what you have. In a widespread outage, gas stations won't have power to pump gas, sell propane, etc. e.g. We had a 13 day outage and it was a two hour drive and a long wait to refill gas cans.


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## agksimon (Jan 25, 2021)

We live in Michigan and worry most about heat in winter. I'll run it for a few hours and get the house up to close to 80 degrees and then shut it off until the temp drops into the mid 60's. A full newer style freezer can easily go a couple of days if you don't open it. Newer fridges too. In summer, we just run fans as our 7000 watt (running) won't run the A/C.


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## Airstreamer67 (Oct 3, 2020)

Browse Deweb said:


> I don't think air cooled units are meant to run continuously. I guess it depends on hot it gets and how well it is made. Prolonged high temperatures can break down the oil, which can then cause other issues with rings and seals. High quality liquid cooled diesel generators like those the military uses can and probably do run continuously for very long periods at high loads and they don't skip a beat if they're well maintained.


Unless the genset is overheating or is otherwise in distress, it does not have to be stopped to cool off the oil or be otherwise given rest periods. Once the machine reaches operating temperatures that are within its design limits, it should not have to be stopped except for refueling or such maintenance as oil replenishment, filters, or whatever might be specified by the manufacturer.

Are there any generators that specify anything less than 100% duty cycle? I don't remember seeing any such generator specifications. I know my soldering gun specifies about a 25% duty cycle, ie it should be rested three minutes for every one minute of operation or whatever, and this is because the gun will overheat and be damaged if used continuously without being allowed to rest and cool off. A professional-grade solder gun probably does not have this restriction due to better construction.

I don't remember seeing generators with such specified duty cycles. The only thing I recall seeing about generators is perhaps some advice from a manufacturer that a particular home generator is not suited for continuous service in the sense that it cannot be expected to replace full-time service provided by an electric utility. I'd think such advice comes from the fact that most consumer generators would have to be regularly rebuilt or replaced if they operated 24-hour-a-day, or the 8,760 hours in a year, simply because they are not constructed to last so many hours, whether such hours come continuously or not.

Generally speaking, water-cooled generators are built to have a longer operating life than air-cooled generators. They are usually constructed better and cost more. Also, water cooling is much more efficient and quieter, and this is why large gensets are water cooled. But most folks don't want to pay that much for just a few hours of emergency usage a year.


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## Bluwolf (Nov 8, 2020)

Browse Deweb said:


> If it's used, it will cool down as fresh cold water is pulled in. One long shower and that hot water is gone.


That part I understand. But it's good to know that after a shower, if the water heater is left on to replenish and get hot, then the gen set is shut down, there's hot water to do a few dishes or something later on.


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## Bluwolf (Nov 8, 2020)

Ground Fault said:


> I've had to run a generator for extended periods quite regularly since the early 80's. Air cooled all of them. They run from the time the power goes off until the power comes on, save for gas refills and oil/air filter changes. I've read all the owner's manuals. None of then stated less than 100% duty cycle. In Texas, and I'm sure in Florida, there is no such thing as turning a temporarily-installed window air conditioner off and it'll be able to "catch up" later after you have "rested" the generator. Hurricane season is BRUTAL around here with temps and humidity. That thing is going to be running 24/7. (Buy one of those $50 pools at Academy, the second absolutely necessary piece of equipment for surviving after a hurricane.)
> 
> Start it, then turn on the A/C, the frige and freezer. That's what you bought it for. If you have to rest your generator, sell it and buy one you don't.
> 
> ...





exmar said:


> Ground Fault, conserving fuel is due to possibly not being able to replenish what you have. In a widespread outage, gas stations won't have power to pump gas, sell propane, etc. e.g. We had a 13 day outage and it was a two hour drive and a long wait to refill gas cans.


This is exactly the point. We were able to borrow a generator for a little while after Irma. The trick was finding enough gas to keep it running. This was everyone's problem. You'd hear about a gas station getting a delivery and rush to get gas, only to find out it was gone by the time you got there. Then it was bad enough that it became a catch-22. You were worried you didn't have enough gas in the car to go looking for gas for the generator any more.

I didn't know about dual fuel generators then. But when I started researching them I started checking around to the places that sold propane. Turns out they were dead in the water for a while too. No power to pump the propane.

I have a dual fuel and I hope to run it only on propane. But I have 5 - 5 gallon gas cans that will be filled when the time comes. I'm just looking for ways to make it go farther. The simplest being, if it ain't running, it ain't using fuel. But having it running when I need it.


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## Gen10K (Jun 25, 2020)

I say, run it and check the oil or change per owner's manual. I see no reason on why it cannot run 24/7. As long the oil is moving, is lubricating all the components. We ran air cooled gens in Iraq, some, even outlasted the Military ones.

Is all about maintenance, adequate ventilation and ambient conditions (sand, dust, dirt, rain, etc...).


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## Old man here (Nov 5, 2020)

I run my generators as needed, that's why we buy them. A generator can run for days or weeks on end as long as they are maintained, oil changes, filters, and have fuel.
Just don't run them at 100% of the rating all of the time. That will kill even the best of generators.


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## Airstreamer67 (Oct 3, 2020)

That's a good point. Most equipment is not built to run at maximum HP or amperage rating all the time. Besides, trying to do so with a genset wouldn't provide the "cushion" needed to start motors and compressors, which require multiples of their running demand.


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## BobS (Aug 26, 2020)

If the generator is of good quality (I have two with Honda GX engines with Mecc Alte alternators), it should be able to run continuous until its next oil change. On long outages (up to 2 weeks), I have hook up a 13 gallon boat tank to the generator and keep it approx 10 feet away from the generator so I can fill it up safely while the generator is running. I usually kept a large fan pointed at the generator. I have in addition a diesel prime generator that is designed to run continuous at a 90% percent load.


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## Gen10K (Jun 25, 2020)

Forgot to mention some about the fuel. My gen is a Tri-Fuel, runs on LP, NG and Gasoline. The output rating is different witg each fuel. Is 8.2KW constant 10KW peak with Gasoline, drops to 6KW constant on NG, Propane is somewhat in between. Is a good gen as a backup but not a 100% replacement for the power grid.

So if you plan to run the gen on different fules, their performance variates.

Some to keep in mind.


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## Airstreamer67 (Oct 3, 2020)

Quote: "I have in addition a diesel prime generator that is designed to run continuous at a 90% percent load."


Yeah, ironically, the problem I have with my diesel is that I don't keep a heavy enough load on it to prevent it from "wet stacking." This is a situation when the diesel does not have enough load to thoroughly burn the fuel, so the fuel tends to soak into the compression rings and the engine chokes up until the load gets heavy enough to burn it all off. That's why diesels are best suited for situations where it is loaded up, whereas gasoline models can run at lighter loads without as much of a problem.


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## Ground Fault (Jun 9, 2020)

> Ground Fault, conserving fuel is due to possibly not being able to replenish what you have. In a widespread outage, gas stations won't have power to pump gas, sell propane, etc. e.g. We had a 13 day outage and it was a two hour drive and a long wait to refill gas cans.


 (Insert long sigh here...)
Exmar I completely understand that your assertion is stating the obvious, and standing in a gas line is only a problem _to a person who wants to have a problem_ or who is incapable or unwilling to plan ahead. So in response to your stating the obvious, I am compelled to respond, sadly, by also have to state the obvious: The need to ration gas is a situation that could be avoided with a little pre-planning. If you don't want to stand in those lines and subject yourself to that then plan ahead. Owning a generator means that the owner has chosen to no longer be in Kansas ToTo. Consequently, this ain't push mower and 2-gallon gas can territory anymore. Sufficient gas cans are required for proper intended generator operation. Buy the necessary gas cans way ahead of time, then buy the necessary gas the day _before the rush for gas invariably begins._ Lighter it home in several five gallon gas cans and deposit it into a larger container sufficient to hold enough gas for the expected outage. Repeat until full. Around here you can buy a new 55 gallon barrel for $20 (last time I bought one). (We take the barrels to the gas station in our pick'em-up trucks down here in Snuff Gully, DOT suspends enforcement of applicable laws during this period so that people like us who desire to plan ahead seriously can do so without fear of penalty. Not safe, but hey...grow a set and get on with it.) Or, fill the tank in your boat, mine is 36 gallon. Or, your neighbor's boat. Or, as you should do anyway, fill you vehicles. Then disconnect the fuel line from the fuel rail and connect the fuel line to a threaded extension line that you have preplanned and prepared before time, one that fits the fuel line fitting. Turn on the ignition and let that gas tank fuel pump rip to fill your gas can. (Now, the vehicle fuel pump you _might want to run intermittently, ESPECIALLY when the gas gauge indicates the tank is down to less than 1/3 full_.) Disclaimer: If you can't do any of the above safely, do not do any of it.

Exmar we too have been through some long ones, the longest 14 days, and the one before that one was 13 days. Too many 3-4 dayers to count. When you live 70 miles from the Gulf of Mexico you learn to do this with informed purpose, dignity, and a little Hank Williams Jr _YEE-HAH!!!_. I'm probably preachin' to the choir to you Gulf Coast boys, huh? Properly done, it is a _staycation, _its execution with style a "Country Boy Can Survive" artform *made possible by a properly provisioned generator. * Heck, this is just campin' out for us, _adult summer camp_ that our parents never sent us too like _all y'all _(different from _y'all_, look it up) northerner kids got to go to. (Yeah, I may have some lingering issues about that...) Once the blue roofs are on, the yard debris cleared, we sit neck deep all day in a cheap swimming pool (I currently hold 4 in reserve, new, in the box, bought on sale, a 8,10 and 12-footer, plus a 3x7 I keep in the truck, because you never know) under the shade of a picnic umbrella to stay cool, a beer, margarita, or ZingZang Bloody Mary as needed, George Jones crooning in the background. Getting out only to tend the BBQ pit and the smoker, both at 220-250 on red oak/hickory, smoking full-time, helping our neighbors with less foresight or forward concern salvage and cook their just-thawed and soon-to-rot frozen meats, a portion of which always generously shared. After all, (_all_ being different from _y'all_ and _all y'all_) otherwise it's just spoiled meat that benefits nobody. They too have a place in the pool. A synergistic community, our neighborhood 20-foot 48-inch smoker down at the pavilion FULL of every kind of meat you can think of, for days on end, smoking for the benefit of any and all who show up, courtesy of the temporary _our cup runneth over_ supply situation for the same reason. It's a party, often with live music, ALWAYS with an emphasis on taking care of and generously feeding the many first responders who thankfully travel here and stay in our homes and in our campground while they assist us in removing debris and restoring power. Many say they eat better here than at home, because Texas-style BBQ! With the assistance of our 120V emergency window A/C units running all day in the sleeping end of the house, we settle into cool beds at night and sleep the sleep of babes, except for me at 4am to refill the gas tank. We get up early so we can go help our neighbors before it gets hot, then back into the pool when it does. Repeat until restored power ruins the party and we have to go back to the real world. When fate deals you lemons...

So Exmar, you tell those people standing in the gas lines that they can choose to stand around lamenting that Dingoes ate their babies, or man-up and decide their own fate. This ain't rocket science. Provision your generator correctly ahead of time. Survive. Enjoy. Repeat.


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## BobS (Aug 26, 2020)

Airstreamer67 said:


> Quote: "I have in addition a diesel prime generator that is designed to run continuous at a 90% percent load."
> 
> 
> Yeah, ironically, the problem I have with my diesel is that I don't keep a heavy enough load on it to prevent it from "wet stacking." This is a situation when the diesel does not have enough load to thoroughly burn the fuel, so the fuel tends to soak into the compression rings and the engine chokes up until the load gets heavy enough to burn it all off. That's why diesels are best suited for situations where it is loaded up, whereas gasoline models can run at lighter loads without as much of a problem.


That is a problem with diesels. I put the smallest one that I could get away with for the residence - 20KW. I exercise it every week for 2 hours and run a total of 7 tons of AC with 2 washers and 2 driers (forces my wife to due the laundry) to load up the generator and get a good test. On normal usage, the load would range from 5% to 25% usage with peaks of 50%. If I ran the generator continuously at a small load without loading it up, it could cause engine problems over a long time period. I always tests / exercise diesels at a high load and gasoline at a low load with occasional high load.


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## iowagold (Jan 22, 2020)

Bluwolf said:


> I read that a full freezer could go 48 hours. But that strikes me as a little optimistic. I think the 12 to 24 hours seems reasonable if kept closed. And I read 4 hours for the fridge which sounds about right. I have no problem with shutting down to give the gen set a break as well as conserve fuel (in my case propane if I can keep from using gas in it). But my wife wants the portable A/C I bought for these ordeals to sleep at night so there's 7 hours straight. I'm good with that. Then leave it running long enough to make coffee in the morning and I'm good
> 
> I didn't realize a water heater would stay hot that long. Good to know. Especially here, during these outages, the days are 95 degrees and 80 to 85 at night. A lot of the water heaters here are in the garage so those kind of temps won't hurt towards keeping the water hot.


do exterior temperature meters on the fridge and freezer.
we set up the probe setups to call for the generator to remote start up.
lots of wiring...
but worth it when you are trying to conserve fuel in remote areas....
or fuel island like you get during a BIG long term outage.

yea hot temps are harder to keep the fridge freezers cold...
I like the idea of an "icebox" just use a pan as a catch tray for the humidity under the ice jug is the pro tip.

we also use the ice jugs in the chest freezers to keep the chest freezer as full.
i wish there was a way to make the fridge freezer insulation better...
some have the heat thing on the outside chest metal these days...


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