Inverters

[Pav]

Hi All,

Sorry this may seem a bit of a thicko question, but is a quassi and a modified sine wave inverter the same thing?

 

Is it worth paying the considerable premium to upgrade to a pure sine wave mode?

 

Views appreciated.

 

Thanks.

 

Pav.

[Tony Brooks]

Hi All,

Sorry this may seem a bit of a thicko question, but is a quassi and a modified sine wave inverter the same thing?

 

Is it worth paying the considerable premium to upgrade to a pure sine wave mode?

 

Views appreciated.

 

Thanks.

 

Pav.

 

 

Pav

 

It all depends upon what you intend to do with them. If you are unsure about your future use and you can afford it buy a pure sine wave one. If you can not afford that take the equipment you want to use with it to the supplier and make sure it all works on a modified sine wave one before buying.

 

Also try to select one that allows the greatest surge (overload) for longest because many pieces of equipment draw a very high starting current - despite what the label says.

 

Tony Brooks

[anhar]

I don't know the technical difference between the two Pav but it doesn't matter because in my view you should go for full sine wave and moreover stick to Victron or Mastervolt. I understand that fsw consumes more electricity when running than the cheaper types but you have to design your electrical system to allow for that.

 

My reason is so that you are certain that any appliances you may purchase will work including the more sensitive ones such as computers, TVs, 'waves with electronic control, drills with electronic speed control and so on.

 

Whilst the cheaper non full sw models may work the appliances you can never be sure and you never know what equipment you may purchase in future so why take risks just to save a bit? The cost difference against the cost of having a boat built is negligible.

 

regards

Steve

Edited November 3, 2007 by anhar

[chris w]

Firstly, modified sinewave and quasi sinewave are usually the same thing. There are however three types of inverter. Some of the really low cost ones are just square wave types and are best avoided. These may also be described as "modified sinewave".

 

The only devices that won't run properly on a quasi inverter are devices for whom the shape of the sinewave is important. These are mainly motor control circuits that use a "light dimmer" type circuit to vary motor speed in washing machines etc.

 

Other devices like TV's, computers, hairdryers, radios, chargers couldn't "give a damn" because they operate from switched mode power supplies nowadays and the AC input waveform is totally unimportant. So if you are told they don't run on it then that is misleading information.

 

Ergo, if you don't have a washing machine/tumble dryer on board you don't need a pure sine wave inverter which will be at least twice the price and will consume more power than a quasi inverter. If price and power are no issue, then by all means go for it but in 90% of cases it's not necessary.

 

Mathematically, the distortion on a quasi (multistep) sine wave inverter is 6.5% compared to a stepped waveform version at around 23% distortion so the quasi version is a good approximation of a sinewave anyway.

 

Chris

 

PS: our local marina/chandler is a Victron agent but hates Victron PSW inverter/chargers because he has so many returns due to faulty operation in the field. I have no personal experience with them myself. The additional issue with a combined inverter/charger is that if one part fails you lose your inverter AND your charger while it's being repaired. Bit like combi washer/tumble dryer. Sounds a great idea till it goes wrong.

[ChrisPy]

what about microwaves, Chris?

[dor]

I tried an old clockwork microwave on my inverters (no digital timers or any other fancy bits). On a MSW it just sat there buzzing and not heating, but worked fine on a PSW..........

[moggyjo]

I'e got a non pure sw 600watt inverter and the only thing it would not run was my cordless drill charger, so I brought a small psw inverter for that.

[Kraken]

Other devices like TV's, computers, hairdryers, radios, chargers couldn't "give a damn" because they operate from switched mode power supplies nowadays and the AC input waveform is totally unimportant. So if you are told they don't run on it then that is misleading information.

On modified sine wave, Mitsubishi and Panasonic TVs have a faint horizontal line migrating slowly upwards. Radio/tape/CD player buzzes loudly. Microwave will not work on it's own but will when something else is running. All work fine on mains. Considering your remarks, any idea why this might be?

Other devices like TV's, computers, hairdryers, radios, chargers couldn't "give a damn" because they operate from switched mode power supplies nowadays and the AC input waveform is totally unimportant. So if you are told they don't run on it then that is misleading information.

On modified sine wave, Mitsubishi and Panasonic TVs have a faint horizontal line migrating slowly upwards. Radio/tape/CD player buzzes loudly. Microwave will not work on it's own but will when something else is running. All work fine on mains. Considering your remarks, any idea why this might be?

[Keeping Up]

My Sony TV also suffered from horizontal lines on the picture when run from a modified sine wave. The picture was fine again when I changed the inverter to a pure sine wave one.

[chris w]

I have only experienced a faint line on a TV where the TV concerned was a CRT version. My 17" LED TV on the boat has no lines operating from a MSW inverter through its 12v power pack.

 

With regard to microwaves, there are two issues:

 

1. The microwave usually does need to have a mechanical timer because (commonly) the timer is synchronising to the sine wave and with a "distorted" sinewave it may time incorrectly or not at all

 

2. A microwave may be marked say 700W but that is a bit of marketing hype. That figure is the electrical power that is actually converted to microwave power. However, not all the electrical power is converted to microwaves.

 

The efficiency (or inefficiency) is only about 50%. So, to run a nominally 700W microwave, you need at least a 1400W inverter and then on top need some good headroom for the start-up current surge. So I would recommend at least an 1800W inverter for a 700W microwave.

 

Chris

[Guest]

I have only experienced a faint line on a TV where the TV concerned was a CRT version. My 17" LED TV on the boat has no lines operating from a MSW inverter through its 12v power pack.

 

With regard to microwaves, there are two issues:

 

1. The microwave usually does need to have a mechanical timer because (commonly) the timer is synchronising to the sine wave and with a "distorted" sinewave it may time incorrectly or not at all

 

2. A microwave may be marked say 700W but that is a bit of marketing hype. That figure is the electrical power that is actually converted to microwave power. However, not all the electrical power is converted to microwaves.

 

The efficiency (or inefficiency) is only about 50%. So, to run a nominally 700W microwave, you need at least a 1400W inverter and then on top need some good headroom for the start-up current surge. So I would recommend at least an 1800W inverter for a 700W microwave.

 

Chris

My plug in ammeter agrees with that.

[dor]

The actual power used will be on the rating plate. My nominal 800W microwave is rated at 1250W.

 

Another problem with MSW inverters is that they can destroy chargers. I've had two wrecked by a MSW inverter. When mentioning this to Charles Sterling he just commented that "yes thy will".

[bottle]

I maybe missing something here!!!!!!!!!!! and probably am.

 

Why would a charger be connected to a MSW inverter, unless you are charging a different battery to the ones supplying the inverter but even then I cannot see why you would.

 

12v to 240v to 12v??????

[dor]

Why would a charger be connected to a MSW inverter, unless you are charging a different battery to the ones supplying the inverter but even then I cannot see why you would.

 

Phone chargers, cordless tool chargers, camera chargers, laptop chargers, even toothbrush chargers!

[bottle]

Ah!!!

 

Thanks Dor

 

See said there was something missing.

 

Did not think of them.

[chris w]

Dor: Another problem with MSW inverters is that they can destroy chargers. I've had two wrecked by a MSW inverter. When mentioning this to Charles Sterling he just commented that "yes thy will".

 

It will only affect them if they are transformer type chargers which are pretty uncommon nowadays. the vast majority of chargers are switched-mode types which don't care what the input waveform looks like because it is immediately rectified to DC (at high voltage) before passing on to the circuitry and a couple of high frequency miniature transformers inside. If your phone charger is very small and weighs next to nothing, it's a switched-mode type.

 

A MSW inverter used with an older transformer-type charger may cause the 50Hz transformer to overheat. If it's a cheapo square wave type inverter it almost certainly will. A true quasi-sinewave inverter should be fine as the harmonic distortion is only about 6% ie: it's not a bad approximation to a sinewave. Any charger that is heavy and big will probably be the older transformer type.

 

Chris

Edited November 7, 2007 by chris w

[anthony]

Im looking into inverters myself and having no end of head scratching thoughts.

 

I write music as a serious hobby using a couple of synths and a drum machine and dont want to ruin them by using a dodgy inverter.

If I want to live on a boat im going to have to though so would spending around £500 on a pure sine wave give me a quality electric source?

I was thinking of getting a Sterling inverter.

Another thing that worries me is how long can I run 100 watts of power while the Mrs is on her laptop or watching tv or both.

How do I work out how much time i can get from batteries before I need to recharge them?

 

I ask this as when writing music I can be doodling away for hours.

[magnetman]

Im looking into inverters myself and having no end of head scratching thoughts.

 

I write music as a serious hobby using a couple of synths and a drum machine and dont want to ruin them by using a dodgy inverter.

If I want to live on a boat im going to have to though so would spending around £500 on a pure sine wave give me a quality electric source?

I was thinking of getting a Sterling inverter.

Another thing that worries me is how long can I run 100 watts of power while the Mrs is on her laptop or watching tv or both.

How do I work out how much time i can get from batteries before I need to recharge them?

 

I ask this as when writing music I can be doodling away for hours.

I'd look at getting something like a honda EU20i petrol generator cos it is a self powered clean electric supply and when running on low output they are very economical and quiet and saves wear on the main engine. .

[Yoda]

Most electronic music machines actually use 12 volts so any imput will be tranformered down. As there would not be a direct link to the mains voltage ie 250 v, I dont think that the wave shape will affect your music. There probably would be a problem with amplifiers causing colouration.

[anhar]

Im looking into inverters myself and having no end of head scratching thoughts.

 

I write music as a serious hobby using a couple of synths and a drum machine and dont want to ruin them by using a dodgy inverter.

If I want to live on a boat im going to have to though so would spending around £500 on a pure sine wave give me a quality electric source?

I was thinking of getting a Sterling inverter.

Another thing that worries me is how long can I run 100 watts of power while the Mrs is on her laptop or watching tv or both.

How do I work out how much time i can get from batteries before I need to recharge them?

 

I ask this as when writing music I can be doodling away for hours.

Don't get Sterling. They have a bad rep. Ask Gibbo of SmartGauge for example or Gary from boatbuilders Ledgard, both of whom are in a position to know. Pay more and go for Victron or Mastervolt. And no, I have no financial interest in the matter but I have researched it.

 

regards

Steve

Edited November 7, 2007 by anhar

[carlt]

I'd look at getting something like a honda EU20i petrol generator cos it is a self powered clean electric supply and when running on low output they are very economical and quiet and saves wear on the main engine. .

I agree, plus get surge protectors just in case the genny throws a bit of a wobbler (even posh hondas can do, occasionally).

[anthony]

I agree, plus get surge protectors just in case the genny throws a bit of a wobbler (even posh hondas can do, occasionally).

I must admit i would prefer to use a generator to charge the batteries as they can throw wobblers would this be a good idea?

[anthony]

Don't get Sterling. They have a bad rep. Ask Gibbo of SmartGauge for example or Gary from boatbuilders Ledgard, both of whom are in a position to know. Pay more and go for Victron or Mastervolt. And no, I have no financial interest in the matter but I have researched it.

 

regards

Steve

 

Thanks for the heads up Steve Ive just looked at the Victron inverters and they seem fair for the price.

[chris w]

Thanks for the heads up Steve Ive just looked at the Victron inverters and they seem fair for the price.

Be aware though, as I've said before, that if you buy a 3000 "watt" inverter from Victron you are actually buying a 3000VA inverter rated at 20degC. If you rate it in watts at 40degC (as Sterling do) it's a 2000W device. So the marketing games can affect how good the pricing really is.

 

Chris

[anthony]

This is all really confusing me and worrying me despite reading old threads ect.