GetUSB.info Logo

How USB Cables Affect Charging – Simple Test

I came across an interesting article today from Dr Gough, a tech nerd. and thought it good enough to summarize here:

The USB specifications for power from a port vary from 100mA to 1.5A and up to 100W of power for USB Type C, but the cables and connectors used in a cable might not align with the power specifications of the product being designed and used. Cables are typically rated for about 1.8A of current, which is most common for cables used for charging.

usb cable

The 1.8A rating is based on safety limits for resistive heating of the cable and connectors. The rating is no guarantee your +5V at 1.5A setup will get you the maximum level of power. The important point here, the cable and connector combination is simply a rating to deal with heat, and ensures nothing melts. Going a step further, most specs ensure nothing gets noticeably warm to the human touch.

Every wire that’s not a superconductor has some finite resistance. Said another way, resistance is transferred into heat. Ohm’s law tells says that E = IR, where E is voltage, I is current, and R is resistance. So when you put power through a wire, the current X resistance gives me the voltage that will be “consumed” across that wire, power that turns into heat, and thus, never makes it to your phone.

I want to end this blog post with the above paragraph as that is the real takeaway here. The more inefficient (or cheap) a cable is, the warmer it will get. So if your iPhone cable is warm to the touch, it sucks. If your wire charging your power bank is warm, it sucks. Get a better cable. From what I can tell, there is no rating posted on all these cables you see on Amazon at cheap prices, so word to the wise using your tactile feel!

Ohm’s Law Wiki.

Was this article helpful?

Tags: , , ,

Rich Gates

Administator for GetUSB.info GetUSB.info started in 2004 with the concept of providing USB information for everything USB related. At the time, USB was gaining momentum and every day new products, articles and news became published. Today, the site is focused on bringing technical information, tricks and hacks to USB related products. The site does publish off topic information as well, to keep the variety up. Please visit the footer area of any page if you or your company is interested in article or product placement via purchased advertising.

Copyright © 2006 +

USB Powered Gadgets and more...

All Rights Reserved

GetUSB Advertising

The opportunities on our website can reach up to 1,000 unique visits per day.

For more information
Visit our advertising agency.

Nexcopy Provides

USB copy protection with digital rights management for data loaded on USB flash drives.

Contact us learn more