What USB adaptor is suitable for a smartwatch?

[Shervan360]

Hello,

I bought a smartwatch and it does not have a charger. The capacity battery is 230mAh. In the manual, they wrote input parameter should be 5V = 500mA.
If I choose a charger with high output power (15W (5V/3A), (5V/2.4A), 20W, or 65W), will the watch's battery be damaged?
Does the charger with fast charging technology and Power Delivery damage the smartwatch?
Please see the attached image. (The first image is from the smartwatch manual and the last three are Kingstar USB adaptors)
I don't know what USB charger/adaptor to buy.
Thanks in advance

 

[Tom.G]

As long as the adapter is puts out the normal 5 Volts DC (which USB chargers do), you will be fine -- the watch will draw whatever current it needs up to the limit of the adapter.

Look at it this way: take a look in the fuse box or breaker box where you live. You will find most of the fuses or breakers rated at 15 or 20 Amps. That is the maximum current they will allow before they break the circuit. If you have only a single 60 Watt light bulb turned on, the bulb will only draw the current it needs for 60 Watts.

The current rating on the adapters is the maximum current they CAN supply while keeping their output at 5 Volts -- just like the fuses or circuit breakers, the current rating of a Supply is the maximum available.

For Loads, like your watch or a light bulb, the current rating is the maximum it will ever Need to operate correctly.

The hard part may be finding a cable with a connector to fit the watch!Cheers,
Tom

 

[Borek]

I suppose you can be talking about USB chargers, not any chargers - and as far as I understand these have their own way of doing things.

They are "intelligent" - that is, they start by "talking" to the connected device, asking for the capabilities. If they can't get confirmation "hit me with the high current", they will somehow limit delivered current to just 500 mA, which is a standard USB specification. All higher currents are extensions to the standard, and won't be produced unless specifically allowed by the charged/powered device.

 

[sophiecentaur]

They are "intelligent" - that is, they start by "talking" to the connected device, asking for the capabilities.

You are right, there. I just bought an Apple Watch which has a magnetic charger that holds the watch whilst charging and they say it needs a 40W charger. Then, I notice that most / all new laptops seems to use a USBC socket but specify high charger requirements. That stuff is very clever.
In the distant past, I remember suspecting that hp equipment would communicate with each other because they all seemed to agree with each other to within one sig fig. (This was pre-bluetooth etc)