On Wed, 27 Jan 2016 18:17:46 -0800, in message 20160127181746.4a63daa8@Devil-Bonobo, John Jason Jordan wrote:
> On Wed, 27 Jan 2016 17:17:20 -0800 > Dick Steffens <[email protected]> dijo: > > >On 01/27/2016 05:08 PM, wes wrote: > >> the center pin is a "data" line, the computer uses it to identify > >> the power adapter powering it. the computer may refuse to do things > >> like run at full speed, or charge the battery, if it cannot verify > >> that the power adapter is capable of handling that load. > >> > >> I think it's some sort of fire prevention scheme? > > >Interesting. Overload protection sounds logical. > > The power brick for my System76 laptop has four contacts. I have been > told that the extra contacts are to communicate the charge level of > the battery to the brick, lest it overcharge the battery. I'm not > sure I buy that, but then, I'm not terribly clever with electrical > circuits. Laptop batteries have small microcircuits in them that detect and communicate to the laptop the charge state of the battery. In doing so, they prevent the laptop from over-charging the batteries. The better batteries can also detect if one or more of the internal cells is going bad. The extra contacts in the power brick connector are indeed a data connection, which the laptop uses to tell the brick to reduce the charge current. At least, that's what my memory tells me. It could be worng. --Dale -- "Text processing has made it possible to right-justify any idea, even one which cannot be justified on any other grounds." -- J. Finnegan, USC.
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