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What does it mean when my acer chromebook 11 charger says "5v ⎓ 3a / 9v ⎓ 3a / 15v ⎓ 3a / 20v ⎓ 2.25a" on the ac adapter? I want it to output 5 volts with 3 amps, but I am confused at why it also has the other options afterward. I am thinking about using this for my Raspberry pi 4b. Will this sub for the offical power supply?

Thanks in advance!

EDIT: Here is the image of the ac adapter: enter image description here

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3 amps at 5 volts should be enough to power any Pi.

Whether your charger can produce this or not is impossible to answer without the actual charger or clear photos.

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  • I have added a clear image of the ac adapter. – answerplease May 19 at 22:07
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It seems this is an auto-charger. You should not use this types of chargers to work with Pi. If accidentally the the voltage rise your Pi would fry.Use a 5V 2.5A adapter if you can manage.

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This means, that the charger can work in any of this options. The default option is usually one with the least power (3V/3A in your case). Then the charger is connected to the device, they can communicate by data wires and, if necessary, increase the power (obviously, by request from the device).

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  • So, does that mean that using the charger should work fine? – answerplease May 19 at 22:20
  • Yes, that should work fine. – totikom May 20 at 0:34
  • However, "there is a strong belief, that standards are something that people obey". If vendor of your charger for any reason made another default, it can be harmful. If you have free USB-C female connector, you can measure the supplied voltage directly. Moreover, you can check rpi's docs for power schematics and read datasheets of its ICs (for max input voltage). – totikom May 20 at 0:42
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The higher voltages on your power supply should only be activated after USB-PD negotiation has taken place. USB-PD stands for USB Power Delivery which is the official standard for the negotiation of power delivery over USB. The Raspberry Pi 4 does not support USB-PD and therefore will not negotiate to a higher voltage. I can't guarantee anything, because I couldn't find if the power supply supports USB-PD.

If it follows standards, it should not go over 5V and work just fine for your Raspberry Pi.

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