Advice sought on why 6.8A USB charger melted USB cable today

[Tony Hwang]

Actually anything to do charger you're saying? Even your laptop battery charger has some smartness in it.

[Tony Hwang]

I am a class of '60 in EE. Started with vacuum tubes all the way to nano-tech in electronics engineering. MTBF has been improving steady over the years. Just have a field trip to a big manufacturing plant and see how QC engineers are screening components for their product. Very serious affair. Even here you get what you pay for. For an example, mil-spec laptops cost few times more than consumer grade. You figure out why! Once back in '70s I witnessed testing mil-spec DEC PDP8 mini computer. From chopper up 3500 ft. it was tossed down, it did not suffer damage. Commercial grade PDP8 would be in pieces scattered all over. Another example, look at Panasonic Toughbook, ever tried one of those? You can run over it with your car without any problem. I always try to buy prosumer level product when I need something.

[Tony Hwang]

And look at today's cars, they are like more electronics than mechanics. Drive one like 2013 onward? Some Runs by wire like air planes(CAN buss)

[Bruce Sinclair]

To be fair, I wouldn't use an iAnything. I was an apple convert (in the II+ era), Apple lost their way for me around the first mac. While they are now a triumph of marketing, they now have nothing I want. :)

I prefer my smartness in people, not in things. :) :)

[Bruce Sinclair]

True. :)

In theory, that's true. What I recall of electronics brands reliabilities however, is that there is actually little in it.

In theory, theory and practice are the same. In practice, they are not. :)

Personal experience with scientific equipment these days suggests that the smarter something tries to be, the more often it will fail. MTBF I guess ... the more bits, the more broken bits. :)

[nospam]

no it doesn't.

the smartness is in the lithium battery itself (it has to be) as well as the host device (laptop, phone, etc.)

[Tony Hwang]

You can take apart like IBM(Lenovo) charger and battery pack, look and see.

[Tony Hwang]

Have ever gone to a police station and taken a look at their Walkie Talkie charging rack? Like wise, how about telephone exchange plant?

[joe]

The charger for an iPad or laptop has smarts to power the device. They provide the right voltage and current for the device.

Profiles for charging the batteries are in the device.

[nospam]

all lithium battery packs have protection circuitry and the charger is in the laptop itself, just like i said.

in other words, you're wrong.

[nospam]

chargers for ipads or laptops just provide power. there are no smarts in them.

the smarts are in the ipad or laptop *and* the battery.

[Danny D.]

nospam wrote, on Mon, 07 Dec 2015 10:11:12 -0500:

That's not true.

At least it's not true for the charger depicted in this thread.

So, it's only the Apple chargers (and similar) that you're talking about, and, for them, you're right.

[nospam]

it absolutely is true.

it's *very* true for the charger in this thread, which is nothing more than a 5vdc power supply over usb.

wrong.

all usb power adapters/chargers are nothing more than 5vdc power supplies, including apple. every single one.

[Danny D.]

nospam wrote, on Mon, 07 Dec 2015 12:16:48 -0500:

Maybe you're right and I'm wrong? Let's just prove it so we can both learn something new.

All I'm doing is reading what the charger package says. It says it's a "smart" charger that "automatically adjusts" the power output.

Here's what it says on the package: "Smart USB Technology: This adapter automatically adjusts power output to fit your charging device. Tablets and e-readers require 2 Amp charging, and this adapter will reroute power to the appropriate USB port you use. Charging Combinations: - 2 tablets + 3 mobile devices - 1 tablet + 4 mobile devices - 5 mobile devices - 3 tablets"

Here's what it says on the web:

"Adjusting the power output for up to 5 different pieces of technology, it's easy to see why the Smart Adapter got its name."

Here is how Walmart describes it: walmart.ca/en/ip/hype-volt-68a-wall-adapter-with-5-usb-ports/6000193376994 "Charge up to 5 devices in one place. The adapter will automatically adjust power output to fit your devices needs."

Since the adapter "automatically adjusts power output", how do you reconcile that fact with then saying it's not a smart charger?

Maybe I'm misinterpreting something you said, because that "sounds" like a smart charger to me. Why doesn't it seem like a smart charger to you? What am I missing that you know, but haven't said to me yet?

[nospam]

no maybe about it.

it adjusts it based on how much the device draws.

all usb devices start off with 100ma and request additional power.

there is no eoc detection in the charger. that's in the device itself (and sometimes the battery).

[Danny D.]

nospam wrote, on Mon, 07 Dec 2015 12:35:48 -0500:

I'm perfectly happy if I'm wrong because that would mean that I learn something, as long as we can explain why I'm wrong.

I am well aware that current is not "shoved" into a device that doesn't "draw" (or "sink") that current.

I realize that the current "sourced" by the charger is whatever the device "sinks", up to the maximum point that the charger is able to "source".

However, what's "smart" about this charger is that it can "source"

2.4 Amps (or so it says) from each port up to a limit of 6.8 amps.

So, if you plug in three devices, two of which are tablets sinking

2.1 Amps, while the third is a phone sinking only 1.0 Amps, then the device will "choose" which ports to source the 2.1 Amps and which ports to source the 1.0 Amps.

I do understand you now in that you're saying that the device "asks" (so to speak) for whatever amps "it" wants to sink, and the charger just blindly supplies that (or it doesn't) when it's an Apple charger.

What you're saying, I think, is that this charger just as blindly does that too, but in the case of this charger, you don't have to choose a low-power (1 Amp) port and a high power (2.4Amp) port because the charger will choose which port to source the 2.4 Amps and which ports to source the 1.0 Amps.

I'm not sure what the smart charger does when I plug in 3 tablets, all "asking" to sink 2.4 Amps though.

[joe]

You shouldn't be using marketing copy to understand technical details.

How do you define smart? You should also learn some basic circuit theory.

Try reading the USB specifications regarding charging.

[Danny D.]

joe wrote, on Mon, 07 Dec 2015 14:35:39 -0600:

The way I define it is that the charger is smart enough to know how to shunt current to where it's needed without me having to do that myself.

I plug in whatever I want to plug in (within the defined limits). And the charger shunts the current to those devices accordingly.

For example.

If I plug in five devices which each "ask" to sink 1 amp of current, then the charger is smart enough to make available a shunt of up to

1 amp each source current into those five sink devices.

Likewise, if I plug in three devices where one asks for 2.0 Amps, and another asks for 1.6 amps and another device asks for 1.4 amps, then the charger is smart enough to shunt 2.0 amps into one, 1.6amps into the other, and 1.4 amps into the third, for a total of 5.0 Amps (or 25 Watts).

With many multi-port chargers, one port is a *dedicated* 2.1 Amp (max) port while the other is a *dedicated* 1.0Amp (max) port.

This charger is "smart" in that the dedication is switched between the ports (i.e., they're not all 2.4Amp ports, but any one or two can be depending on what you plug into it).

That's smart.

But maybe I misunderstand since you people are telling me otherwise.

[Daniel James]

More than you might think!

I came across this recently:

[nospam]

the smartness in that charger is for communicating with the laptop about the adapter's capabilities, not charging strategies, which is handled by the macbook based on the reported capabilities.

a magsafe charger tells the macbook its maximum power and the macbook budgets it appropriately. if the adapter has less power than what was originally supplied, the macbook will charge at a reduced rate or even not at all, depending on how much power is actually available and what the macbook needs.

in any event, the thread is about a usb charger which doesn't do any of that. it outputs 5vdc, hopefully compliant with the usb charging spec (some noname crap is not).