USB charging from molex

[m4n14c]

Hi guys,

Can I connect the power of a Molex connector to a USB port and use that for (fast) charging?
I found this

Do you have any idea about this?

[Levent]

that is wired for 5v (hence no "quickcharge" and wire used seems to be shitty one so I wouldnt expect decent amperage through that cable), I wouldnt waste a single cent on that cable.

[mariushm]

Yes, the molex connector has 5v and 12v  - if you connect the 5v and ground wires from the molex connector to the usb  voltage and ground wires, then you have a usb port with power in it.

Your device may charge or not, or may charge at very low rate ... most devices search for some signal on the data wires in the usb port and your data wires would not be connected to anything.

 

The most basic way to indicate this is a charging port would be to connect a simple resistor (less than 200 ohm) between the data pins of the usb port.

 

 

A more complex signaling would be like this :

 

[m4n14c]

12 minutes ago, Levent said:

that is wired for 5v (hence no "quickcharge" and wire used seems to be shitty one so I wouldnt expect decent amperage through that cable), I wouldnt waste a single cent on that cable.

I don't intend to buy that, as you said it's bad. It's the same idea. USB 3 transfers up to 0.8A, Molex can do more, the idea is to use the 5V from Molex for that with good cable. The phones have communication with chargers to be able for fast charging, I think I need something in between the power source and the phone.

[mariushm]

Phones that support QuickCharge and all that often negociate with a chip inside the charger and switch from 5v to using 9v or even 12v in order to transfer more power from the charger to the phone.

The amount of current that goes through the wire is what causes voltage drop on the cable and power losses (and cable heating up) - if you raise the voltage you can lower the current and send the same amount of power with less losses

With just the power from the molex connector, you're limited to at most around 2.5A but you really shouldn't go over around 1.5-2A - it's not the molex connector which is rated for up to around 6A, it's the usb connector which isn't rated for more than around 1.5-2A. 

Wires also affect things but if your cable is short, they don't affect that much.  AWG18 is good for 10A+ , AWG20 is good for 8A+ , AWG24 (the wires inside ethernet cable) are good for around 3-4A

[m4n14c]

9 minutes ago, mariushm said:

Yes, the molex connector has 5v and 12v  - if you connect the 5v and ground wires from the molex connector to the usb  voltage and ground wires, then you have a usb port with power in it.

Your device may charge or not, or may charge at very low rate ... most devices search for some signal on the data wires in the usb port and your data wires would not be connected to anything.

 

The most basic way to indicate this is a charging port would be to connect a simple resistor (less than 200 ohm) between the data pins of the usb port.

 

A more complex signaling would be like this :

 

9

Thanks, that is my concern.

So I connect the USB power to 5V from Molex and the Data together with a resistor between?

[mariushm]

3 minutes ago, m4n14c said:

Thanks, that is my concern.

So I connect the USB power to 5V from Molex and the Data together with a resistor between?

That would be the simplest standard for chargers. 

It's up to the device if it understands the standard or not - worst case scenario your device will charge at 0.1 or 0.5A (the smallest charge speeds) but wouldn't damage your devices. It's very safe.

 

[m4n14c]

Thank you all for the information, I will try it at some time, I need to find the materials first.

[m4n14c]

11 minutes ago, mariushm said:

That would be the simplest standard for chargers. 

It's up to the device if it understands the standard or not - worst case scenario your device will charge at 0.1 or 0.5A (the smallest charge speeds) but wouldn't damage your devices. It's very safe.

 

I understand that, I will start with the basic first to see. And I will search more, in general, for USB chargers.