Break in Period for Predator 3500 W Generator

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kente

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Jun 1, 2018
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Just bought a new Predator Generator from Harbor Freight.  The specs are impressive and it starts right up and runs very quietly.  I am replacing a smaller generator with the hope that I will be able to occasionally run my AC unit.    One thing that troubles me is that they say not to run the gen with more than a 75% load until after a 30 hour break in period.    They don't specify exactly what that means.    The steady state capability is 3000 watts and 75% of that is 2250 Watts, which may be enough to run the AC but I'm not sure.    The starting capability is 3500W and at 75% that would be 2625W, which might be exceeded during the AC start up.    I hate to just run the gen for 30 hours without getting any use out of it.  Anyone have any idea what the risk factors are in just going ahead and using it after a much shorter break in period?    I currently have 4 hours on the gen.
 

Harry B

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A 15000 btu A/C will not draw more than 1800 watts running continuesly, so well within your 75% maximum. Running a generator without a load is not good. A 50% load is typically adviced.

Most break-in periods for engines suggest  varying the speed from time to time and not to apply full load or full RPMs until past the breakin period.
 

Henry J Fate

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The initial start up load from your ac is not ideal for the break-in period. Each time the ac starts up it will put a pretty good strain on the 3k generator. I would at the very least put at least half the break-in hours on the generator before hooking up the ac. Another factor will be if any other appliances will be running or do you plan to isolate the generator to the ac only? It would be best to break-in the generator properly and not over load it or lug it down on the many ac starts it would incur if you run the ac.

The engine wants to run freely with no strain under reasonable load. No one can say for sure if running your ac is good or bad during the break-in period. I would recommend to break-in the generator without the ac and sleep better.
 

Gary RV_Wizard

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Don't overthink this.  The genset is NOT going to explode if it hits 76% for a few seconds.  Or even an hour. They want you to avoid near-max sustained loads until the engine was worn its internals metal surfaces smooth.  They pick a number to represent that, but it's just an approximation.

The start-up load for an a/c unit lasts maybe 2 seconds, a brief time period that is pretty much irrelevant for break-in (or anything else).  The sustained load with the a/c running will be about 1500 watts, plus another 200-300 watts for odds and ends (the RV's converter/charger, for example). You will still be well under the 75% x 3000 watts.
 

Henry J Fate

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Break-in periods for engines are primarily designed to help assure an expected quality of life and life span. Blowing up the engine is not the issue. If the engineers have determined a certain break-in period, it should be based on testing and other forms of data and not arbitrarily plucked off the tree. One of the factors during the break-in period is heat. Not just the overall heat one would notice coming from the engine but more importantly the heat from friction at the points of contact internally in the engine and the generator. Excessive heat during the initial break-in period will directly affect quality of life and life expectancies. It is very important that the engine is broken-in properly.

I have serious doubts about the mentioned 200-300 Watts of additional power. Those numbers could be easily 1000-1500 watts or more.

I can hear my 4k generator lug some when the ac comes on. Although it is a short jolt, the lug on the genset is enough to tell me that I would not burden a brand new 3.5k generator with that sort of lug during break-in. It is only a very small percentage of the life of the generator but with good maintenance and proper use, it is the most important time.

 

Gizmo100

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We have that generator and it's been great.

I did the break in at home. It's been a while but as I recall....

I ran the unit for 10 hours then changed the oil.
I again ran the unit for another 10 hours then changed the oil.
At 20 hours I changed to synthetic oil and ran for 10 more hours.

I used a electric heater to maintain the wattage desired.

I did all of this to really test the generator. The warranty is short and if it's going to quit, I would rather it quit at home.

So far it's been great
 

Lou Schneider

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Changing the oil at the specified intervals or sooner will make the biggest contribution towards long engine life.  Usually the initial oil change is scheduled sooner than subsequent changes, to flush out the metal particles created as the engine smooths out it's internal surfaces during the break-in cycle.
 

Henry J Fate

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Oil is cheap given the quantity needed. When in doubt change it and change it often and definitely like Lou has suggested, change it at least what the manufacturer recommends during the break-in period. I would fit in an extra change if you can do it. It can only be a positive result.
 

Gary RV_Wizard

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I have serious doubts about the mentioned 200-300 Watts of additional power. Those numbers could be easily 1000-1500 watts or more.
It could be if other stuff was being operated, but kente is only trying to run the a/c, at least initially.  The 200-300 watts mentioned was for background loads that never get turned off, i.e. the converter/charger.  If the fridge and/or water heater are in 120vac mode, they would indeed cause a big jump in the load whenever their thermostats cycled on. All bets are off in that case.
 

skydivemark

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I bought the predator 8750 for use at our property, we're often there a week or more at a time and don't want to build hours on the Onan.
Anyway, I went that size simply due to it has one outlet  that's 120v/28A (close enough to 30 amps for me) and then a few other regular "Edison" 120v/15A outlets on separate breakers. I'm - so far - very pleased with it (check back in a couple years to see if I'm still happy with it). Doesn't strain much at all when a/c kicks on and we can run a/c, water heater, coffeemaker etc all at once with no problem.
My first oil change was at about 3 hours, second at 7 more (total of 10), third at about 25, then after about 50 hours total I switched to synthetic and now change it every 24 or so hours (once a day in summer). There's about 125 hours on it now.
It is rather heavy but fits nice in the back of the Jeep for transporting.
I did buy the extended warranty but even with that it's far less costly than a comparable name brand.
 

kente

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Gary, you are right about the minimal additional loads.  I keep the fridge on gas as well as the water heater and I even have a circuit breaker that allows me to switch out the converter so there would be absolutely minimal loads when running the AC during the break in period.  I think I will give it a at least 10 hours of break in and then run the AC.  I have two issues, first I hate running a generator for no reason other than to accumulate hours, and second, since the generator only has a 90 day warranty I want to confirm that it will run the AC while it is in warranty.
 

scale obsession

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I don't have any break in suggestions, but I will chime in and say that we have the same 3500 inverter. It runs our 15k ac with 0 issues. We currently have about 40 hours on the unit. I purchased the extended warranty, so if it dies, I suppose we will deal with it then.
 

72cougarxr7

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Wow, 30 hours seems a bit excessive for a break in period.
I bought a Champion 3400 inverter over tge summer and they only recommend a 5 hour break in.
I broke mine in alternating between a 500w halogen light and a 1500 watt heater. Did this for 5 hours, changed the oil, and have been using it normally since then, running ac and all.
I did do a 2nd oil change after another 5 hours or so just to be sure all break in metals are flushed out.

Honestly my 3400 doesnt really seem to work that hard to run my 13.5k btu ac. Starts it in econo mode, reves up high for a few seconds when the c ompressor first comes on, then settles in around half throttle.
I think you would be fine with a 5-10 hour break in.
 
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