inverters
Submitted: Friday, Jan 07, 2011 at 17:03
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margs tribe
Gday everyone just chasing some advice on
inverters. I am heading over east shortlly and would like to use my laptop on the way across .I was wondering if i can use the 150 watt can type inveter that plugs into the cig lighter without harming my laptop cheers
Reply By: KenInPerth - Saturday, Jan 08, 2011 at 01:41
Saturday, Jan 08, 2011 at 01:41
Just to add my bit, I would suggest most newer laptops require far more than 150 Watt to run them - 150 Watt is only about 0.65Amp at 240 Volt and most laptop power supplies I see these days require more like 1.5 Amp (around 350 Watt) or more.
Pure Sine Wave units are good advice for reduced risk to equipment.
If you look at your power supply for the latptop it will have an input voltage and current rating - I think
mine is 240V and 1.5A - multiply that together and you get the required output power of the inverter (my case 360VA). While this is far from accurate and this may be a maximum rating, it will give a reasonable idea of what is probably required as inverter output to not have any problems.
You will also have to be aware if using larger
inverters that you are powering it from something capable of supplying the current required by that inverter from your 12Volt supply - eg. it may not run off your cigar lighter - you may need a direct connection to your batery or fuse box.
Hope that helps. It is not very scientific but it is one of those cases where you probably need to try it before you buy it if possible. If not play safe and go a bit bigger.
Ken
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Follow Up By: Member - John and Val - Saturday, Jan 08, 2011 at 10:42
Saturday, Jan 08, 2011 at 10:42
Ken,
Not quite correct. A laptop power supply will typically be rated 110-250V, 1.5A input, and 19V, 3.5A output. The first though are peak figures - 250x1.5=375W peak input during the starting surge, while 19x3.5=66W output, being the maximum that the thing can deliver. In fact a typical laptop draws around 2A (a bit more for big fast ones) from a 12V battery, say 30W tops.
As Val and others have said, a 12V power supply is the way to go, unless you have some other use for the inverter. Much cheaper and more efficient. The offers from ABR are hard to go past. ABR has an excellent reputation for quality and support.
Cheers
John | J and V
"Not everything that can be counted counts, and not everything that counts can be counted."
- Albert Einstein
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Follow Up By: KenInPerth - Saturday, Jan 08, 2011 at 11:09
Saturday, Jan 08, 2011 at 11:09
John
I agree that a 12 Volt DC-DC unit is the best option - no issues with AC quality and easier to match to the laptop requirements purely based on the Output rating of the laptop power supply.
But they do need to make sure they match the notebook voltage for reliability of operation - in general these days 15V and 19V seem to be most common with the odd weird voltage now and then, and the odd one also that has a dual voltage power supply. As far as we go we generally will not supply anything other than the laptop manufacturers own 12V car adaptors as the laptops are usually under warranty, and not using the manufacturers own will be the first thing they blame if something bad happens under warranty.
You have obviously done some measurements which is far better than theory and I don't disagree with you - but I did not want to get into a confusing discussion of efficiencies and peak requirements. Using the output voltage of the laptop supply does not take into account the efficiency of the supply, and to put a voltage range with only one current rating is not accurate as on 110V it will draw more current than at 240 Volt (for the same output) - so we have to assume the 1.5A is 240 Volt peak current - lots of assumptions to make hence I said it was "far from accurate".
My guess (again without doing any tests) is that the 150Watt inverter may shut down on initial start up surge and that is going to be hopeless for them - hence I was suggesting working on the maximum rating of the power supply for safety margins. Thinking afterwards I may not have had the 500 Watt inverter I was playing with on a high enough current 12V source and it may have been the 12Volt supply shutting down and not the inverter. If only I had more time to play .......
Ken
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Follow Up By: Member - Graham H (QLD) - Saturday, Jan 08, 2011 at 12:12
Saturday, Jan 08, 2011 at 12:12
A 12-19v DC converter if you buy the 6000ma one will run almost any laptop.
Have run my Netbook, Compaq 14in and an Asus 15in no trouble at all.
They wont run on a 3500ma one.
Projecta make both and can be bought at Battery World shops or Big W.
Just make sure you get the one that says on the back Output 6000ma
The model number is DC 6000
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