benoit_f wrote: ↑Wed Jan 01, 2020 5:24 pm
I finally replaced my USB charger by the official PSU, and I do confirm it solved my issue. Thanks.
I am just a little disappointed RPi cannot be used any more with any USB charger as it was possible with RPi 1 or 2.
Then why aren't you still using a RPi1 or 2?
I'm going to guess you want the additional performance and features of the 3B+ model, and that requires more power. The Raspberry Pi 3B+ is more than 10X faster than the old Pi1. It also has built-in Bluetooth and dual-band WiFi. All of that requires more power.
Your assumption that "RPi were to be used with any phone charger" has not been true for any Pi after the original A(+) and B(+) models (except for the Pi Zero, which has the same single-core SoC as the original models). Even with the Pi 2B it was recommended to use the official power supply (the fact they you got away with using a phone charger was just luck).
benoit_f wrote: ↑Sat Nov 02, 2019 10:18 pm
Can you please explain (or give me a link explaining) the differences between a charger and a power supply?
Phones do not require precise voltage control for charging (most only need a little over 4.2V to charge). Because of that, many phone chargers do not have good voltage regulation and will allow voltage to sag under load. I used to have a "5V/2.4A" charger that dropped well below 5V at only a 1A load. It charged my phone and tablet fine, but it was a lousy Pi PSU.
In addition to that, many phone chargers use a separate micro USB cable to supply power to the device, and standard micro USB 2.0 cables are not designed to deliver much more than 500mA without voltage loss. So you not only need a charger with good voltage regulation, you need a USB cable designed for higher current charging (charge cables included with high-end smart phones are often rated for 2.4A).
So are all phone chargers crap? No, some have very good regulation, and with a good micro-USB cable they work fine. The problem is, you'll never know for sure unless you can properly load-test the charger and cable, and most people don't own adjustable constant current load testers. The charger might seem to work fine, and you may be able to run your system trouble free for a long time, only to have problems later when you subject the system to higher loads than before (run more demanding software, plug in a power hungry USB device or HAT, etc.).
This is why phone chargers are not recommended as power supplies for any of the multi-core models of Raspberry Pi computers. Some may work fine, some may not, and others are just trouble waiting for the right conditions to fail. The official power supply is a proven performer that works, and is usually pretty inexpensive (depending on where you live and who you buy it from).
There are other power supplies that may work, but many so-called "power supplies" marketed for the Raspberry Pi are just re-labelled phone chargers, so again, the recommendation is to buy the official one.
The older official power supply released around the time of the Pi 2B was 5.1V/2A. The newer one for the Pi 3B and 3B+ models is 5.1V/2.5A, and the very latest one for the 4B is 3A, but that has a USB-C connector that will not fit the older models (adapters are available). I've had very good results from the RPF Universal Power supply (picture below is link), but there's also a country specific (fixed plug) model that costs less.
Of course, I made sure to use some branded stuff.