Be careful which USB charger you buy and use

[OneMoreFarang]

I needed a new USB charger for a trip so I thought I just buy one in 7/11.

I saw one which advertised 3.4A so I thought fine, I will buy that one for 300B.

 

 

And when I returned home I had the idea to test the current and I connected the charger via a USB Voltmeter which I bought some time ago.

This is a product photo from the Voltmeter (not the values which I saw today)

 

 

The voltmeter showed 1A and 9V, not 5V which I expected. 9V will most likely destroy lots of devices which expect 5V USB voltage.

So then I had a closer look at the box and it includes a USB-C cable and on the adapter is written that it supports 5V, 9V and 12V. That is obviously nice for people who want that but I am pretty sure lots of people will get more Volts then they were expecting...

 

So I suggest better look twice what you buy - especially if you don't have one of those wonderful USB Voltmeters at home.

[jackdd]

It sets the voltage according to the device, if you connect a device to it which only supports 5v it will most likely output 5v and not kill the device.

Did you connect your phone on the other end of your voltage measuring device? If not the data connections are probably not connected at all and it outputs "something" (which seems to be 9v in this case). In case you had your phone connected, then this is the voltage which the phone requested.

 

Edited February 14, 2020 by jackdd

[SkyNets]

Fast charger voltage bumps to 9v.

[OneMoreFarang]

5 minutes ago, jackdd said:

It sets the voltage according to the device, if you connect a device to it which only supports 5v it will most likely output 5v and not kill the device.

Did you connect your phone on the other end of your voltage measuring device? If not the data connections are probably not connected at all and it outputs "something" (which seems to be 9v in this case)

I connected it to my phone. And it showed 1A like I wrote above. That wouldn't show if no load is connected. Believe me I know which cable should be connected in which way. ????

 

But I connected it to my phone with a standard Micro-USB cable because that is what my phone needs.

In the box of the USB charger was a cable with USB-C plug. I ignored that first because I had the cable which I needed.

Likely the adapter will work correct if the cable with USB-C plug is used with a device with USB-C connector.

But the adapter has a standard (blue) USB connecter like many other adapters. So any standard USB cable fits in that adapter.

 

I admit that if I would have been very careful then I could have discovered all these things before I plugged it in.

But to be fair how many of us look at the little lable of a USB charger with standard USB connector before we connect anything?

That's the reason I post this information here. So that others learn from my mistake and don't to that mistake as well.

[OneMoreFarang]

8 minutes ago, SkyNets said:

Fast charger voltage bumps to 9v.

No!

A 5V device is charged with 5V, not with 9V.

 

[jackdd]

2 minutes ago, OneMoreFarang said:

I connected it to my phone. And it showed 1A like I wrote above. That wouldn't show if no load is connected. Believe me I know which cable should be connected in which way.

Which phone are you using? Most likely it supports quickcharge and tells the charger to deliver 9v.

[OneMoreFarang]

7 minutes ago, jackdd said:

Which phone are you using? Most likely it supports quickcharge and tells the charger to deliver 9v.

You might be right.

Until now I thought the different USB voltages were introduced with USB-C.

And I thought a Micro USB connector would always expect 5V. But maybe I am wrong and not up to date.

My phone is from Xiaomi MI. I will check the technical details tomorrow.

[OneMoreFarang]

12 minutes ago, OneMoreFarang said:

22 minutes ago, SkyNets said:

Fast charger voltage bumps to 9v.

No!

A 5V device is charged with 5V, not with 9V.

@SkyNets it seems maybe you are right. Until now I thought that is only a USB-C technology which changes the voltage. 

Please forgive me my fast "No!" reply.

[OneMoreFarang]

16 minutes ago, jackdd said:

Which phone are you using? Most likely it supports quickcharge and tells the charger to deliver 9v.

Ok, I am convinced. Thanks for bringing me up to date.

 

[observer90210]

Not to enter into the voltage issue as I am no specialist, as a rule of the thumb better to spend the extra bucks and stick to the overrated cheating prices of the original chargers. Besides the voltage issue, the short circuit and fire hazard risk is better to avoid.

[OneMoreFarang]

11 hours ago, observer90210 said:

Not to enter into the voltage issue as I am no specialist, as a rule of the thumb better to spend the extra bucks and stick to the overrated cheating prices of the original chargers. Besides the voltage issue, the short circuit and fire hazard risk is better to avoid.

In principle I agree with you.

In my case I think I did what I would describe as a step in between. I did not buy one of those chargers for 100B, without any name, in one of the mobile phone shops even when I walked by one of those shops on the same day.

I bought one in 7/11 with a box and a name because I guess that they are likely not the worst of all at least with some kind of quality control.