efficiency of laptop 12v power supply?

[Wits' End]

I want to power my laptop from 12v (cigarette plug). Not in a car but run off a simple (cheap) solar/battery "system". So efficiency is very important. I wonder if anyone knows, are the auto/air adapters sold for this purpose more efficient than using an inexpensive inverter (not Trace /ubbthreads/images/graemlins/icon23.gif ) and the existing ac power supply.
I have a Dell Inspiron 7500 and I believe the DC input is 15-18 volts. I know it is more than 12V and less than 24V.
TIA

 

[James S]

Yes, almost certainly it will be much better to use an inverter that only ups the voltage to the 17v or so that the output is rather than going from 12 to 120 and then back down to 17 again.

Plus, it will be better for your power supply. The output from the cheap inverts isn't really a good sine wave and may cause your 120v power supply to overheat. Some of these inverters are "electronics" rated and some are not.

You'll definitely want to go the route of the car/plane adaptor rather than the inverter to 120v and then the powersupply.

 

[Wits' End]

Thanks James!! That's sort of what I figured /ubbthreads/images/graemlins/mecry.gif but more $$
Could someone move this to Electronics forum. I will have more sympathy for those 'people' that post something to the wrong forum. I did this quick at the Library and when I came back to see if there were responses it wasn't there /ubbthreads/images/graemlins/ohgeez.gif . I don't know how it got here /ubbthreads/images/graemlins/blush.gif .

Isn't it amazing how computers make all these errors especialy when you are in a hurry :tongue-in-cheek: