I'm going on holiday soon and we planned to take a USB hub to charge all of our devices rather than take several wall adapters, however when I checked that my 7" Samsung Galaxy Tab 3 would charge, I found that it didn't. After investigating, I found that my iPad charger wouldn't charge it either and in fact the only that would charge it was the USB wall adapter that came in the box with the tablet, even though the port on the USB hub and the iPad charger are rated at 2.1 A (5 V).  When I plug the tablet into to a non-Samsung adapter powered off however, the screen flashes lighter and darker but nothing else happens which seems odd behavior to me.  What is the reason it will not charge by any other means, and is there a solution?
121497
The USB has various purposes for data transfer, movement of input and output signals for hardware like connecting an Android device to another Display screen (USB on the go), charging the device etc.(during a device charge the voltage drawn from the USB is same irrespective of the device or OEM then Why are two USB Cables different ?  A USB of one manufacturer may not be supporting another manufacturer. We get problems if we do connect them like      or
12483
The aluminum Macbook Pro gives a mild shock when connected to a wall socket and charging. It only happens when I'm, for example, not wearing shoes or slippers and my feet are resting on the ground (i.e. by body is acting as a conductor). I contacted apple and I was told to perform the following steps:  Shutdown  hold ⇧+ctrl+⌥+power for 10 seconds  wait 30 seconds then hold ⇧+ctrl+⌥+R+power (Let the Mac reboot three times with that apple tone, then let go. The Mac reboots again.)   This did not fix the problem and I was not told what these steps were supposed to do. They have asked me to purchase a three pin version of the adapter and see if that fixes my problem. My last MacBook Pro was giving pretty severe jolts towards end of life. Hence a bit concerned. Question  Has anyone here experienced such a problem?  Is anyone aware of what the above sequence of steps supposed to do?  Also, will this damage the Macbook in some way?
44120
Apple's  decision to convert all the ports on their 2016 MacBook Pro lineup to USB-C ports contributes to blur the difference between ports that supply power (such as a power adapters) and ports that can power external devices (such as USB keys, mice or other gadgets).    This made me think about the following scenario: you sit at a table where your laptop is plugged in on the right, and don't notice that it is plugged in, so you decide to charge it with a second nearby charger that is laying around (i.e. belonging to someone who lives with you and who recently sat at the same spot).  What would happen then?   Would the computer charge twice as fast, would one of the chargers be dismissed by the system (which one?), or would it generate a surcharge that would destroy the computer?  I couldn't find anything about this online, but since I am always trying to force a USB in the MagSafe charger of my MacBook Air, I think that I could easily end up making this kind of mistake.  Note: My question asks what happens when two chargers are inserted into a MacBook Pro, but I am also wondering what would happend if 3, or 4 chargers were inserted. Although this scenario is unlikely to happen by mistake, it would constitute an obvious vulnerability to an exposed device, i.e. in a public space.
5421
I purchased a Hubbell "USB Dual Port Charger with 15A Duplex Receptacle" from Lowes to replace the duplex receptacle on my kitchen island.  I first opened the circuit labelled for the island.  The breaker takes two slots.  I removed the existing receptacle and noticed that the brass screws had a black and red wire.  The bridge between the screws was not broken.  I connected the new USB charging receptacle as: white wire to silver screw, bare to green screw, and the black and red wires to the brass screw.  I put everything back together.  When I closed the circuit the fuse blew as well as tripping the mains to the house.  I took the receptacle out of the metal gang box to ensure that it wasn't touching.  I verified the connections as stated above.  With the receptacle hanging outside of the gang box I closed the breaker only to have it and the mains trip.  I reconnected the old simple receptacle and closed the breaker with no problems.  I tried with just the black wire in the new receptacle and it worked!  But now I can't connect the new receptacle with this new red wire.  I researched the uses of the red wire however none of them seem to apply to my kitchen.  The fuse box lists the island as the only part to control and nothing else in the kitchen turned off when I opened the circuit.  There is only one receptacle on the island and no other electrical items including lights.  Why would the kitchen island of only one receptacle require both black and red? why would this USB charger receptacle be so sensitive to two hot wires? why would this single outlet require such a large breaker switch?  And finally... is there anything I can do so that I can install this receptacle?  Thanks!
45582
I will travel from USA to London in Aug. I want to buy an iPad in USA which will work with a data sim card, which I assume to be available in London.  Questions:    Which type of iPad has the highest probability of working with a data sim card bought in London? Also, once I land in London with my iPad, what would be an optimal type of data sim card?   I hope to find people who are walking around in London now with a data sim card in their iPad. I'd like to find out how happy they are with the service and any pitfalls which might await me.  I have studied ; it told me to contact my carrier, so I called T-Mobile USA and found them not to be knowledgeable. I spent lots of time on their site and talking to phone support. Also I tried contacting T-Mobile UK via their website and gave up after it seemed they want me to have a UK phone to set up an account.
86412
I have powerbank that provides 5v (presumably regulated) power, as typical of most usb interface powerbanks. I have been trying out my powerbank with different phones. It works on all except one. I have tried it with various USB cables, making sure I didn't overlook anything foolish. Then, I looked at the AC adapter of the phone that it didn't seem to be compatible with. The adapter read: 5.4v DC output. The device's official website or manual doesn't tell me what the input voltage should be. So I have the following questions   Is the fact that the device's AC adapter creates a DC 5.4v output enough to assume that, this is the correct voltage for my cell phone? If 5.4v is the input voltage, then when I attempt to power it with a 5v power bank, am I hurting it? Thus far, it just seems to be non-responsive when I try this. It seems another explanation is polarity mismatch. I'm aware that laptops have a polarity correction feature, which could explain why I can charge this phone via my laptop. Is there any other way to tell if polarity is an issue, given that I don't have access to detailed product information (unless the official website is updated, or something)   So that's the gist of it, I'm not sure why my powerbank isn't charging my phone. And I'm having difficulty troubleshooting the underlying problem by myself. Any tips big or small will be appreciated.
79712
I experienced this behavior two days ago (My MacBook Air is late 2011 version (4.2):   I can still power up my Mac, with or without MacSafe charger connected Battery is not charging There is no light. I tried to reset SMC but it does not help Battery condition is normal I tried with few different MagSafe charger but still can't charge my MacBook Air   What is the problem and what should I do?  Here is the result of System Information:  Battery Information:    Model Information:   Serial Number:    xxxxxxxxxx   Manufacturer: SMP   Device Name:  bq20z451   Pack Lot Code:    0   PCB Lot Code: 0   Firmware Version: 406   Hardware Revision:    000a   Cell Revision:    162   Charge Information:   Charge Remaining (mAh):   4743   Fully Charged:    No   Charging: No   Full Charge Capacity (mAh):   5788   Health Information:   Cycle Count:  269   Condition:    Normal   Battery Installed:    Yes   Amperage (mA):    0   Voltage (mV): 8032  System Power Settings:    AC Power:   System Sleep Timer (Minutes): 10   Disk Sleep Timer (Minutes):   10   Display Sleep Timer (Minutes):    10   Wake on AC Change:    No   Wake on Clamshell Open:   Yes   Wake on LAN:  Yes   Current Power Source: Yes   DarkWakeBackgroundTasks:  1   Display Sleep Uses Dim:   Yes   PrioritizeNetworkReachabilityOverSleep:   0   Standby Delay:    4200   Standby Enabled:  1   Battery Power:   System Sleep Timer (Minutes): 10   Disk Sleep Timer (Minutes):   10   Display Sleep Timer (Minutes):    2   Wake on AC Change:    No   Wake on Clamshell Open:   Yes   DarkWakeBackgroundTasks:  0   Display Sleep Uses Dim:   Yes   Reduce Brightness:    Yes   Standby Delay:    4200   Standby Enabled:  1  Hardware Configuration:    UPS Installed:    No  AC Charger Information:    Connected:    Yes   ID:   0x0000   Revision: 0x0000   Family:   0x0000   Serial Number:    0x00000000   Charging: No
40979
I have an HP Chromebook and a Nexus 6P smartphone, and both of them use USB-C connections for charging.  When I plug the Chromebook into the Nexus's charging cable, it works fine and I just get a message that says I am connected to a "low-power charger".  However, is it safe to plug the cell phone into the laptop's power supply?  I'm afraid that doing so might fry the phone.
117524
I own a 2016 Macbook (with the USB-C charging) - at the time and in response to all of the reports of poor cables and poor chargers, I bought a meter so I could see what the throughput of my cables/chargers was. However, having run some tests I'm now not sure what to consider normal / what is harmless to the battery.   For all tests I used an original Apple C-C cable - though was able to replicate with two third party cables I own.  I have the original Apple block charging at 14.3 V / 1.99 A and a third party block that charges the same.  Another third party block which advertises USB PD and 3 A is currently charging at 20 V / 1.43 A  I've done some research online but I can't find any articles that indicate what a normal USB PD output is relative to the devices that connect to it and would appreciate any guidance / assistance.   TL;DR: Have Apple charger which charges at one voltage/amperage. Bought several others advertised at PD which are higher voltage, lower amperage. Not sure what is 'safe', or 'fast', or does least overall damage to battery.
91689
I'm about to buy an iPhone XR. Technical specification says it's possible to charge 50% of the battery in 30 minutes. However, seems that the provided 5W charger is not able to do that. I've been in the Apple Store and they said I need an iPad charger, but which one?  When a search for "charger" and filter for "XR model," I get . Is it the correct one?
87952
If the host computer for an USB device doesn't provide enough power for a device which has no dedicated power port, can I connect the power-only-plug of a Y-USB-cable to an other computer, an USB-charger or even a regular mobile charger? I'm afraid this could damage some of the devices.  Edit: The device in question is a USB Hard drive (Samsung S2 Portable 640GB (but on the back it's written to use 0.85A)) which is supposed to work whit just a single USB port. It did so well on a other laptop and whit some cables even on my actual net book back in Europe. But now in Malaysia it works only some times (I still try to figure out what the conditions are) and then it stops working after a while (maybe when it goes to power save mode). I heard from others their hard drives need one more power plug here in Malaysia to but can't imagine why...
77723
Possible Duplicates:             I have an ASUS K50IN laptop which requires an input of 19&nbsp;V at 3.42&nbsp;A. Its charger has stopped working (wires cut by rats!). My brother have a charger that is 19&nbsp;V, 7.1&nbsp;A. Their polarity is the same and the tip fits correctly.. Can I use this charger on my laptop?
39136
MacBook Pro (15-inch, 2016) with 2 USB-C to HDMI adapters. The setup works great if I start up in that configuration.   If I connect the adapters while the machine is running or simply sleeping, one of the monitors will never get a signal and stay in low power mode. The OS sees the monitor, it shows in the display arrangement settings and I can move the mouse into it, but until I restart, I can't see anything on it.  Once I have restarted I can let the machine sleep or whatever, and the display still works unless I disconnect the adapter. As soon as I do that a restart is required to use it again.   Using MacOS Sierra (10.12.4)  Using this adapter:
91587
I'm attempting to connect to an Android smartphone (Samsung Galaxy S3) whose screen is broken (i.e. completely black) in order to save all files on it. The whole phone is (almost) completely beyond repair as the USB slot does not allow for a stable connection at all. Even though I already attempted to fixate the USB cable with duct tape (I'm not kidding), this is what I always end up with (according to dmesg):  [  750.075987] usb 1-1.6: new high-speed USB device number 14 using ehci-pci [  750.186084] usb 1-1.6: New USB device found, idVendor=04e8, idProduct=6860 [  750.186091] usb 1-1.6: New USB device strings: Mfr=1, Product=2, SerialNumber=3 [  750.186095] usb 1-1.6: Product: SAMSUNG_Android [  750.186098] usb 1-1.6: Manufacturer: SAMSUNG [  750.186101] usb 1-1.6: SerialNumber: 9baf4266 [  780.783212] usb 1-1.6: USB disconnect, device number 14 [  793.596612] usb 1-1.6: new high-speed USB device number 15 using ehci-pci [...] [  852.507428] usb 1-1.6: USB disconnect, device number 15 [  866.039114] usb 1-1.6: new high-speed USB device number 16 using ehci-pci [...] [  944.407661] usb 1-1.6: USB disconnect, device number 16 [...]  I.e. the connection is reset roughly every minute due to USB connection problems. I'm on Debian 9 and use libmtp. The command &quot;mtp-detect&quot; always fails with the following output:  libmtp version: 1.1.13 Listing raw device(s) Device 0 (VID=04e8 and PID=6860) is a Samsung Galaxy models (MTP). Found 1 device(s): Samsung: Galaxy models (MTP) (04e8:6860) @ bus 1, dev 14 Attempting to connect device(s) PTP_ERROR_IO: failed to open session, trying again after resetting USB interface LIBMTP libusb: Attempt to reset device inep: usb_get_endpoint_status(): No such device outep: usb_get_endpoint_status(): No such device libusb_open() failed!: No such device LIBMTP PANIC: Could not init USB on second attempt Unable to open raw device 0 OK.  My question is: Is there any way to use libmtp (or any other free software) to (bash) copy files from my Android device to my laptop via an unstable connection? Thank you very much for any suggestions.
32964
This is something I always wondered about: when I leave my charger plugged on the wall socket but not charging anything, is it still consuming energy?   Some notebook chargers have a led that is always on, so I guess it's consuming at least a bit. But what about Apple chargers? I want to leave my iPhone and iPad chargers always plugged under my desk (so I can just connect my device when I want to charge) but I'm worried they shouldn't be plugged all the time due to safety risks or phantom power consumption.  Is there any way to measure this to be sure?
12549
I have found that many USB wall chargers use a resistive voltage divider to set the D+ and D- pins to a specific voltage, usually between 2 and 3 volts.  Other USB wall chargers short the D+ and D- pins together with no connection to anything else.  From my experience some devices will not accept a charge rate above 500mA on the chargers using the voltage dividers, but will charge up to their max input on a charger with the data pins shorted. I have read things that suggest the opposite may be true as well, but have been unable to verify this. I am hoping to figure out which method provides the best compatibility with all USB devices.
103182
I have a few day old Nexus 7 tablet, unrooted, bootloader still locked, and otherwise in factory condition. This morning, it ran its charge out. When I plugged in it, this happens:   Google Logo appears. Nexus Logo appears. Lock screen which shows charging: 0%. White screen, device powers off. Repeat.   What is happening? Thanks!