Nexus 7 wireless charging mod? - General Questions and Answers

I was wondering is the wireless charger in a Nexus 7 takes the same volts as the regular USB charging port. Im asking cause I want to solder wire straight on to them and connect straight to a 5v power supply. It's for a dash install and I've already removed the battery and have it wired straight to the car battery through a 5v power supply. I'm just using the charge as a trigger to tell it to cut on and I want to do away with the USB connection completely. Thanks for any input.

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Fast charging N1

It seems the only way to fast charge a N1 is with the supplied wall charger. Standard Micro USB chargers whould only allow at much as 450mA of charge current regardless of the adapter current capacity.
The bundled charger however, manages to push 900mA into the N1. I made a cut in the charger wires and measured the current draw to make sure.
Now.. I'd like my car charger to be able to do the same. There must be some hack in the plug of the N1 charger since there are only 2 conductors from the case to the plug. You can see that the plug is somewhat longer than similar Micro USB plugs..
So I tried to see if one of the 3 unused pins can tell me anything but.. they seem unconnected as far as I could tell. Diode measurement (to test for any digital part inside) also did not produce any results. The next obvious step is to take the molded plug apart but I'd rather not...
Does anyone have any clue as to what makes that plug so special?
And please - I did my tests with a bench power supply - not the car chargers - so don't go around telling me it has to do with charger current capacity.
Thanks,
Nir
are you sure the micro usb cords you are using are able to handle the amps? most chargers made prior to now, only push about 450mA, the G1, and N1 chargers i have push a full amp though. I just ordered a car charger that pushes an amp too. There is nothing "special" about the plug.
followinginsanity said:
are you sure the micro usb cords you are using are able to handle the amps? most chargers made prior to now, only push about 450mA, the G1, and N1 chargers i have push a full amp though. I just ordered a car charger that pushes an amp too. There is nothing "special" about the plug.
Click to expand...
Click to collapse
I beg to differ. All the cords can easily supply 1 AMP. It is the phone itself that decides how much to draw from the charger based on something IN THE PLUG.
I am an electronics engineer so do understand I know perfectly what I am talking about
And your 1A car charger does not supply anything over 0.45A to the phone.. you will see that if you are using the phone while it charges (say nav or phone call) the phone actually looses some charge albeit it being charged... This will not happen with the stock wall charger.
I have a 900mAh car charger that I use and it does in fact give 900mAh to the phone while charging. I can tell because I used a 450mAh charger at home before and it was slooow and I could drain my phone while charging it. With the car charger I can stream music with spotify, use the GPS, have the screen on full brightness and the battery % will still go up.
I also bought a new wall charger recently, which is 850mAh on the USB port and has a 350mAh charger for a loose battery as well, works quite nice.
Has anyone measured the voltage or put a scope on the output of the stock charger?
maybe stock charger has a slight variance in voltage over USB chargers or some signalling going on and this tells the N1 to take more current from it?
I would like a solution to this too I've seen my phone discharge while on a supposedly 1A car charger using co-pilot.
SBS_ said:
I have a 900mAh car charger that I use and it does in fact give 900mAh to the phone while charging. I can tell because I used a 450mAh charger at home before and it was slooow and I could drain my phone while charging it. With the car charger I can stream music with spotify, use the GPS, have the screen on full brightness and the battery % will still go up.
I also bought a new wall charger recently, which is 850mAh on the USB port and has a 350mAh charger for a loose battery as well, works quite nice.
Click to expand...
Click to collapse
Forget the numbers on the chargers - what counts is what really goes into the phone and that needs to be measured with a current meter (test equipment). What you may think to be fast might not be that.
Original HTC chargers obviously do the trick of fast charging but this comes at a price compared to the $3-$4 garden variety on Ebay and the likes.
now I cannot help you with the electronics at all, but, my old HTC Touch Pro charger seems to charge the same as the one which came with the phone, is this correct?
(suits me if it is, as then I have a charger for home and work)
my blackberry bold 2 charger only says it outputs 700MAh, but both the google and htc chargers both say 1.0A
dnts said:
Forget the numbers on the chargers - what counts is what really goes into the phone and that needs to be measured with a current meter (test equipment). What you may think to be fast might not be that.
Original HTC chargers obviously do the trick of fast charging but this comes at a price compared to the $3-$4 garden variety on Ebay and the likes.
Click to expand...
Click to collapse
Yes, it is just anecdotal evidence as I don't have any equipment to measure it. But my phone no longer discharges when I use it while charging, which it used to do with the old charger I used. So while I can say for a fact that the charger I use now is faster, I can't say by how much (this goes for both the car charger and the one I put in the wall socket).
I ordered this charger a few weeks ago and it charges my phone as fast as the original charger. The label says 5v / 1200mA.
Genuine Nokia Mini AC-10U US Type AC Charger (100~240V)
$7,25 and free shipping. (Takes a while before you get it tho.)
GazzaK said:
now I cannot help you with the electronics at all, but, my old HTC Touch Pro charger seems to charge the same as the one which came with the phone, is this correct?
Click to expand...
Click to collapse
HTC Touch Pro = mini USB
Nexus One = micro USB
Not an engineering here, but I am guessing the phone not always drawing more than 500ma may be is to do with the charger itself.
There is this "fast charge" USB standard where a wall plug has the USB data pins shorted to indicate that it is a wall plug and hence the phone knows when to draw more power. So even if the charger is rated 1A, the phone might not know if it could utilize that if those pins aren't shorted. Try doing a quick Google on this ....
If someone can test if the stock charger that came with the phone in fact does have those pins shorted that would confirm part of this theory.
For all practical purpose - I used two cables/plugs with a bench adjustable power supply. Simple micro USB plug would only let me draw 450mA regardless of power supply voltage in the range 4.5-5.5V. Tried shorting data pins - nothing. Tried shorting spare pin to VCC or GND or any of the other pins - nothing.
Used original cable and plug - draws 900mA at voltages from 4.9-5.5.
So it's in the plug somehow.
Tried (very difficult) to see if the pins on the plug are shorted and all 3 spares (except for 5V and GND) seems unconnected.
Next step is the irreversible hot knife...
I'm bugged by this, too. I tested with my desktop dock connected to my car charger (which states 1000 mA): it loads slowly and my battery widget reports USB- instead of AC-charger.
Might it be that the phone tries to load more than 1000 mA at the beginning to be sure that it doesn't overload the charger? And if that fails, it falls back to 500 mA?
Could N1 use a simple logic of:
- always watch the voltage
- start drawing 500ma (or whichever is the lowest current as per USB spec)
- increment in say 50ma steps
- if voltage drops below 4.x V, back off and stay at that level
I just did a little test of my own. I have a Palm Pre car charger (actual Palm brand one labeled as 1000ma output) and I plunged my N1 into it on my way home from work. In twenty eight minutes, my battery went from 47% to 70%. Much faster than plugging into my computer, which is 500ma max. I don't have any fancy test equipment, and don't claim to know a whole lot about electronics, but seems pretty fast to me.
I have a 4-port 2A 5v USB charger, and connecting it to my Nexus OR Milestone with a MicroUSB cable (the one that shipped with either phone, or the one from my Kindle) yields painfully slow charging - it basically won't charge if you are using the phone.
Connecting the Nexus One charger yields fast charging on either phone - so it is not HTC (or Motorola) proprietary.
The Milestone comes with a 900mA USB plug, and connecting THAT to either phone with either of the MicroUSB cables yields fast charging.
I have another aftermarket 2 port 2A 5V USB wall charger (brand: T'nB) AND I have an iPhone USB plug, and both give fast charging on the Milestone, and I have not yet tried them on the Nexus One.
Breakdown (on things I've tried):
FAST CHARGING on Nexus One AND Milestone:
Nexus charger (either in the US (110v/60hz) or in France (220v/50hz) through an adaptor)
Milestone wall French USB plug (which I think is something odd like 850mA at 5.9v) with ANY microUSB cable (in fact, it seems to charge both of the phones faster than the stock Nexus One plug)
SLOW CHARGING on Nexus One AND Milestone:
USB plug on computer
One aftermarket 4 port 2A 5V USB charger (NOT a hub, only a charger)
FAST CHARGING on Milestone, untested with Nexus One
T'nB 2 port 5v 2A USB wall charger
Apple iPhone 1 port 1A 5v USB wall adaptor
Seems found the answer for Fast Charging N1
I had just do some test for Charging N1 With Original AC Charger , Other band USB Charger and PC USB charger.
1. Orginal Charger give N1 from 0% to 100% at about 2 hour and something.
2. The other band AC charger and PC USB Charger can only finish the same job over 5 to 6 hours.
The Fast Charging is Due to 5.1V (Measured at N1) and 5.2V(Measured inside AC charger). 0.1V Drop is due to resistance of USB cable.
The Slow charged is due to 4.8V (measured at N1) and 5.0V (measured on PC USB and Other AC Charger)
i.e. Original Charger mod from 5.0 V to 5.2V (about 10% increase in Voltage)
Looks my theory is correct then ? N1 watches the voltage and if it droops too much, it backs off the current.
So the key would be: get a charger than can maintain at least 1A @ 5.2V, use
a decent gauge, short wire from the brick to N1.
Has anyone tried a Blackberry charger on the N1? Will they work to full capacity as well? (They're on Amazon for a fiver)
Because the nokia charger is working
http://pinoutsguide.com/CellularPhones-Nokia/micro_usb_connector_pinout.shtml
see info under table.
I tested also HP charger + standard USB cable delivered with Nexus, and it is charching cca 1A.
Then I tested one noname Carcharger + standard USB cable delivered with Nexus, and also charging cca 1A.
I dismantle the noname carcharger and here is a result:
data line (pin2+3) is shorted and connected do + (pin1 ,Vcc) thrue resistor cca 630kOhm.
1 - 4 = 5.1V
2,3 - 4 = 3.2V
rashid11 said:
Looks my theory is correct then ? N1 watches the voltage and if it droops too much, it backs off the current.
So the key would be: get a charger than can maintain at least 1A @ 5.2V, use
a decent gauge, short wire from the brick to N1.
Click to expand...
Click to collapse
I try to use power supply 5.2V 2A with cable without dataline (pin 2and3 not connected) and it is charging 480mA only.
I have now tested with an HTC car charger for the HD2. It's fast charging (tested with Waze running, two bluetooth connections and playing mp3 - and it's still loading the battery, whereas before it would be stuck at the current percentage) and even shows AC power instead of USB.

[Q] Power Usage While Plugged In

Currently using BuoyAOSPsy v131 ROM
I have noticed that my battery still drains while I am plugged in and the phone indicates it is plugged in. Have not tested this while plugged into a wall jack, only in my car or via USB to computer.
When this occurs I am using GPS/Navigation software, active data connection (ofc), and playing music.
Does USB or car adapter not supply enough "juice" for this phone to run multiple applications/features? Is there anything I can do to remedy this, such as try a different car adapter? What specs do I need to look for to ensure appropriate power transfer?
Thanks!
**@ Moderators: Hopefully I placed this in the correct forum. Since it is not necessarily directly related to the ROM I thought it should be kept out of the ROM's thread.
Yes you can easily draw more power then its supplying when using computer or car charger. Most of the time its only charging 500 ma when charging that method. Wall charger's I believe are 1000 ma. Navagation is a HUGE draw on battery.
u921333 said:
Yes you can easily draw more power then its supplying when using computer or car charger. Most of the time its only charging 500 ma when charging that method. Wall charger's I believe are 1000 ma. Navagation is a HUGE draw on battery.
Click to expand...
Click to collapse
Thank you for the info. Guess I'll just have to find a higher quality car adapter.
Actually ive read when using a data cable ie stock or regular micro usb cable on a usb port on your pc or a regular charger the max it will get is 500ma. one of the oem wall chargers (block with usb port) is able to supply 1000ma and the phone is only able to sense this the data pin + and - are shorted together. this tells the phone its charging ac plugged vs usb. now check the output of your car charger and if its able to supply more than 500ma then you can either short pins 2-3 on your cable or on your charger and you will get maximum current draw. Research it you ill there was an article posted on xda somwhere.
I'm getting 1000ma from both my ccar charger and AC adapter. u don't want to pin short a cable and charge from usb. drawing that much power will damage the port, it wasn't designed for that (1.0,2.0). USB 3.0, on the other hand :-D

[Q]: Where can i find an extended mains power charger

hi,
i have just bought the S4, the only problem is the white mains power charger cable is too short for me.
Can anyone recommend an extended mains power charger that is compatible with the S4 i9505?
Thanks
Any micro usb will be fine just keep in mind the longer the cable the slower it will charge the phone. I personally bought a power strip to add more distance ... but I also have a 10ft usb cable that charges my phone very slowly
Don't listen to anyone that says to get a usb extension cable.
to answer you'r question, you can't get a longer cable for the s4, at this time.
the usb cable and charger are "special" you have to use what came in the box to be charging the phone at ~1.5 amps, if you so much as just use a different microUSB cable, the current will go down to ~0.75 amps (effectively doubling the required charging time). same goes for the wall adapter.

USB charging on some amps, AC on others

As far as I know, if you plug in your Nexus5 (or any phone) into a power source with high amperage (>1A), your phone should utilize the amps it actually needs to charge at full speed (AC Charging).*
For example, if i plug my Nexus 5 into a 2.1A charger, it will charge just fine and draw only the required amps needed.*
Ive noticed my phone (rooted with faux) and my wifes (stock) and very finicky when it comes to the amps a charger uses. *It appears that if a charger is not exactly 1.0A or 1.2/1.3A, the phone charges as USB and not AC (no matter which USB cable I use). *Below is what I have found out, *with charge type/amp and how the phone sees it
Stock charger (1.2A) - AC
Anker 25W 5-Port Wall charger (1A Android port) - AC
Anker 25W 5-Port Wall charger (1A iPhone port) - USB (not sure why??)
Anker 25W 5-Port Wall charger (1.3A Galaxy Tab Port) - AC
Anker 25W 5-Port Wall charger (2.1A iPad ports) - USB
Anker E4 13000mah battery (2A) - USB
ANker E4 13000mah battery (1A) - AC
Anyone else experience this?
Sent from my Nexus 5 using Tapatalk
What you've observed here actually has nothing to do with the amperage of your ports and everything to do with how their data pins are wired. The N5 (and most other android devices) looks for the data +/- pins in the USB port to be shorted together, this is how it determines it's connected to a charger. Apple devices do this differently, they look for a specific combination of voltages to be present on the data +/- pins. When you connect your N5 to an Apple port, it ignores these voltages and just charges as if it were connected to a PC.
Now the fact that it sees the Galaxy Tab port as a charger is kind of interesting because the Tab uses yet another method for charger detection. It looks for resistors of a specific value connecting the data +/- pins to the power +/- pins. Cool that the N5 recognizes this configuration as well.
Anyway, this is why your Anker charger has ports dedicated to specific devices, each one is configured a little differently.
That would make sense, however, I would expect the same thing on my Nexus 4 but that doesn't happen. It charges as AC for every port
Sent from my Nexus 5 using Tapatalk
It could simply be that the N4 uses a different power control IC from the N5 (they almost certainly do). That and the software controlling the charging determine whether the phone enables AC charging from different ports or not.
I believe (I have not tried this) that some custom kernels have a setting that enables fast charging unconditionally, to draw as much current as the hardware allows.
Yeah I'm waiting for a kernel to support Fast charge, don't believe any do at the moment
Sent from my Nexus 5 using Tapatalk
the phone may revert to lower power usb charging if some condition isn't met... the phone is completely ignorant of the rated power of the wall wart. current is drawn, it depends on ohms.. so it has nothing to do with the "power output." what i mean is there is no situation where too many amps is going to trigger something in the phone, the phone controls the amps and is ignorant of the max the supply can give unless the phone actually exceeds that and detects a voltage drop, the supply can't force more amps without raising voltage to do so but that's just not how these devices work. so it's not because of the amps of the charger, it must be some other aspect.
what the phone can see is voltage. the state of the microusb "Id" pin (which will probably be open if you are using a data cable and not a specific dock to put it in desk mode or car mode, not that i think the n5 has those modes, but the Id pin is what tells the phone these things, as well as set them into download mode to flash them) and the state of the data pins. generally the data pins need to be shorted together to tell the phone to go into ac charging.
it's possible however that if the voltage is lower than 5v, the phone assumes there is voltage drop from too low a power rating on the supply and it's unable to supply the current. in this situation the phone may default to a lower current charging mode. some ac chargers may not go all the way to 5.0v they may put out as low as 4.45v... if the voltage is either low or unstable from the "high output" charger it may cause the phone to think it has exceeded the output rating of the supply when infact it's just getting unclean power. try it with an official tablet charger for a kindle or something and not a store bought anything..... some of the high output chargers just have substandard regulators and/or filtering.
there may also be more to this. usb 3.0 has a higher current rating than usb 2.0 if the phone can detect the type of port it's connected to, that may also determine the charge mode.. (in thoery anyway, no reason it can't work that way, but i can't say i know that it does on any current device)
It's getting pretty aggravating now that my Nexus 5 charges as USB when connected to my anker slim 2 1A external battery as well as my anker astro e4 1A port. No reason why it should do this
Sent from my Nexus 5 using Tapatalk
If you use a fast charging USB cable with the proper pins shorted you should get it to charge with in AC mode. I grabbed one from Amazon and it changed from DC to AC on the same charger.
jalanjkcarp said:
If you use a fast charging USB cable with the proper pins shorted you should get it to charge with in AC mode. I grabbed one from Amazon and it changed from DC to AC on the same charger.
Click to expand...
Click to collapse
Oh thanks for that tip. I'll order one on Amazon right now and update this thread
Sent from my Nexus 5 using Tapatalk
What happens if you connect an Apple device to one with the shorted pins?
Earth explodes
Sent from my Nexus 5 using Tapatalk
jalanjkcarp said:
If you use a fast charging USB cable with the proper pins shorted you should get it to charge with in AC mode. I grabbed one from Amazon and it changed from DC to AC on the same charger.
Click to expand...
Click to collapse
Tested the new USB cord on all ports, charges as AC. Thanks a lot
Sent from my Nexus 5 using Tapatalk

[Q] Nexus 5 fast charge

How can I enable fast/quick charge ability on Nexus 5. I notice that with the OEM cable I get fast charge on my wall outlet but if I plug in any other cable it doesn't charge at more than 500mA. Is there anyway I can make it fast charge with any cable or is there a cable that I can use that is longer than the OEM one that will put the phone in fast charge? I use CurrentBattery widget to determine the current.
Thank You.
Custom kernel is the way to enable it.
What ^ said
Sent from my Nexus 5 using Tapatalk
Milocha said:
How can I enable fast/quick charge ability on Nexus 5. I notice that with the OEM cable I get fast charge on my wall outlet but if I plug in any other cable it doesn't charge at more than 500mA. Is there anyway I can make it fast charge with any cable or is there a cable that I can use that is longer than the OEM one that will put the phone in fast charge? I use CurrentBattery widget to determine the current.
Thank You.
Click to expand...
Click to collapse
[FAQ] Charger mod, howto USB fast charge.
http://forum.xda-developers.com/showthread.php?t=844284
Get yourself a short USB extender wire, male at one end, female at the other.
Cut the wire in half.
Connect the red and black wires up as they were before (or don't cut them in step 1).
On the Female side of the wire connect the green and white wires together.
On the Male side of the wire simply leave the green and white wires connected to nothing.
Insulate the ends of all of the wires with insulating tape.
Tie a knot in the wire so if the wire is pulled the knot is pulled and not the connection you made, it doesn't look pretty but the wire will last a lifetime this way.

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