Voltage drop in passthrough??

[props76]

I need an electrical expert on this one.

I have a passthrough. Run off my desktop, it requires a 5 foot usb extension , then plugged into the passthrough, since the only ports are on the back.

I've measured the voltage at the passthrough at its 5 volts. On another computer where I don't have to use the 5 foot extension, I still read 5 volts, but it seems to work better.

So does voltage drop over a long cable only happen under load or the greater resistance of the longer cord, so that the volt meter at .0001 amp wouldn't see it, but the passthough would? Or is it all in my head?

 

[Jim Davis]

You shouldn't concern yourself with this issue. The thing you *should* be concerned with, is blowing out your computer ports if your passthrough goes bad. Get a 110v to USB converter and plug your passthrough into the wall. A converter is easier to replace than your computer.

As to your question, the longer the wire, the more resistance. More resistance = less voltage.

 

[boxhead]

yeah, what JD said but adding more resistance=less voltage under load. yes you get 5volts, just not mAh...like a skillsaw plugged in the wall and the skillsaw on on a long extension cord, cord get hot, circut breakers trip... or computer`s usb gets a suprise along with mother board, i `ve spent too much money on the computers to want to do any thing but data transfer with them, every thing that needs a charge i use separte charger for, yes a pain but a cheap one. so no not in your head

 

[Jim Davis]

Right on the mah issue. I think they should put warnings on the USB devices. Too many people are creating problems. Maybe I'll go into business. E-cig sales & Computer repairs.

 

[RenaissancePuffer]

Pick up one of these, it's cheap and works well. Runs 1 port at 2A 2 ports at 1A each.

USB Dual Power Adapter