O/T What size generator to run 1 1/2hp. electric motor

750 watts per HP if I remember right, it might not have enough amps to start but should run.
 
It might not start an actual 1.5 HP cap start motor. A brush type tool motor would start easier My uncle used a 2000 watt Honda inverter generator to run the roof AC on a pickup camper. It had a hard time starting a warm AC unit, it would really struggle and sometimes kicked out the breaker. I would assume the roof AC unit pulled about 15 amps running, maybe 3 times that starting.

I have one of those little HF 800 watt generators that struggles a bit on starting, but runs a large electric string trimmer and electric chain saw. Both have brush type motors.
 
No. A true 1 1/2 HP motor would need a lot bigger than a 2000 watt generator. Most motors that size would be run on 220 volts.
 
What kind of motor and what equipment is it driving? A 2000W generator would be touch and go to start a 1-1/2 HP motor sitting on the bench with a bare shaft. 6500W generator on 240V sometimes won't start a 1-1/2 HP motor.
 
Duane, as an engineer I see this as a question thats a bit close in the limited data we have WE JUST CANT SAY FOR SURE. Those Hondas are good generatoRs and have a surge capacity and it also depends on the type of motor BUT ID GO OUT ON A LIMB AND SAY THERES A GOOD CHANCE IT WILL START THAT MOTOR.....Buttttttttt without the exact detailed generator and motor specs in front of me to evaluate NO WARRANTY LOL

I will also say its close enough that the only way is to give it a try REGARDLESS what we may think based on such limited available data. I bet the Honda will hunker down n growl when she starts lol but if it can supply 2000 watts continous???? (can it????) and I know thay have a good short term surge capacity IT OUGHT TO BE ABLE TO START IT (again subject to surge capacity and motor type and starting requirements CANT GUARANTEE THIS)

If the 1.5 HP motor requires in the vicinity of 1125 watts and its an easier to start type (capacitor start or even repulsion/brushes) Id sure giver her a try

LET US ALL KNOW

John T
 
What is the motor hooked up to? If it"s something like a compressor pump, forget it, you"ll burn out the starting windings real fast. Maybe okay for a saw, but I would not chance it if you don"t have money to burn on a new motor.
 
Unless the motor drive a VERY easy starting load (low inertia fan, etc) your generator won't start it.

Assuming the motor is 80% efficient, a 1-1/2 HP motor running requires about 1,400 watts. STARTING the motor however requires 4x that wattage briefly - around 5,500 watts - until it gets up to speed. No way a 2 kw generator - especially an inverter type - will have that kind of surge capacity.

----

Incidentally I have a 4 KW (5 KW surge rating) generator. It struggles to start a 1 HP, 240 volt belt-drive portable compressor.
 
Hey my old friend you rascal lol You Mechanical Engineers are better at this stuff ESPECIALLY one who spent much of his career in the electrical field also.

Id still give that Honda a fighting chance, they do have a decent surge rating ya know

Of course it still depends on his motor, lets hook one up and take bets on if it will start or not lol

Maybe we can meet again like we did in New York those other times

John T
 
I've got two air compressors with electric motors rated at 1 1/2 horse - but both very different.

The bigger one won't even think about starting with my Coleman 1850 or 3000 watt generator. It does work with my Homelite 4400 watt gen. This same compressor will trip a 15 amp breaker when starting but is fine on a 20 amp breaker (with grid power). It WILL however blow a 20 amp fuse if not a slow-blow type. This motor has a 20 amp/120 volt plug on it - NOT a 15 amp plug.

My small "1 1/2" horse pancake air-compressor will not start with my Coleman 1850, but does work with my 2000 watt Honeywell Inverter generator. It will also run off my Xantrex 2000 watt inverter hooked to a couple of DC batteries.
 
Yo JD, youre probably alredy aware of this being an old lineman but the NEC at least allows an oversized breaker (seems like 175% maybe???) to allow a motor to start but when I was a designer I preferred the dual element time delay Class K5 I believe fuses instead of breakers for motor start ups. Thy allowed the short term surge allowing start up but then worked normal

I agree the genny needs some serious short term surge protection to start a 1.5 HP but again the type of motor sure makes a difference

Take care up North there now

John T
 
My 4000 watt / 5000 watt surge 8hp generator does OK on a 3/4hp 220v submersable pump, but it sure barks when the pump starts up. Wonder if it"s going to keep running or stall. Fortunately, startup is very brief interval.
 

Many of these new air compressors are not as many true horses that we are used to. They are rated at just before stall hp not continuous hp.
If you can start that motor without a load then your generator stands a better chance of starting it. Then engage the load after motor is up to speed.

Dusty
 
I agree. The "locked rotor" hence starting current of a motor is easily 10x of the running current. Question is, can you sneak that amount of current out of your APU before it knows it's been "had".

If unloaded, the inrush should be short and probably will get by. Getting the motor running and then slowly adding the load would work......but where and how are you going to do that?

If you try to start a motor with too much starting current, the internal resistance of the gen will limit the available current and the motor will not spin up, develop the necessary rpm's to get to the run configuration (develop the necessary current limiting counter EMF), will suck wazoo amps as a result and you will smoke your generator.

HTH,
Mark
 
Given what a Honda 2000i costs. I would purchase a cheapo Champion 6500 or larger. I suspect this 1-1/2 HP motor is wired 120 V. It's tough to find a generator larger than 4000W that will switch all output to a single 120V receptacle. There maybe some camper type gen sets with a true 120V , 50Amp receptacle ???
 
I'll have to get some more info for the application not sure what type of clutching is involved. It is a high inertia log splitter called SuperSplit if you want to check it out. Certain serenity about it when equipped with electric motor; there are some youtube videos floating around. Lots of times I could be plugged in, but would like the flexibility to run it in remote locations. Thanks for the replies. Maybe should just go with gas engine? Meantime it's a splitting maul. uggh.
 
The only reason why I saw that compressor trip breakers and blow fuses is due to my former cheap farmer-neighbor. He used to borrow my portable 1 1/2 horse compressor and use it at various buildings at his farm. Then he'd blow a fuse or trip a breaker and call me for help. So I got to see the many types of poorly wired buildings he had. Fast blow fuses, 15 amp breakers, 20 amp circuits with 14 gauge wiring, and him using 50 foot extension cords with 16 gauge wire inside.

This guy was a chronic borrower and rarely returned anything until he ruined it.
 
Hey John T - I know about this stuff not so much from my M.E. background as from first hand experience - AKA "the school of hard knocks"(!).

My advice however is as yours: Try the generator and see if will start the motor.

---

I've enjoyed meeting you and talking shop at the JD events. Hope you (and the lovely Mrs N!) plan attend the 2013 NY JD Expo at Canandaigua!

Bob
 
On go with a gas engine, sounds like a plan to me. I agree with BD or whomever said that motors of today are hp rated right at stall torque....just before the curves start to fall off.

There ought to be a law against it but so far there isn't and what we have to do as consumers is read the running full load watts if you want to know what it really can do. 1 hp is 741 watts (at a power factor of 1...which you don't get with a motor) as I remember so for a 120v 1 hp motor it should produce it's hp at about 1.15% (internal losses and some PF adjustment) of that or just over 7 amperes.

Mark
 
Ought to be a law indeed Mark!

I have a 35 year old C-H 1 HP belt-driven compressor. I also have nearly new, Tisco (Chinese-built) 2 HP direct drive compressor. It was given to me after the original owner got fed up with it's refusal to start whenever the temp drops below about 60 deg.

Amazingly - or perhaps not - the old C-H unit makes more air than the Tisco unit. Clearly the "2 HP" rating of the Tisco unit is grossly optimistic. (Incidentally the old C-H compressor also runs MUCH more quietly...)
 
One of my pet peeves is the vacuum cleaner industry. They blow off about all these vacuum HP but looking at the cord, with 25' of 20 AWG wire to supply a 5 hp motor.........gimme a break.

Mark
 
I have a 2hp Ram Air compressor (sold by Snap On) and a 6000 surge 5000 continuous generator. The compressor trips the breaker on the generator once it hits about 40 psi. You're going to need probably closer to 10,000 continuous watts for it to work.
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top