Power supply for raspberry pi 3

[ricardoseriani]

Hi

Please, can anyone tell me if this power supply will work with raspberry pi 3 ?

Power Supply

IMG_20180505_174425.jpg (231.54 KiB) Viewed 1810 times

I'm in doubt because of the out line that says:"5V .2.5A/9V 2A/12V 1.5A", so I don't know which they will supply.

Thanks in advance.

Best Regards.

[wh7qq]

Are there 3 separate outputs or a switch? If so, you have to check them with a voltmeter to determine which is the 5V output if they aren't marked. It probably does not have a micro-usb output so you would have to adapt. There is very little difference in cost between the adapter and a new power supply so I would go for the new supply specified to work with the RPi...that way, you have no confusion and no chance of a fried RPi from using either of the wrong outputs. If it has a switch, the danger of accidentally selecting a higher voltage than 5V is instant death for the RPi and possibly whatever you have connected to it.

[wh7qq]

Duplicate deleted.

[allfox]

The Chinese on it says it's a phone charger.

So, while it might be working, I suggest you get a real power supply unit.

I don't know the output either. Maybe you need post another photo about the backside.

The brand says XIAOMI, it's a little strange, as the 小米 I know would brand as MI, not XIAOMI: http://www.mi.com/en/

I still suggest get an official power supply unit.

[ricardoseriani]

Indeed, this "power supply" is a phone charger for a Xiaomi Phone.
This charger has no switch, which is exactly why I'm so confused about this.
There is any power supply that your suggest ? ( I live em Brazil, so maybe it's a little harder to get one "official" (unfortunately, the taxes in Brazil is a bit high).

Thanks

[bertlea]

I am interested to know that too. This Xiomi phone charger is based on Qualcomm Quick Charge (version 2 or 3). That means the phone shall able to communicate to the charger using the USB data lines to set the voltage and amps the phone wanted. As Raspberry Pi do not support that, I am not sure if that implies the charger will just offer the 5v 3A by default. If that is the case, then it is a good news that we shall able to use these “smart charger” for our Pi in the future. However, I got a description on-line that seems to indicate the default will limit the amps to 2 amps only.

“Qualcomm’s Quick Charge 1.0 and 2.0 technologies are also backwards compatible with one another, meaning that you can use a 2.0 devices with a 1.0 supply, or a 1.0 device and 2.0 supply and get your 2 Amps. However, only a 2.0 device and compatible 2.0 charger will allow for 3 amps of current and higher power ratings.”

I really hope someone with Qualcomm Quick Charge charger can actually test that or confirm that if they know it for sure.

[HawaiianPi]

The charger supports Qualcomm Quick Charge protocol.
https://www.qualcomm.com/solutions/mobi ... ick-charge

In simple terms, the device can negotiate with the charger to supply higher voltage (9 or 12V) for faster charging. At 5V it supplies up to 12.5W, while at 9 or 12 volts it supplies up to 18W. Samsung Adaptive Fast Charge is basically the same thing.

It is a 2 way handshake that fails to normal 5V charging, so as far as voltage is concerned, it's safe to us on a Pi computer (the Pi can't negotiate for higher voltage, so it will only get 5V). HOWEVER, phone charging does not require very precise voltage regulation, and as a result, some phone chargers will not maintain a stable 5V under load. I have tested "5V 2.4A" chargers that dipped well below 5V at only a 1A load.

So in theory that charger *should* work, but reality may offer a different experience. The only way to know is to give it a try. Fire up your Pi, plug in some USB peripherals, and run a CPU benchmark or load/stability test to push the system hard, then see if you get a low voltage warning.

Oh, and make sure you are using a good micro USB cable with fat power wires, because all the power in the world won't help if you are using a standard USB 2.0 cable with 28 (or thinner) gauge wires.

[ricardoseriani]

I know that this forum is english, but anyone can tell me if this https://produto.mercadolivre.com.br/MLB ... 1a-usb-_JM is a good power supply for Raspberry Pi 3 ?

[davidcoton]

I know that this forum is english, but anyone can tell me if this https://produto.mercadolivre.com.br/MLB ... 1a-usb-_JM is a good power supply for Raspberry Pi 3 ?

It seems to have the same issues as the Xiaomi charger. You need a supply capable of between 5V and 5V25 at the Pi socket, while at the same time delivering at least 2A5. Whether any charger can do that is a lottery.

[ricardoseriani]

I know that this forum is english, but anyone can tell me if this https://produto.mercadolivre.com.br/MLB ... 1a-usb-_JM is a good power supply for Raspberry Pi 3 ?

It seems to have the same issues as the Xiaomi charger. You need a supply capable of between 5V and 5V25 at the Pi socket, while at the same time delivering at least 2A5. Whether any charger can do that is a lottery.

You mean the "5V .2.5A/9V 2A/12V 1.5A" ?
Because AFAIK, the announcement apparently says its "output 5.0V = 3.1 A".

[davidcoton]

I know that this forum is english, but anyone can tell me if this https://produto.mercadolivre.com.br/MLB ... 1a-usb-_JM is a good power supply for Raspberry Pi 3 ?

It seems to have the same issues as the Xiaomi charger. You need a supply capable of between 5V and 5V25 at the Pi socket, while at the same time delivering at least 2A5. Whether any charger can do that is a lottery.

You mean the "5V .2.5A/9V 2A/12V 1.5A" ?
Because AFAIK, the announcement apparently says its "output 5.0V = 3.1 A".

No, I mean the likely inability to maintain the correct voltage at the rated current.
Given that it is described as a "fast charger", it is also possible that the spec has forgotten to mention what other modes are available and how --eg, is the 3A1 available by default or by negotiation? (It is less likely that higher voltages are available, but that is not an issue since Pis do not negotiate with PSUs.)

[ricardoseriani]

It seems to have the same issues as the Xiaomi charger. You need a supply capable of between 5V and 5V25 at the Pi socket, while at the same time delivering at least 2A5. Whether any charger can do that is a lottery.

You mean the "5V .2.5A/9V 2A/12V 1.5A" ?
Because AFAIK, the announcement apparently says its "output 5.0V = 3.1 A".

No, I mean the likely inability to maintain the correct voltage at the rated current.
Given that it is described as a "fast charger", it is also possible that the spec has forgotten to mention what other modes are available and how --eg, is the 3A1 available by default or by negotiation? (It is less likely that higher voltages are available, but that is not an issue since Pis do not negotiate with PSUs.)

Ohh,I understood your doubt.
Thanks for pointing that.