Can Arduino Uno be powered from USB wall, car or portable battery chargers for smartphones?
To be more precise I am talking about chargers like these:
Wall and car phone chargers
Source: Robot or human?
Portable battery chargers
Source: The best power banks 2023: top portable chargers for devices | TechRadar
Check the data sheet for your particular board.
I know that certain MEGA's use center pin positive, up to 12VDC input safely.
I am powering a standalone 328 based board from a portable charger right now. The thing with the one that I am using is that it will turn itself off if the current is too low. I found that if I draw about 30 mA it will stay on. It doesn't need to be a constant draw. I have an LED on pin 8 that draws 15 mA that I flash on for 20 mS every 8 seconds. That combined with the 20mA that the board normally draws is enough to keep the supply turned on without wasting much power. I have also used the mains and car charger USB chargers to power other projects. I buy them from my local thrift shop for about a US dollar apiece.
YellowGTM:
Check the data sheet for your particular board.
I have an Arduino Uno R3.
groundfungus:
I am powering a standalone 328 based board from a portable charger right now. The thing with the one that I am using is that it will turn itself off if the current is too low. I found that if I draw about 30 mA it will stay on.
In this case the chargers I have mentioned are not so good for powering Arduino boards. I need something reliable that can power even a stand alone Atmega328p without further complications with additional loads dimentioned to keep the total current above 30 mA.
I am still experimenting with the battery pack (portable charger). I reduced the pulse width to 10mS and the charger is staying on. So I pull a total of 35 mA for 10mS every 8 seconds. The rest of the time the board pulls only its normal current. My charger is 8000mAh with a 1 A and a 2A output.
update: With the 10mS pulse every 8 seconds the charger turned off after a while. I changed back to a 20mS pulse and it has stayed on for over 45 minutes so far.
Those orange things in the first picture are NOT chargers.
They are 5volt power supplies.
They can e.g. power a phone, that has an inbuild charger, that charges the internal battery.
I suppose they can be connected, with the proper USB lead, to the USB connector of an Arduino.
Not to the DC-in jack. That needs 7.5-12volt to work.
AFAIK, battery powered 5volt supplies have a boost converter inside that switches off at a certain minimum load.
The boost converter is needed to convert the internal battery voltage (~3.5-4.2) to a constant 5volt.
Leo..
So, Portable battery chargers (second picture) have something inside that switches off the charger if the load draws less than a certain current Imin (for instance Imin = 30 mA).
Question: Do the 5 V power supplies (first picture) have the same limitation or I can power with them loads that need only: 1 mA, 200 microA, even 20 uA or less?
Those orange things in the first picture are NOT chargers.
They are 5volt power supplies. They can e.g. power a phone, that has an inbuild charger, that charges the internal battery.
Possible, but they are officially called "Chargers".
If they behave like an USB port (the difference being that some of them can deliver more current) than they should not stop working when the current necessary to the load drops below a certain value.
Delta_G:
You have to look at the particular charger you want to use.
I have seen that the max current delivered by those wall little cubic chargers (5V power supplies) varies and the higher it is the better.
simplex:
....they are officially called "Chargers".
Things are often called what they do, not what they are.
Those orange things are just supplies, and work from zero current draw.
They are high-tech switchmode, so I expect them to have a current limiter.
Most likely printed on the case.
Leo..