USB chargers for phones, etc

[Donald]

I know some chargers put out more and some less current thant others. Some claim to be SMART and detect the device and charge it appropriately.

So my question is where are the smarts to allow a device to be charged fast but also shut off when full charged? In the charger or device?

Obviously the charger needs to put out enough current in the first place to charge fast.

I would guess the device decides when to shutdown charging rather than the charger. But I am not sure.

 

[EdwardC]

For the most part, I believe that the device does all the controlling (plus the charge controlling).

The charger uses the data lines to indicate to the device how much current it is capable of. That's where you run in to compatibility issues. I think that the signal indicating the current capability varies with the manufacturer (mostly apple vs non-apple devices).

 

[rjundi]

The 2.1 Amp ones(iiPad and Nexus 7) way faster on my iPhone vs the suppled 1 Amp ones.

Not sure there are smarts in charger as you can also plug into a computer for example, car usb, or my case I use my TV (very slow).

 

[EdwardC]

Couple interesting links for more information:

https://learn.adafruit.com/minty-boost/icharging

http://blog.workingsi.com/2012/11/modify-usb-auto-charger-to-actually.html

 

[ARCOgraphite]

I would guess if its not PIP the you get std usb 5v dc rail. Current is determined by the slave device circuit impedance.

 

[razel]

It depends on the device, cable, charger.

USB port on PC when on is 250-500ma max.
USB port on PC with a lightening bolt next to it is 1 amp.
Many USB chargers are usually 1 amp.
iPad, Qualcomm quick charge 2.0 are > 2 amp.

Your device will draw whatever it needs.
iPhone - 1 amp
iPad - 2.4 amp
Nexus 5 - 1.5 amp
Qualcomm quick charge 15-30 watts total @ various voltages (5,9,12v)

However... the kick is also the cable! For Apple devices, always use MFi certified cables. The cheap ones, iPads will complain about. For USB, Anker USB cables are the best I found and handle 2 amps reliably. However, depending on your USB charger you may need a charge only USB cable. PortaPow was inconsistent. A charge only adapter or shorting the Anker USB data pins with aluminum foil was better.

For example, my Nexus 5 will usually get 1 amp. With a short cheap USB charge only cable connected to the 12watt iPad charger, it gets 1.5 amp 70% of the time. It wasn't until I bought the Anker USB cables that it ALWAYS gets 1.5 amp, but only from iPad 12 watt, QUALCOMM quick chargers, Scoche 12 watt dual car charger. Also my Nexus 5 only does 1.5 amp when the battery is between 15%-70%. This is true for many devices, where at the bottom or top end, charging is not at max.

For safety, only buy chargers that are UL rated. They tend to be well built, heat up less and reliably charge more consistent at the higher rates. Duracell and G.E. chargers are nearly always UL rated. Duracell you'll find at Big Lots, Staples. G.E. you'll find in the electrical surge protector section at Target, Walmart.

TLDNR. Use iPad 12 watt or QUALCOMM Quick Charge 2.0 charger. Use Apple MFi or Anker USB cables. Charge only USB cables are great for travelling since there is not chance of any data exchange.

 

[eljefino]

FWIW those data cables screw up older garmin GPS's, they believe they're plugged into a computer and you have to jump through hoops to get them to work normally. I thought I was suave using my car stereo USB to power one with a data cable; need a charge one.

 

[IndyIan]

Originally Posted By: rjundi
The 2.1 Amp ones(iiPad and Nexus 7) way faster on my iPhone vs the suppled 1 Amp ones.

Not sure there are smarts in charger as you can also plug into a computer for example, car usb, or my case I use my TV (very slow).

I use a 2.1 amp one as well for my iphone and it seems to handle it just fine. Perhaps with a case and a lot of wifi download/upload the phone may heat up too much? I don't normally use mine while its charging so I don't know.

 

[aquariuscsm]

Oem branded chargers are definitely better than the junk you get a Walmart.

 

[BearZDefect]

What about PS3 controllers? They will charge using any generic USB cable, but they are picky about the power source at the other end of the cable. Could it simply be the amperage available?

These work: USB ports on a laptop, USB ports on a PS3.

These do not work: USB plug on various phone and tablet power bricks, built-in USB charging plugs on an AC power strip.

 

[racer12306]

I remember reading about PS3 controllers when I got mine. Those need the data pin, wall chargers don't utilize the data pin.