can i use Mi 27W SonicCharge Adapter to power raspberry pi 4?

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  • oyubir
    Lv 6
    2 months ago

    It will probably work.

    But no better than any 5V 2A charger.

    It will work, because in practice (but not in theory) Rpi4 has enough with 2A.

    And because in practice (but not in theory) a charger provides a steady 5V power (even the Mi27W, which is able to provide way more than 5V in QC mode, but won't on a RPi).

    Now, it is not a good idea.

    Because

    1. It is a charger. A strangely popular one sure (there might be good reason. I just never took the time to understand why a charger is popular). But still a charger. And a charger job is to provide enough power to charge the battery. If it has a voltage drop (as long as it is over 4.2V), it is of no importance for a charger (battery still charges), as long as it maintains power (current increases slightly to compensate). And even if it drops under 4.2V, or if it has to decrease current for 1 second, no big deal. Whereas, of course, for a power supply, a 1 second fail is a big deal.

    Chargers are not designed to provide a steady, stable, voltage, under heavy current.

    And this is precisely what you really need for the RPi.

    2. Because RPi4 may need more than 2A. It won't under most normal usage. But, in theory, it may. If you use everything at once (all CPU cores, 4K output, wifi, etc.). Which the Mi27W won't provide

    3. Because you won't benefit the capabilities of Mi27W. If would be just like any other USB charger once plugged on the RPi4.

    Mi27W is able to provide 27W, because it uses Qualcomm QuickCharge capability. Which allows to charge over USB at a higher voltage than the traditionnal 5V of USB. Typically 9V, 3A for example (which is 9x3=27 W)

    But RPi4 don't use quickcharge.

    So, the Mi27W would do what it would do for any "slow charge" usb device. And behave as a normal 5V USB charger.

    So, if you really insist on the  not so good (but in practice not so bad) idea of using a USB charger for the RPi4, put your money in a good quality USB charger, rather that on the Mi27W (whose extra cost is on that QC thing that you won't use).

    The best option is to use the official PSU of the RPi4.

    It provides all needed power. It is stable. Etc.

    (This is not what I do, tho. I use old ATX powers supply, that I plug on the GPIO power input. But that is because I tend to overkill things, and because esthetics, noise and room is not a concern for me. Plus all my RPi are used in context where I also need 12V, which the ATX conveniently also provides)

    Shorter, maybe more pragmatical answer:

    If you have already a spare MI27W that you want to use with your RPi4, go ahead and try. You won't destroy your RPi. The worst that can happen is that you'll see that you have unwanted shutdown.

    If you plan to buy one for your RPI, don't.

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