Powering a laptop in the car

Hi David,
My computer is a Toshiba 2410 and I power it from an inverter on my sailboat - no problems.
I tested it also on the troopie (stationary) and it operates fine. Its just a common 150W modified sine wave inverter (was $99.- on special at Altronics).
The current drain on the battery varies, up to 6A when the hard drive is doing something but mostly hovering around 4A.

As there is a double conversion of voltages, the computer sees only the voltage coming from its switch mode power pack, for which it is designed for.
The power pack gets the modified sine wave 240V AC from the inverter, it does not seem to mind about that and happily converts it to 15v DC for the laptop.
Any voltage spikes in the car wiring do not get past the double voltage conversion.
You might want to wire in a seperate lighter socket for the inverter, directly from the battery via its own fuse so you will not kill the computer if you switch off the engine at a petrol station. These thing are very finiky as to how they are shut down - pulling the power is not on the list :-)

I would not use my laptop to play DVD's while on the move, I have no idea how shock proof the DVD drives in a laptop are. This might be your biggest problem, it is noticable when one uses a cheaper CD player while driving on rough roads.
you also need some secure mounting (pref. cushioned) for the laptop, last thing you want is it taking off when you hit the brakes :-(

If you want to power electronic equipment designed for only 240V AC directly from an inverter you might have proplems with the modified sine wave ones, better using a true sine wave inverter in that case. Usually in a caravan application where mains powered computers/DVD's or TV's might get used.
Battery operated laptops (and other gizmo's) are in another league, as mentioned above.
Klaus

I use a product that I bought from Dick Smith called a Kerio Energy Knight, which hooks into the ciggie lighter and plugs into my Toshiba laptop. Certainly not as sophisticated as a sine wave inverter, but so far I have had no problems.
They are supplied with a range of plugs to suit varius laptops. The product has been designed to provide power for both "airplane and auto" applications. Might be worth considering.
JackNo trees were harmed in the making or sending of this message.
However a great number of electrons were terribly inconvenienced.

HN have been advertising portable DVD players for $499. Might be a cheaper option if thats all you need. The other cheaper option is to use a small desktop computer with a TFT monitor - run both off inverter (some monitors run on 12V).Bob

The "Kerio" converter (Dick Smith, Tandy) is the most efficient and safest as it is a pure Dc converter-ie: converts your battery 12-14 volts to about 19v dc.

However, the inverter option works (You are making 230v AC from 14v DC, then using your computer's power supply to convert 230v AC back to about 19v DC (depends on your make/model of laptop). Many computer power supplies run very hot using the modified sinewave inverters, and I have seen a few of these power supplies die as a result. Not efficient and not really very safe IMHO to have all these cords running around in your car with 230v ac- however it does work OK and many people do this successfully. The choice is yours, but if you go with the second option I'd be very carefull and make sure the power supply (and inverter) get plenty of cooling air. Accidently cover them with an item of clothing or something similar (say a rag?) and you'll fry them pretty quickly.
Hope this helps, cheers.

Moneypit, the Kerio is the preferred option but I didn't want to spend money on an inverter and the Kerio so I use the inverter with my Dell.

V8Troopie is right - a 6 hr battery is not enough to get through a DVD movie.

My kids use the lap-top when on the black-top or graded dirt roads, connected to the (modified sine wave) inverter and we haven't had any problems so far. I don't let them use it while in 4x4 country. Smile, you're on ExplorOz
Rohan (Sydney - on the QLD side of the Harbour Bridge)

We use a 300 Watt Pure Sine Wave inverter - costs a little more but is perfect for the laptop, camera charges (still and video), small blender - lights etc etc. I used to only use 12 V everthing and now I would not bother - just get the 240V inverter and you are away. I would suggest that you invest a few more $ in the Sine Wave model. Some computer will work fine on the modified wave however you may find the batteries will not charge at the same time, power supplies get hot etc. We use our laptop everytime we take the car out of the city (we are digitally recording every road we travel on). In the last few years of 240V operation we have had no problems at all.

Good luck.Regards
ExplorOz Team - David
--------------------------
Always working, not enough travelling ;-)

I spoke to an electrician the other day who said that a low watt inverter may cause problems with a laptop. Theoretically, a 150W inverter at 240V should only be able to deliver about 0.6A, while a laptop requires up to 3A especially if the battery is very low.

The solution - you can get a charger that plugs into the lighter, and has a range of voltage outputs and different plugs. I think someone mentioned this above. I run a Toshiba Satellite 4300 using one of these no problems. I also use it for my jumpstarter (which I use as a power source) as the 3pin socket transformer that came with this outputs at 15v.

I'd go with the laptop option rather than just a DVD as suggested above. We have lots of information downloaded onto ours, and it is just great for not having bits of paper everywhere.

Most Iverters will generate a square wave power signal that could (if used alot) damage your switch mode power pack for your laptop. Jaycar have a DC-DC adaptor for about $70-$80 that will handle 19vdc at 4amps (which is what most laptops are running) it is switchable to other settings, it has a simple cigarette lighter plug on it that you can use or just chop off and hardwire. Best way to go, much more effeciant than an inverter, cheaper and ultimatly more reliable.

Having run a Toshiba laptop for mapping purposes in a 4wd for over 6 years now the 12v laptop power supply is the way to go. We've tried both the power supply and 240v inverter and as was said earlier the power supply is the safer more efficient system also much kinder to the laptop power supply and it's batteries longterm.
The Kerio one mentioned and the Jaycar one are both good units, I think Toshiba actually sell their own badged version of a Kerio at a higher price.
Also no worries with 240v leads running around in the vehicle and kids standing on them etc.
If you decide to go with the 12v supply give every cigarette lighter plug the flick and use the Hella bayonet type, fag lighters are useless for long term use, they cause more probs than they are worth.
I've never had a problem with the bayonet type, they click in and out positively and make a good connection that can handle sustained high currents.
We've had both cheap and very expensive inverters die on us, usually after the warranty runs out, the heat and vibration and possibly voltage fluctuations eventually kill them.
Peter

Thanks for all the info. Time to ponder me thinks.

Dave