Would like to find a USB charging cable not a data cable. Are they available and where? As I understand it, data/charging cable will not allow the Nexus 7 to charge quickly. I plan to buy a car charger that can deliver 2.1 amps out for fast recharging.
Need USB Charging Cable NOT Data Cable
- Thread starter magicrat21
- Start date
Link.
That said, my Nexus 7 charges dead slow using this cable connected to my MacBook and only gets to 96% no matter how long it sits (I don't understand this). I need to use the wall adapter to get an acceptable recharge (full in under an hour).
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You don't need a special cable, just a good quality one. Poor quality cables can't handle the full 2 amps needed to charge quickly.
Sent from my Nexus 7 using Android Central Forums
Sent from my Nexus 7 using Android Central Forums
How much current can the Macbook deliver through the USB port? I'd guess it's only 0.5 amps, not the 2 amps that the N7 needs. The problem may not be the cable, but the power source.
Don
Don
psyke45
Well-known member
a USB cable is a USB cable, but like retsaw mentions, a better quality one doesn't hurt.
I'm actually surprised that the N7 will charge off a computer at all; ASUS's other products specifically say they will not charge via USB to PC and require the 2A adapter. The N7 will charge, but only if it's asleep; If the screen is on, it'll draw too much power to be able to charge the battery, resulting in a slower drain, but a drain none the less.
Pick up an app like battery monitor and it'll show how many mA's are going to the battery, or how much drain is occurring; I've found it good to test different USB power supplies I've accumulated over the years.
cheers!
Steph S.
I'm actually surprised that the N7 will charge off a computer at all; ASUS's other products specifically say they will not charge via USB to PC and require the 2A adapter. The N7 will charge, but only if it's asleep; If the screen is on, it'll draw too much power to be able to charge the battery, resulting in a slower drain, but a drain none the less.
Pick up an app like battery monitor and it'll show how many mA's are going to the battery, or how much drain is occurring; I've found it good to test different USB power supplies I've accumulated over the years.
cheers!
Steph S.
It is a big battery and the manual does state that it will charge slower and only if the screen is off.
I guess I wasn't clear......after a little research, I've found out that to get the Nexus 7 to charge as if its being charged via the AC charger you need to have the data pins shorted, and that is what a USB charging cable does and allows you to charge at the AC adapter rate. I've since found a cable on Amazon that should work, but want to know if anyone has such cable and if it works on the Nexus 7.
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pawber
Active member
Charge rate depends on the usb source, some only supply .5 amp. Most older computer usb ports are not going to charge as fast as an ac adapter.
I got this cable yesterday from Amazon. It took a couple of weeks to get here but does seem to charge as fast as the short cable with my ASUS Nexus 7 recharger. It was $2.39 and no shipping cost.
GTMax 6ft. USB 2.0 A to Micro-USB Cable for T-Mobile Samsung Galaxy S 4G
GTMax 6ft. USB 2.0 A to Micro-USB Cable for T-Mobile Samsung Galaxy S 4G
Thanks for the info but I have already ordered this cable from Amazon. Charge Only PureGear Cable (Retail Package) for Universal Micro USB....may have over paid but it has good reviews. We'll see how it comes out.
If you want to see it charging, you need a charge only (no data pins connected). And some chargers won't charge at all with a standard sync cable, like my iPad charger that I bough because of its high output.
Interesting, I've never had a problem charging my 2 N7s with a plain old micro USB cable.
Like others have said, the charger is the key in this. There are basically three types of chargers: USB port, 1 Amp and 2 Amp or higher. (yes, I know this is a simplification)
Apple chargers look at the signal lines as a request for higher power - I don't bother with them since they tend to be ridiculously expensive compared to other chargers.
Like others have said, the charger is the key in this. There are basically three types of chargers: USB port, 1 Amp and 2 Amp or higher. (yes, I know this is a simplification)
- USB Port: Using a computer USB 2.0 port, the best you will see is .5 Amp and that's going to take a while. Some (most?) computers expect the device to ask for .5A and, if they don't, only supply .1A. A USB 3.0 port can deliver a little more but it doesn't change the basic point here.
- 1 Amp: A standard phone charger is typically a 1A device and will charge the N7 but will take longer, especially if powered on while charging.
- 2 Amp or higher: The official Asus charger that comes with the N7 is a 2A charger. I have several 2A or greater chargers and they all charge the N7 pretty fast. I see a number of chargers listed as 2.1A
Apple chargers look at the signal lines as a request for higher power - I don't bother with them since they tend to be ridiculously expensive compared to other chargers.
More on this charging redux. Doing a little math on the specs (4200 mAh battery, USB current ratings, 10 hr run time) gives some interesting numbers. Average draw will be on the order of 400 mA (though probably a bit less as batteries don't give all their energy). A PC with USB 2.0 can deliver up to 500 mA so a running N7 would have around 100 mA to put into the battery which would lead to a charge time of 42 hrs. Even with the N7 off, it would take 9 hrs to fully charge the battery. Needless to say, the PC port is a very poor choice though worth it in a pinch.
A good 2A charger will take about 2 hrs to charge a powered down N7 and about 4 hrs to charge a running one. Some where in between for a sleeping one.
Apple devices and chargers use the data lines of the USB cable to signal how much power the device will take. In fact, a charger that doesn't do anything with the data lines, can't be used to charge an apple device - it will complain about incompatible charger. If you try to charge an N7 with an apple charger, it's not clear what will happen. I wouldn't try it. If you care, adafruit did some reverse engineering of apple's USB power protocol.
Disclaimer: these are rough calculations and don't take into account things like battery age, temperature and other things.
A good 2A charger will take about 2 hrs to charge a powered down N7 and about 4 hrs to charge a running one. Some where in between for a sleeping one.
Apple devices and chargers use the data lines of the USB cable to signal how much power the device will take. In fact, a charger that doesn't do anything with the data lines, can't be used to charge an apple device - it will complain about incompatible charger. If you try to charge an N7 with an apple charger, it's not clear what will happen. I wouldn't try it. If you care, adafruit did some reverse engineering of apple's USB power protocol.
Disclaimer: these are rough calculations and don't take into account things like battery age, temperature and other things.
ShinyTop
Well-known member
Since the cable that comes with the N7 is both data and charges at high speed with a good charger I don't believe it has anything do with whether or not it is a data cable, too. I have an external battery with a 2A port and a car charger with a 2A port. Both indicate AC charging when I look at the battery app in the OS.
ok well i have similar problem i have a HD tablet and somehow i messed up and managed to bend the metal parts on the cable. From a store near me i got a "replacement" that i was told it was same but i noticed it did not want to charge properly was dead slow. anyway also own a Kindle lite and that one came with its own cord so i used that cord and charged it just fine. i think that any amazon kindle product UPS cables would work??
Just to sum up and clarify what people are experiencing.
These cables seem to be few and far between, you might try 6ft Micro USB Android Phone Tablet Fast Charger Cable AC DC Samsung Galaxy | eBay
Or the easiest way I've seen to mod it without the hassle of soldering is to stick some self adhesive foil tape over the center 2 pins in the USB socket on the charger. When the
data cable is plugged in it will then short the data pins fooling the device into thinking the charger is "Normal". Not sure how long that will last with constant insertion and removal
though.
Permanent mod to charger is here Samsung Galaxy Phone Rapid Charger Mod - xda-developers
Hope this helps.
- The USB "PC" connection standard limits power output.
The USB "CHARGING" standard allows higher output BUT this must be signalled by chargers shorting the data pins which a PC would use for syncing.
Apple ignore the standard and use the data pins to signal how much power the charger can give. Apple devices will not charge from a charger
that conforms to the International standard which shorts the data pins.
Device manufacturers who comply with the standard will short the data pins on their original (OEM) chargers and this is picked and carried by any standard
data cable.
Third party charger manufacturers who want to capture the Apple market do not short the pins. This means that when an Android device uses
a normal data cable it thinks it's connected to a PC and only draws the lower amount of power.
If you short the data pins on the third party charger OR on the cable, the International standard compliant device will draw the full current it can take
up to whatever that charger can provide.
These cables seem to be few and far between, you might try 6ft Micro USB Android Phone Tablet Fast Charger Cable AC DC Samsung Galaxy | eBay
Or the easiest way I've seen to mod it without the hassle of soldering is to stick some self adhesive foil tape over the center 2 pins in the USB socket on the charger. When the
data cable is plugged in it will then short the data pins fooling the device into thinking the charger is "Normal". Not sure how long that will last with constant insertion and removal
though.
Permanent mod to charger is here Samsung Galaxy Phone Rapid Charger Mod - xda-developers
Hope this helps.
Re: warning...
I just came across this thread from Google search. Here's what I have learned about USB cables from various sources.
If you make a custom cable, you need to make absolute certain that it does not go into a computer.
There are four pins that are used as part of orthodox USB. +5v, ground, data+ and data -. Micro and mini connectors also have a discretionary 5th pin and its use is completely at the device designers discretion.
Even cables with 5 pin connectors on both ends have a 4-wire cable with omitted 5th pin.
It is the phone itself that regulates how much current it draws. There are two means of doing so. With the use of 5th pin, or without. Charging current is decided by manipulating the data pins or the 5th pin to signal the phone to select the current range, or the "speed limit" so to speak.
LG phones for example receives "ok to pull 0.7A" by shorting data pins. Permanent cord LG chargers do this by a jumper molded into the phone-end connector. Detachable LG chargers do this by shorting data pins on the charger side.
A universal charger I have has a USB port, and comes with a cord that has normal USB male connector on charger and and connection for detachable tips on the other end. On this design, the jumper is built into the tip. This is a bad idea, because it authorizes the phone to draw 0.7A regardless of where its hooked up. If you take this cord and hook it up to a computer, car stereo or etc, it will draw 0.7A from the device and can lead to very expensive damage to your computer much the same way as using a universal adapter in wrong polarity or voltage. Rather than just short vs open, device manufacturers are free to do such things as data - hooked to +5v, or 12k ohm between data - and + or whatever.
Garmin GPS units take another approach and uses a 14.7 kohm resistor on 5th pin built inside the device end of cable to tell the unit its ok to pull 1A. This type of cable is difficult to emulate, because you'll need a pigtail with five pin connector on one end and loose wires on the other and this is not something you find easily.
So, base universal charger will just apply 5v between + and - and it is restricted to 0.5A charging. A real universal charger that allows full speed charging would have a permanently attached cord, and have 5 pins coming to the tip end, and have a 5-pin attachments for device specific application.
I just came across this thread from Google search. Here's what I have learned about USB cables from various sources.
If you make a custom cable, you need to make absolute certain that it does not go into a computer.
There are four pins that are used as part of orthodox USB. +5v, ground, data+ and data -. Micro and mini connectors also have a discretionary 5th pin and its use is completely at the device designers discretion.
Even cables with 5 pin connectors on both ends have a 4-wire cable with omitted 5th pin.
It is the phone itself that regulates how much current it draws. There are two means of doing so. With the use of 5th pin, or without. Charging current is decided by manipulating the data pins or the 5th pin to signal the phone to select the current range, or the "speed limit" so to speak.
LG phones for example receives "ok to pull 0.7A" by shorting data pins. Permanent cord LG chargers do this by a jumper molded into the phone-end connector. Detachable LG chargers do this by shorting data pins on the charger side.
A universal charger I have has a USB port, and comes with a cord that has normal USB male connector on charger and and connection for detachable tips on the other end. On this design, the jumper is built into the tip. This is a bad idea, because it authorizes the phone to draw 0.7A regardless of where its hooked up. If you take this cord and hook it up to a computer, car stereo or etc, it will draw 0.7A from the device and can lead to very expensive damage to your computer much the same way as using a universal adapter in wrong polarity or voltage. Rather than just short vs open, device manufacturers are free to do such things as data - hooked to +5v, or 12k ohm between data - and + or whatever.
Garmin GPS units take another approach and uses a 14.7 kohm resistor on 5th pin built inside the device end of cable to tell the unit its ok to pull 1A. This type of cable is difficult to emulate, because you'll need a pigtail with five pin connector on one end and loose wires on the other and this is not something you find easily.
So, base universal charger will just apply 5v between + and - and it is restricted to 0.5A charging. A real universal charger that allows full speed charging would have a permanently attached cord, and have 5 pins coming to the tip end, and have a 5-pin attachments for device specific application.
Re: warning...
Funny, I just went round and round on this with a cellular accessories vendor. They said it was the cord. They were right and I was wrong ;-( My SG4 would not stay charged while navigating with GPS, Bluetooth Music and navigation all going at the same time. So I bought a new car charger that boasted 2A and a 1A charging slot. Problem was that it didn't do any better, or at least not until I called their support and was told that problem was probably the cord. The cord from my old HTC and was pretty good quality. I downloaded an app to test the charging rate. (Works nice) I saw that the old and new charger(s) only showed 460mA to 500mA. I went in the house and tried it on the OEM Samsung Charger and cord. It showed 1900mA (my hat flew off!).
Hmmm, then I took the old HTC cord an plugged it into the Samsung charger(on A/C). It got exactly 500mA. So finally I took the Samsung OEM charging(and data) cord out to the car and found out that it charged the SG4 at 1900mA. The lower side of the car charger now charged at 1200maA which is also enough to gain ground white navigating. As noted above the OEM Samsung cord is also a data cord but it still chargers at the higher rate. I am not sure why.
I cannot tell from the marking on the cord the difference in the specification. The Cord I bought from the vendor looks almost exactly like the OEM cord but it tops out a 500mA. Until the standard that works is identified and marked we will all have to use the OEM cord supplied with 2A chargers.
-Bopity
Funny, I just went round and round on this with a cellular accessories vendor. They said it was the cord. They were right and I was wrong ;-( My SG4 would not stay charged while navigating with GPS, Bluetooth Music and navigation all going at the same time. So I bought a new car charger that boasted 2A and a 1A charging slot. Problem was that it didn't do any better, or at least not until I called their support and was told that problem was probably the cord. The cord from my old HTC and was pretty good quality. I downloaded an app to test the charging rate. (Works nice) I saw that the old and new charger(s) only showed 460mA to 500mA. I went in the house and tried it on the OEM Samsung Charger and cord. It showed 1900mA (my hat flew off!).
Hmmm, then I took the old HTC cord an plugged it into the Samsung charger(on A/C). It got exactly 500mA. So finally I took the Samsung OEM charging(and data) cord out to the car and found out that it charged the SG4 at 1900mA. The lower side of the car charger now charged at 1200maA which is also enough to gain ground white navigating. As noted above the OEM Samsung cord is also a data cord but it still chargers at the higher rate. I am not sure why.
I cannot tell from the marking on the cord the difference in the specification. The Cord I bought from the vendor looks almost exactly like the OEM cord but it tops out a 500mA. Until the standard that works is identified and marked we will all have to use the OEM cord supplied with 2A chargers.
-Bopity
I know I'm a year late on this but for others who've just found this, the cable that comes with the N7 is a standard USB charge/data cable. However the charger that comes with the N7 has the data connections already shorted. To get the same charge rate with a standard wall charger, you do need a data only USB cable (has the data pins shorted). If you use a standard charger and a standard cable, so the data connections are there, the charge rate will be very slow and may not show as charging at all.
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