USB Charge current indicator ?

Those things are called ampere meter. Sometimes part of a multimeter.

Sjouke Burry wrote in news:5c869867 $0$31754$ snipped-for-privacy@textnews.kpn.nl:

It functions flawlessly and will fast charge on all ports as well.

Well worth it. There are others, but I have no experience with any.

Maybe this:

There are others...

snipped-for-privacy@gmail.com wrote in news: snipped-for-privacy@googlegroups.com:

I'll bet it is not all that accurate. But yeah, there are hundreds of those little single port pass thru thingys out there.

ebay is your friend

Mike wrote in news:q6670s$1b9$ snipped-for-privacy@dont-email.me:

No... bluetooth is...

Nice. But this is funny:

"Fast 2.4A Smart USB Charging Ports: Each port of the charging station recognizes the exact current requirements of a connected device and delivers the right amount of the current for a safe and fast possible charging.(Does not support Qualcomm Quick Charge)"

Sounds like a voltage source to me.

John Larkin wrote in news: snipped-for-privacy@4ax.com:

What do you think the behaviors of device charging circuits are?

There is a minimum voltage requisite and that is what they measure. AT that voltage, the device works at a specific current level. When that voltage is not met, the device declares "slow charging", etc. This means that it cares about voltage. BECAUSE if the supply can sustain a specific voltage, that AUTOMATICALLY means that the device charging circuitry is going to be happy with it and charge its battery without producing too much heat to make the battery charging current.

This is why ripple also matters. Too much ripple, and the charging circuit is gonna flag it as lame.

So sure... it is a current source based on a minimum produced voltage.

The smart delivery claim is no more than a claim as you and I know that delivering less current to the same load by definition means a lower voltage.

Unless it has a negative input impedance, as switchers usually do.

John Larkin wrote in news: snipped-for-privacy@4ax.com:

The USB spec is specific. So the dongle or other USB device capable of providing the full USB voltage has to comply (is supposed to).

The device input circuits manage that USB spec fed voltage to make a voltage which exceeds the voltage of the battery the device is designed to "fill back up". That voltage is maintained in the form of never exceeding a max charging current, and would therefore taper down as the battery tops off.

Since that charging voltage is on a battery which is typically less than the 5 volt USB spec, Most use a switch mode, step-down type circuit. It relies on a pumping voltage above what it provides on its output.

Nooo. USB charging ports use a protocol to determine the current requirements of the connected device. An old and dumb device (or just two wires) is current-limited to 0.5A, a newer device with a certain resistor between the datalines is current-limited to 1.0A and the newest devices which talk to the charger are capable of draining more current and also asking for higher voltages. The newest devices (when used with USB-C connectors) can ask for up to 20V and draw up to 5A.

But the sources all supply 5 volts, except for the 20V weirdos. 20V would blow out most USB devices.

"Each port of the charging station recognizes the exact current requirements of a connected device and delivers the right amount of the current for a safe and fast possible charging."

is silly. They supply 5 volts.

not quite, a standard USB port is 500mA/900mA for USB2/3 once configured. a dedicated charger is +1500mA with the data lines shorted, that's you usual ~2A wallwart, Apple have something with a data line tied with resistors

some devices come with chargers that can do more and they will try to see how much the charger can supply before the voltage sags in case you don't use the supplied charger

that's totally different with intelligence at both ends and negotication

Silly marketing speak is sensible cos it sells stuff.

NT

John Larkin wrote in news: snipped-for-privacy@4ax.com:

For the 5 volt standard essentially the best thing is a good clean well regulated supply as THAT is what makes for 'good charging current'.

Ripple is not just (voltage) noise. It affects efficiency and produces a 'current ripple' as well. A crappy 5 volt charging wall wart may only provide 4.7 volts once the noisey ripple at load is considered.

I have looked at cable conductor differences as well, and it does matter. At home I use one foot long high current cables for charging devices.

That and a proper designed circuit that utilizes USB as its interface will likely top out on input efficiency at 5.1 volts input max and start switching to "slow charging" at 4.9. Those are just guessed at numbers, but the limits work that way. With too little or too noisy an input it switches to slow charging so as not to tax the little switcher too much to produce the charging current they want to pump the battery with.

There is usually a happy point. I am sure a designer aims for that point to actually be 5 volts.

ALL of the ports on that device (I posted a link to) report correct voltages and currents and ALL of my devices charge the fastest on it even faster than my fastest (and warmest) dongles and wall warts.

Asus ADP-18BW

It uses a USB3 connector with only the center pin installed. IIRC, you ground that pin to make it 15V on the standard USB power pins.

After reading this thread, I ordered one of these.

because it reads out the voltages on D+ and D- and might come in handy debugging power control functions.

The negotiation sets the current limit. More importantly, it tells the device how much current it can draw from the source. The negotiation can also be used to set the voltage to make up for any drop in the wiring of the charging device.

Silly suggestion...

That's exactly what I want.Thanks.