Check the polarity and current rating. -Denis On Sun, Aug 17, 2025 at 12:27 PM Michael Barnes <barnmich...@gmail.com> wrote:
> Here's a confusing one. I have an HP laptop with the usual 45W 19V power > supply. I'm doing some work with an associate's Dell laptop, which also has > the typical line lump 45W 19V supply. I figured I'd just plug my HP supply > into the Dell as the connectors are the same (generic 2.5mm barrel). When I > powered up the Dell, I get a BIOS warning screen that says questionable > power supply and it would not charge the battery. > > I've checked both supplies with voltmeter and oscilloscope, nothing is > riding on the DC, both outputs are clean and identical. > > What does Dell do that it knows it is not a Dell supply and will not charge > the battery? I've seen this with USB-C and micro-USB connectors that have > ID pins incorporated, but that doesn't account for a straight 2-wire DC > barrel plug. > > Any one run into anything like this? > > Thanks, > Michael >
