Question Converting PSU to a power hub

312e

Junior Member
Jun 12, 2022
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I am making a power hub out of an old ATX PSU. All wires will be stripped except Molex (and maybe SATA) connector wires. 12V will be connected to barrel jacks, PC fan sockets, and (maybe) lighter plug sockets (the plugs in a car). 5V will be connected to a dummy load, USB sockets (and maybe more barrel jacks). 3.3V will be connected to 2xAA battery eliminators. When I attempt to charge my phone off the connected USB ports, the USB to Lightning wire gets hot that the glue even melts (PSU wires normal temp). I have been powering 12V multimedia devices with the 12V barrel jacks, powered PC fans with the makeshift fan sockets, charged BT speakers and powered USB fans with 5V without problems. How to stop that?
 

TheELF

Diamond Member
Dec 22, 2012
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When I attempt to charge my phone off the connected USB ports, the USB to Lightning wire gets hot that the glue even melts (PSU wires normal temp).
That's probably due to fast charging where the phone tries to draw as much charge as it can but the PSU has more than the phone cable can handle.
Normally usb gets routet through voltage regulators and USB circuitry so that they can't get the full power of a PSU.
 
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VirtualLarry

No Lifer
Aug 25, 2001
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LOL. OP is so cheap he's going to burn his house down, rather than spend $10 on a USB charging hub for his devices. I guess some people are like that.
 

312e

Junior Member
Jun 12, 2022
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LOL. OP is so cheap he's going to burn his house down, rather than spend $10 on a USB charging hub for his devices. I guess some people are like that.
The power hub will power 12V multimedia devices and fans along with 5V barrel jack and USB devices.
 

VirtualLarry

No Lifer
Aug 25, 2001
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The power hub will power 12V multimedia devices and fans along with 5V barrel jack and USB devices.
And burn down your house after popping some cell phone Li-Ion batteries, and starting fires, due to not using a proper USB charge controller circuit.
 

TheELF

Diamond Member
Dec 22, 2012
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LOL. OP is so cheap he's going to burn his house down, rather than spend $10 on a USB charging hub for his devices. I guess some people are like that.
There are such things as hobbies, making a bench power supply out of an PSU is an extremely common thing, look it up on google.
 
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mindless1

Diamond Member
Aug 11, 2001
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I am making a power hub out of an old ATX PSU. All wires will be stripped except Molex (and maybe SATA) connector wires. 12V will be connected to barrel jacks, PC fan sockets, and (maybe) lighter plug sockets (the plugs in a car). 5V will be connected to a dummy load, USB sockets (and maybe more barrel jacks). 3.3V will be connected to 2xAA battery eliminators. When I attempt to charge my phone off the connected USB ports, the USB to Lightning wire gets hot that the glue even melts (PSU wires normal temp). I have been powering 12V multimedia devices with the 12V barrel jacks, powered PC fans with the makeshift fan sockets, charged BT speakers and powered USB fans with 5V without problems. How to stop that?
More details needed.

Is this PSU group regulated?

What does "5V will be connected to a dummy load", mean?

Does it have the dummy load?

Have you measured to see the actual voltage of the 5V rail during this phone charging event?

Have you measured to see the current during the charging event?

What does "glue even melts", mean? Did you build this cable yourself and possibly use too small a wire gauge for the current? Did you do some weird construction method where hot gun is holding it all together?

Is it possible the charging cable is low quality or worn out with the wire conductors frayed inside? Is the entire length of the charging cable equally hot or more so at one end or the other and if the end, which end? If at the USB socket end, did you reuse an old socket (dirty or mechanically compromised) or buy some generic chinese junk that might not have good contacts, and be causing resistive heat buildup?

I doubt it is an issue of an ATX PSU having so much higher current potential. The phone should limit that.

Maybe pictures of the setup would help.

I agree with VL, the simplest solution is just use a proper charger for the phone. Also keep in mind that if the ATX PSU isn't powering several things at once, probably more than everything combined that you intend to power from it, that it won't be as efficient as any reasonably designed, phone charger, especially if the ATX PSU is left running 24/7, even more so with a dummy load on it so within 1-2 years (if even that long) you are probably paying more for the extra power consumption, than a phone charger would cost if just getting a basic 5V type instead of fancy quickcharger.

If not left running 24/7, power wasted is much lower, so if that's the case then you need to look at what is the excessive resistance to cause the heat.
 
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312e

Junior Member
Jun 12, 2022
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0
6
More details needed.

Is this PSU group regulated?

What does "5V will be connected to a dummy load", mean?

Does it have the dummy load?

Have you measured to see the actual voltage of the 5V rail during this phone charging event?

Have you measured to see the current during the charging event?

What does "glue even melts", mean? Did you build this cable yourself and possibly use too small a wire gauge for the current? Did you do some weird construction method where hot gun is holding it all together?

Is it possible the charging cable is low quality or worn out with the wire conductors frayed inside? Is the entire length of the charging cable equally hot or more so at one end or the other and if the end, which end? If at the USB socket end, did you reuse an old socket (dirty or mechanically compromised) or buy some generic chinese junk that might not have good contacts, and be causing resistive heat buildup?

I doubt it is an issue of an ATX PSU having so much higher current potential. The phone should limit that.

Maybe pictures of the setup would help.

I agree with VL, the simplest solution is just use a proper charger for the phone. Also keep in mind that if the ATX PSU isn't powering several things at once, probably more than everything combined that you intend to power from it, that it won't be as efficient as any reasonably designed, phone charger, especially if the ATX PSU is left running 24/7, even more so with a dummy load on it so within 1-2 years (if even that long) you are probably paying more for the extra power consumption, than a phone charger would cost if just getting a basic 5V type instead of fancy quickcharger.

If not left running 24/7, power wasted is much lower, so if that's the case then you need to look at what is the excessive resistance to cause the heat.
The voltage was 5v. I unbridge PS_ON and GND (to turn it off) when not in use.
 

mindless1

Diamond Member
Aug 11, 2001
7,093
1,045
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^ 5V assumed, or 5.0V measured? You didn't address the rest of my questions so there's nothing else to go on, like whether group regulated and actually 5.0V, or what the current draw was, etc, etc.
 

312e

Junior Member
Jun 12, 2022
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0
6
^ 5V assumed, or 5.0V measured? You didn't address the rest of my questions so there's nothing else to go on, like whether group regulated and actually 5.0V, or what the current draw was, etc, etc.
It was 5V MEASURED, current 3A, dummy load is a 10 ohm 100W resistor, with a very good PSU. The wire became hot enough that the glue connecting the screw mount and the wire together melted. When using a normal phone charger, the USB cord was OK. I may be powering multimedia devices and USB devices while simultaneously charging my phone from it. The whole USB to lightning cable had equal temp.
 
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mindless1

Diamond Member
Aug 11, 2001
7,093
1,045
126
I have lost interest because you didn't supply info in the first place.

It's still what I wrote, some series resistance causing heat. Solve that.

You can measure the voltage drop across any area if nothing else, to see where the power loss is.
 
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Leeea

Golden Member
Apr 3, 2020
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LOL. OP is so cheap he's going to burn his house down, rather than spend $10 on a USB charging hub for his devices. I guess some people are like that.
come on!

this is a super cool project to avoid trashing a perfectly good PSU.

When I attempt to charge my phone off the connected USB ports, the USB to Lightning wire gets hot that the glue even melts (PSU wires normal temp).
That sounds like a bad connection or joint.

Likely your phone is the only thing that pulls real current through there.

Only thing you can do is to go through the circuit and find the bad connection. Either redo them all, or probe after each one looking for voltage drop when the phone is plugged into it.

Also keep in mind that if the ATX PSU isn't powering several things at once, probably more than everything combined that you intend to power from it, that it won't be as efficient as any reasonably designed
Looks like he is planning to put 12v loads on this thing. A quality PSU is going to get very efficient once he loads it down with about 40 watts or so.

Especially if he gets rid of the dummy load.


5V MEASURED, current 3A, dummy load is a 10 ohm 100W resistor
Recommend you just dump that. I doubt it is doing anything at all for you except make heat inefficiently.



Wait, you measured 3 amps of current to a 10 ohm resister on the dummy load? That makes no sense, 5V / 10 ohm = 0.5 amps = 2.5 watts. You sure you have a 10 ohm resister there?

3 amps is enough to heat up any defective connection though. That will melt glue real quick.
 
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