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How to evaluate a used generator?
#1
I have been socking away money to buy a generator since I lost power for 5 days after Sandy. I've pretty much decided to go with a used generator to (Hopefully!) stretch my money further and get a nicer model.

My question is how to evaluate a used generator? Obviously I will want to have it cranked up and running to listen, but what else to look for in evaluating it? I plan on bringing several heat guns and blowdryers to plug-in and put a load on it but any other suggestions?
Overthetop, proud to be a member of pa2a.org since Sep 2012.
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#2
Overthetop;95067 Wrote:I have been socking away money to buy a generator since I lost power for 5 days after Sandy. I've pretty much decided to go with a used generator to (Hopefully!) stretch my money further and get a nicer model.

My question is how to evaluate a used generator? Obviously I will want to have it cranked up and running to listen, but what else to look for in evaluating it? I plan on bringing several heat guns and blowdryers to plug-in and put a load on it but any other suggestions?

Put an AC voltmeter on it while you hit it with the progressively increasing loads. Among the best things to do is to bring a friend with an oscilloscope and take a look at the output wave-form both unloaded and under load. You'd be surprised how many generators have spiky wave-forms when they're NOT heavily loaded. You'd also be surprised how many generators over-voltage when lightly loaded---- not good for your phone charger!
gascolator, proud to be a member of pa2a.org since Nov 2012.
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#3
Remember that motor start load is different than static load. You can probably load it up pretty good using hair dryers but you're not going to get a real good idea if it can maintain itself unless you can load it with a motor that takes some real energy to start. Fridge/Freezer compressors, sump pumps, well pumps and such are good examples of what you could use to test it.

If you have a 120v circular saw, that might be a good way to test it. Try cutting some hardwood with it while running off the generator with other things running.

When checking it over, obviously you'll want to see how difficult it is to start. A gas generator, unless it's electric start is going to take a few pulls to get it going. Once I converted mine over to propane, I can get it started in one or two pulls.

Any of them that you're looking at, make sure it has an engine that's well known, Briggs & Stratton, Honda, Tecumseh, common engines. You don't want to get some chinese piece of junk that you can't find parts for in 5 years. I personally prefer B&S just because there's always so many of them out there you can normally find a replacement engine just by visiting mower shops.
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#4
Hmmm, I could put a load on it with the hair dryer, and then plug my pancake compressor in to spike the load. I'm aiming for a 6500 watt gen, so it will need a power hungry device to make it jump. The skilsaw is a good idea too.
Overthetop, proud to be a member of pa2a.org since Sep 2012.
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#5
What you should hear when you do that is the generator drop a for a couple seconds in RPM's and then pick right back up when you load it down. As long as it doesn't stall out, then you should be good to do. Your compressor and your skilsaw should have labels on them as to how much current they draw at nominal load, maybe even on start up too. You can do the math to determine how much load you're putting on it fairly easily.

My 6500 was running an upright freezer, two fridges, two sump pumps, and a few lights with no problems. There were only a couple of times that I was concerned and that's when the sump pumps happened to both run at the same time, but that's a rare occurrence.

Also, whatever generator you're looking at, see if it can be converted to propane if it isn't already propane. The link to the company that sells the conversions is in this thread: http://www.pa2a.org/thread-converting-a-...o-tri-fuel
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#6
streaker69;95085 Wrote:Remember that motor start load is different than static load. You can probably load it up pretty good using hair dryers but you're not going to get a real good idea if it can maintain itself unless you can load it with a motor that takes some real energy to start. Fridge/Freezer compressors, sump pumps, well pumps and such are good examples of what you could use to test it.

If you have a 120v circular saw, that might be a good way to test it. Try cutting some hardwood with it while running off the generator with other things running.

When checking it over, obviously you'll want to see how difficult it is to start. A gas generator, unless it's electric start is going to take a few pulls to get it going. Once I converted mine over to propane, I can get it started in one or two pulls.

Any of them that you're looking at, make sure it has an engine that's well known, Briggs & Stratton, Honda, Tecumseh, common engines. You don't want to get some chinese piece of junk that you can't find parts for in 5 years. I personally prefer B&S just because there's always so many of them out there you can normally find a replacement engine just by visiting mower shops.

Around here, we call that "Parts & Scrappin'."

Check the oil. Oil on a generator should be changed every 24 hours or so. If the owner didn't properly maintain the engine, the oil will probably be black.

In fact, before you check the oil, ask the owner how often he changes it. If he says anything more than 30 hours, walk away.
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#7
bac0nfat;95102 Wrote:
streaker69;95085 Wrote:Remember that motor start load is different than static load. You can probably load it up pretty good using hair dryers but you're not going to get a real good idea if it can maintain itself unless you can load it with a motor that takes some real energy to start. Fridge/Freezer compressors, sump pumps, well pumps and such are good examples of what you could use to test it.

If you have a 120v circular saw, that might be a good way to test it. Try cutting some hardwood with it while running off the generator with other things running.

When checking it over, obviously you'll want to see how difficult it is to start. A gas generator, unless it's electric start is going to take a few pulls to get it going. Once I converted mine over to propane, I can get it started in one or two pulls.

Any of them that you're looking at, make sure it has an engine that's well known, Briggs & Stratton, Honda, Tecumseh, common engines. You don't want to get some chinese piece of junk that you can't find parts for in 5 years. I personally prefer B&S just because there's always so many of them out there you can normally find a replacement engine just by visiting mower shops.

Around here, we call that "Parts & Scrappin'."

Check the oil. Oil on a generator should be changed every 24 hours or so. If the owner didn't properly maintain the engine, the oil will probably be black.

I've never had a problem on any properly maintained B&S engine. Smile
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#8
streaker69;95103 Wrote:
bac0nfat;95102 Wrote:Around here, we call that "Parts & Scrappin'."

Check the oil. Oil on a generator should be changed every 24 hours or so. If the owner didn't properly maintain the engine, the oil will probably be black.

I've never had a problem on any properly maintained B&S engine. Smile

Yeah but "Parts & Scrappin" is fun to say. Kinda like "Paymore & Shenanigans," the furniture store.
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#9
The nice thing about used generator shopping is that the vast majority of them haven't been used anywhere close to 24 hrs. Many of the ones on Craigslist were impulse buys AFTER the person's power came back on, and have sat unused, so they are NIB.

Definitely planning on installing the tri-fuel adapter and run propane. I like the longterm storage option of a 50 or 100# propane tank over gallons of gas in my garage.
Overthetop, proud to be a member of pa2a.org since Sep 2012.
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#10
I have had good luck with government liquidation web site. I purchased a mep 002a 5kw with 323 hours it is a diesel generator off of it for $850 just before sandy hit. I ran it for 6 days straight after sandy worked like a charm. It will run my whole house on about 8 gallons of diesel per 24 hours. Very happy with it
Rcpaul, proud to be a member of pa2a.org since Jan 2013.
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