# inverters am I missing something



## Pudsey_Bear (Sep 25, 2008)

Whilst still planning our PVC I got to thinking inverter , and on looking on Ebay, modified and pure sine wave seem on the face of it to be a similar price, or is there more to it.

I currently run a 600w and a 300w for different purposes, both supplied by 2 x 110ah batteries, I like the idea of a 3000/6000w pure sine wave inverter which would be mostly switched off, but there to power a micky or other short term high powered item, and have a smaller 300w (possibly PSW) to do the more mundane stuff and use 12v where possible and financially practical.

As an additional query, is there any difference in the way or the amount of power they suck out of the batteries in use.

I like electrickery but sometimes the plot escapes me, so please excuse the simpleness of my questions and the way I ask for info, don't talk over my head as simple answers work best then I don't have to ask what you mean


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## andrewball1000 (Oct 16, 2009)

I am not an expert so my way of looking at inverters is based on the following:- 

Amps = Watts / Volts (the only formula I remembered from school) 
Therefore on EHU on 240v system, 480 watts/220v = 2 amps 
While an inverter on 12v batteries, 480 watts/12v = 40 amps

The time you are drawing the current matters. A Remoska of this wattage would flatten (halve the capacity) an 80amp/hour battery in one hour, while a microwave, hairdryer or toaster of twice the wattage running for 10 minutes would only take 80amps x 10/60ths = 14amp hours (16%) which is fine as long as you keep it short and put it back after.

The bigger the amperage, the bigger the cables and shorter the run required.


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## DABurleigh (May 9, 2005)

Read the Members Guide on Inverters, Kev (from Resources menu) and if still unclear come back.

Dave


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## Pudsey_Bear (Sep 25, 2008)

DABurleigh said:


> Read the Members Guide on Inverters, Kev (from Resources menu) and if still unclear come back.
> 
> Dave


Thanks for the advice Dave, I had already been there, and just re-read it again, and it does answer some of my questions,

But is there any difference in the way or the amount of power they suck out of the batteries in use, didn't seem to be there unless it's couched in a different way and I missed it.

Also the lack of price difference, modified v pure, how come they're similar prices now, whats changed, which was the point of this post in the first place, not be sparked up things have passed me by somewhat.

And unclear (to me) is an understatement, I just struggle absorbing written info, Yuotube works so much better for me, diagrams and video etc, monkey see monkey do I suppose, That and being a bit ffickk.


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## pieterv (Feb 3, 2009)

I don't think there is a difference in the way pure and modified sine wave inverters use power.

There is, however, a difference in available battery capacity for different sized loads. So, if you draw a big current, the capacity in Ah of the battery will be less then when you draw a small current.

So, just taking the normal battery capacity to base calculations on for huge (1-2kW) inverters will not work. You will be able to use them for a much shorter time than you think.

Also, remeber you don't want to deep discharge batteries, this really limits their life.

Pieter


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## DABurleigh (May 9, 2005)

Like for like, a pure sine-wave inverter is more costly to make than a modified sine-wave inverter. If they were not, modified sine-wave inverters would not be sold!

However, cost is one thing. Price, marketing, selling cheap [email protected] at a high price to customers who can't judge the value of what they are buying, all confuse matters.

Efficiency per se is not affected by modified vs. pure sine-wave. I have a couple of cheap modified inverters, one fixed in the van dedicated to TV, motorised satellite dish, LNB and receiver, and the other at home to throw in the car as required, and both will run at 90-95% efficiency as I load them over 50% each time. I also have a 1.6kW pure sine wave inverter as part of an integrated Victron set-up powering all mains sockets in the van and roof aircon, its efficiency is no greater, but because of the quality of its components its no-load current is low. That said I'd be daft to use that to just charge up something small, as I would be wasting my batteries, as the guide explains.

Dave


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## Addie (Aug 5, 2008)

If you can find a Pure Sine Wave inverter for the price of a middle of the road modified sine one (such as Silverline or Ring) then its a poor quality Chinese one and don't touch it, just google Power Jack inverters on Youtube.

There is no difference in how they consume power but how 'clean' their output is - eg you will get 'noise' on some TV / Modified Sine combinations. As such Pure Sine is always the preference but make sure you buy a decent make / model but for most applications a Modified is just fine.

Just watch out with 'continuous' and 'peak' powers - you never want to exceed the continuous'

No idea what on earth you need a 6000w inverter for - sounds total madness, you'd flatten your battery in minutes!! We have a 2100w ring we use for a hairdryer only when the engine is running and it draws 186 amps (alternator supplies 160, cab battery takes up the slack).

A 2000w Silverline modified sine can be had for £150 and would power a Microwave if that's your poison - would be my preference over a cheapo pure sine.


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## Pudsey_Bear (Sep 25, 2008)

Hmm, I was using the 6000x (surge) as an example of Ebay prices, as you say a 2kw one would be man enough for the common micky.


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## spatz1 (May 19, 2011)

my tronic 150w inverter bought from lydl in zante just burnt out the other day


I replaced it with a cheap chinese one to find the cooling fan is on all the time and its really noisy and uses 9watts just on standby which wasnt quoted when i bought it .....

finally found a replacement that looks ok but had to go to 300w to have a silent fan... (4w on standbye, 90% efficient)

http://cgi.ebay.co.uk/ws/eBayISAPI....18169360&category=36798&_trksid=p5197.c0.m619


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## eddievanbitz (May 1, 2005)

Kev_n_Liz said:


> As an additional query, is there any difference in the way or the amount of power they suck out of the batteries in use.


An easy rule of thumb is to divide the AC wattage by ten. The answer would then be the DC power your "sucking out of your battery)

There are so many variables such as efficiency, AC/DC conversion, voltage, voltage drop that the formula is probably only understood by a Government Chief Scientist ( :wink: )

But in essence. If you have a 220 volt cooker that used 1000 watts when on and you wished to use it for one hour you could simply divide the 1000 by ten and you would consume 100 (amps) from your batteries

As you should only look to use 50% of the capacity of your batteries you would need a battery (bank) with the capacity in excess of 200 Ah.

Bear in mind that you would also want DC (battery power) for all the normal things that you would want to use in addition to this.

Hows that? :wink:

Eddie


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## spatz1 (May 19, 2011)

spatz1 said:


> my tronic 150w inverter bought from lydl in zante just burnt out the other day
> 
> 
> I replaced it with a cheap chinese one to find the cooling fan is on all the time and its really noisy and uses 9watts just on standby which wasnt quoted when i bought it .....
> ...


got to coment on this inverter as it really is top quality now its arrived and i almost feel guilty as it cost him £4.90 to send it .... makes the chinese one look like a kids made it (probably has)
spoke to him and he s just clearing stock due to the downturn...


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