Dell barrel chargers have 3 pins actually: outer barrel, inner barrel and center pin.
HP and other chargers only have outer (just simple) barrel an center pin. The third pin on dell charger is id pin. Probe to see the charger id protocol. -Tomas On Sun, Aug 17, 2025, 15:50 Michael Barnes <[email protected]> wrote: > On Sun, Aug 17, 2025 at 12:32 PM Denis Heidtmann < > [email protected]> > wrote: > > > Check the polarity and current rating. > > -Denis > > > > On Sun, Aug 17, 2025 at 12:27 PM Michael Barnes <[email protected]> > > 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 > > > > > > > All ratings identical, voltage, current, polarity, etc. Found another > laptop supply, a generic no-name, same issue. All supplies work fine with > my HP, all but the Dell branded supply give an error trying to power the > Dell and do not charge the Dell battery. > > Michael >
