# Advice on an inverter please



## 107506 (Oct 7, 2007)

Hi all I have just bought an 800 watt inverter off ebay for £17. It was sold as faulty as the guy did not have leads to test it, however being a sparky I thought I'd give it a go and all that was wrong was one of the terminals was broken. The inverter is an argos one (740/2223 ) it claims it can be plugged into a ciggarette lighter. Well like I say I'm a sparky and to calculate cable size etc we use power divide by voltage to find current so this equates to 66amps. Am i missing something because i feel you would struggle to get 16mm cable into a ciggarette lighter plug or do you work out DC supply differently ? your advice would be much appreciated.

Russ


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## DABurleigh (May 9, 2005)

From memory most ciggy lighters are around the 10 amp, max 15 amp if you're lucky, capacity.

Dave


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## 107506 (Oct 7, 2007)

So does that mean straight to the battery then Dave ? Is that right then it will draw about 66 amps ? How can they say to connect it to the ciggarrette lighter ? Sorry for all the questions but as you know high currents and bad connections are a potential fire hazard 

Many thanks Russ


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## mep (Jan 4, 2008)

I just recently bought a 600w inverter from maplin and i expected it to come with the cigar plug, but it came with two thick cables and large clips to connect to the battery, i have now hard wired it to the battery.
Strangely if i switch it on with a test plug fitted it indicates that it has no nuetral or earth? if i switch it on with the engine running then i get two lights which indicates correct polarity but no earth. It stays like this after the engine is stopped?
There is now earth connected as the instructions dont show one and just says connect red and black wires to the battery.
There is an earth terminal but was worried about connecting it the the vans chassis AC 240 shareing same earth negative of Van
The invertrer works my electric drill whether the engine is running or not.
I have read today in a product catalog listing inverters that all inverters ovcer 150W have clips instead of cigar plug, perhaps that answers your question.
Mick


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## 107506 (Oct 7, 2007)

Thanks for that Mick, I meant to say that I plugged a socket tester in to mine when testing it and got two lights indicating no earth, there is no earth terminal on mine so I wondered about this, sorry what did you with your earth ? Many thanks Russ


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## 107558 (Oct 10, 2007)

_*Some*_ higher power Inverters allow you to connect to the cigarette lighter socket but will only allow a 150w draw. To get the full wattage you need to connect directly to the battery.

If you Google the make of Inverter you may find an instruction manual for it.


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## 107506 (Oct 7, 2007)

Hi JQL thanks for that I tried the google approach but no joy maybe its just an economy argos version  

Thanks Russ


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## mep (Jan 4, 2008)

Rusky at the moment i have no earth connected. I am waiting for someone to offer advice on this. I fitted mine to power / charge laptop and for the TV assume it will be OK without the Earth.
I believe if the inverter earth was connected to the chassis then it would not cause any problems. But need reassurance.


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## allan01273 (May 23, 2007)

*Help me too please*

This got me thinking about my little set up - hope you don't mind me adding to this.
I have 500 inverter across the 85 amp battery, from there I have a lead that goes outside though the cab door and plugs in to the EHU. I turn off the battery charger and the fridge switch and then use the 13A sockets to run the computer, phone charger and aaa battery charger.
Obviously there is insufficient power to run the wifes hairdryer and other major items but the plug tester shows that we have correctly earthed and polarised sockets.

Is there anything wrong in this set up

Allan


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## safariboy (May 1, 2005)

If your device is "double" or "all" insulated I do not see why an earth will improve safety. Many double insulated appliances have a plastic earth pin anyway so efforts to earth the appliance will be in vain.
I am not very happy dealing with floating power supplies which is what an unearthed inverter will be but have never heard of a problem. Perhaps someone knows better?
Safariboy


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## 107506 (Oct 7, 2007)

Hi safariboy, I totally agree with you about double insulated equipment being safe with no earth it just feels that as a sparky we spend our lives checking the earthing ! So that was the reason for the query.

Cheers Russ


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