Laptop power in van - Inverter or 12V?

[nesty]

I am taking my lappy away with me. I got a 2000W inverter that I have hard wired into my Trojan batterys. They should handle the load ok. Though I want to know how does an inverter work powerwise?

Does it just take a set energy of the inverter strength, or just the power that required? Or would it take less power to run the laptop via a 12V plug adaptor?

Nesty

[daschmoo]

I'd invest in the branded 12v adapter as using it through the inverter is just wasting energy as it's effectively converting the power twice as the normal power lead for your lappy will have a transformer on it. Lost energy in the form of heat through the inverter. Don't get a cheapy off eBay cos they aren't rated correctly and my old one used to blow fuses like it was going out of fashion!

[horns]

I'd say get the 12v adaptor too - I use one to power my laptop, have run it for hours without caning the battery. Much more efficient that going from 12v DC to 240V AC, just to transform it back down into a dirty DC supply...

[Mocki]

yes, a 12v step transformer is better than a invertor, as has been said the invertor will cain the battery, make more heat than power whilst you are converting the 12v up to 240 then back down to 18v.....just do the one conversion and be done with it.

also, never leave a invertor switchedon ( powered up) unattended unles you are very confident of the invertor and your installation, they cause many fires in campers, two of which i have witnessed, you dont want that happening.

[nesty]

The inverter is always switched off when not in use!

Also it's a last resort to powering the laptop. I am hoping to get hook up on my travels.

[Willoughby]

Inverters only draw the current the attached device needs +what it needs to run.

The the majority of cases the are around 90% efficent on full load.

I have a constant 1000W and it draws 0.8 Amp before anything is plugged it.

But have to side with those above, best to splash out on a decent 12V - Laptop transformer.

K

[nesty]

OK thanks for the replies. Where could I get one quickly. I set off on Monday. Do Maplins do a decent one?

[horns]

http://www.maplin.co.uk/Module.aspx?ModuleNo=44736" onclick="window.open(this.href);return false;

[nesty]

Cheers with these adaptors. You set the voltage. How you find this out? I have a Fujitsu Amilo.

[horns]

It'll be written on the AC adaptor.

[nesty]

cheers

[nesty]

OK my Fujitsu Siemens laptop transformer says on it 20V @ 4.5Amp. I take it that I require a 120W adaptor. I wouldn't get away with the 40W version?

As 20V x 4.5 amps = 90 watts?

Right?

[horns]

Yep. P=VI.

[nesty]

OK many thanks. I went for the 120W version in the end!

[albertramsbottom]

Inverters are 90 % ish efficent so wont waste that much energy and they only draw what is plugged in. Also whilst you are plugged in to an inverter it charges your laptop battery. So every hour you can turn of the inverter.

I have found that there is very little difference between 12v charger and inverter