Quasi sine inverters

[OldGoat]

Who uses a quasi sine inverter and what device(s) does it drive?

(FWIW I bought a 2Kw quasi inverter from that nice Mr Sterling some years ago because it was an inexpensive eBay return and I thought I'd use its battery charging function.

However, I see occasional posts on this forum mentioning thar they use one. So what for and what are the drawbacks, please?

 

With more and more equipment running at low votlage internally, the 240v power input is usually converted to lower voltage DC internally and I suspect that the 'less than sine waveform' is less of a problem than it used to be. Ence the question.

 

Any practical experience please, folks??

 

[john6767]

We have a 2Kw Ring cheapo inverter that was on the boat when we bought it   It has been used for charging phones, VHF and Laptops in the past, but all that is done from 12V now.  I think the only thing now would be occasional hair dryer use (not me), but not done that for ages either.

[Alan de Enfield]

We have a Sterling 1800w Quasi sine wave or, to put in another way, a 'squareish sine wave'

 

Runs :

700w Microwave

1000w Electric Kettle

Freezer

George Forman Grill

1400w Air Fryer

Dehumidifier

 

 

Not all at once !

 

Everything else is either 12v or 5v

[Tony Brooks]

1 hour ago, OldGoat said:

With more and more equipment running at low votlage internally, the 240v power input is usually converted to lower voltage DC internally and I suspect that the 'less than sine waveform' is less of a problem than it used to be. Ence the question.

 

Except there have been credible reports on here about modified sine wave inverters wrecking electric tooth  brushes and electric hair curlers/straighteners. 

 

It is also known that they can cause noise and or image problems with some audio-visual equipment and may also make some motors run noisily and/or hot.

 

Much will depend upon the way an individual product has been designed.

[Chewbacka]

17 minutes ago, Tony Brooks said:

 

Except there have been credible reports on here about modified sine wave inverters wrecking electric tooth  brushes and electric hair curlers/straighteners. 

 

It is also known that they can cause noise and or image problems with some audio-visual equipment and may also make some motors run noisily and/or hot.

 

Much will depend upon the way an individual product has been designed.

And also how close (or far) from the ideal wave form is the inverter output.

[OldGoat]

57 minutes ago, Tony Brooks said:

 

Except there have been credible reports on here about modified sine wave inverters wrecking electric tooth  brushes and electric hair curlers/straighteners. 

That is strange because both those are essentialiy resistive loads

It is also known that they can cause noise and or image problems with some audio-visual equipment and may also make some motors run noisily and/or hot.

That's 'credible'  - for AV kit as the noisy waveform could (if improperly flitered) transfer to the amplifier, but more difficult to understand for a motor - unless the waveform is very crude.

 

Looking at CS's device - its very heavy with a massive transformer accounting for most of the weight and I wondered why. I asked CS senior - but didn't get a reasonable answer (he could be evasive on occasion). I had hoped that the asnwer might be some form of 'mechanical smoothing' but that would only work if there are many steps in the waveform.

These things are still on sale and quite expensive, so there must be some applications for them!

57 minutes ago, Tony Brooks said:

 

 

Much will depend upon the way an individual product has been designed.

 

[Tony Brooks]

38 minutes ago, OldGoat said:

unless the waveform is very crude.

 

That is what we don't know. You talk of a large transformer and that makes me think the wave form will be nothing like that produced by more sophisticated methods.

 

I think the harmonics such devices tend to produce in the waveform cause the issues in motors and possibly other equipment as well. I don't but I ma sure others will chip and. know enough about electronics

[PineappleGuy]

On 15/04/2022 at 14:02, Alan de Enfield said:

We have a Sterling 1800w Quasi sine wave or, to put in another way, a 'squareish sine wave'

 

Runs :

700w Microwave

1000w Electric Kettle

Freezer

George Forman Grill

1400w Air Fryer

Dehumidifier

 

 

Not all at once !

 

Everything else is either 12v or 5v

How about a Dyson vacuum cleaner? The charger for ours says it outputs 26.1V so I guess that can only be off the inverter too.

[Alan de Enfield]

12 minutes ago, PineappleGuy said:

How about a Dyson vacuum cleaner? The charger for ours says it outputs 26.1V so I guess that can only be off the inverter too.

 

 

Either an inverter that takes 12v DC, inverts it to 230v AC and then your charger takes 230v AC and converts it to 26V DC VERY VERY inneficient and waste a lot of valuable 'leccy - something that is in short supply on a boat.

 

The other way to do it (more efficiently) is to use a 12v DC to 26v DC converter.

 

 

 

Edit to add : other models and types are available - this was just the 1st one on a Google search, here is a simpler cheaper one that does the same job.

 

High Efficiency 12 Volt to 26 Volt DC to DC Boost Converter 12V to 26V Step Up 9 20V 6A 8A 10A 12A Vehicles Power Supply|Inverters & Converters| - AliExpress

 

But you need to add 20% VAT to the price. So ends up about £14.50 delivered.

 

 

I use a 12v DC to 19v DC converter for my Laptop. Worlks well and no quiescent current.

Edited April 16, 2022 by Alan de Enfield

[Ryeland]

Beware, I suspect that the Dyson power supply is in fact a lithium charger, and replacing it with any old 26v psu wouldn't do the battery any good. My Dyson charges happily during our cruising time with the inverter on.

 

Richard 

[Tracy D'arth]

On 15/04/2022 at 14:02, Alan de Enfield said:

We have a Sterling 1800w Quasi sine wave or, to put in another way, a 'squareish sine wave'

 

Runs :

700w Microwave

1000w Electric Kettle

Freezer

George Forman Grill

1400w Air Fryer

Dehumidifier

 

 

Not all at once !

 

Everything else is either 12v or 5v

You are very fortunate if a quasi sine wave inverter runs you microwave properly, most don't.

[Alan de Enfield]

15 minutes ago, Tracy D'arth said:

You are very fortunate if a quasi sine wave inverter runs you microwave properly, most don't.

 

 

It is a very simple (mechanical knobs - no digital screen)  and it seems to work fine.

 

 

[Peugeot 106]

I bought a second hand 350 watt Sterling Pro Power Q Advanced digital Quasi Sine Wave Inverter. I’m intending to run a 200 watt stick blender off it. Does anyone think I may have problems.

i looked everywhere for a 12volt blender and did think of using my cordless drill but then I would still need to charge that!

[Tony Brooks]

10 hours ago, Peugeot 106 said:

I bought a second hand 350 watt Sterling Pro Power Q Advanced digital Quasi Sine Wave Inverter. I’m intending to run a 200 watt stick blender off it. Does anyone think I may have problems.

i looked everywhere for a 12volt blender and did think of using my cordless drill but then I would still need to charge that!

 

I charged my portable power tools and phones from a cheap Maplin modified sine wave inverter. I think there is every chnace the blends will work unless it has electronic speed controls. If it has then things get a lot more iffy. If its a cheap one give it a try, if it is an expensive one with speed control I would not risk it just in case. If it just has a on off switch then there is  a very good chance it will work.

[Peugeot 106]

13 hours ago, Tony Brooks said:

 

I charged my portable power tools and phones from a cheap Maplin modified sine wave inverter. I think there is every chnace the blends will work unless it has electronic speed controls. If it has then things get a lot more iffy. If its a cheap one give it a try, if it is an expensive one with speed control I would not risk it just in case. If it just has a on off switch then there is  a very good chance it will work.

Thanks Tony I tried it today and it seems to work fine. The blender is a cheap on/off one with no speed control. I bought a Victron pure sine inverter but the DC wire connectors are not good for mobile use. They will i’m sure cut through the wires as the terminal connector is quite a sharp blade. The Sterling quasi sine inverter is much handier (smaller and lighter) with better permanent DC feed wiring and it will i’ve no doubt stand up to being got out and put away. The Victron seems to be designed for permanent mounting which in my case is not possible so if I can get away with the Sterling unit I will.