Sign in with
Sign up | Sign in
Your question

Utility that returns psu laptop input voltage?

Last response: in Components
April 26, 2011 7:39:51 AM

Hello, my concern is that of incoming voltage. Primarily on a laptop system but i suppose aside from apc it would be cool for desktops too, but mostly laptops. I use an APC and its utility actually returns line voltage as a parameter. I also know of utilities that will return battery status and voltage. So as a tech it would be nice to know if there are problems with the laptop ac converter. I know, why not just switch out the power adapter to check, right? What if I don't have a spare to swap out? What if I'm just curious? I'd like to know load input voltage. I could just VOM the adapter tip but it just isn't representative of voltage under load. Anyone out there know of anything like this?
a b ) Power supply
a b D Laptop
April 26, 2011 1:27:13 PM

The problem is most laptops do not provide a "sample point" for the DC input (ie at the DC input jack). Requires an A->D converter which would return a Hexdecimal value for the analog voltage. The software would convert this Hexdecimal value to a voltage reading either thru a look up table, or an algorithm.
April 28, 2011 9:00:32 PM

I was afraid of that problem. I will probably have to build some sort of custom rig to do this... which honestly may be more $ and time than would be buying a universal with many tips for testing haha. Thanks though @RetiredChief.
a b ) Power supply
a b D Laptop
April 28, 2011 9:45:26 PM

Also not sure the info (Input voltage) would be without also knowing the current.
A typical AC adaptor (for Li-ion) is rated 19 @ 4 Amps. The output will vary some due to current and if you read say 17 v is that becaues the adaptor is not putting out, or is the current drain loading the Adaptor. Not sure Putting xxx is politically correct any more.