I've read that the Nexus 7 charges via regular micro USB (no proprietary port or cable) and that the charger is a 2A charger. Has anyone figured out the proprietary aspects of the charger that signal to the Nexus 7 that it's connected to the charger and that it's ok to draw 2A?
Bump.
I think it just dumps 2A into all the devices. 99% of USB devices have resistors in them to limit the current
Sent from my Nexus 7 using xda app-developers app
It needs a 2amp charger... 1amp will keep it on indefinitely but wont charge... with less than 1amp (say keyboard USB port) the battery will lowly drain on while the power indicator shows charging and eventually the screen will go nuts and the device will crash/shutoff
Sent from my Nexus 7 using xda premium
pixelchemist said:
It needs a 2amp charger... 1amp will keep it on indefinitely but wont charge... with less than 1amp (say keyboard USB port) the battery will lowly drain on while the power indicator shows charging and eventually the screen will go nuts and the device will crash/shutoff
Sent from my Nexus 7 using xda premium
Click to expand...
Click to collapse
Don't think you are accurate. If computer usb can charge the device (0.5A from usb port on computer), any charger can charge n7, albeit charger with lower current will take longer to fully charge the device. Tried 1A charger on N7, no problem.
Sent from my Galaxy Nexus using xda premium
There is the standard CYA in the manual to only use the cable and charger supplied with the unit. If it is fully powered down, pretty much any microUSB will charge it... eventually. That's not necessarily the best thing for the battery. If the power is under 2A as suggested, depending upon what you're doing with the tablet, it may just be enough to keep it running, or, could actually drop to zero even in use. (This happened with my Nook Color, for example). YMMV, but on the stock charger, the recharge is pretty quick. My only quibble is that there is no notification light to alert you to charge completion, or other notifications you might get (gMail, texts through Google voice, etc.).
tylerwatt12 said:
I think it just dumps 2A into all the devices. 99% of USB devices have resistors in them to limit the current
Sent from my Nexus 7 using xda app-developers app
Click to expand...
Click to collapse
This is incorrect. It's not up to the charger to push 2A, but rather up to the device to pull 2A through signaling of specific voltages on the data lines. For example, if you were to normally plug any tablet besides an iPad into an iPad charger (2.1A), the most you can expect to pull is 1A because the tablet doesn't know that it's connected to a 2.1A charger. The internals of the iPad charger will only tell an iPad that it's connected to a 2.1A charger. In order to charge at 2A with another tablet on the iPad charger, you need to do something like this example with the Galaxy Tab:
http://forum.xda-developers.com/showthread.php?t=845844
Or buy a pre-made adapter:
http://www.dealextreme.com/p/usb-ma...ung-galaxy-tab-p7500-more-black-127843?item=6
So the Nexus 7 charger must have something going on to tell the Nexus 7 that it's connected to the right charger because it can't try to pull 2A from every USB port that it's plugged into (some computers will actually shut down if something tries to draw too much power through the USB ports).
bitbearmi said:
My only quibble is that there is no notification light to alert you to charge completion, or other notifications you might get (gMail, texts through Google voice, etc.).
Click to expand...
Click to collapse
NoLED can alert you about notifications by flashing icons corresponding to the notification on the screen. It turns the screen on, which will obviously drain your battery, but there's a setting to disable turning on the screen when the proximity sensor is "close", so what you can do is put it screen-side down when it's off the charger to keep it from turning on the screen. It's not as elegant as a notification LED or backlight notifications (which is what I'm used to), but it's better than nothing.
Something I'd like to add not sure if its true but it was an explanation relating to this I saw when shopping around for an in car charger and makes some sense.
Android will reduce the power it pulls from a USB port if it detects it as a data port as opposed to an AC connection in order to conform to the official USB specs.
Apparently some chargers are wired incorrectly (data pins should be cross connected in chargers for it to be recognised as a charger if I remember the description) and will be picked up as a data port. Some devices will just use as much power as possible on data ports but ones that conform to the specs will take only the amperage outlined in USB specs.
Like I said its just something I remember don;t shout at me if I'm talking mince.
Sent from my Transformer while the N7 is lost in the Play Store Black Hole.
16gb N7 UK ordered 3rd July.
It's mildly related to proper charging. Basically, for any tablet, there are three charging states. The first is USB mode, where the data pins aren't shorted (as if the device was connected to a computer's USB port), which draws a maximum of 0.5A. The second is AC mode, where the data pins are shorted, which draws a maximum of 1A. The third mode is what I'll call high speed AC, and this is the mode we're after. Not only are the data pins shorted, but voltage is being applied to the data pins in a specific way to each device family. When the device detects this mode, it'll think that it's connected to its own charger and try to draw up to 2A.
Every device family has its own required voltages on the data lines, and by families, I mean products that have interchangeable chargers (like iPads, Galaxy Tabs, Transformers, etc) so if we can figure out what the Nexus 7 needs, then we can use any 2A charger with it (like using an iPad car charger). I just realized that others have said that they were able to charge at high speed with their Transformer charger, so I suspect that we can refer to Transformer charging adapters to get it working.
I haven't taken apart my Nexus 7 charger to see what's inside mainly because I've only got the one...
but I did verify that the D+ and D- pins on the USB are shorted, but there is no discernable voltage being applied to either.
So I set up my meter (and sacrificed my really short asus OEM charging cable) to measure the current draw while charging... this is what I found:
OEM charging cable appears to be just a regular old USB cable, unless there is something happening in the micro usb end, which I really doubt.. but I don't have any adapter to check if this is the case.
When D- and D+ are floating and not shorted together, the Nexus 7 draws ~1A but the charging indicator does not come on.
When D- and D+ are shorted together the Nexus 7 draws ~1A and the charging indicator does come on.
I could not get the Nexus 7 to draw 2A. Maybe I broke something
-J
Thanks for making the sacrifice. I guess more testing is needed.
I think the theory that it doesn't draw more than 1.0a may be correct. But it is still finicky about the charger. I have a palm OEM charger with palm cable and it doesn't charge the N7. I have a Nokia 1.2a charger and Blackberry 1.8a charger and they both seem to charge near the same rate, as fast as the Asus OEM charger.
Just as another data point, I tried connecting my n7 to the ipad ac charger, which is a 2A charger. It doesn't charge at all against the ipad charger.
kmandel said:
Just as another data point, I tried connecting my n7 to the ipad ac charger, which is a 2A charger. It doesn't charge at all against the ipad charger.
Click to expand...
Click to collapse
Anybody with the N7 that charges on the iPad charger? If so, I want to return it.
Domi
Limited charging options
dmalovic said:
Anybody with the N7 that charges on the iPad charger? If so, I want to return it.
Domi
Click to expand...
Click to collapse
It won't charge off an OEM iPad charger, just checked. It also won't charge off a Monoprice 3x outlet with 2x 2.1a usb directly connected to the usb ports or a 2.1a backup battery. Damn device is really picky about the source.
It will charge off my Touchpad and Vizio tablet charger.
I'm really bummed out it won't charge off the monoprice 3x outlets 2x usb since I bought a bunch of them when they were on sale and put them through out my house.
kkeo said:
It won't charge off an OEM iPad charger, just checked. It also won't charge off a Monoprice 3x outlet with 2x 2.1a usb directly connected to the usb ports or a 2.1a backup battery. Damn device is really picky about the source.
It will charge off my Touchpad and Vizio tablet charger.
I'm really bummed out it won't charge off the monoprice 3x outlets 2x usb since I bought a bunch of them when they were on sale and put them through out my house.
Click to expand...
Click to collapse
Same here.. just tried an ipad charger and it didn't work.. this is the oem ipad 3 charger. Also tried ipad 1 charger (should be same thing) didn't work.. going to try a charger for a Dell Streak 7.. see if it works.
Mine is also very picky. I used the stock Asus charger with a longer micro usb cable and it didn't charge while I was using the tablet over a period of around an hour. It maintained the % charge of the battery but didn't increase it. When I went back to the stock cable, it charged during use. Wouldn't be a real big deal if they hadn't scrimped on the cable to where it's only 3 feet long. What a pain.
A little OT, but my ASUS 1366 motherboard has an update you can install that allows the USB ports to charge an iPad at 1 amp instead of the normal .5 amp. I haven't tried it with the N7, but I suspect it won't work. Maybe another update will be released considering they make both devices, although my mb is kind of old...2009. I wonder if the USB2 specs allow for 2A charging and also if the newer USB3 spec allows more amps to be provided. If it doesn't, it should considering some of the latest power hungry devices.
Sent from my Nexus 7 using xda app-developers app
I looked at this too, and tried a few different configurations.
Measurements taken with my N7 at 95% charge. I expect higher power draw at lower charge.
.445mA - PC USB port
.440mA - APC USB battery pack directly connected
.443mA - iPhone 3G USB charger
.820mA - stock charger
.815mA - APC USB battery pack with D+/- disconnected at the host and shorted at the device end (actually 10 ohm resistor)
.818mA - APC USB battery pack with D+/- removed on host, shorted on device, and resistor divider for 1.2V on both pins (Samsung type)
I chose the APC battery pack as it provides a solid 5V at 1A. It also has D+/- wired iPhone-style.
Wondering what the charger driver thinks of this, I looked at dmesg just after every attempt. I see:
connected to PC USB:
Code:
smb347_charger: [cable_type_detect] Reg3F : 0xc0
smb347_charger: [cable_type_detect] Reg3E : 0x0c
Cable: SDP
========================================================
battery_callback usb_cable_state = 0
========================================================
connected to iPhone or APC charger:
Code:
smb347_charger: [cable_type_detect] Reg3F : 0xc0
smb347_charger: [cable_type_detect] Reg3E : 0x0b
Cable: OTHER
========================================================
battery_callback usb_cable_state = 0
========================================================
connected to stock, or APC with either of my adapters (cut & shorted or Samsung):
Code:
smb347_charger: [cable_type_detect] Reg3F : 0x83
smb347_charger: [cable_type_detect] Reg3E : 0x0a
Cable: DCP
========================================================
battery_callback usb_cable_state = 3
========================================================
So the charger limits to ~500mA when using an iPhone-pinned charger (OTHER) or a live USB host (SDP), and allows high current charging when D+/- is shorted regardless of being pulled to a given voltage. SDP is USB 2.0. charging spec terminology for Stanard Device Port, meaning a 500mA limited USB port, while DCP means Dedicated Charging Port which means that D+/- are shorted and can supply up to 1.5A.
This uses the SMB347 USB charge controller, same as the Kindle Fire, which works the exact same way.
TL;DR: Cut D+/- between the charger and device and short D+/- at the device for full current charging.
Related
Hi all! I have a htc diamond wall charger. As some of you might know, it plugs to a usb cable. Can anyone tell me if i can plug sgs data cable to the diamond's wall charger and charge the SGS?
Yes, you can. But it probably will only charge at a slower rate @ 500mA. Sometimes, when battery level is very low, 500mA probably won't be enough to start the charging. So, don't leve home without the OEM charger.
Yes, you can. I do this using a miniUSB to microUSB adaptor plug that I keep on the end of a USB-A Male to miniUSB cable.
From memory, the HTC charger is rated at 5.0V @ 1.0A, which is greater than the OEM Galaxy one (700mA I think?). I even use the same microUSB plug with the HTC car charger for the Galaxy.
Yes, the stock HTC charger is probably rated at 1A but SGS is very picky about the charger. Unless the charger is properly terminated, the phone will only use regular USB mode (500ma MAX). You can check which mode your phone is charged as by going to Settings->About Phone->Status->Battery Status. If it says "Charging (AC)", it recognizes the charger as AC charger and can charge at higher current (up to 1A). If it says "Charging (PC USB)", it does not recognize the charger as AC charger and charges at 500mA max mode.
Update: my HTC charger from my AT&T Pure (TD2) shows up as AC charger for my SGS. So, it should operate in full 1Amp mode.
I went out of town this week and made sure to grab my USB cable, but left the AC adapter at home figuring I'd just charge off my laptop via usb. Apparently not... I also tried plugging the USB cord into my iPhone AC/usb adapter with no luck. The only thing I've found is that when you turn off the Tab and connect to one of these devices, a green battery indicator will pop up showing that it is charging. Well, after about 16 hours, it made it from 15% all the way up to 48%. Does anyone know any way around turning it off to charge or why it is barely charging when it is off?
Jaydawgx7 said:
I went out of town this week and made sure to grab my USB cable, but left the AC adapter at home figuring I'd just charge off my laptop via usb. Apparently not... I also tried plugging the USB cord into my iPhone AC/usb adapter with no luck. The only thing I've found is that when you turn off the Tab and connect to one of these devices, a green battery indicator will pop up showing that it is charging. Well, after about 16 hours, it made it from 15% all the way up to 48%. Does anyone know any way around turning it off to charge or why it is barely charging when it is off?
Click to expand...
Click to collapse
Well seeing as it has a 7000mAh battery, just about any run-of-the-mill USB charger isn't going to cut it. The amperage would have higher as well. Now i would hazard that an iPad charger (10 watts) would probably work just fine vs an iPod charger.
Your laptop's USB port isn't providing enough juice to charge fully. With the screen off it will only trickle charge and very slowly at that.
You'll need at least 5 Volt 2 Amp chargers.
You can also try this:
http://forum.xda-developers.com/showpost.php?p=14890063&postcount=16
Or this:
http://cgi.ebay.com/190522553195?ru...ee-All-Categories&_fvi=1&_rdc=1#ht_3085wt_905
I've ordered both last week but neither have arrived yet. I'll report back.
You need a 5vdc supply that will provide 2A. 10W, not 5w as the previous post said. That adapter on ebay won't help the charge, it just disconnects the data line so it does not change its mode when connected to a computer. There are a lot of power supplies that will work and even more that won't, just made sure it supplies 2a. If you want to charge off your laptop then you will want a Y adapter similar to what is on usb powered hard drives but even then you will need to use 2 usb 2.0 or 3.0 ports and will provably only get 1a out.
Sent from my GT-P7510 using XDA Premium App
I have been closely watching these threads and found some mixed results.
http://forum.xda-developers.com/showthread.php?t=1791717
http://forum.xda-developers.com/showthread.php?t=1780211
http://forum.xda-developers.com/showthread.php?t=1793059
http://forum.xda-developers.com/showthread.php?t=1781680
http://forum.xda-developers.com/showthread.php?t=1784322
http://forum.xda-developers.com/showthread.php?t=1785976
So, I conducted some experiments and the results are below. For those of you that don't care for the data, you can scroll down to the CONCLUSION.
Some of the information presented here are derived directly from the above threads and from the Internet. All values are approximate and measured using a digital multimeter. Some of you may already know but for the sake of other readers, I will be using the following terminology and acronyms.
AWG = American Wire Gauge. The thickness or the diameter of an electrical conductor(s) within a single wire. Most flexible wires contain multi-stranded conductors instead of a single solid conductor. The important thing is, as the AWG number DECREASES, the thickness of the conductor INCREASE. Thicker wires can carry more current
OEM = Original Equipment Manufacturer
Connector Pigtail = A connector with its individual wires exposed and part of the wire's insulation removed as a means to perform electrical measurements.
(XX / YY) = "XX" represents the AWG of the data wires (D+ / D-). "YY" represents the AWG of the power / ground wires (+5v / GRN). Some USB cables will be imprinted with its rating on the cable itself such as "28AWG/1P 26AWG/2C". I will be referring to this cable as (28/26) meaning the data cables are 28AWG and the power / ground wires are 26AWG
USB data wires = The White wire (D-) and the Green wire (D+) contained within the USB cable.
Testing Jig:
1. 12 inch USB A male to USB A female extension cable (28/28) cut in half to produce 1-USB A Male pigtail and 1-USB A Female pigtail.
2. 12 inch MicroUSB B male to MicroUSB B female extension cable (28/26) cut in half to produce 1-MicroUSB B Male pigtail and 1-MicroUSB B Female pigtail. http://www.ebay.com/itm/Micro-USB-B..._USB_Cables_Hubs_Adapters&hash=item3f1497b3e1
3. 18 inch test leads (18 AWG). http://www.harborfreight.com/18-inch-low-voltage-multi-colored-test-leads-66717.html
I used 3 different MicroUSB cables and 1 USB A extension cable:
OEM = 3 feet, unknown AWG (not imprinted on the cable), impedance of power/ground wires = 0.2 ohms, length of MicroUSB male end = 6 mm, resistance / continuity check reveals nothing special. It is a standard MicroUSB cable.
Monoprice = 6 feet, (28/24), impedance of power/ground wires = 0.2 ohms, length of MicroUSB male end = 5.5 mm, resistance/continuity check reveals nothing special. I purchased 2 of this cable. The MicroUSB male end on the other cable measured 6 mm. http://www.monoprice.com/products/p...=10303&cs_id=1030307&p_id=5458&seq=1&format=2
Amazon = 6 feet, unknown AWG (not imprinted on the cable), impedance of power/ground wires = 0.5 ohms, length of MicroUSB male end = 5.5 mm on both, resistance/continuity check reveals nothing special. http://www.amazon.com/Case-Star-Bla...id=1344416273&sr=8-70&keywords=microusb+cable
Generic extension cable = USB A male to USB A female, 6 feet, (28/24), impedance of power/ground wires = 0.2 ohms.
I used 4 different chargers:
OEM = Rated at 2 A, resistance between data pins = 0.5 ohms (shorted).
iPhone 4 OEM charger = rated at 1 A, resistance between data pins = 53100 ohms.
Belkin = 2 port, each port rated at 500 mA, resistance between data pins = 58000 ohms. http://www.amazon.com/Belkin-Mini-Surge-Protector-Charger/dp/B0015DYMVO
AT&T Car charger = An iPhone charger with an auxiliary USB charging port, unknown rating, resistance between data pins = not connected (infinity).
Amperage readings measured at the cable using connector pigtails with test leads and with a completely drained Nexus 7 (Surprising Results!!!):
OEM charger + OEM cable = Charges at 821mA AND displays AC charging.
OEM charger + OEM cable with the data wires disconnected (open)= Charges at 821mA BUT displays Discharging.
OEM charger + OEM cable + Generic extension cable = Charges at 631 mA AND displays AC charging.
OEM charger + OEM cable with the data wires disconnected (open) + Generic extension cable = Charges at 631 mA BUT displays Discharging.
OEM charger + Monoprice cable = charges at 823 mA BUT displays Discharging.
OEM charger + Monoprice cable with data wires shorted = charges at 823 mA AND displays AC charging.
OEM charger + Monoprice cable + Generic extension cable = charges at 635 mA BUT displays Discharging.
OEM charger + Monoprice cable with data wires shorted + Generic extension cable = charges at 635 mA AND displays AC charging.
OEM charger + Amazon cable = charges at 451 mA BUT displays Discharging.
OEM charger + Amazon cable with data wires shorted = charges at 451 mA AND displays AC charging.
OEM charger + Amazon cable + Generic extension cable= charges at 258 mA BUT displays Discharging.
OEM charger + Amazon cable with data wires shorted + Generic extension cable= charges at 258 mA AND displays AC charging.
iPhone 4 OEM charger + all above cable combination = charges at a maximum rate of 635 mA BUT displays Discharging. Increasing the length of the cable decreased the charging rate.
iPhone 4 OEM charger + all above cable combination + data wires shorted = charges at a maximum rate of 635 mA AND displays AC charging. Increasing the length of the cable decreased the charging rate.
Belkin charger + all above cable combination = charges at 259 mA BUT displays discharging. Increasing the length of the cable did not change charging rate.
Belkin charger + all above cable combination + data wires shorted = charges at 259 mA AND displays AC charging. Increasing the length of the cable did not change charging rate.
AT&T car charger + all above cable combination = maximum charging rate of 830 mA BUT displays discharging. Increasing the length of the cable decreased the charging rate.
AT&T car charger + all above cable combination + data wires shorted = maximum charging rate of 830 mA AND displays AC charging. Increasing the length of the cable decreased the charging rate.
NOTE: With the Nexus 7 powered off, all combinations of above chargers and cables, regardless of whether the data wires were shorted or not displayed the charging indicator.
CONCLUSION:
1. Nexus 7 OEM charger is nothing special, just the data pins are shorted.
2. Nexus 7 OEM MicroUSB cable is nothing special. It is a standard MicroUSB cable.
3. Any USB car/wall charger should charge the Nexus 7.
4. Nexus 7 will charge regardless of whether it displays "AC Charging" or not.
5. The charging rate is dependent on the capacity of the charger and the total charging circuit impedance (lower the impedance the better).
6. Increasing the length of the cable increases the charging circuit impedance and decreases the charging rate.
SOLUTION:
1. Use a high quality, high amperage USB charger.
2. Use a cable with an AWG of (28/24) or lower.
3. Cables longer than 6 feet is not suggested regardless of lower AWG as the connectors itself (especially at the MicroUSB end) will be the bulk of the impedance for that cable.
4. If you desire to have "AC Charging" be displayed on your Nexus 7, short the data wires/pins. Remember, this has no effect on the charging rate.
5. If you plan to modify the charger, take a resistance measurement of the data pins first (unplugged), any readings other than 0 ohms or infinity (open or not connected), you will need to isolate the data pins from the charging circuit prior to shorting. If you do not, you risk damaging the charger and/or your precious Nexus 7.
6. If you plan to modify the cable, short the data wires at the MicroUSB end and leave the data wires open or not connected at the charger end. Use heat shrink to insulate the exposed conductor of the data wires.
7. Make sure the MicroUSB connector end is about 6.0 mm in length.
Thanks for this great post.
I have been switching back and forth all morning between the oem cable/charger and a blackberry charger with removable usb cable. This post solves the riddle of why the oem charger with the longer blackberry usb cable was charging demonstrably slower than the oem combo (at least according to my battery widget).
Thank you for the detailed information. This was driving me nuts.
I am surprised with the charging rate of 821mA ...
OEM charger + OEM cable = Charges at 821mA AND displays AC charging.
Click to expand...
Click to collapse
So, basically, we don't really need 2A charger?
Will charging my phone (HTC Desire S) with the Nexus 7 charger have any damage on my phone?
generationgav said:
Will charging my phone (HTC Desire S) with the Nexus 7 charger have any damage on my phone?
Click to expand...
Click to collapse
No, there's current limiters that keep it at a safe level.
Sent from my LG-P999 using xda app-developers app
Thanks for all the info, that was what we really needed.
Now.. what's our best source for a quality cable with long enough connector for a reasonable price?
Edit: I think I'll short some data pins and trim some hoods back with a knife tonight.
Awesome. Perhaps I don't need to replace my car setup. I've shorted out the DATA pins IN the charger. My Galaxy Nexus reads it as AC charging now but the N7 doesn't even detect it. I'll throw it on the charger on my way home from work and see if it does in fact charge it.
This is exactly the way my Samsung Galaxy Tab behaves. It was dead when I got it (used) and none of my chargers would work (display charging). I found that even if it didn't say charging, it was, in fact, charging.
So technically the unit is sucking down the juice but telling us it isn't. Perhaps some devs can figure out how to force it to display charging any time it grabs juice. Just seems like a software bug. There is no reason my Galaxy Nexus see's my car charger as AC (1A) but nothing on the N7.
Glad you did this test. It proves very helpful.
gogol said:
I am surprised with the charging rate of 821mA ...
So, basically, we don't really need 2A charger?
Click to expand...
Click to collapse
You do need a 2A charger. All testing was done when the N7 was completely dead. I suspect when the battery is at like 50%, the charging rate will peak to 1300-1500mA and start decreasing when the battery nears its capacity.
I didn't make measurements at the various charge stages as this experiment was just about whether it charges with the various chargers and cable combinations.
janedoesmith: When you said that the Nexus 7 was completely drained, does that mean that it was turned off? If it was off, then would you mind performing the stock charger test with it turned on (and maybe something like 50% charge)? I'm just curious to see if it draws more current when turned on. Would you also mind testing charging from your computer's USB port? Since your testing has shown that the Nexus 7 tries to draw greater than 500mA even when the data pins are open, then it means that it doesn't follow USB charging specs (with open data pins, a device should never try to draw more than 500mA).
AZImmortal said:
janedoesmith: When you said that the Nexus 7 was completely drained, does that mean that it was turned off? If it was off, then would you mind performing the stock charger test with it turned on (and maybe something like 50% charge)? I'm just curious to see if it draws more current when turned on. Would you also mind testing charging from your computer's USB port? Since your testing has shown that the Nexus 7 tries to draw greater than 500mA even when the data pins are open, then it means that it doesn't follow USB charging specs (with open data pins, a device should never try to draw more than 500mA).
Click to expand...
Click to collapse
The tests were performed with the N7 powered on and powered off. The current draw was the same for both conditions.
My N7 is currently fully charged. I will make one additional amperage measurement when it discharges to 50%.
Basically, a charging circuit cannot draw no more than what the charger can supply. When my N7 discharges to 50%. I'll make some measurements from the computer's USB port.
I understand about not being able to provide more than the charger can supply. I brought up the USB charging specs issue because some computers will shut down if the connected device tries to draw more than 500mA, which is why there's supposed to be a difference between having the data pins bridged or not. Open is supposed to make the device think that it's connected to a computer's USB port, meaning it shouldn't try to draw over 500mA. Bridged is supposed to signal that it's ok to draw up to 1A because it's supposedly connected to a dedicated charging port.
AZImmortal said:
I understand about not being able to provide more than the charger can supply. I brought up the USB charging specs issue because some computers will shut down if the connected device tries to draw more than 500mA, which is why there's supposed to be a difference between having the data pins bridged or not. Open is supposed to make the device think that it's connected to a computer's USB port, meaning it shouldn't try to draw over 500mA. Bridged is supposed to signal that it's ok to draw up to 1A because it's supposedly connected to a dedicated charging port.
Click to expand...
Click to collapse
I'm no expert when it comes USB specifications but this is what I suspect:
When a device connects to a host via USB, the data lines are no longer open and it becomes and active data circuit. Once a handshake takes place, the device and the host knows what its roles are and the N7 displays " USB charging". Due to this active data circuit, I will not be disconnecting nor shorting the data lines when I perform the additional tests when my N7 discharges to 50%. I will be just measuring amperage with various cables and lengths.
I picked up one of these: http://www.monoprice.com/products/p...=10303&cs_id=1030307&p_id=5458&seq=1&format=2
Has worked without a concern of charging or not and seems to feed sufficient current to charge the device in a timely manner. I know this isn't scientific, but wanted to provide the cable that I am using without issue.
Mustang7302 said:
I picked up one of these: http://www.monoprice.com/products/p...=10303&cs_id=1030307&p_id=5458&seq=1&format=2
Has worked without a concern of charging or not and seems to feed sufficient current to charge the device in a timely manner. I know this isn't scientific, but wanted to provide the cable that I am using without issue.
Click to expand...
Click to collapse
Thank you. That cable was used in the experiment. Any 6 foot cable with a AWG of (28/24) will work flawlessly.
janedoesmith said:
Thank you. That cable was used in the experiment. Any 6 foot cable with a AWG of (28/24) will work flawlessly.
Click to expand...
Click to collapse
Not necessarily - it seems that a lot of MicroUSB cables have male connectors that are excessively short. These interfere with the N7's case.
However, those Monoprice 24/28AWG "premium with ferrite" cables work flawlessly for me. I have a whole pile of them.
I have had the following chargers work properly with my N7 and cables like the Monoprice ones:
Samsung Tab 10.1 charger - Shorts D+ and D- and additionally floats them at 1.8 with a weak voltage divider (the latter is not necessary for N7, but it happens to be a method that is compatible with standards-compliant devices like the N7 and all of my phones)
Scosche iPad car charger modified so that it behaves just like the Samsung Tab charger (Shorted D+ and D-, removed one of the pullup resistors in the voltage divider)
Galaxy Note charger (shorts D+ and D-)
Old HTC charger (shorts D+ and D-)
Using CurrentWidget (my kernel is patched so it works - see http://review.cyanogenmod.com/#/c/20891/), I see the following:
Tab 10.1 charger seems to charge faster than stock. This doesn't make sense as when unloaded, the 10.1 is dead-on at 5.0 volts, and the stock charger is 5.1 volts. However the stock charger may behave differently under load. This may just be test variance - CurrentWidget is reporting current into the battery, so this will vary depending on CPU/screen power usage. I'm still looking to see if there is a separate current measurement device somewhere that will report USB input current.
The Galaxy Note charger reports significantly lower charging current than the stock charger or Tab 10.1 charger - not surprised, it's only rated 1.0A
Entropy512 said:
janedoesmith said:
Thank you. That cable was used in the experiment. Any 6 foot cable with a AWG of (28/24) will work flawlessly.
Click to expand...
Click to collapse
Not necessarily - it seems that a lot of MicroUSB cables have male connectors that are excessively short. These interfere with the N7's case.
Click to expand...
Click to collapse
The length of the MicroUSB connector was covered in the first post.
Interesting results, what did you use to measure the mA rate? Is it possible from a battery app? I have a kill-a-watt plug lying around though, will see tomorrow if it can display mA but I doubt it.
Salty Wagyu said:
Interesting results, what did you use to measure the mA rate? Is it possible from a battery app? I have a kill-a-watt plug lying around though, will see tomorrow if it can display mA but I doubt it.
Click to expand...
Click to collapse
I used a digital multimeter and measured it at the cable.
Great topic! Thank you!
At home I have an iPhone 5 charger and a Blackberry Bold 9900 Charger along with a Cooler Master Battery Bank. The out put on the battery bank claimed 5 Volts 2.1 Amps but when hooked up to my HTC One it showed USB Charging. I hooked it up via my iPhone 5 charger which has an output of 5 Volts and 1A and also got USB Charging but when I hooked it up via Blackberry Charger with an output of 5V / 750 mA I got Charging (AC) on my HTC One. Looks like it won't accept any higher power input than what it needs for faster charging.
Picture posted is via Blackberry Charger.
Here is a picture via Cooler Master Battery Bank showing charging (USB)
The maximum current is drawn when the battery is empty. The first phase of charging is constant current, where it will draw up to 1A from AC and 500ma from USB, then moves to constant voltage, where the current will drop off. Your battery is probably too charged to be drawing max current.
HTC phones switch to AC charging when the data pins on the USB are shorted, otherwise it's USB charging.
BenPope said:
The maximum current is drawn when the battery is empty. The first phase of charging is constant current, where it will draw up to 1A from AC and 500ma from USB, then moves to constant voltage, where the current will drop off. Your battery is probably too charged to be drawing max current.
HTC phones switch to AC charging when the data pins on the USB are shorted, otherwise it's USB charging.
Click to expand...
Click to collapse
I need to double check which USB cable I had used. At work now but just saw that the USB cable I had at work was the Blackberry USB Cable and when I hooked that one up with my new HTC ONE I got AC Charging on my HTC ONE. A sales person had told me that the USB cable can make a difference at times. Will try messin around with a few wires along with my Cooler Master Battery Bank to see if the results change.
desiregeek said:
I need to double check which USB cable I had used. At work now but just saw that the USB cable I had at work was the Blackberry USB Cable and when I hooked that one up with my new HTC ONE I got AC Charging on my HTC ONE. A sales person had told me that the USB cable can make a difference at times. Will try messin around with a few wires along with my Cooler Master Battery Bank to see if the results change.
Click to expand...
Click to collapse
I find that the charger it came with charges it fastest. The other chargers I have used are my neuxs 4 and gs4.
The phone is looking for a 'short' across the two data wires, I believe. The HTC chargers have this so that the phone knows it's not a USB port that isn't able to deliver the current. I'm surprised the blackberry charger fooled the phone to think it's AC.
My S4 has developed a problem where it seems to stop charging overnight, leaving me with a low battery in the morning. When I plug it into the charger the red light comes on, but when I return in the morning it has stopped charging and the battery has lost 20% of its charge.
A different USB cable, plugged into the same charger, seems to be charging it for now. Does this mean that the original cable is faulty, or do I need to get the USB connector on the phone checked out?
itm said:
My S4 has developed a problem where it seems to stop charging overnight, leaving me with a low battery in the morning. When I plug it into the charger the red light comes on, but when I return in the morning it has stopped charging and the battery has lost 20% of its charge.
A different USB cable, plugged into the same charger, seems to be charging it for now. Does this mean that the original cable is faulty, or do I need to get the USB connector on the phone checked out?
Click to expand...
Click to collapse
Maybe there is overheating problem so phone stops charging process. Try to start charging and observe it. When it stops charging again, check if it is hot.
Diamond 2 owner said:
Maybe there is overheating problem so phone stops charging process. Try to start charging and observe it. When it stops charging again, check if it is hot.
Click to expand...
Click to collapse
Seems to be, i've noticed this myself too on days my room is very hot. Ever since i've undervolted a little it hasn't happened again.
Sent from my GT-I9505 using xda app-developers app
Kenablo said:
Seems to be, i've noticed this myself too on days my room is very hot. Ever since i've undervolted a little it hasn't happened again.
Sent from my GT-I9505 using xda app-developers app
Click to expand...
Click to collapse
First make sure that phone is placed on clean, flat surface with good air flow. Worst case is placing it on bed, blanket or pillow - it will overheat for sure.
Undervolting will not help a lot, as it only affect CPU/GPU heating, while they are usually idling during charging. Main source of heat in that situation is not a CPU/GPU but charging itself.
If you have really high room temperature, and you can do nothing about it, than you can slow down charging process, so it will decrease charging heating. Just use regular USB port (computer or generic USB charger) instead dedicated Samsung S4 charger. Charging current will be decreased from 1.9A to 500mA.
If you want to have more control over charging and temperatures you could install Battery Monitor Widget Pro (https://play.google.com/store/apps/details?id=ccc71.bmw.pro). See example of data which you can got with on wireless charging thread: http://forum.xda-developers.com/showpost.php?p=43224425&postcount=1018
My battery temperature goes up to 35C during charging (wireless charging).
The theory re. heat is interesting, but doesn't seem to explain why switching USB cables fixed the problem immediately in this case. Is the S4 particularly sensitive to the fit of the USB cable in the socket??
itm said:
The theory re. heat is interesting, but doesn't seem to explain why switching USB cables fixed the problem immediately in this case. Is the S4 particularly sensitive to the fit of the USB cable in the socket??
Click to expand...
Click to collapse
No, S4 is not particularly sensitive to the fit of the USB cable in the socket.
Keep in mind, that max charging current on S4 is based on detection routine which tries to figure it out what is phone connected to (is it regular USB port specified for up to 500mA or dedicated 2 amps charger). It is necessary to accomplish down compatibility with generic USB hosts (you can connect S4 to every USB device) and fast charging feature (less then 2h charging time).
So, you can say, that S4 is sensitive to USB cable/device type. Switching from dedicated cable/charger to 3rd party, could decrease charging current and generated heat.
I hope, this theory explains all your doubts
Diamond 2 owner said:
No, S4 is not particularly sensitive to the fit of the USB cable in the socket.
Keep in mind, that max charging current on S4 is based on detection routine which tries to figure it out what is phone connected to (is it regular USB port specified for up to 500mA or dedicated 2 amps charger). It is necessary to accomplish down compatibility with generic USB hosts (you can connect S4 to every USB device) and fast charging feature (less then 2h charging time).
So, you can say, that S4 is sensitive to USB cable/device type. Switching from dedicated cable/charger to 3rd party, could decrease charging current and generated heat.
I hope, this theory explains all your doubts
Click to expand...
Click to collapse
Thanks for the explanation - it certainly does help. It looks as if the flaw may be with the detection routine, which was preventing it from charging when connected to the stock charger/stock cable, but was happy to allow it when using a different cable with the stock charger.
It also explains another anomaly - when using the S4 as a Sat Nav in the car with a TomTom High-Speed multi charger the phone will only charge if the screen is turned off. With the screen on it actually loses charge.
Is there any way to "hack" this logic to eradicate these anomalies and ensure that the phone charges when you want it to? Or could it be that there is actually a fault with my phone that needs to be checked out?
I suspect this may not be normal...I've just plugged the phone into the stock charger/cable. The phone/battery are not remotely warm, but the phone isn't charging, even though the battery icon in the notification bar says that it is (there's a lightning bolt in the battery icon but it just lost 1% charge in 2 mins with the screen turned off).
The LED went red when I first plugged it in, but the red light went out after a minute, although the lightning bolt remained in the battery icon in the notification bar.
???
itm said:
I suspect this may not be normal...I've just plugged the phone into the stock charger/cable. The phone/battery are not remotely warm, but the phone isn't charging, even though the battery icon in the notification bar says that it is (there's a lightning bolt in the battery icon but it just lost 1% charge in 2 mins with the screen turned off).
The LED went red when I first plugged it in, but the red light went out after a minute, although the lightning bolt remained in the battery icon in the notification bar.
???
Click to expand...
Click to collapse
At this point it sounds like you have a defective battery/phone Anyway, here's a sample test you can try:
Get this app: Galaxy Charging Current Lite
With the stock charger/cable you should be seeing (remember to keep refreshing):
- Not charging - -
- Screen on - 1200 mA
- Screen off - 1900 mA
(yes, there's a difference in the charging current depending on whether the screen is off or on)
Plugged to a standard USB port: 460 mA
Plugged to a car charger - depends on the output of the charger - most car chargers are 1A these days
Try with different cables plugged into a PC USB port - you should be getting a constant 460 mA charge. If it stops as described and you tried a few cable it's likely the battery/phone. HTH
Breach1337 said:
At this point it sounds like you have a defective battery/phone Anyway, here's a sample test you can try:
Get this app: Galaxy Charging Current Lite
With the stock charger/cable you should be seeing (remember to keep refreshing):
- Not charging - -
- Screen on - 1200 mA
- Screen off - 1900 mA
(yes, there's a difference in the charging current depending on whether the screen is off or on)
Plugged to a standard USB port: 460 mA
Plugged to a car charger - depends on the output of the charger - most car chargers are 1A these days
Try with different cables plugged into a PC USB port - you should be getting a constant 460 mA charge. If it stops as described and you tried a few cable it's likely the battery/phone. HTH
Click to expand...
Click to collapse
Thanks. The Galaxy Charging Current Lite app shows:
- Connected to stock charger, screen on, with stock battery: a steady 340
- Connected to stock charger, screen off, with stock battery: 380
- Connected to PC USB port, with stock battery: 460
- Connected to car charger, with stock battery: 500
- Connected to stock charger, screen on, with 3rd party battery: a steady 300
Can I assume from the above that the phone is faulty?
itm said:
Thanks. The Galaxy Charging Current Lite app shows:
- Connected to stock charger, screen on, with stock battery: a steady 340
- Connected to stock charger, screen off, with stock battery: 380
- Connected to PC USB port, with stock battery: 460
- Connected to car charger, with stock battery: 500
- Connected to stock charger, screen on, with 3rd party battery: a steady 300
Can I assume from the above that the phone is faulty?
Click to expand...
Click to collapse
I just tried a few different USB cables with the stock charger - these gave me interesting results:
- Cable 1 : 1200
- Cable 2: 1200
- Cable 3: 420
So maybe it's the stock cable that's the problem?
itm said:
Thanks. The Galaxy Charging Current Lite app shows:
- Connected to stock charger, screen on, with stock battery: a steady 340
- Connected to stock charger, screen off, with stock battery: 380
- Connected to PC USB port, with stock battery: 460
- Connected to car charger, with stock battery: 500
- Connected to stock charger, screen on, with 3rd party battery: a steady 300
Can I assume from the above that the phone is faulty?
Click to expand...
Click to collapse
Actually it looks like more of a problem with your stock charger (as you're getting normal charge from a USB port)!
- Are you using the same cable with your stock charger, when connected to the PC USB port and your car charger? Try a different cable in all this scenarios to rule out the cable as a factor.
- What I'd recommend is to find another stock charger - go to a Samsung shop / service center - ask to test on site and see what input your phone is getting. You may test with any other mains charger but as you need to be sure of the power it delivers I'd test with an official Samsung 2A charger. If you don't get 1200/1900 with another official charger (and a working cable) then it's an issue with the phone/battery.
Re your car charger. It's possible that your car charger is 500 ma only (check the writing) if it's 0.5 A you need a new one (get a 2A one). Is it a real 12V cigarette charger or are you plugging the cable in a USB port on your car?
---------- Post added at 12:15 PM ---------- Previous post was at 12:11 PM ----------
itm said:
I just tried a few different USB cables with the stock charger - these gave me interesting results:
- Cable 1 : 1200
- Cable 2: 1200
- Cable 3: 420
So maybe it's the stock cable that's the problem?
Click to expand...
Click to collapse
There you go I fried two old cables already so not all of them can sustain the 2A charge. Use Cable 1 or 2. Make sure it also charges at 1900 ma - plug it in, open the app, refresh so that it shows 1200 ma. Turn the screen off. Give it 5 seconds (red led should turn on). Turn the screen back on. immediately refresh - you should see 1900.
I'm getting 1200/1900 from the stock charger if I use "Cable 1" or "Cable 2" as referred to above, so I guess that indicates that the charger is OK? (the stock cable only gives 300 from the same charger)
I'm surprised that I can only get 500 from the car charger using Cable 1/2, as it is advertised as having a 2amp port. In fact I get a higher charge rate (740) using the "slower" port on the TomTom charger - i.e. the port labelled "high-speed" actually delivers less current.
???
Yes cable 3 has gone bad. You should be good with the others.
Re the car charger - is 500 all you get with cable 1 or 2? Is the charger rated 2A for Android phones? Note that some high current chargers are high current only for Apple products and default to much lower output with non Apple products. It can also be a bad charger.- I had a defective 2A Anker car charger which wouldn't charge above 760. I RMAed it and the replacement works as intended.
Sent from my GT-I9505 using xda app-developers app
Breach1337 said:
Yes cable 3 has gone bad. You should be good with the others.
Re the car charger - is 500 all you get with cable 1 or 2? Is the charger rated 2A for Android phones? Note that some high current chargers are high current only for Apple products and default to much lower output with non Apple products. It can also be a bad charger.- I had a defective 2A Anker car charger which wouldn't charge above 760. I RMAed it and the replacement works as intended.
Sent from my GT-I9505 using xda app-developers app
Click to expand...
Click to collapse
I can get 1200 from the car charger with Cable 1. It's rated at 2A for TomTom devices.
Now this is bizzarre...I just took delivery of a brand new Nexus 10 and immediately tried the charger and cable from that with the Galaxy S4 - I only got 300ma. Can this really be coincidence??
Yes, weird. What about the the other way around - not sure whether the app will work on the Nexus but you can try. Try the S4 charger and cable with the Nexus.
Sent from my GT-I9505 using xda app-developers app
Breach1337 said:
Yes, weird. What about the the other way around - not sure whether the app will work on the Nexus but you can try. Try the S4 charger and cable with the Nexus.
Sent from my GT-I9505 using xda app-developers app
Click to expand...
Click to collapse
The Galaxy Charging Current App doesn't work on the Nexus 10 for some reason - it doesn't respond to a charger being connected to it
Can Samsung really be shipping dodgy cables on a mass scale?
itm said:
The Galaxy Charging Current App doesn't work on the Nexus 10 for some reason - it doesn't respond to a charger being connected to it
Can Samsung really be shipping dodgy cables on a mass scale?
Click to expand...
Click to collapse
I doubt it. No surprises that the app doesn't work on non-Galaxy devices.
By the way how did you try the cable from the Nexus? Isn't is a pogo cable (the wider one)?
Breach1337 said:
By the way how did you try the cable from the Nexus? Isn't is a pogo cable (the wider one)?
Click to expand...
Click to collapse
No it's a standard Micro USB.
itm said:
No it's a standard Micro USB.
Click to expand...
Click to collapse
If you get the same low charge rate with the Nexus charger/cable I'd take it to Samsung and show them the charge rate you're getting. Even if it works with another cable something is definitely not right - let them figure it out.