Wires overheated while charging iPad with ATX PSU

formatting link
it's wired. With my wiring, the USB wires are heating up to around 200-300F. Am I using the right voltage? Is the iPad demanding too much power? The PSU worked fine after the incident.

Reply to
s7382
Loading thread data ...

Remember, D+ and D- are shorted to show the port is a dedicated charging port (DCP).

Reply to
s7382

I expect the iPad can draw a fair amount of current, and the ATX PS could certainly supply it. How thick are the conductors?

Sylvia.

Reply to
Sylvia Else

I wonder what the actual voltage is.

Reply to
jlarkin

Presumably 5V, unless you're thinking that it's drawing too little current for the ATX PS to be stable.

Sylvia.

Reply to
Sylvia Else

Some "USB" (irony emphasis on the U) cables are specifically resistive, to limit current.

I'd expect that an ATX switching supply might make a lot of voltage with a light load.

OP could measure both.

Reply to
John Larkin

tirsdag den 22. februar 2022 kl. 20.30.01 UTC+1 skrev John Larkin:

examples?

can't see any reason to a USB cable being resistive other and as a side effect of trying save money on copper

Reply to
Lasse Langwadt Christensen

A VOM seems like the easiest way to VERIFY that.

You may find the PSU requires a heavier load on the supply than you are providing.

Putting an ammeter in series with the load to give you a rough idea of the amount of current flowing would be a good idea. Likewise, the voltage DROP across the cable's length.

iPad get warm (battery)?

If you disconnect iPad from your "adapter", there should be NO current flowing and no "heat", right? (i.e., wiring error)

Reply to
Don Y

I've seen gadgets that come with a specifically resistive USB power cable and warnings to use only that one. I don't have a link.

Reply to
John Larkin

Seems like a good way to destroy the ipad.

Reply to
John Larkin

In that case it isn't a USB cable. Its something else with USB-style connectors.

John

Reply to
John Walliker

Aren't they all?

USB is a mess.

Reply to
John Larkin

tirsdag den 22. februar 2022 kl. 22.36.05 UTC+1 skrev John Larkin:

no, random Chinese dothats convinnietly powered by the 5V from a USB port is not USB

how so?

Reply to
Lasse Langwadt Christensen

I don't think computer supplies work that way. They either regulate or shut down. The problem is keeping it working while running a relatively light load. However, 3 amps is not a uniquely light load for a PC supply. I don't think that is the problem. Much more likely is the supply is providing all the power the iPad is asking for and the wires are too small. Or maybe the connector contacts are bad and the OP is feeling the heat there.

Reply to
Rick C

In an ideal world, certainly.

But who knows what some cheap PS from China might do? Not that I'm saying that the OP has such a PS, but anything is possible.

Sylvia.

Reply to
Sylvia Else

Of course, everyone leaves out unneeded parts, so the design that suits PCs is a circuit that requires a minimum load (not sure from which voltage). The supply does not go out of regulation in the sense of overvoltage. It does not output current on all outputs. There is no reason why it would overvoltage because of a light load. But, as I've mentioned, the iPad is not going to draw a light load and obviously *is* drawing a heavy load, at least for the wires being used.

20 years ago PC supplies powered the CPU through the 5 volt rail. But the current go so excessive they bumped it up to the 12 volt rail. Now the 5 volt rail powers a lot less of a PC and so, not as much current.
Reply to
Rick C

There are a zillion barely-different but incompatible connectors, nearly all with non-obvious polarization.

The C connector scheme is pretty good... decades late.

Reply to
John Larkin

iPad battery is OK, it's the USB wire that gets hot,

Reply to
s7382

But, with the iPad electrically NOT connected to the "adapter" that you've made, do the wires get hot?

I.e., if you've accidentally miswired/shorted the adapter in your construction attempt, then the "fault" may be independent of the iPad's presence.

(actually having *numbers* for V and I would *really* help you!)

Reply to
Don Y

The battery may not be OK for long!

Why not use the right iPad charger?

Reply to
John Larkin

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.