Charging Voltages
 

Those little cubes we use to charge things have specs. Some say they are 5V. They all seem to say something different. I have imagined that I need to match the charging cube to the device being charged.

But yesterday I received a Bluetooth dongle that has a "0.5V" charging port. This dongle did not come with a charging cube. All of my charging cubes have WAY higher voltages than this. Hmmmm......

In news that may be related, the cube that came with my Mac lists four output voltages and amperages separated by the word "or". 20V/1.5A or 15V/2.0A or 9V/3.0A or 5V/3.0A.

Here is what I wonder: Do devices draw whatever their voltage and current needs are, regardless of what the cube is capable of providing. This would make sense for current, but I don't see how devices could change voltages. If I connect the 0.5V Bluetooth dongle to a 5.0V cube, will the 0.5V dongle be happy?

USB is 5v.

IMO 0.5v is a misprint.

If it has a USB shaped hole it's 5V.


The amperage rating on the charger determines how fast it will charge whatever you're putting on it.

If you take a teeny little 1A or whatever charger and try to charge your iPad it will work, but you're going to be waiting forever.

A bigger, 2.4A or 4A more robust charger will charge your stuff faster, and won't hurt anything. It is just capable of providing more.

Right you are! Al my USB cubes say 5V, except the Apple one, which has a USB-C port and four different voltages printed on it. The inescapable conclusion here is that I am overthinking again. ;)

Charging voltages are based on the cell chemistry and the number of cells put in series.
There are no cells that have a charging voltage of 0.5V, because it would make no sense to build such cell. Single lead acid cells charge at 2.3V, LiPO charges at 3.6V, Li/NCM is 4.2V…nothing charges at 0.5V because you would need 10 cells in series to build a 5V pack, and 24 to build a 12V pack.
Also the lower the voltage, the higher the current must be to reach a certain charging power, but high current causes heat loss, that is why higher voltage systems are always preferred.