My phone is a “Samsung Galaxy S6″. It is not an ‘
S6 Edge‘, nor an ‘ S6 Edge+’. As the ‘S6′ goes, when it was first released onto the market, this phone was considered to be advanced, because it did not require a special cover for wireless charging, and because the built-in charging capability included compatibility with both the ‘Qi’ and the ‘PMA’ systems, which were maintained by independent companies.
Yet, by default I had been charging this phone with a USB cable and a special USB wall-power adapter,
that lets the phone know via the data wires that it can draw 2A of charging current, instead of 500mA. Doing so always put wear and tear on the USB jack of the phone.
Starting a few days ago, I had bought myself a Qi wireless charging pad by the brand-name “JETech”, and I find that this charging pad does the job well. I was surprised to learn, that these charging pads no longer come with 110VAC cords to plug in, but that we connect the pad to its power source, via the 5VDC, 2A, USB power adapter.
Charging the phone from 50% all the way back up to 100% via Qi-wireless takes about 1 hour and 20 minutes time, which I think is impressive.
But there is a more recent development in this realm, that I should also mention. Starting with the ‘Note 5′ and the ‘Samsung Galaxy S6 Edge+’, and including the ‘S7′, Samsung has decided to produce its own type of wireless charging system, which is supposed to be even faster. In fact, when I first went to the store to request a charging pad for my S6, the tech person in charge automatically sold me a ‘Samsung Fast Charging Pad’, knowing the fast charging feature would only work with the Edge+, but nevertheless assuming that slower charging would still work with my S6.
As it turns out, the Samsung Fast Charger that I received did not work with my S6, even at standard charging speeds. This could be due to an incompatibility, or due to one defective unit sold to me. I rather suspect the former. The symptom was, that charging would seem to begin, but that after charging for about 1 second, charging would pause, and that 1 second after that, charging would start again – endlessly. And this would also happen eventually, after I had removed the phone from its case, which in my case is an “Otter Box”.
So I had to return the Samsung-brand Charger to the store, where I received a refund. And that was when I decided to buy the ‘JETech’.
The JETech actually does a better job on my S6 than the brand charger did, especially since in my case, the brand charger only produced an endless series of notifications, and accomplished no charging effect at all. And I can leave my phone in its Otter Box case, while charging successfully on the JETech pad.
If it becomes possible for my use of the JETech charging pad to replace my former use of the Micro-USB-port on the phone completely, doing so may also increase the overall usage period of the phone, since if it was ever to become impossible to charge, it would also become impossible to use…
(Edit 03/23/2016 : ) I had observed that modern devices with USB charging have some mechanism by which to increase the charging speed from ‘Cable Charging’ to ‘Fast Charging’, which the notification will indicate. I also know that usually, the power source will define the voltage, while the load will decide to draw some amount of current. It all becomes difficult to manage, at low voltages and high current levels. But I had not known the exact details until today.
At least with Samsung, the way this works is as follows:
An “Adaptive Charger” is capable of delivering either 5VDC or 9VDC. At 5VDC, it can handle loads of up to 2A. At 9VDC, it can handle loads of up to 1.67A. The device to be fast-charged actually sends a signal to the charger, which triggers it to deliver 9VDC on the USB cable, instead of the usual 5VDC. At 9VDC, Fast Charging mode can commence.
One problem with fast-charging at 5V would have been, how impractically close this voltage is to that of the battery in the mobile device. A fully-charged Li-Ion battery has approximately 4.5V, which is only 1/2 Volt less than the standard USB voltage was.
Wires, connectors and control circuits all add series resistance to a circuit, and even if the series resistance was only 1/2Ω (Ohm), then at a theoretical current of 2A, the circuit would lose 1 Volt right there. This would put the voltage arriving at the battery at 4V, which is already lower than that of the battery nearly charged. And so it would have been an improbable – and destructive – feat to get the device actually to draw 2A when connected to the USB port of a computer.
The version of what happens which I now entertain, is that the USB port of a computer may have a ‘current-limiting transistor’, which limits the output current to 500mA actively, even if doing so only means inserting a resistance of 1Ω (Ohm), and thus inserting a voltage drop of 1/2V. It may be the case that when connected to a charging adapter capable of supporting 2A at 5V, the actual mobile device still achieved much less charging current than that.