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
