Need a new power Inverter - 750W +

[SwampSurvivor]

Well, was trying to be nice for a friend and I hooked the inverter up backwards. Popped it.

It was a 750/1400w Harbor Freight model. Served well for many years. It was very heavily used during many power outages at my parents house and college.

Part of me wants to go and pick up another 750W from harbor freight. I can say it held up well.

I also see some 1000/1200W ones on Amazon for around $80

Anyone have any suggestions?

 

[JHZR2]

What are you running with it? "Served well" is irrelevant if it's harming your equipment - power quality and harmonics are important...

 

[SwampSurvivor]

Over the years:
TV, Xbox 360, Laptops, Air compressor, sound system.


One power outage in college I had my laptop, sound system and peltier refrigerator running off of it. Worked well!

The harbor freight one has a modified sine wave, but that didn't affect electronics. Only issue I ever had was I coldn't charge a UPS with it.

 

[Dave Sherman]

Did you check the fuses? Might have protection built in so it just popped the fuse instead of letting the smoke out.

 

[The_Jeff]

If you like it go back. Odds are decent they changed suppliers and the next one won't be as good. Or maybe it's twice as good. You also can't compare to the amazon one.

 

[rjundi]

With that kind of equipment who cares on HF. It does not appear to be life critical anyway.

 

[SwampSurvivor]

Originally Posted By: Dave Sherman
Did you check the fuses? Might have protection built in so it just popped the fuse instead of letting the smoke out.


It went up in smoke. And melted stuff.

 

[Schmoe]

Brings up a question I have. I got one of those "back of the semi 6K watts generators during a blizzard" sales. Made in China and actually worked well. After some research over the years, found out about "dirty" power and be willing to bet my genset isn't exactly clean, just based on cost per KW. If I wanted to run some critical components...say the refrigerator/some deep freezers/computer. etc. etc., should I be looking at getting one of these power inverters to run those items and just use the generator to charge it? Or....it just doesn't work that way???

 

[SwampSurvivor]

Dirty power isn't really "good" for anything, but if it runs your appliances, you should be okay.

Prolonged use may be hard on some things like power supplies for DC items.

I went back to HF and bought another 750W inverter. Hopefully this one works well too!

They also had the mini pumps on sale too; the ones that are a copy of the slime pumps. Bought one of those.

The good news is ... two of my tires are low on the Focus and the Jeep. Will be fun to try this

 

[The_Jeff]

A 3600 RPM generator puts out a theoretically ideal sine wave, except for the interference from the brushes.

An inverter puts out a "digital wave", and while you can make a ramp-shaped pseudo-sine wave out of a series of tiny squares and rectangles, it'll only come close to perfect.

You can tell when your fridge sounds "unhappy" with dirty power. If it gets real bad, your compressor will start to run warmer and you'll smell dust burning off of it. Dirty power turns into heat, in a nutshell, when spinning motors.

I would just get a decent sized mechanical generator for emergency use. Start motorized stuff one at a time... In other words, don't shut the generator down for two hours to save gas then jam the extension cord in all at once. Shed load at the other end and start stuff up slowly.

 

[SwampSurvivor]

Originally Posted By: eljefino
A 3600 RPM generator puts out a theoretically ideal sine wave, except for the interference from the brushes.

An inverter puts out a "digital wave", and while you can make a ramp-shaped pseudo-sine wave out of a series of tiny squares and rectangles, it'll only come close to perfect.

You can tell when your fridge sounds "unhappy" with dirty power. If it gets real bad, your compressor will start to run warmer and you'll smell dust burning off of it. Dirty power turns into heat, in a nutshell, when spinning motors.

I would just get a decent sized mechanical generator for emergency use. Start motorized stuff one at a time... In other words, don't shut the generator down for two hours to save gas then jam the extension cord in all at once. Shed load at the other end and start stuff up slowly.


I have a box fan that really buzzes when plugged into the inverters.

 

[Dave Sherman]

Originally Posted By: eljefino
A 3600 RPM generator puts out a theoretically ideal sine wave, except for the interference from the brushes.

An inverter puts out a "digital wave", and while you can make a ramp-shaped pseudo-sine wave out of a series of tiny squares and rectangles, it'll only come close to perfect.


Actually, some conventional generators aren't very sinusoidal or badly distorted. One of my amateur radio journals did some comparisons between conventional generators and inverter generators, and the inverter generators were actually cleaner. I've even looked at the output of the one I have under load, and it's very sinusoidal with no noticeable steps in the waveform.

Hams are very concerned about clean power from generators, between not wanting to damage expensive equipment and avoiding RF interference.

One problem with conventional generators is when it bogs down after putting a load on it, that speed reduction shows up directly in the output because the frequency is reduced.

http://www.arrl.org/files/file/QST Binaries/QS0608Kleinschmidt.pdf
http://www.arrl.org/files/file/QST Binaries/Jun2012/QS0612ProdRev.pdf

 

[JHZR2]

Originally Posted By: Dave Sherman
Originally Posted By: eljefino
A 3600 RPM generator puts out a theoretically ideal sine wave, except for the interference from the brushes.

An inverter puts out a "digital wave", and while you can make a ramp-shaped pseudo-sine wave out of a series of tiny squares and rectangles, it'll only come close to perfect.


Actually, some conventional generators aren't very sinusoidal or badly distorted. One of my amateur radio journals did some comparisons between conventional generators and inverter generators, and the inverter generators were actually cleaner. I've even looked at the output of the one I have under load, and it's very sinusoidal with no noticeable steps in the waveform.

Hams are very concerned about clean power from generators, between not wanting to damage expensive equipment and avoiding RF interference.

One problem with conventional generators is when it bogs down after putting a load on it, that speed reduction shows up directly in the output because the frequency is reduced.

http://www.arrl.org/files/file/QST Binaries/QS0608Kleinschmidt.pdf
http://www.arrl.org/files/file/QST Binaries/Jun2012/QS0612ProdRev.pdf


yes but inverter generators are paying a pretty penny for must faster switching of the electrical components inside to give a much cleaner wave.

The sine wave off a 3600 RPM generator, especially under any sort of transient is absolutely horrid.

Given the prevalence of circuit boards in things as benign as a refrigerator, Id nottrust its longevity to a cheapo inverter.

If it was cold and I was trying to run a 600W resistive heater or something like that, different story...

 

[Schmoe]

Hmmmm....might explain why my circuit board in my HVAC went out about a month after I used that genset for about 3 days, but refrigerator and two deep freezers are still working. Even with this type of power setup, and say using a computer/tab/smartphone that charges only through a DC converter that you plug into the wall....i.e. no direct power chord plug in, could that hurt them as well? I guess I'm thinking along the lines that the DC converter acts like some sort of filtering mechanism.

 

[SwampSurvivor]

Originally Posted By: Schmoe
Hmmmm....might explain why my circuit board in my HVAC went out about a month after I used that genset for about 3 days, but refrigerator and two deep freezers are still working. Even with this type of power setup, and say using a computer/tab/smartphone that charges only through a DC converter that you plug into the wall....i.e. no direct power chord plug in, could that hurt them as well? I guess I'm thinking along the lines that the DC converter acts like some sort of filtering mechanism.


The power supply (adapter) will sacrifice itself if needed to provide "good" power to it's device.

They are pretty tough, though, as they are designed to operate in all sorts of odd conditions. But they will notice.

 

[JHZR2]

Originally Posted By: Miller88
Originally Posted By: Schmoe
Hmmmm....might explain why my circuit board in my HVAC went out about a month after I used that genset for about 3 days, but refrigerator and two deep freezers are still working. Even with this type of power setup, and say using a computer/tab/smartphone that charges only through a DC converter that you plug into the wall....i.e. no direct power chord plug in, could that hurt them as well? I guess I'm thinking along the lines that the DC converter acts like some sort of filtering mechanism.


The power supply (adapter) will sacrifice itself if needed to provide "good" power to it's device.

They are pretty tough, though, as they are designed to operate in all sorts of odd conditions. But they will notice.


AC ripple has been shown to shorten the life of batteries due to constant micro-charge/discharge cycles and localized internal heating.

Dinky power supplies dont have fast enough switching frequency either to make true clean DC.

 

[Schmoe]

......after reading all this....I'm surprised my house didn't just blow up....LOL.