Why can't this phone charge on a universal charger?

[Se7enLC]

When it's plugged in, go into Settings | Battery and see what it says up top. If it says "Charging (AC)", you are good-to-go! If it says "Charging (USB)", read-on.

To differentiate between a USB port on a computer (capable of supplying 500mA unless a higher current draw is negotiated through USB communications) and a wall or car charger that has a USB port, a new specification is used. If the two middle pins of the USB port (D+ and D-) are shorted together (anything <200 Ohms), the phone will know that it's not a computer USB port and will draw the maximum power it can. If those pins are NOT shorted, it will only draw 500mA - which as many of you have discovered, is not enough current to supply a charge while the device is being used. If you turn the screen on, it will barely maintain. If you are Navigating in a car, the battery will actually drain!

When you are looking at a charger, you need to look for two things:
1). That the current it can supply is at least 1A (1000mA). 500mA is not enough. You might be able to get away with 700-850mA, but you may as well just go with 1A.
2). That the two middle pins are shorted together! You could have a 20A charger and your phone will still only draw 500mA off it if those middle pins aren't shorted! To test it, you can use a multimeter in continuity or resistance mode (make sure to unplug it first), or you can just plug your phone in to test what mode it charges in. "Charging (USB)"==BAD, "Charging (AC)"==GOOD

I don't know of any marketing names or specific products that will or won't have those pins properly bridged. My Samsung and Droid wall chargers both had the pins properly bridged, but none of my other wall or car chargers did. I modified two car chargers already to short D- and D+, and they are working great now. I posted another thread about a week ago listing the two specific car chargers that I modded - they are both easy to disassemble, modify, and reassemble.

http://www.droidforums.net/forum/galaxy-nexus-general-discussions/190328-car-charging-issues-solved-hw-hack.html#post1937165

Additional Information:
http://bec-systems.com/site/800/how-do-modern-usb-chargers-work
http://www.ti.com/general/docs/lit/getliterature.tsp?literatureNumber=slua551&fileType=pdf
http://www.maxim-ic.com/app-notes/index.mvp/id/4803
https://www.google.com/search?q=D++D-+shorted+USB+charging

 

[bryantjopplin]

I knew it was supposed to be shorted you explained it better then me

Edit. I actually had it backwards.

Sent From My Sexy Nexy

 

[madr1727]

I got a universal usb car charger that charges 4 thing at once and it works perfectly with my phone, iPod, and GPS all at the same time.
I would highly recommend this to anyone with a vehicle. I think it was only like 10 bucks too, which makes it even better.

 

[GalaxyFlatulence]

dont use cheap universal chrgrs.

 

[whatuseekisfire]

dont use cheap universal chrgrs.

+1...

Sent from my Galaxy Nexus using DroidForums

 

[GenieAngel]

I'm not using a cheap universal charger. I was trying to use a Verizon charger that came with my previous phone. So far these new universal chargers were working beautifully until this phone. The industry was supposedly changing over to universal charges for all cell phones for a green planet. It used to be that every phone had their own unique charger. Now they all have a mini usb and they are suppose to be interchangeable. Why not for this phone? (I am not speaking about after market chargers.)

 

[spider210]

I'll tell you , I work for vzdub and ya we hear about this all the time. It goes back to even the fascinate which certain chargers do not charge the phone. We have bunch of chargers from all sorts of phones. Certain ones charge the nexus others don't.

I dunno the answer tho, just saying it is known and not an 'issue' with the phone