# Maplins 75W Mini Inverter



## namder (Sep 20, 2006)

I've read many posts on here re inverters but still find some aspects confusing. I have just purchased a satellite system from Aldi for the very odd occasion when camping where no tv signal. The sat box is rated at 25amp. Having read that maximum efficiency is gained at 80%+ the smallest Maplin offering is this one at 75W.

http://www.maplin.co.uk/75w-mini-inverter-with-usb-charging-socket-398481

This plugs directly into the cig lighter socket and I assume the other end takes a 3pin mains plug although it looks a bit too narrow to do so!

I have 2x110 leisure batteries but I don't know if the sockets are wired into engine or leisure batteries. I charge my batteries with an 80W solar panel - both engine and leisure.

If the above inverter isn't suitable, any recommendations for one that plugs into the lighter socket.

My other concern is that the ignition needs to be on to power the sockets, is this a drain on the battery?

John


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## 747 (Oct 2, 2009)

You need a 150watt inverter. The 75 watt is OK for charging mobile phones etc. but that is all. I know, I did the same as you. :roll: 

I have used a fairly cheap 150 watt inverter, bought from Go Outdoors, and it powers my Sky digibox (30 watt) without problem.


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## JLDWW (May 16, 2012)

John be careful. 
The sat box rated 25 Amps, at I presume 12 volts. 
12 x 25 = 300 Watts. That Maplin inverter is 75W for 1/2 hour. 60w continuously. 
I would only consider a pure (or true) sine wave inverter. That is good clean 230 colts AC as good or better than the power you get at home. Modified sine wave inverters can give trouble. Electronic clocks may not work. Electric motors can run hot. I heard of a vaccuum cleaner motor burning out. All because of quality of power. 
2 years ago I bought a 600w pure sine wave inverter from Maplin, for my UK motorhome.. I think it cost £150. It works well. I run it off 90Amp hour deep cycle house battery. Runs notebook 120w. Would draw 120 ÷ 12 ÷ .8 = 12.5 Amps. 
Cigarette lighter plugs are only designed for 10 Amps. 10 x 12 is 120 watts. 
The Maplin reference you give go down and you will see a pure sinewave inverter 300 watts £110. It should be wired in to 12 volts with reasonably thick wire. How thick? Depends on length of wire. The longer the wire the thicker it needs to be to keep the voltage drop down. 
Here in NZ I have an 1800w continuous inverter and I use heavy duty battery cable for the 12 volt DC supply with a battery switch and 250 amp fuse. It could run a microwave oven.
Hope this is of some help.
John


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## tonka (Apr 24, 2006)

I think you have read the label wrong... 
No way will it be 25amps!  

As mentioned, go with a 150w inverter.. They are the right sort of size at reasonable money. Will run your sat box no problem and also come in useful for other things.

Check out ebay as a lot cheaper than Maplins unless they have one of their sales..

JLDWW.. 
I think you are really going to confuse them.. 
Good explanation though.
It's a sat receiver running an LNB max current would only be about 1.5 - 2 amps.


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## namder (Sep 20, 2006)

Sorry for confusion, should have said rated at 25W. Re my initial question, will the 75W inverter be suitable.


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## gnscloz (Oct 4, 2008)

namder said:


> Sorry for confusion, should have said rated at 25W. Re my initial question, will the 75W inverter be suitable.[/quote
> 
> A ring 75 watt won't cope with my sky box fine for 30 mins then overheats now use cheap 150 with plug in cigarette adaptor not had problem since


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## tonka (Apr 24, 2006)

Go with a 150w..
The 75 watt is often rated at it's max, not very efficient and does not give scope for other uses... Not good value in my opinion.

Ref your socket and the ignition.. Do you not have a socket in the rear of the van ?? Most do and they run off the leisure battery.


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## namder (Sep 20, 2006)

tonka said:


> Go with a 150w..
> The 75 watt is often rated at it's max, not very efficient and does not give scope for other uses... Not good value in my opinion.
> 
> Ref your socket and the ignition.. Do you not have a socket in the rear of the van ?? Most do and they run off the leisure battery.


I may have misunderstood but the view of the electrical experts on here suggest that an inverter is most efficient working at 80%+ of its maximum. If correct, a 150W inverter supplying 25W is only working at 17% of its maximum = not very efficient. A 75W inverter would be working at 33% of its max, not good but better than 17%. I don't have any other applications requiring more than my sat box.

We both have an Apache so you may have noticed from my avatar that I have the rear bunk/bathroom setup so no 12v sockets in the rear. My TV is built in to the front headlining and has composite video sockets, so a cab 12v supply is ideal for the inverter. Just wonder how wasteful it is having the ignition on to make the sockets live.

John


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## namder (Sep 20, 2006)

747 said:


> You need a 150watt inverter. The 75 watt is OK for charging mobile phones etc. but that is all. I know, I did the same as you. :roll:
> 
> I have used a fairly cheap 150 watt inverter, bought from Go Outdoors, and it powers my Sky digibox (30 watt) without problem.


I am aware a 150W inverter will power my sat box without problems, but apparently isn't efficient.

John


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## Jean-Luc (Jul 21, 2005)

The 75watt inverter sold by Maplins is rated as follows
Maximum of 75 watts of power for 5 minutes and 60 watts of power continuously, with 120 watts surge capacity.

A Sky box requires a in the region of 25 watts so the above inverter should more than cope. 

However, I opted for the 175watt (140watt continuous) version which has a cooling fan and will also run my 230v TV.


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## 747 (Oct 2, 2009)

namder said:


> 747 said:
> 
> 
> > You need a 150watt inverter. The 75 watt is OK for charging mobile phones etc. but that is all. I know, I did the same as you. :roll:
> ...


There is nothing wrong with you going ahead and buying the 75 watt inverter. It will either work or it will not. If not, it will be useful for charging small items like a phone.

If you think the 150 watt inverter will be wasteful of your battery power, you really need to address that. Fit a second battery or a solar panel. I never have a hookup and can easily run a 240 volt Sky digibox and 15" TV for quite a long time. The drain is about 5.5 amps. When times are bad, I just run a 10" TV which only takes a smidge over 1 amp.


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## namder (Sep 20, 2006)

747 wrote

"If you think the 150 watt inverter will be wasteful of your battery power, you really need to address that. Fit a second battery or a solar panel"

Thanks for your response but if you had read my original post, you would have noted that I have 2x110 batteries plus an 80W solar panel. I don't see your point that it's OK to waste battery power by having too large an inverter than you need.

I'm still gathering advice on here before I make a purchase.

John


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## tonka (Apr 24, 2006)

The amount of power " wasted" on this excersise is not worth all the hassle.. I think we have wasted more power on these messages... :lol: 
You are talking about percentage power waste on a 25w draw.. 


The 80% figure you mentioned i have never heard of..
You have 80w solar and 2 x batteries.. Thats a full battery more than me and i have no issues running a 15" TV and satellite system.. 

Go buy a 75w from Maplins and see how you go, I think you have convinced yourself thats what you want to try. Give us some feedback on how it goes..


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## spykal (May 9, 2005)

namder said:


> snip: I don't see your point that it's OK to waste battery power by having too large an inverter than you need.
> 
> I'm still gathering advice on here before I make a purchase.
> 
> John


Just to confuse you even more ...a well designed circuit in a 150 watt or a 300 watt inverter may be more efficient than a badly designed 75 watt one. Bear in mind that the power needed by the inverter varies with the load.

The waste, as you put it, that you are dealing with here are the system losses within the invertor. Some good invertors may be 85 -90 % efficient... bad ones anybody's guess. I did quite a few tests when I was into comparing various inverters against switch mode voltage regulators and they do vary in their efficiency quite a bit.... and the price you pay seems to have little bearing on it. The cheap 300 watt inverter that I use to charge our electric bikes cost about £15 and is the most efficient of all the ones I have tested.

Best advice suck it and see, get the 75watt one while it is on offer and give it a go.

Mike


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## Bill_OR (Feb 6, 2010)

Namder - just have another think about anything else you might want to power so you don't end up having to buy a different one in a few months time.

My requirements were a little different to yours in that I wanted to be able to charge my laptop, razor and toothbrush - not all at the same time! Hence I needed a pure sine wave inverter and I went for the 150w one from Maplins:
http://www.maplin.co.uk/pure-sine-wave-150w-12v-inverter-386169

Don't forget that by registering on the Maplins website you can obtain discount vouchers so I got it for £72.99 (delivered).

With my solar panel and this inverter I don't see me needing EHU at any point.

Bill


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