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I have a monitor and a laptop and their chargers together are 91W. Both of them are 19V. So I was wondering whether I could just use a 90W charger and a cheap one male to two female 5.5x2.1mm splitter and adequate plug converters. Is there any danger to either the laptop or the monitor? I am not sure whether a laptop charger needs to be anything special or it just needs to supply the right voltage and amperage.

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  • "...their chargers together are 91W..." you mean, the sum of the wattages of the two adapters is 91W?
    – uint128_t
    Apr 10, 2016 at 0:17
  • Why was this moved? This seems out of place.
    – Ramhound
    Apr 10, 2016 at 0:30
  • @uint128_t yes.
    – chx
    Apr 10, 2016 at 1:04

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The brick which are calling a "charger" is not actually a charger. It's an AC to DC converter. Monitor and the laptop each have their own built-in charge controllers (and do those special things that keep Lithium batteries out of trouble).

This AC to DC converter's purpose is to supply the right voltage and sufficient current (or power, since P=IV).

If you execute this correctly, there is likely no danger to the monitor or the laptop. Be aware, however, that AC to DC converters should (and usually do) have over-current protection. So, if your equipment pulls more current from the AC to DC converter than it can supply, then the converter may shut off.

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  • Also unlike voltage where the number needs to remain constant (19v), in the case of wattages they must be added together. Thus if both devices say 90w that means 180w combined.
    – Tyson
    Apr 10, 2016 at 0:23
  • The monitor claims 26W (and 35W when an MHL device is connected but I won't do that) and the laptop has a 65W charger. As for the answer: thanks! That's exactly what I was unsure about -- is the AC adapter completely dumb or not. I knew most of the smarts were in the laptop but whether all of it or not, I didn't.
    – chx
    Apr 10, 2016 at 1:02
  • @chx The output is fairly dumb/unassuming: constant voltage, current and power up to the rated value. (As an aside, you'd be surprised by the [relative] complexity of modern AC to DC converters that you find around consumer gadgetry. A lot of effort goes into making them as lightweight, cheap, and efficient as they presently are.) Apr 10, 2016 at 1:14
  • I'd note though, 'smart' chargers exist, that do some sort of negotiation - dell's notorious for this, and sometimes a first party, shipped with the device charger may not be detected as such too.
    – Journeyman Geek
    Apr 10, 2016 at 3:09

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