using alternate power source for my laptop.

Our laptop has two favorite locations. The problem is that it’s sort of a pain in the ass to unplug/plug it everytime we want to use it.

I have two power sources, one is from an old HP printer that we don’t use anymore, and one came with the laptop itself. They have the same plug style (on the end that goes to the laptop), but obviously, I don’t just want to plug a different power supply into the laptop.

They both have the same input rating, but one of them says “output 18v” and one says “18.5v”.

It would be nice to be able to just keep the power supplies plugged in, and swap the laptop back and forth.

Is the DEFINITELY a no-no? Definitely OK? Or somewhere in between?

Is there any other info you might need from the power supply to indicate whether it’s OK?

The Laptop power supply will be a switched mode power supply - the printer one probably won’t be. Don’t try it.

Buy a 3rd party laptop power adapter - you should be able to set the correct voltage and it will be switched mode.


If there is a docking station available for the laptop, that might include a PS, and be convienient if one of the locations also has a printer etc.

Beyond the output voltage, you also need to consider the current ratings. The printer PS is probably rated at an amp or two, while the laptop supply is probably at least 5 amps, and probably more than that.

Whether it’s a switching supply, or a transformer-based supply should make no difference. 18 volts is 18 volts.

You do need to be sure that it’s AC or DC, and the right polarity (for DC) on the plug.

The .5 volt difference shouldn’t be an issue, but you need to check the current ratings. If the laptop power supply puts out 18 volts at 4 amps, and the printer supply puts out 18.5 volts at 1 amp, it won’t work for long before the printer supply overloads and fails. If the printer supply puts out 6 amps, no problem. It’s just unused capacity.

But first, have a quick look online to see what a proper spare/replacement power adapter for the laptop would cost.

Considering it’s likely a lithium battery in the computer, you should be aware that you could start a fire without the approved power source, and you’ll likely void your warantee on the computer. You should purchase an approve power supply for the computer.


I’ll look into picking up another power supply instead of just plugging in

You might want to look into a universal power supply like the iGo. I got the 130 off ebay for about half the list price. Not only will it power other future laptops (and many other devices), you can use car lighters and even the funky EMPower ports that some planes have as power sources.

You might get a methane burning generator and surf at Taco Bell;)