Information on an Inverter?

Sep 26, 2007
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Hi, we bought a 500 inverter thinking it would power my laptop in the motorhome - no chance it screams as soon as I plug it in. It will power the Sky + box, but is not happy and only lasts for an hour or so before squeaking!

How big an inverter will I need to power a laptop which reads: input 1.5a 50-60 hz
output 19v 3.42A?

Thanks for any help or advice

Ginny
 

scotjimland

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Jul 25, 2007
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Hi Ginny

Volts x Amps = Watts, so,

1.5 A x 230v = 345 watt.. in theory a 500 watt inverter is more than enough.

Can you give more details on your inverter..
 

Geo

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Jul 29, 2007
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Sounds like very poor Batteries, or a duff Inverter to me, I have a 300 and it runs laptop ,Tv and Sky box all at once:Sad:
 
OP
Teasy2007
Sep 26, 2007
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Hi Ginny

Volts x Amps = Watts, so,

1.5 A x 230v = 345 watt.. in theory a 500 watt inverter is more than enough.

Can you give more details on your inverter..
What sort of details do you need?

On the box it says 500W, 50 hz.

In the instruction booklet it reads : Continuous power 500 w, peak power 1000w, no load current draw 0.6a.

All this is Spanish to me!!

Ginny
 
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Teasy2007
Sep 26, 2007
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Sounds like very poor Batteries, or a duff Inverter to me, I have a 300 and it runs laptop ,Tv and Sky box all at once:Sad:
We have a one year old motorhome and there are two leisure batteries! We always check the power of the batteries, which are topped up by a solar panel and they are fine.

Sounds like it might be the inverter.
 

superk

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Aug 22, 2007
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You haven't specified the make or source of the inverter but my experience is that you get what you pay for - we bought a 2,000watt inverter that couldn't pull 600watt.

One thing to check is how long and thick are the leads from the batteries to the inverter. The inverter should be positioned as close as possible to the battery with thick wires otherwise you will lose power.

:Smile:
Keith
 

Beachbum

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Keith, I am surprised you cannot pull 600w from a 2kw inverter. A guy in Spain told me you should be able to pull 1/3 of wattage of whatever your inverter is. Example 100w appliance, you need min: 300w inverter. 500w appliance, you need min: 1500w inverter. So with a 600w appliance, 2kws is sufficient. Perhaps I was told wrong. I hope someone else is the wiser.
I agree your inverter cables should be the heavy type and as close to the battery as possible. my batteries are banked together and less than 2 feet from the inverter.
 
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superk

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I agree it should but not if it's a crap inverter:Sad: the Waeco one we have in this van has no problem.

To start a new thread go to Forums above, find the section you want to post in then New Thread.

:Smile:
Keith
 
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Teasy2007
Sep 26, 2007
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Hi, We bought the inverter at Newark show last year, and the salesman advised us to buy the cigarette lighter plug with two round ends which we just plug into the 12 volt supply.

Could this be the problem?

We have two leads supplied with the inverter which we have never used. It would be difficult to plug the sky+ into the inverter as the lead is not long enough.

Any suggestions??
 
Nov 17, 2008
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I happen to be with Dave Newell today for some work and was discussing inverters with him earlier.

I fitted a 150W pure sine wave inverter from Sterling that should be quite able to power a laptop. It plugs into a cigar lighter socket, but 150W is the largest that Sterling sell with this connection. Anything bigger needs to be connected straight to the battery I believe.

I have experienced the same problem of 'screaming' when powering a laptop and speakers (load 115W in total). However, it is intermittent. When I first used it last summer there was no problem, then it began to complain in the cold months of February. The diagnosis is voltage-drop. Firstly this should be helped by two new batteries being fitted today, as one of the pair has failed, but then I intend to wire it direct from the batteries with heavy cable (and fuse of course).
 

scotjimland

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Hi, We bought the inverter at Newark show last year, and the salesman advised us to buy the cigarette lighter plug with two round ends which we just plug into the 12 volt supply.

Could this be the problem?

Yes, most likely ..

a 500 watt inverter on full load will pull 40A..

If you want to use it to it's full potential then, as previously suggested, have it hard wired to the battery, if unsure about doing this have it done professionally..

If your reasonably competent with electrics, site it as close as possible to the battery and fit an in line 40A fuse..

From the output you will need to run a 3 core cable to where ever you need the supply with a four way extension socket..

However, be aware that pulling a heavy load from the battery (s) will drain it very quickly ..

As a battery should never be drained more than 50% an 85 ah battery has a useful capacity of around 40 ah

Your laptop is taking say 100 watt, or about 8 ah .. so after five hours it will have used most of the available power from the battery .. 40ah

Then you have a TV, digi box .. it all adds up..
 

Redjumpa

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I'm a novice to the motorhoming world and I also had a screeming invertor when using my laptop. Was advised to remove the laptop battery and that has worked.

Don't know why? i'm guessing the laptop is trying to charge and play at the same time.

Having said it's working, I think I need to check the cables to the invertor as they are quite small and a good 4m from the leisure battery.
 
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vindiboy

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May 22, 2008
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Sounds to me that the feed cables from cigar lighter are too small so voltage drop ,also batteries may be low, why not connect the inverter direct to your batteries with suitable cables and of course fuse the cables.:Eeek:
 

Beachbum

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I had the same problem. This is what I done and I am no electrician, but it works for me. First check it out with someone who knows best. Ok, here goes.
I ran a 3 core household cable from the inverter, through the floor board, under the van and up through where I wanted my TV system and any 240v usage. I screwed a 3er bank socket onto the wall and connected the cable to the socket. I filled in the 2 holes I drilled with silicon. Now I have 240v at my disposal. No problems on my 6 month trip last summer at all. I ALWAYS switch off at the inverter when not in use. Don't do it if you are not sure.
 

Timber

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information on inverters

An inverter is an inefficient way of powering a laptop which probaly works on 16 volts direct current (check details on the mains unit.) The 12volt battery voltage is changed to 220volts by the inverter, then the mains unit takes it down to 16, two operations and two sets of losses.

A better solution is to obtain a 12volt power unit, plugs directly into the cigar socket. Google suggest:- www.TechnoField.co.uk Only £20.99, FAST Delivery All laptops compatible, Low Prices
 
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koffee

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Mar 22, 2008
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Resurrect this thread?

Hi all,

please may I resurrect this thread, as we are looking around for an inverter to power such things as toothbrush, Ian's beard trimmer, lap top etc.

Ian was under the impression that we could merely plug into the cigar lighter and power the inverter that way. Now reading this thread it looks as though you guys who have more experience don't recommend this and that Ginny was having probs with this, am I correct in this understanding , and if so what do you all recommend, that the inverter is powered direct from the battery?
 
T

TJ-RV

Deleted User
A small inverter to power the things you mentioned will work fine plugged into a cigar(ette) lighter. However, if the lighter socket is a long way from where you want to plug in the toothbrush and beard trimmer, use a mains (240V) extension cord. Don't be tempted to use a 12V extension cord between the inverter and the lighter socket.

Brushing your teeth or shaving while sitting in the driver's seat is something I used to see folks do every morning while commuting to work. Others would be eating their breakfast, reading a newspaper, or putting on their makeup :RollEyes:
 
Last edited by a moderator:
S

sinbad1

Deleted User
I am a newbie here , however my thoughts are that your inverter needs to be close as possible to your batteries using the thick cable supplied with the inverter.

I think the problem here is using a modified sine wave to run a (laptop) transformer, quality of the 240v affects things like transformers ,unlike light bulbs and tv's that can cope and work with a certain voltage variation transformers can't
 
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