AC Chargers - Watts? Volts? mAmps?

[jj2me]

Originally Posted by odamizu

If I'm understanding correctly, Sony #1 and Kindle #1 are the same, and most USB chargers can be used with most devices, which will only draw the amount they need, but it's not 100% sure so there's always a risk (generally small) of frying your device if you don't use the "official" charger that goes with it? Does that pretty much sum it up?

So the safest thing is to buy the "official" charger or use one with the exact equivalent voltage and amperage?

I'll daresay that if both devices take a micro-USB plug, then you're not in any danger of frying anything, because no manufacturer will make a device that has a micro-USB jack that wants anything other than 5V (+/- a bit).

As dwig points out, a USB device may drain while using an incompatible charger or cable, but there's virtually no risk of frying it.

[odamizu]

It sounds like most of you are comfortable using unofficial or "universal" chargers with your devices, but don't want to tell me it's 100% safe, just in case. Okay, that's fair. I get that Thanks for all the info!

[Cinisajoy]

Originally Posted by odamizu

It sounds like most of you are comfortable using unofficial or "universal" chargers with your devices, but don't want to tell me it's 100% safe, just in case. Okay, that's fair. I get that Thanks for all the info!

That is because we don't know what charger you will use and cannot 100% guarantee it will work.

[jj2me]

Originally Posted by odamizu

It sounds like most of you are comfortable using unofficial or "universal" chargers with your devices, but don't want to tell me it's 100% safe, just in case. Okay, that's fair. I get that Thanks for all the info!

It is virtually 100% safe. Here are the highly, highly unlikely, but theoretical, circumstances that are just never going to happen.

- excessive drain and you can't restart your device. This might happen in an extremely rare circumstance to an extremely rare person who tries to charge the device for days (even though the charging light is not on) and the charger/device combination drains the battery, and then that person doesn't try hard enough to wake the device up from completely dead. Just not gonna happen to you, because you'll notice the device is not charging, know that can happen to chargers (incompatible or just went bad), and simply try some other charger.

- some idiotic manufacturer doesn't adhere to USB specs and makes a device with a micro-USB jack that takes a micro-USB charger that puts out, say, 12V, and you use that charger on your e-reader. Just not gonna happen.

[theducks]

What you may find, like I did, is those universal chargers work perfectly fine for charging, but your wireless devices now have connectivity problems (while the charger is attached to the mains).

Old, heavy chargers used Iron transformers to lower the voltage.
New,tiny, light use Switched Mode Electronics. If it is too cheap, the waveform RF filtering is poor (and probably does not meet EMI standards)

[odamizu]

Originally Posted by jj2me

It is virtually 100% safe ...

Now this is what I wanted to hear

But seriously, I appreciate all the info everyone has shared. You've been very helpful. Thank you!

[Katsunami]

Originally Posted by odamizu

If I'm understanding correctly, Sony #1 and Kindle #1 are the same, and most USB chargers can be used with most devices, which will only draw the amount they need, but it's not 100% sure so there's always a risk (generally small) of frying your device if you don't use the "official" charger that goes with it? Does that pretty much sum it up?

So the safest thing is to buy the "official" charger or use one with the exact equivalent voltage and amperage?

For what it is worth, I've used many chargers with many different USB-devices, including my Kindle Paperwhite. Most USB-chargers are 5 volts, and between 1 and 2 Amps. If a device supports it, a charger with higher amps will charge it faster.

Just look at the specs of the original charger. If it's 5V, and 1 or 2 Amps, it can be used with most devices that charge through USB, and it can be replaced by a generic, off-brand charger of good quality. If the charger is different, such as 9V 2A, for example, it will probably have its own plug that is not (micro)-USB.

I've been using (micro/mini)-USB chargers for over 10 years now, all of them between 5V/1A and 5V/2A, and I've never had a problem; I do use chargers of a good brand though. Don't just pick an $2 charger from e-bay. They can be shoddy. While they adhere to electrical specifications, build quality often leaves much to be desired.

Spoiler:

Originally Posted by Bricorn

What we forget is that electricity isn't a willing servant, it's a chained demon. .

Very aptly, the Autobots found this out in the 1980's



(Episode: Kremzeek!)

[Andy_T]

I typically use a device like this:

http://www.amazon.com/dp/B0115MVRO4/...ti+usb+charger

to be able to charge multiple electronic devices, with quick charging capability.

Our Kindles (about 4 in the household) pose the smallest challenge, as they only very seldom need to be recharged.

iPhones, iPads, Android phones and tablets, however, do require their juice every day. I find that especially Android tabs are not happy until they are at least fed 2 A, e.g. my Asus tab complains with most normal chargers that the power is not sufficient.

[Cinisajoy]

Originally Posted by Andy_T

I typically use a device like this:

http://www.amazon.com/dp/B0115MVRO4/...ti+usb+charger

to be able to charge multiple electronic devices, with quick charging capability.

Our Kindles (about 4 in the household) pose the smallest challenge, as they only very seldom need to be recharged.

iPhones, iPads, Android phones and tablets, however, do require their juice every day. I find that especially Android tabs are not happy until they are at least fed 2 A, e.g. my Asus tab complains with most normal chargers that the power is not sufficient.

I like that.

[crane3]

"Official" vs universal chargers. Seems like no one mentioned the apple recall of their iphone chargers in the news in Jan, 2016. Google search for "iphone charger recall" has lots of news articles; of course, the recalled official chargers were from apple products from macs to ipads to iphones.

So much for "better" or "safer" official chargers even from a company that is touted as having a "quality" product. Stuff happens........

[Andy_T]

I keep buying cheap cables (iphone, usb) ... that keep breaking or otherwise losing their function.

There are some "brand" cables (e.g. Belkin, Hama) but I have no hard experience whether those are really more stable and more reliable than the no-name stuff that possibly comes from the same Chinese factory... Have gotten a Hama iPhone cable recently and that looks and feels a bit more sturdy at least.

I was disappointed with the "Amazon Basic" ipad (old version) cables I bought ... have had good experiences with Amazon Basic stuff so far (affordable and decent quality), but the iPad cables I got from them also did not last much longer than any no-name stuff you can get at the typical street corner phone accessory vendor.

[Emma Santiago]

If you multiply amph to volts then you will get Watts. higher Watts means shorter charging time but if device supports otherwise your device will be damaged...

[dwig]

Originally Posted by Emma Santiago

If you multiply amph to volts then you will get Watts. higher Watts means shorter charging time but if device supports otherwise your device will be damaged...

Not quite correct.

It's true that A * V = W, but while voltage is much like water pressure in that is is forced on the device, amperage is like flow rate (gallons per hour) and the device is not "obligated" to use the full current.

Some devices, rather few these days, do rely on the charger to be the limiting device. These will consume whatever amperage the charger allows and when used with a charger that offers higher current levels will "over eat", which can damage the device. Most devices have their own current limiters and will only draw the amount of current that they were designed for regardless of the charger's capacity.

[Katsunami]

Originally Posted by dwig

Some devices, rather few these days, do rely on the charger to be the limiting device. These will consume whatever amperage the charger allows and when used with a charger that offers higher current levels will "over eat", which can damage the device. Most devices have their own current limiters and will only draw the amount of current that they were designed for regardless of the charger's capacity.

Also, in the past, it could be very dangerous to use a charger that offered not enough power. The charger would overheat. Nowadays, a lot of devices measure the power coming from the charger as soon as you plug it in, and refuse to recharge if the power is not enough. Windows Phone 8.x and higher actually displays a warning on the screen that the device won't recharge because the charger is underpowered.

[geekmaster]

Originally Posted by dwig

... Back to chargers, there is another issue to consider. With most tablets and phones the "data" lines (USB2 uses 2 wires for power and 2 wires + the power ground wire for data) are often used to signal the device that a charger is present. There is a USB standard for this, but many devices use their own proprietary system.

True in many cases (especially full-sized USB connectors), but many devices also use a cheaper approach where the fifth pin in the microUSB connector is pulled up with a specific value resistor that determines which function any particular microUSB cable or device supports. In the case of quick charging, resistors are commonly used to tell the charger the device can charge at a much higher current. Without such resistors, the charger defaults to typically 500mA to act like a PC USB jack (except for apple, which refuses to work for marketing reasons). That fifth (ID) pin is also used in USB OTG connectors, to tell the e-reader or cellphone to act as a host and to suppy power to the microUSB connector. Other than OTG, resistor values and functions are proprietary and vary by manufacturer, so using the wrong cable or charger could have unsatisfactory results (in most cases just taking longer to charge, or failure to function as expected).

Here are some resistor "standards" for full-size USB (most chargers, as you described) used by various manufacturers:



https://en.wikipedia.org/wiki/USB_On-The-Go
"Three additional ID pin states are defined at the nominal resistance values of 124 kΩ, 68 kΩ, and 36.5 kΩ, with respect to the ground pin. These permit the device to work with USB Accessory Charger Adapters that allows the OTG device to be attached to both a charger and another device simultaneously."

More fun with microUSB ID resistors:
http://forum.xda-developers.com/showthread.php?t=820275

Resistors are also used to select data speeds. With no real standards regarding many resistor-selected special USB functions, it is all rather confusing. Best to use the charger that goes with the device, and sometimes the matching cable as well. However, some say specialized chargers are just a waste of money.

And in some cases, device features are selected via digital signalling over the USB data lines, instead of using fixed resistors (e.g. USB Power Delivery signaling).

And if you think that is complicated, my Samsung Galaxy smartphone has ELEVEN pins in its microUSB jack (which include 4K video out, which did not work on my first non-Samsung 4K-compatible cable even though it claimed such support).

I think an XKCD cartoon explains this situation pretty well: How standards proliferate.

Now, getting back to the ORIGINAL question in the first post, even if your charger tries to charge a battery too quickly, they have built in protection circuits to prevent a fire in your pocket, so it will generally not harm them other than shortening their life a bit. But still, better not to do that, just in case. But beware of cheap dollar-store chargers -- some of those put out 9v or even 12v (or worse) without checking the resistor values on the cable. Some devices will not tolerate that.

Thus ends another exciting installment of the "little professor" lecture series. Stay tuned for more.