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Small Cabin Forum / Off-Grid Living / What size generator?
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Jared
Member
# Posted: 30 Nov 2011 12:24
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How many watts does a generator need to be useful? I have no idea how much would end up be powered off of it. If you could, let me know how many watts will power how many things. I'm pretty ignorant on these things. Thanks!

Bzzzzzt
Member
# Posted: 30 Nov 2011 13:01
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I personally wouldn't buy any generator less than 2000 watts unless you have a specific purpose for it in mind. No matter what you think you'll need you almost always end up wanting more. Usually a 3500 watt model will sufice most loads. Make sure to get one that is quiet and has at least a 2 gal gas tank. Lots of models tell you how long they will run at 50% load. The longer the better. Stay away from the ones at Harbor Freight and Wal Mart. Cheaper does not always a better deal make.

For the most part you need to figure how much load you're gonna anticipate and then triple it. Most appliances are measured in watts or volt-amps (VA) which are essentially the same thing. If it's measured in amps multiply voltage (usually 120V) by the amps to get the volt-amps. Add them all up and go from there.

Hope thats helpful.

~Bzzzzzt

MtnDon
Member
# Posted: 30 Nov 2011 13:31
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Quoting: Jared
How many watts does a generator need to be useful?


Depends on what you are goping to power off it. Depends if there are any motors involved, especially motors that run things like air compressors and air conditioners. As Bzzzzzt mentioned above, many of those may require 2 to 3 times the rated power to start them. If you are simply running resistance loads (lights, electric heater, or small tool motors like a drill you won't need the reserve capacity for hd motor starting.

An inverter generator, though more expensive than the typical noisy beasts that are advertised, are much quieter and under low loads give much better fuel economy. Sometimes the best solution may be two generators, smaller and bigger. Depends on the loads.

Also note that if the generator is going to be used at higher elevations their capacity is reduced. The advertised numbers are for sea level performance. Unless the engine is generously oversized the output will be as much as 3% less for every 1000 feet of elevation.

PA_Bound
Member
# Posted: 30 Nov 2011 14:20
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Bzzzzzt and MtnDon are right on here.

Adding on to what Bzzzzzt said, don't get anything smaller than a 2000 watt unless you are *certain* that is all you will ever need. A few years ago four guys went together and bought a Honda eu1000i for our hunting cabin. We had no electricity before that, so we thought 1000 watts would be more than enough. And it is,... for simple lighting needs. But it wasn't long before we got greedy and decided to throw a coffee pot on it- and that brought her to her knees. We learned that the only way to brew the coffee is to turn off all the lights. If we would have just popped a few dollars more and purchased the eu2000i we could have gotten twice the capacity- or all our lights, and coffee too. Argh!

For my recreational cabin I'm building, I'm considering what MtnDon stated and considering two generators- one big and one small. I have a Honda EG3500, but to MtnDon's point- that thing is a "beast". It's heavy and loud- but it runs like a tank and drives my 3/4hp well pump easily. But for security reasons I can't leave it there, and with a water holding tank I won't need that well pump very often. So I'm thinking about a smaller, *quieter* model for quick overnights or evenings where some AC would be handy but not the noise of the 3500.

bushbunkie
Member
# Posted: 30 Nov 2011 18:12
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I have a King 2000 Watt Quiet Inverter generator...would have gotten a Honda, but it was out of my price range at the time.
Picked up the King brand new for $500. two years ago and it has not let me down. Ran my space heater in the Bunkie at minus 20 (Ontario), all night, no problem. It has been surprisingly reliable.
Also has Gas saver mode...But I like the quiet decibal rating the most...same as the Honda...can hardly even hear it when I put it in the bush and run the extension cord.

neb
Member
# Posted: 30 Nov 2011 20:16
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Watts divided by volts equal AMPS. So if a 60 watt bulb divided by 120 volts would give you .5 amps. You need to add up what you want to run and buy generator that is greater then amps you want to pull.

Just to add to the rest of the great advice you have gotten.

Mtnviewer
Member
# Posted: 30 Nov 2011 20:21 - Edited by: Mtnviewer
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We can't really tell you what size to get as we don't know what you want to run off of the power produced, one appliance at a time or several at once. Your best bet is to look at the base, back or the manual specs for EVERY appliance that you want to use & add up how many watts or amps that each appliance needs / uses, & then size your generator accordingly. If you only want a few LED lights, that's WAY DIFFERENT than what a table saw or a toaster needs for power, which is lots.

Also, "generators" are actually 2 different units, an engine, & an altinator. Some units have a third component which is an inverter, for cleaner, Pure Sine wave power, which is safer for many electronics such as computers, batteries, other delicate electronics. Cheap "generators" can have loud poor engines & fluctuating modified sine wave power from low budget altinators. There is no quality correlation between engine & altinator, one is only used to spin the other. You can get a good engine, but poor electricity, & the opposite too. Do a Google search for energy appliance audit. Visit homepower.com or backwoodshome.com for free generator articles to start your learning. Make a list of your appliances, the power each needs, how long they will be used, & do the math.

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