Cheap Generator powering Decent Monitor+Laptop

[rjundi]

Hi,

I am writing to inquire if a Harbor Freight $90 generator 800W is okay to use for a backup of home office. Items include LCD flat panel and T500 laptop, cable modem and Cisco Router.

The wattage would be fine however more concerned if power is stable enough etc to not damage the $500+ monitor.

 

[redhat]

It should be fine. I would definitely use a line-interactive UPS to keep a good, clean, continuous supply of power.

I'd even use one with the regular electricity.

 

[Nick R]

You may or not be able to run it off a UPS. A UPS will not take a modified sine-wave inverter output. It will just flip over to internal battery power due to electrical noise.

It's the same reason you can't put daisy chain UPSs. Now, this applies at the very least to cheap UPS which aren't 100% on. Whether this would apply to the full-time UPSs, I don't know.

Either way though, I would think you'd be fine. Keep in mind, all of your devices, computer, laptop, monitors have a AC-DC Inverter, with filters on it. So the input won't hurt them as long as it remains within voltage spec, and it stays at 60Hz.

 

[eljefino]

I'd skip the UPS. The HF sine wave will be as close to perfect as its brushes etc can support.

Computer gear can take 100-240 volts, 50-60 Hz. I'd worry more about running a fridge, truthfully.

 

[AandPDan]

You'll be fine. I did it for 5 days after a snow storm and we routinely use that same generator at our local HAMfest.

 

[HardbodyLoyalist]

I'd definitely use a line conditioner if it were my stuff---even with a high-end generator.

 

[dparm]

Line conditioner probably isn't necessary -- a power supply, by definition, will smooth things out.

 

[Rand]

there is no modified sine wave or inverter.
the cheap HF generator runs at 3600rpm = 60hz

is the power dirty? possibly.. nothing that would prevent a ups from running.

Inverter generators use an alternator so they can run slower.
and a DC-AC inverter. These are expensive units and produce a true sine wave.

Originally Posted By: Nick R
You may or not be able to run it off a UPS. A UPS will not take a modified sine-wave inverter output. It will just flip over to internal battery power due to electrical noise.

 

[rjundi]

Expensive is the problem. I already have a large UPS to power my cable router/modem for 7hours. Running my laptop longer than 2hrs is what I seek and in a docking station with real keyboard, mouse, and 27" monitor(my 14" latop screen hurts my eyes at 1400x1050 resolution).

I already have a large used 6800 running watt portable (Rigid/Yamaha) generator(due to 240V well & wife who wants to use 2000W hair dryer) with low THD apparently okay for electronics. However it is loud/obnoxious/drinks fuel and it a pain to drag out for a likely 1-4 hr power loss.

It sounds like for $90 the harbour freight generator set will meet my needs.

 

[Dave Sherman]

Rand is correct, the $90 Harbor Freight is not an inverter generator. At the very least I would use a surge protector; I thought a review of that little generator revealed it didn't have very good voltage regulation.

 

[JHZR2]

Originally Posted By: redhat
It should be fine. I would definitely use a line-interactive UPS to keep a good, clean, continuous supply of power.



+1. While a computer and monitor should pull less than 800W, Id be very wary of the power quality, especially at the upper range of the draw.

 

[JHZR2]

Originally Posted By: rjundi
Expensive is the problem. I already have a large UPS to power my cable router/modem for 7hours. Running my laptop longer than 2hrs is what I seek and in a docking station with real keyboard, mouse, and 27" monitor(my 14" latop screen hurts my eyes at 1400x1050 resolution).



So what's the draw??? Use a kill-a-watt meter on it when the laptop is fully charged but running a heavy load. I'd say it probably is smart to run off a generator because the battery could get large, but the UPS is still prudent due to the poor power quality.

 

[Cujet]

Here, I've put a 250W halogen lamp on my HF 2 stroke generator. The blue/green line is the generator sine wave. It has 2 obvious flaws in the sine wave. But it seems to run anything I hook to it, without difficulty. Motors, laptop, lights, fan, whatever.

 

[JHZR2]

whats with the hiccup in the sine wave?

 

[Cujet]

Originally Posted By: JHZR2
whats with the hiccup in the sine wave?


I'm not certain how this thing is wired internally. On some "self exciting" generators, there is an additional stator winding that only provides the current for the rotor. On other units, the stator is "tapped" to provide rotor power.

In the first case, this "Z" winding interacts with the magnetic field and affects the output waveform a bit. I suspect this is the case here. Every time the rotor passes the Z winding, there is a clear distortion.