Wiring a power adapter question

[Djard]

I have a 90w power adapter from an older notebook that will work with my HP DV5-1015nr. I transport my notebook between home and office. I'd like to utilize the older power brick, so that I won't need to transport a power brick back and forth. The tips on both adapters, of course, are of a different diameter. So I bought a plug for the older adapter.

My multi-tester identifies that the tip is hot for both adapters. The older power brick has two wires: core wire to center pin (19VDC +) and shield wire to outer cylindrical part of plug (0 VDC -). The newer power adapter has three wires: shield wire connected to the core tip (delivering 19 VDC +), white connected to inner part of cylindrical plug (also 19VDC +), and black wire connected to outer part of cylindrical plug that must be the ground (0 VDC).

Logically the hot shield and white wires on the new plug need to be connected to the hot wire on the older adapter. I just need someone who is 100% certain to confirm this, so I can feel comfortable proceeding.

 

[PreferLinux]

I'd probably say that the hot shield would be left disconnected. But maybe not.

 

[C1]

Look at these:
http://www.tomshardware.com/forum/9519-2-dell-laptop-power-jack-pinout

http://www.laptop-junction.com/toast/content/dell-ac-power-adapter-not-recognized

Sometimes a second voltage is used to authenticate an OEM power adapter, but usually it is a different voltage.

 

[Modelworks]

The difference is the new supply is a smart adapter. They use the white wire you mentioned to measure the voltage drop between the +19VDC power provided and then feed that back to the adapter. The reason they do this is because they often reuse the same jack on other devices like docks. A 65W adapter might power the laptop but the dock may need 110W. If a user plugs the 65W adapter into the dock the power adapter will notice that the voltage drops too far using that white wire, it then will disable the power output to keep the user from burning out the adapter.

It has +19vdc on it because that is a reference voltage, but it cannot supply power on that wire above a few microamps. You don't need to connect the white wire, that is for the adapters use. HP adapters generally don't use authentication like dell. They just shut off the power from the adapter if the voltage drops too far below 19VDC signifying the adapter is overloaded.

 

[OS]

check the current rating on both also before even thinking about this anymore

 

[Djard]

Thanks for the info.

After visiting the suggested links, I am persuaded that Modelworks' explanation qualifies him as a superior technician: he is refreshingly clear. I feel confident now to proceed and skip the white wire.

I never did install the battery, keeping it in a cool, dry place. If I need to charge it up for a trip of some kind, I'll use the original power adapter. This way I should be able to avoid the battery life being reduced to < 20 min./charge after a couple of years.

PreferLinux, I noticed your references. Since Ro.16:16 is in the imperative mode (a command), do we sin by not kissing one another? You might find interesting the a fortiori argument against the Big Bang Theory at Dr.T's site: http://www.mednetconnection.com/18051/18201.html

 

[PreferLinux]

PreferLinux, I noticed your references. Since Ro.16:16 is in the imperative mode (a command), do we sin by not kissing one another? You might find interesting the a fortiori argument against the Big Bang Theory at Dr.T's site: http://www.mednetconnection.com/18051/18201.html

I think that was probably a "command" by Paul to those he was writing to (it was part of his farewell), but I definitely think we don't sin by not doing it. But I haven't studied it or anything!

That link was interesting, thanks.