Pure Sine wave vs. Modified Sine wave

[DrewChan]

I see varying debates regarding whether you can successfully use modified sinewave inverters for PC's and TV's,

Some say no
Some say Yes with buzzing
Others say, modern modified sinewave inverters are fine for electonics

For those with modified sinewave, what are your experiences?

 

[AntennaMan]

Most electronics using switched-mode power supplies should be fine with modified sine wave inverters. The little black box power supply shipped with LCD TV's, laptops and cellphones are all examples of switched-mode power supplies.

Electrical equipment with electric motors or pumps do not like modified sine wave inverters. Things like fridges (pumps) and washing machines (motors) are good examples.

 

[ScottulusMaximus]

Most electronics using switched-mode power supplies should be fine with modified sine wave inverters. The little black box power supply shipped with LCD TV's, laptops and cellphones are all examples of switched-mode power supplies.

Electrical equipment with electric motors or pumps do not like modified sine wave inverters. Things like fridges (pumps) and washing machines (motors) are good examples.

What he said.

The only electronics I wouldn't plug into a modified sine would be high end audio stuff, probably wont damage it but would freak me out.

 

[The_Traveller]

Buy what your gut tells you to buy and hope for the best ...

 

[TehStranger]

Most electronics using switched-mode power supplies should be fine with modified sine wave inverters. The little black box power supply shipped with LCD TV's, laptops and cellphones are all examples of switched-mode power supplies.

Electrical equipment with electric motors or pumps do not like modified sine wave inverters. Things like fridges (pumps) and washing machines (motors) are good examples.

+1

I've got a modified sine wave inverter at home for the electronics and haven't had a day's trouble. The same inverter (slightly older model) has done duty in the SO's folks' house for years with no damage to electronics.

If you can afford to go pure sine wave, do it because they are better. But if you can't, modified sine wave is a perfectly viable alternative.

 

[biometrics]

Huge price difference between the two for the same watts.

I'd rather pay more and know for sure there won't be issues.

In any case, the more watts the more batteries. Best to keep your consumption to a minimum. I get by fine with a 200W sine wave inverter, 105 Ah battery and a decade old 85W solar panel.

 

[ProAsm]

As AntennaMan and biometrics says, I have a 300 watt Modified Sinewave Inverter from Makro which I paid R499 for at the time and it's been in operation now for a year operating 6 x 11 watt energy saving lights, my 55 inch Smart TV, a SD-PVR and sometimes a desktop computer.
I have had no problems what so ever.
I intend getting a 100 watt solar panel and a second battery.

 

[TehStranger]

Huge price difference between the two for the same watts.

I'd rather pay more and know for sure there won't be issues.

In any case, the more watts the more batteries. Best to keep your consumption to a minimum. I get by fine with a 200W sine wave inverter, 105 Ah battery and a decade old 85W solar panel.

What do you actually run with that?

My typical inverter load is around the 400w mark, though I went for a 1,200w inverter that allows me to scale if I need to.

I agree with keeping consumption to a minimum though.

 

[biometrics]

What do you actually run with that?

My typical inverter load is around the 400w mark, though I went for a 1,200w inverter that allows me to scale if I need to.

I agree with keeping consumption to a minimum though.

I have four battery power lights that go on automatically when the power goes out, so lighting is fine. I only run my 24" LED, laptop, docking station, router and a desk CFL lamp. That's about 100W. I have another device I use sometimes that uses 100W. That's all I need for the two hours the power is out.

 

[TehStranger]

I have four battery power lights that go on automatically when the power goes out, so lighting is fine. I only run my 24" LCD, laptop, docking station, router and a desk CFL lamp. That's about 100W. I have another device I use sometimes that uses 100W. That's all I need for the two hours the power is out.

Is the "other device" a motorised fleshlight of some kind?

That makes sense. We run 30W of lighting (5 x 4w leds + 1 x 10w CFL), a 46 inch tv, DSTV Explorer PVR, sound system (we don't really need this, but it's nice to have), router, laptop and a few cellphone chargers. However we have run two TVs, two decoders and multiple laptops before without an issue - which is why I'm a fan of higher capacity inverters. If you want to scale, you can.

 

[TehStranger]

I have four battery power lights that go on automatically when the power goes out, so lighting is fine. I only run my 24" LCD, laptop, docking station, router and a desk CFL lamp. That's about 100W. I have another device I use sometimes that uses 100W. That's all I need for the two hours the power is out.

Is the "other device" a motorised fleshlight of some kind?

That makes sense. We run 30W of lighting (5 x 4w leds + 1 x 10w CFL), a 46 inch tv, DSTV Explorer PVR, sound system (we don't really need this, but it's nice to have), router, laptop and a few cellphone chargers. However we have run two TVs, two decoders and multiple laptops before without an issue - which is why I'm a fan of higher capacity inverters. If you want to scale, you can.

 

[Gnome]

The reason you get different answers is because the answer is it depends.

All power supplies aren't made the same.

Most modern switched mode power supplies start by rectifying the power using diodes. Those power supplies do not care about sine wave VS modified sine. In fact they'll even accept DC.

Some devices however use a transformer or power factor correction that relies on inductors.

When you feed a transformer or inductor with DC/modified sine it heats them up and causes them to become saturated which you hear as audible humming.

The question of if it is ok? Well that depends. If they cannot deal with the extra heat, then no, it isn't OK.
Most of them will be designed to have high enough tolerance to deal with it however.

An AC electric motor is also an inductor, hence the reason you shouldn't run it with modified sine. So the motor will run slower and hotter. Reducing the life and not running within tolerances.
Since a motor is a moving part that may have mechanical stress associated it isn't as simple as the transformer case where you simply have higher tolerance.

 

[biometrics]

Is the "other device" a motorised fleshlight of some kind?

That makes sense. We run 30W of lighting (5 x 4w leds + 1 x 10w CFL), a 46 inch tv, DSTV Explorer PVR, sound system (we don't really need this, but it's nice to have), router, laptop and a few cellphone chargers. However we have run two TVs, two decoders and multiple laptops before without an issue - which is why I'm a fan of higher capacity inverters. If you want to scale, you can.

Something like that

I bought it about 12 years ago when I had a plot on a farm with no electricity. Eventually sold it and kept the gear. Been very handy since 2008 ...

I actually have two of the 200W sine wave inverters but only use the one.

 

[Marvo]

The reason you get different answers is because the answer is it depends........

^^^ What Gnome says. There's no clear cut answer. If you use a modified sine inverter it may give issues with some devices and not with others. Pretty much pot luck.

 

[mmacleod]

^^^ What Gnome says. There's no clear cut answer. If you use a modified sine inverter it may give issues with some devices and not with others. Pretty much pot luck.

I think this is further complicated by the fact that you may not see issues immediately, I mean running for a month or even a year and not having an issue does not mean for sure that there isn't one.
It may cause you to lose a power supply once every 2 years instead of once every 5 years, or other subtle problems like that.

This may not sound like a big thing, but when a PSU blows it often takes other things with it, so it can end up being a costly gamble, that alone (having once in my life lost a lot of expensive hardware to a bad PSU), is enough to put me off the idea of gambling on this sort of thing entirely.


One doesn't have to search very hard to find things like e.g. http://electronics.stackexchange.co...er-destroy-damage-the-ac-adapter-for-a-laptop
Maybe it isn't 100% conclusive and a lot of the stories are anecdotal, but is it really worth taking that risk, I don't personally think so.

 

[biometrics]

Another consideration, it wastes energy so you have to pay more for electricity.

 

[mmacleod]

Another consideration, it wastes energy so you have to pay more for electricity.

And that alone should tell you something, I mean if energy is being wasted where is it going? Energy never magically vanishes. The usual answer applies here, HEAT.

And more heat when it comes to electronics means more risk of things breaking, this of course doesn't mean that things will break for sure, it just means that there is an increased percentage chance of things breaking...

 

[lived666]

I have a 3000watt modified sine wave, laptops, router all fine, tv makes slight buzzing sound

 

[Bowsie10]

My Samsung 46" LCD buzzed loudly on modified wave inverter for about 2 weeks during load shedding. Now its dead apparently the power pack is gone. My plasma runs fine though.

 

[ProAsm]

I also found our old Samsung CRT and Sinotec 47" LCD buzzed a bit but our new 55" Hisense works 100% on the Modified Sine Wave Inverter.