I checked some of the random old laptop chargers in my horde - it seems that the double barrel + third center pin is pretty common.
I hope it helps, -T On Sun, Aug 17, 2025, 17:10 Tomas Kuchta <tomas.kuchta.li...@gmail.com> wrote: > 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 <barnmich...@gmail.com> wrote: > >> On Sun, Aug 17, 2025 at 12:32 PM Denis Heidtmann < >> denis.heidtm...@gmail.com> >> wrote: >> >> > 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 >> > > >> > >> >> 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 >> >
