Hi. I've solved the problem of using other chargers with GT.
Like Apple, Samsung used a little trick with their chargers.
To charge your GT with any usb charger you have to make a little adapter.
Usb pinout:
gnd d- d+ 5v
To work you must short d+ and d-.
From 5v use a 33k resistor to d+/d-.
From gnd use a 10k resistor to d+/d-.
If you have multimeter you should obtain ~4v between 5v and d+/d-; and ~1v between gnd and d+/d-.
I tested it and it's working.
Hi, it's not a trick but a standard. You only need to short d+ with d-, the resistors are not needed. Just be sure that the charger outputs closest to 5v possible, around 5.2~3 usually work for everything. About 5.6v and it start not to work on some devices, like apple..
Maybe, I have to test that
I know it's not a trick, I should wrote "trick".
For example GT adapter outputs 5.31v.
Apple adapter worked with 1 22k resistor between d- d+.
WarlockM said:
Hi. I've solved the problem of using other chargers with GT.
Like Apple, Samsung used a little trick with their chargers.
To charge your GT with any usb charger you have to make a little adapter.
Usb pinout:
gnd d- d+ 5v
To work you must short d+ and d-.
From 5v use a 33k resistor to d+/d-.
From gnd use a 10k resistor to d+/d-.
If you have multimeter you should obtain ~4v between 5v and d+/d-; and ~1v between gnd and d+/d-.
I tested it and it's working.
Click to expand...
Click to collapse
WarlockM said:
To charge your GT with any usb charger you have to make a little adapter.
Click to expand...
Click to collapse
How can you do that? You need an extra device adapter? Please explain.
I've tested with d-/d+ shorted and it's not working.
@MizGarfield if u have 1 usb extension cable u can cut it on half.
Tie together white and green wires.
Tie black wires and conected to that 1 end of 10kohm resistor, the other end tie it to green/white wire.
Same to red wires but use 33kohm resistor.
See att. Sry for drawing.
bookmarking this for later use
WarlockM said:
I've tested with d-/d+ shorted and it's not working.
@MizGarfield if u have 1 usb extension cable u can cut it on half.
Tie together white and green wires.
Tie black wires and conected to that 1 end of 10kohm resistor, the other end tie it to green/white wire.
Same to red wires but use 33kohm resistor.
See att. Sry for drawing.
Click to expand...
Click to collapse
You don't need that for modern devices has i told you. It did not work because you did it wrong. I have all my usb chargers working the new way, you even have wikipedia talking about it. You have to cut the data + and - on the power supply from the female usb port and short only the female d+ and d-. Trust me it works and it is alot simpler.
Edit : from wikipedia "The Dedicated Charging Port shorts the D+ and D- pins with a resistance of at most 200 Ω. The short disables data transfer, but allows devices to detect the Dedicated Charging Port and allows very simple, high current chargers to be manufactured. The increased current (faster, 9 W charging) will occur once both the host/hub and devices support the new charging specification."
""As of June 14, 2007, all new mobile phones applying for a license in China are required to use the USB port as a power port.[35][36] This was the first standard to use the convention of shorting D+ and D-.[37]""
http://apple.slashdot.org/story/10/08/03/1743240/Hardware-Hackers-Reveal-Apples-Charger-Secrets
""We all love to call out Apple when they design deliberate incompatibility into their devices, but there is a perfectly valid technical reason for what Apple is doing here, and, in fact, they are following a USB specification (which LadyAda unfortunaterly didn't even test).
Without data communications or when suspended, devices may legally draw no more than 2.5mA from a host, which is useless for charging. In fact, even if you're generous and pretend they're connected, devices are not allowed to draw more than 100mA without negotiating for a higher current, which requires actually talking to the host, and 100mA is still too little to charge properly. 500mA is the maximum allowed by the USB spec, but devices must negotiate it (there may be too many devices on the bus for negotiation to succeed).
Before there was a spec for "dumb" USB chargers, Apple used the resistors as a sentinel to avoid drawing too much current from undersized chargers in order to avoid damaging the host. This is a hack, but it works, and honestly, we're smart enough to figure out a couple resistors on the data lines. It's not like they're using crypto auth on the charger. They have a perfectly valid reason to do this. Devices which charge from "dumb" chargers aren't following the spec, though this is a common industry practice.
As it turns out, the USB-IF came up with a USB Battery Charging spec [usb.org]. The spec is long and boring, but it boils down to: short together the data lines (no resistors required) and you indicate that you're a dumb charger that can supply anywhere from 0.5A to 1.5A.
Guess what happens when you short the data lines of an iPhone 3G and supply 5V [marcansoft.com]. Did Apple just follow a standard? Incredible!
(Yes, I'm not following the USB spec there by in turn using a USB cable to supply the 5V and not negotiating over its data lines. I didn't feel like grabbing a dedicated 5V PSU for the shot, so sue me.)"""
http://marcansoft.com/transf/iphonechg.jpg
ok ??? no need for resistors, only 5.3V MAX and d+ and d- shorted
Thnx for the tip gonna try this later on my sanyo eneloop power booster tried it yesterday without this mod and it doesn't charge so gonna look for a AF to AF converter and modify it to gound the D+ and D-
@adolfotregosa
I tried again shorting d-d+, with iphone it works but with GT it's not working.
I use BatteryWatch and it is saying Not Charging. It's detecting the connection like usb port but is not. I use some device build by myself with 1 amp capabilities. D- and D+ r free of any connection and i can do with them what i want.
I dont say you r wrong but it's not working with GT.
Sent from my GT-P1000 using XDA App
but smt is wrong on your custom setup, voltage ??
EDIT: i just measure the original charger and it has no resistance between the data and power pins.
I think i know what could be wrong, when you plug in the Tab and it says not charging, how many volts have you got at that time ?
The original charger is very good because when it not charging the tab it has 5.3x volts but when you plug it in it lowers to 4.8x V Max and that is very good ! most chargers tend to lower much more (bad quality or just not powerful enough) and that is what causes the not charging messages on the tab or other devices.
Well i rest my case on this.
My device with no load it have 5.21v and with load 5.03v so it's not from him and i have another supply 5v/12 amp and it's doing the same (not charging, only with data shorted).
When u r trying to measure the original ps u can read ~7k between gnd and data but from 5v to data u cant because it have some capacitors.
Maybe samsund did something else, i have to try, maybe data pins drawing some current (mA) and that's why it's not working with only shorting them.
For the moment it's the only (working) solution i've found and i'm happy with it .
P.S. If i'm not finding anything else the last resort will be to open the original ps
Sent from my GT-P1000 using XDA App
USB Charger
This is what worked for me.
Items Needed:
USB Extension Cable
33k-Ohm Resistor (Shack Part No. 271-1129)
10k-Ohm Resistor (Shack Part No. 271-006)
Steps:
1. Cut USB Extension Cable in half, lets name the 2 halves, the half you will plug into the power suppy will be called "Cable A" and the half that you plug into the Galaxy Tab Data Cable will be called "Cable B"
2. On 'Cable A" strip outer plastic to expose all wires within, eliminate Green and White on this cable only as it will not be needed, leaving you with only the Red and the Black Cables
3. On "Cable B" strip outer plastic to expose all wires within, this should leave you exposing all 4 wires
4. On "Cable B" strip both the Green and White wires and join thes 2 wires with the 2 resistor ends (you should be using the resistor ends that have the red band with these wires), these can be joined by either soldering or just twisting together.
5. Strip Red wire from both cables and join together with the 33k-Ohm Resister (this will be the larger of the 2 resistors and should also be the end with the Gold Band) and as well join these together with solder or just twisting together.
6. Repeat the above process with the Black wires and 10K-Ohm Resistor.
7. No finally use Electrical Tape or Shrink Tubing to cover all your work.
This worked using it on a Champtek 5v 2.1a USB Car Charger and Home Charger. Also worked with iPhone charger. Also works with Original Galaxy Tab.
Hope this helps out.
May I just ask some clarifying questions?
rick75204 said:
This is what worked for me.
...
4. On "Cable B" strip both the Green and White wires and join thes 2 wires with the 2 resistor ends (you should be using the resistor ends that have the red band with these wires), these can be joined by either soldering or just twisting together.
Click to expand...
Click to collapse
Does it matter WHICH resistor you join to which of these two wires?
rick75204 said:
5. Strip Red wire from both cables and join together with the 33k-Ohm Resister (this will be the larger of the 2 resistors and should also be the end with the Gold Band) and as well join these together with solder or just twisting together.
Click to expand...
Click to collapse
So that you have effectively bridged the red wire with 30K-Ohms to one of either green or white running to the TAB?
rick75204 said:
6. Repeat the above process with the Black wires and 10K-Ohm Resistor.
Click to expand...
Click to collapse
And bridged the black wire with 10K-Ohms to the other of either green or white running to the TAB?
Would this be an accurate picture, with the 33K Ohm Resistor on the left, and the 10K Ohm Resistor on the right?
I think the intention was that you short the green and white wires together: so you are connecting both wires to both resistors.
That way the two data lines are both held at a fixed voltage of about 1.2V
Thanks, that clarified it.
I noticed today that if I connect my Tab to my keyboard (standard Apple USB KB with keypad, connected to a circa 2006 iMac), the device started charging according to battery stats. When it was plugged in it was at 48% and it ended up at around 60% after a few hours. Am I being deceived or something? I was under the impression that it would only charge if connected to the mains charger. Well I guess I'll see how long it runs now it's off the leash and see if it lasts till the morning (left my charging cable at work - D'oh!).
No, it definitely does charge even when it says it isn't - just slowly. I've got a 2A non-official USB charger that charges it up pretty quick, but still says it isn't charging. If the screen is off, it will even charge off one of those tiny Kindle chargers that must be delivering less than 500mA, but *really* slowly.
Clarify
Sorry guys, only a clarification.
As far as i understood:
the GT DOES charge with *any* charger (or connection to PC);
if you use the original charger (2Amp), it charges showing the charging-icon;
if you use a non-original charger, it charges in any case but NOT showing the charging-icon and depending on the charger power (even 1Amp charges, or 500mAmp, *VERY-REALLY* slowly);
if you use a non-original charger with the two resistors (33k + 10k) it charges showing the icon (even with a 1Amp).
Can anybody confirm if i understood well?
Thanks!!
eiem said:
Sorry guys, only a clarification.
As far as i understood:
the GT DOES charge with *any* charger (or connection to PC); Yes but slower than the original charger
if you use the original charger (2Amp), it charges showing the charging-icon; Yes, exactly
if you use a non-original charger, it charges in any case but NOT showing the charging-icon and depending on the charger power (even 1Amp charges, or 500mAmp, *VERY-REALLY* slowly); Yes.
if you use a non-original charger with the two resistors (33k + 10k) it charges showing the icon (even with a 1Amp). Depends, i get various results even though i am using the mod since day 1.
Can anybody confirm if i understood well?
Thanks!!
Click to expand...
Click to collapse
Thats it for now.
It seems that the Tab could recognize the status of the usb connection by measuring the usb data rx/tx wire level. If it is not shorted, the "pluged in but not in charging" status will appear, as the mismatch voltage of the usb connection is made.
Sent from my XT701 using XDA App
Related
Does anyone have experience using 3rd party chargers with the Treo Pro or HTC devices in general?
I've purchased a kensington 4-port USB wall charger. It's an interesting concept which allows you to plug in up to 4 USB cables (iPods, iPhones, Treo Pro) and only use one outlet. A neat trick when you have multiple phones and devices in your family.
My problem is that the kensington won't charge the Treo Pro. When I plug it in, the LCD lights up, but the charge indicator does not appear nor does the tone sound that it has been plugged in. Note, as far as I can tell the Treo Pro charger outputs 5v DC exactly the same as the Kensington charger.
I've read several posts that lead me to believe that HTC does something to their devices that only allow certain chargers to work or that their USB cables have a certain pin-out that allows them to charge. Anyone have any advice?
Thanks!
Well, I got my wall charger and car charger from Officemax. The charger brand is "Just Wireless". Both are working fine for me. Before, I tried to use the sync cable to plug the regular USB power adapter for wall or car charger, some work, some don't. It seems Palm modified the micro-usb cable...
So my suggestion, if you are looking for charger for Treo Pro, you should look for compable with Moto R9 (which using micro-usb plug, too) I used to have one Moto charger, It worked in my Treo Pro!
jbinmn said:
My problem is that the kensington won't charge the Treo Pro. When I plug it in, the LCD lights up, but the charge indicator does not appear nor does the tone sound that it has been plugged in. Note, as far as I can tell the Treo Pro charger outputs 5v DC exactly the same as the Kensington charger.
I've read several posts that lead me to believe that HTC does something to their devices that only allow certain chargers to work or that their USB cables have a certain pin-out that allows them to charge. Anyone have any advice?
Click to expand...
Click to collapse
There's really nothing "special" going on here. It's all in the USB spec. http://http://en.wikipedia.org/wiki/USB#Power
That said, there are few other devices that demand a dedicated charger (or a communicating host), so in that sense it is special.
The problem being that the TP won't draw more power than agreed upon with the host (or in this case the carger). And since your charger doesn't tell the Treo that is has power to spare, the Treo trying being a good little device won't start charging.
Now, for the charger to tell the Treo that it is, in fact, a dedicated charger and "go ahead, draw as much power as you want up to 1.8A" it would only have to short its data pins.
Now that is something YOU could do to get the charger to work with your Treo. Either open the charger and solder the data pins (the two middle ones in a normal sized usb socket). Or if you can't for some reason, slice a micro-usb cable open and short the two data (usually the thinnest (green/white maybe)) wires inside.
I got a couple of desktop chargers from ebay for about £8 each. Work fine.
frause said:
There's really nothing "special" going on here. It's all in the USB spec. http://http://en.wikipedia.org/wiki/USB#Power
That said, there are few other devices that demand a dedicated charger (or a communicating host), so in that sense it is special.
The problem being that the TP won't draw more power than agreed upon with the host (or in this case the carger). And since your charger doesn't tell the Treo that is has power to spare, the Treo trying being a good little device won't start charging.
Now, for the charger to tell the Treo that it is, in fact, a dedicated charger and "go ahead, draw as much power as you want up to 1.8A" it would only have to short its data pins.
Now that is something YOU could do to get the charger to work with your Treo. Either open the charger and solder the data pins (the two middle ones in a normal sized usb socket). Or if you can't for some reason, slice a micro-usb cable open and short the two data (usually the thinnest (green/white maybe)) wires inside.
Click to expand...
Click to collapse
Hi!
Yep i just bought two kensington 4 port chargers and looks like it doesnt charge the TP
Im about to buy a microusb cable to do the trick you suggested, (i cant seem to open the Kensington 4 port!), any reference websites you could suggest that could explain abit more about the shorting of the data wires inside? Just like to read up abit more before the cable arrives
Thanks!
shorting two center pins solves problem
Thank you for the details. I was able to get two car chargers to work with Palm cables after opening them up and shorting the middle pins with a dab of solder. I opened up a non-Palm cable and discovered only two wires, red and white, and no surprise: it did not work even with the "fixed" adapters. So you need to have pins shorted, and a cable that can return the short to the Treo from the adapter, or if you have a cable with all leads inside you could short the two wires instead and leave the adapter alone. However, if you only have two wires inside the cable you would have to short inside the micro plug, which is a little cramped to work in. If you have only two wires in your cable (hard to tell really without cutting it open; too small to get a continuity probe in there), and/or an adapter without the pins shorted, the Treo will not pull current and charge itself.
The Wikipedia USB Spec referenced by frause above says in part:
" A Dedicated Charging Port can supply a maximum of 1.8*A of current at 5.25*V. A portable device can draw up to 1.8*A from a Dedicated Charging Port. The Dedicated Charging Port shorts the D+ and D- pins with a resistance of at most 200O. The short disables data transfer, but allows devices to detect the Dedicated Charging Port and allows very simple, high current chargers to be manufactured."
An interpretation of the reported observations and this spec is that a charger can communicte to the device under charge the maximum current the charger is able to supply. This communication occurs by the charger either "shorting" the data pins or not. Non-shorted data pins indicates that the charger is capable of at most 500 mA. Its possible that the Treo Pro(TP) is smart enough to know it should conserve power when being charged from a low current charger. One way for the TP to conserve power would be to not power the LED on the TP if there is only 500 mA available for charging.
NOTE THAT IF THIS INTERPRETATION IS TRUE THEN IT IS ACTUALLY DISADVANTAGEOUS TO ARTIFICIALLY SHORT THE DATA PINS.
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!
I just bought a universal wall charger for my defy that likes to freeze my touchscreen when plugged in. after some research i found that, if i understood it correctly, typical smart phone wall chargers have the 2 data pins (pins 2 and 3) shorted with a 200k ohm resistor at the phone. I opened my wall charger (at the male usb port, cause thats how its wired) and it has pins 3 and 5 (data + and ground) shorted with a 200k ohm resistor. i believe this is whats causing my frozen touch screen issue.
can someone tell me if the data ports are what needs to be shorted, or is the data/ground short is fine?:cyclops::good:
Hello
I'm hoping some USB expert can help me out here, I'm trying to make a USB to DC (2.5mm plug) cable that can supply 2A, I have the popular HP Touchpad wallcharger that's rated 5v 2A , so I took a spare quality usb cable (copper cables) it has red, black, green, white (and a big bare metal cable and aluminum wrapping, shielding probably), the DC plug end has two wires red + black, so I hook up red to red black to black (red is 5V black is ground, tested using a multimeter) but I don't seem to be getting as good of results that the stock cable I have gets, the stock cable charges the device at around 1.8 Amps , the cable I made only outputs 800ma to 1.3 amps and if I turn the brightness up it stops charging like it can't supply enough power amps (again stock cable works fine with full brightness).
I'm wondering if on the charger end I need to do something with the green, white wires they both output around 2 volts should these be shorted to the black or possibly red wires to add additional amperage?
I found a youtube video where someone made a similar PSP charger and they spliced both the green, white and blacks wires together, I just want to make sure this is correct way to do things.
youtube.com/watch?v=8WhMeZkrK8U
Btw I also purchased a pre-made cable from dealsextreme but it exhibits the same behavior where full-brightness the charging light dims and goes out on my device, I assumed the low quality of the cable was to blame or again something needs to be connected with the green, white wires.
I know similar questions have been asked before but most have dealt with USB to USB fast charging , with USB to DC I'm confused on what to do with the D- and D+ wires at the charger end should they be shorted together? or to the black cable
ok I think I answered my own question, I tried to do a Ohm test on the stock cable and it seems there was no connection to the green and white or to any of the other wires, since the Ohm reading always returned 0, red and black got a 1+ reading meaning they were connected and a circuit was completed.
Looking at my stock cable it has a big black magnet on it, researching google i found this might be a ferrite core cable, so maybe this somehow boosts the signal and lets the cable pull more amperage or something.
The cylindrical lump on some cables is a ferrite core.
Its purpose is to reduce the amount of logic-generated RF noise from finding its way onto the main span of cable and using it as an antenna.
It will not affect any aspect of charging/powering a device.
Yes, the white/green data pair are used sometimes to indicate a dedicated charger.
A dedicated charger can have more current drawn from it than a normal USB connection.
This subject is handled exhaustively here: http://forum.xda-developers.com/showthread.php?t=1384253
otyg said:
ok I think I answered my own question, I tried to do a Ohm test on the stock cable and it seems there was no connection to the green and white or to any of the other wires, since the Ohm reading always returned 0, red and black got a 1+ reading meaning they were connected and a circuit was completed.
Looking at my stock cable it has a big black magnet on it, researching google i found this might be a ferrite core cable, so maybe this somehow boosts the signal and lets the cable pull more amperage or something.
Click to expand...
Click to collapse
What are you trying to do, make another Touchpad charger? I assume you made sure it can supply up to 2A at 5V.
Many chargers including the HP Touchpad one IIRC short the green and white data wires and this tells the device it can draw more current. If your ohmmeter was reading 0 then that would mean they are shorted. I don't think they are tied to ground (black) just to each other.
The ferrite choke is there to suppress noise from the switching transformer so the device gets clean DC power when charging.
Thanks,
I was trying to make a cable for a Chinese tablet that cannot be charged through it's USB port and only has a 2.5mm dc power port, it seems to be pretty picky about the cable being used, so far the Stock cable to USB-DC to wall USB charger works fine (hp touchpad charger), and a true DC brick rated 2000ma , 5v to DC port works good, I wanted an extra cable to use to charge it with my HP usb charger so I ordered this from dx.com
http://dx.com/p/usb-to-2-5mm-dc-charging-cable-2538
as always I check the polarity and voltage of the cable and it showed 5.13 volts, and center pin positive, strangely when I hooked it to the tablet I saw the battery charging , at 100% I turned brightness up and ran a 3d game, suddenly I saw the red light switch on the tablet to indicate it's charging, strange since it was hooked up to power and was already fully charged, and another test battery was around 40% and I charged to around 80% I rebooted the tablet and the battery was at 40% again!, so thinking my battery died I re-hooked up the stock cable and charged to 80% rebooted again and battery was 80% , narrowed it down to the cheap dx.com cable not supplying enough amps or some short in the cable, this is when I decided to make my own cable.
In my post above, The USB cable I was using I ended up taking apart the usb male connector and found out although the cable was decent quality copper wires.. where it was making the connection at the USB male end the connector only had little push pins puncturing through the wire (two little metal prongs), they weren't soldiered or anything so I guess it was another cheap cable .
So I searched for another cable, finally I found an older usb cable that none of my devices use anymore, this cable actually had a copper metal shield I just connected red and black, left green and white alone not connected to anything, so far it is operating like the stock cable when fully charged I can run full brightness , cpu at fullspeed, and 3d game without the charger light on the tablet going on (I assume this means the tablet is getting enough power from the dc port and doesn't need to switch to battery), I haven't had time to charge the device with the cable yet, but I'm assuming it will work like intended.
I guess they don't make cables like they used to.
hey guys you can check this site out http://techno-fix.com/ . i found my pinout searches there. there are very usefull things
Charging faster by shorting data wires in charger cables.
I've seen recently on videos on youtube the practice of slicing USB charger cables and shorting the green and white wires ( slicing them, covering them with electrical tape)- the idea being the device's recognition of a possible data connection slows charging. There is also video of using foil on the larger USB end's central two pins (the data pins), to short that way. The videos are all old. In one the guy uses an app to tell us the amperage had increased from 4 amps (bull****) to 8 amps (bull**** more). ?
Questions.
Are the data wires in the charge cable always green and white? Really? Um..
Has anyone actually tried this?
thank you
(Edit: )
And the videos I referred to above-
https://m.youtube.com/watch?v=-9-rfImR86g
(Splicing wires)
https://m.youtube.com/watch?v=eg4jF25AW4c
(Using aluminum or aluminum tape to short the USB connector itself)
another example- http://swimminginthought.com/fixing-usb-cable-making-fast-charge-cable/
Rubbish.
Even if you ruin a perfectly good cord, and do cut the data lines, it won't help. The data lines are not used by the charging circuitry anyway!
Also, some cables use different colored wires.
9volts said:
Rubbish.
Even if you ruin a perfectly good cord, and do cut the data lines, it won't help. The data lines are not used by the charging circuitry anyway!
Also, some cables use different colored wires.
Click to expand...
Click to collapse
if it has smart charger it might work. the data cables can create a resistance to tell the battery percentage. so when he creates a short, it sees a full resistance and it means fully discharged. so it charges with full amp.