PDA

View Full Version : Why there are no standard voltage USB devices that use 3 amps (18 watts)



ZenOps
04-23-2019, 04:31 AM
https://goughlui.com/2014/10/01/usb-cable-resistance-why-your-phonetablet-might-be-charging-slow/

15 to especially 18 watts becomes extremely tough to do.

Comes right down to cable size. Even the beefiest (20 awg) and shortest cable at 5 volts will have a near impossible time maintaining minimum specifications.

ExtraSlow
04-23-2019, 07:54 AM
I'm pretty happy with anything 1000 mA or higher. That charges my devices at an acceptable rate.

I have spent more time than I care to admit calculating voltage drops in DC circuits for my trailer. Would love to buy thicker charging cables of they were available readily. For now, I just test my cables every six months or so, and toss any weak ones out.

Mitsu3000gt
04-23-2019, 10:32 AM
It's a complete non-issue in my experience - the slowest charging device I own now is 18W (2A/20V) and the others are 30W+. All verified with an outlet meter, and most of them charge slightly above their advertised wattage values. Quality chargers/cables that support these rates are also cheap. 15W is pretty common too (usually at 3A/5V).

ZenOps
04-25-2019, 07:33 AM
Thing is, it matters out there because you cannot charge a modern USB device at a distance over 2 meters or so simply due to cable voltage losses.

Which is absolutely fine in your house, where you can put your phone on a nightstand, and move the nightstand right on top of a power outlet. But in the real world, you can't always get the one starbucks table that is hovering two meters distance power outlet to a table.

But what I'm getting at mainly is that I am disappointed that more micro USB cable manufacturers have not standardized on 20 AWG. Its literally a few strands of copper more expensive, probably two pennies worth of copper - having zero downside. And yet, they stick with 24 (and even 28 awg) A tablet user is probably used to putting their tablet on the floor, just so that it works with a 50 cm cable.

USB C? Its actually an inferior design from a power physical standpoint. Sure, they can up the voltages and push 100 watts, but the connector is actually ass backwards to having two thick power lines (and two data lines) Two power lines, like a house outlet (and one ground)

Even more retarded are the USB solar panel manufacturers who insist on using a pigtail, and then attaching it to the center of the panel. Absolutely retarded.

If I made the rules, I'd have a micro USB trade-in program, where you can recycle your old 28 AWG for a loonie - and get a brand new 20 AWG cable back.

revelations
04-25-2019, 09:59 AM
How is this related to the Nickel conspiracy? What happened to the old zenflops?

HiTempguy1
04-25-2019, 10:00 AM
Thing is, it matters out there because you cannot charge a modern USB device at a distance over 2 meters or so simply due to cable voltage losses.


You are in crazy ZenOps conspiracy land.

My 10 foot Belkin braided cable from Amazon, I can assure you, has zero issues charging my OnePlus 5. With a standard charger, it easily supports 2amp charging, which means my 3300mah battery from essentially dead takes about 1.5 hours to charge.

Also, just so we are clear:

https://www.engineeringtoolbox.com/wire-gauges-d_419.html

As someone who deals with wiring in small packages everyday (unfortunately), I need to keep current requirements of wire gauge sizes in mind. 7-24 core 22 gauge will handle a max of 2.1 amps. And another thing to consider is the assumption being made is that the device you are charging is drawing max amps at all times, which isn't how it works with devices self regulating now.

speedog
04-25-2019, 12:44 PM
If I made the rules, I'd have a micro USB trade-in program, where you can recycle your old 28 AWG for a loonie - and get a brand new 20 AWG cable back.

Micro USB? Man, you've got to get with the times.

dirtsniffer
04-25-2019, 01:22 PM
.....

Not surprising to read that you are used to dealing with unfortunately small packages.

pheoxs
04-25-2019, 02:12 PM
USB C? Its actually an inferior design from a power physical standpoint. Sure, they can up the voltages and push 100 watts, but the connector is actually ass backwards to having two thick power lines (and two data lines) Two power lines, like a house outlet (and one ground)


Care to explain this? The USB-C has 4 power pins (A4, A9, B4, B9) and 4 ground pins (A1, A12, B1,B12) to distribute the power. Most are rated for 3 amps just fine which is pushing the limit of what Micro-usb could do.