Database Users

Faster USB charging?

Just got a new motheboard which has high output USB charging for iPhones, pads etc.
Can this work on N1 ?
http://gigabyte.com/MicroSite/185/on-off-charge.htm
edit: driver link is at the bottom for all the hackers. Hopefully its just changing string from apple to android hehe

kazprotos said:
Just got a new motheboard which has high output USB charging for iPhones, pads etc.
Can this work on N1 ?
http://gigabyte.com/MicroSite/185/on-off-charge.htm
edit: driver link is at the bottom for all the hackers. Hopefully its just changing string from apple to android hehe
Click to expand...
Click to collapse
Hopefully not, I dont want my nexus one to be iphone.
But as you know nexus one is using qualcomm motherboard.
But aslong cyanogen and fm transmitter is working there is no problem wiith your phone.

Dear lord what a crappy reply. Stick to disney mate.

It should, it basically just converts the USB port from .5 amps to 1 amp, like a wall charger.

elkyur said:
Hopefully not, I dont want my nexus one to be iphone.
But as you know nexus one is using qualcomm motherboard.
But aslong cyanogen and fm transmitter is working there is no problem wiith your phone.
Click to expand...
Click to collapse
WTF??? May want to lay off the halucinogenics

elkyur said:
Hopefully not, I dont want my nexus one to be iphone.
But as you know nexus one is using qualcomm motherboard.
But aslong cyanogen and fm transmitter is working there is no problem wiith your phone.
Click to expand...
Click to collapse
lol I seriously hope this is a joke!
I agree with JCopernicus, it should definitely work.

I installed the software in the first post but it still charges very slow compared to wall outlet

Slightly OT, but I've got a USB adapter that plugs into the wall that came with my iphone and when I plug the N1 USB cable into this to charge the N1, it still charges very slowly compared to using the proper wall adapter, why is this? Does this iphone adapter restrict the voltage or something?

Generally, "charger detected" is a circuit that has USB data pins shorted together. So when the phone's USB device probes the lines and detects them shorted, it knows it's connected to a power supply.
But since USB max current spec is 500mA, the current draw is restricted - either by the phone or by the supply.
There might be some other connectivity trick that allows the phone to know it can draw x2 current from the socket and won't damage anything. Most phones probably don't limit the current draw and count on the board to do it. Some boards don't limit the current output, or limit it higher. And the fast chargers provide pulsing voltage - which isn't like USB.
So for the board to be able to charge the device, it needs to detect a device that can use pulsing voltage, and enable such voltage on the socket. It doesn't detect Nexus as such a device, I believe, and that's why the charging is slow.

Faster charging with USB
Building on Jack_R1's response, I believe that the phone is limiting the charge rate. You can make the phone "realize" it is connected to a charger rather than a data connection by shorting the 2 middle USB pins together. I have done this in several car chargers, and the N1 About/Status shows charging (AC), which is the faster charge mode. While you can short the pins in the larger end of a dedicated USB cable, if you can disassemble the connector, I found it much easier to open the charger itself to short the pins.

i also have a gigabyte mobo that has this feature but i havent gotten around to test it out yet. I dont think it would work because the feature is software based and will only bump up the voltage if the program detects an iphone connecting to your computer. Gigabyte doesnt want to be liable if they bump up voltage on every device you plug in and fry something.
btw I have tried charging my n1 from my computer and its extremely slow. started charging at around 5pm on sunday and at 11pm it went from about 23%-97% lol.

Yes, USB charging is very slow. It's actually good for the battery, though.

Maybe someone with some know how can look at the driver files for this 3x tech and see how it checks if its an Apple device. Then fool the check and presto!
Shame I don't know how to do any of this

There is a simple hardware (don't worry, it's on the cable) mod for faster charging; however, make sure the phone has good air vent (it means NO CASE when charging).
1. modify your microUSB cable, disconnect the data connector the A (host) plug, then shorten the data connector to the B plug. (This can charge N900 properly, and speed up n1 charging).
2. modify your powered (with AC adapter plugged) USB hub. Simply shorten the #2 and 3 connectors on USB jack. Make sure you cut the copper strip going to the chip or malfunction may occur.
These modification can greatly speed up the charging, but phone will produce a lot of heat (that's why you must have the phone "naked").

I don't understand this. If the phone + battery are capable of being charged at 1000 mAh from the wall charger then why need extra cooling when asking for 1000 mAh from a PC USB socket?
Mine's still defo getting only 500 mAh from the PC USB despite it being able to give up to 2700 mAh for iPad!!! All I want is my 100 mAh charge.

Because what he suggests isn't a proper charging but rather removal of slot power control, and will damage the battery / phone, if succeeds.
Proper charging at 1000mAh requires pulsing voltage - his hack doesn't provide that. Your MB does, but it requires SW intervention to turn it on.

So can someone brew the intervention ?

martinl1030 said:
i also have a gigabyte mobo that has this feature but i havent gotten around to test it out yet. I dont think it would work because the feature is software based and will only bump up the voltage if the program detects an iphone connecting to your computer. Gigabyte doesnt want to be liable if they bump up voltage on every device you plug in and fry something.
btw I have tried charging my n1 from my computer and its extremely slow. started charging at around 5pm on sunday and at 11pm it went from about 23%-97% lol.
Click to expand...
Click to collapse
They are not doing anything to the voltage, simply allowing more current to pass.
And as said in this thread, any typical data USB cable will charge very slowly. And most standard USB ports charge well less than the max specced 500mAh, in fact my subnote at work I found charged my old phone at around 150mah one time when I was dead and needed to top off and it's all I had available.

i'm not sure of the pinout on the micro USB port but i'm pretty sure that that the Mini USB-B port that was used on phones like the G1 used shorting the -Data pin to the unused 5th pin (actually pin 4 on the connector pinout) to activate AC charge mode. some devices actually require a resister of a certain value to be placed across them to work(i know older motorola phones did like IDEN's)
one thing people often forget but should not forget is that current is drawn from the device using power. its not forced on the device. voltage is forced on a device and while a variance is usually ok for devices depending on how they were designed generally its not a good idea to exceed +1.5v on any low power DC device. 120V AC devices are designed to actually work in a much wider range like 100-130V but thats because of the power supply/nature of AC power. it always varies and in japan they use 100v 60hz AC so many electronics power supplies are designed to work in the full range to save costs and only have to make 1 unit for all (same deal with 220-240 switches on PC power supplies)
the reason why you don't want to do this mod is you could damage you PC's motherboard by pulling too much current from its circuits. USB spec is 500ma. performing this type of mod on a power adapter (car or AC) that does not get recognized as an AC charger by the phone is a safer way to go. worst case senario is you break the charger (unless you mess up on the pinout then you could damage you phone too though)

"Data only" usb cable possibility?

Would a usb cable work for the HD2 if there was only the data+ and data- connection? (no power goes through it, meaning the vcc and gnd pins are unused.
Thanks in advance.

It should be theoritically possible. I mean its just like if you disable power charging on your phone when it's connected to the computer.

Ok thanks for the quick reply
Going to solder a cable now.

noup, i think it won't work since the phone's usb controller is brought online only by applying +5v via usb connector. Without that, the data pins will be inactive.

oh.. bummer
Yeah it doesn't work

Sorry. I was convinced that it will work since i thought the battery will supply the energy required.

No, it do not work! I try it out with a peace of paper inside the plug to cover the outboard pins.

@Abdul9 It doesn't work because even if you disable usb charging in the phone's menu..although the battery isn't charged, power is still being supplied to hd2's motherboard. Based on the usb specifications&standards, usb clients are supposed to have some sort of +5 volt sense circuitry in order to register when voltage is applied and start their internal controller. That also consumes power, actually some 30mA are being drawn from the usb bus in order to power hd2's usb controller (or whatever part of that qualcomm snapdragon chip that is doing that).
This is also valid for any standard usb client/slave device, be it phone or something else.

motoi_bogdan said:
@Abdul9 It doesn't work because even if you disable usb charging in the phone's menu..although the battery isn't charged, power is still being supplied to hd2's motherboard. Based on the usb specifications&standards, usb clients are supposed to have some sort of +5 volt sense circuitry in order to register when voltage is applied and start their internal controller. That also consumes power, actually some 30mA are being drawn from the usb bus in order to power hd2's usb controller (or whatever part of that qualcomm snapdragon chip that is doing that).
This is also valid for any standard usb client/slave device, be it phone or something else.
Click to expand...
Click to collapse
Old thread, but new and hot for me. I want to use my cellphone as a wifi-hotspot for my laptop on the road, but I don't want to drain my laptop's battery since it is just powerful enough for only the laptop itself during my time on the road: the extra powerconsumption by charging my cellphone-battery would be just too much. And "charging throug usb" can't be switched off in my phone. So I was thinking about cutting the +5V wire in the cable, but that appears to be a bad idea.
But what if I would build a small electronic circuit in the datacable which would limit the current through the +5Vlead to about 50mA? That would be enough to feed the USB-controller in the phone, but it would save my laptopbattery from overconsumption.
What do you think?

Need some help from someone who knows legit electronics(diodes, resistors, etc.)

So, i'm trying to add in a usb microsd adapter to my Kindle Fire.
Threads before I started, just discussing ideas:
KF forum: http://forum.xda-developers.com/showthread.php?t=1615055
Hardware hacking forum: http://forum.xda-developers.com/showthread.php?t=1615059
Now, I just about completed the project, but I dropped the motherboard and broke it while soldering a wire onto it. I've just bought another KF off of ebay and will continue at that point, but while i'm waiting I need some advice/help.
I've made a diagram of what i'm going to do. It's pretty horrible, but I think it's understandable.
Few questions that go with the diagram:
*DC only flows one way, do I need the diodes?
*If I should use the diodes will these work? (max output they would need to withstand would be 7v and 1A cause of the wall charger)
*The wall charger puts out 1000mA(1A) when charging. USB puts out 100mA, would that 1A ruin the adapter since it's designed for USB? If so, should I use some resistors?(Unsure cause they would change the regular, lower output to the adapter)(Or the resistors could be put into the charger)
*More questions/concerns on the diagram
Diagram:
Taken off because it was incorrect.

I'm still a bit fuzzy on what's going on here.
I'm not sure what the (2) 3.7V batteries and the 4.4V boards are.
Is that the stock Kindle Fire power supply that you are showing?
Th first question: Have you gotten the USB SD card to work normally plugged in externally?
If not, have you gotten the USB SD card to work through a powered hub?
All the diodes on the black lines are drawn backwards.
You don't need any diodes there or even a reed switch on the black line.
You might have a problem activating the 4 (remaining) reed switches simultaneously and reliably.
If you've never seen voltage out of the KF USB connector, that means that you've not gotten it into USB host mode.
Oh, of course the KF has a single 3.7V battery so I don't know what that whole right side is doing.

Renate NST said:
I'm still a bit fuzzy on what's going on here.
I'm not sure what the (2) 3.7V batteries and the 4.4V boards are.
Is that the stock Kindle Fire power supply that you are showing?
Th first question: Have you gotten the USB SD card to work normally plugged in externally?
If not, have you gotten the USB SD card to work through a powered hub?
All the diodes on the black lines are drawn backwards.
You don't need any diodes there or even a reed switch on the black line.
You might have a problem activating the 4 (remaining) reed switches simultaneously and reliably.
If you've never seen voltage out of the KF USB connector, that means that you've not gotten it into USB host mode.
Oh, of course the KF has a single 3.7V battery so I don't know what that whole right side is doing.
Click to expand...
Click to collapse
The battery is made up of two 3.7v batteries, they just stuck them together and put a board there to control the power flow or whatever. I said it's lowered to 4.4v cause normally when two batteries are put together their voltage gets added together, but that 4.4v is coming from the very end pins, there are 10 total. I get 4.4v when trying the other pins too, so since i'm only connecting it to one set of pins i'm just going with 4.4v.
No, I haven't. I have not been able to successfully get USB host working at all, even with a USB host cable. I don't have a powered hub, but I tried taking the power from a USB port on my computer and that didn't work either. Other people have it working though, some with powered hubs, and a few without.
It might have just been my Kindle, so i'll see when I get the other Kindle I ordered.
I thought I was doing them backwards, I know how they go on physically, but I wasn't sure about on paper.
I'm not sure that i'll need all the reed switches, I may just need two; one to disconnect the ID(blue wire) from the back, and one to disconnect one of the data lines. I wasn't able to experiment though since I never got USB host working.
I tried measuring the voltage directly on the board and from the USB host cable and didn't a reading from either.(When I measured on the board I shorted out the ID an GND wires like they are on a USB host cable)
What I was trying to do with the battery there was prevent power from the charger going directly to the battery, that would be bad. So I do need at least one diode on each line there, but the other two I added cause I didn't want any extra power to be wasted. Of course, it doesn't make much sense to me(not sure what I was thinking), that's why I asked if it was necessary.
Picture of the battery and the board connected to it. I took it apart and removed the second one to move it over and resolder it so there was space down the middle for the wires. The adapter will be at the top where the speakers are.
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This whole idea has lots of problems.
Taking power directly off the battery is not a good idea for many reasons,
the least of which is that many (most?) USB devices won't work on 4.4 volt.
Throw in a silicon diode and you're down a further 0.7 volts.
Ok, you could make it a Schottky diode if you want.
You're still going to have to disconnect both data lines to get this to work,
unless you are planning to only use the external USB connector for charging.
Using host mode, the power should be coming out of the USB interface.
As mentioned, if you don't have it there, it's not working.
Here's a sequence of a Kindle Fire teardown: http://www.ifixit.com/Teardown/Kindle-Fire-Teardown/7099/1

Renate NST said:
This whole idea has lots of problems.
Taking power directly off the battery is not a good idea for many reasons,
the least of which is that many (most?) USB devices won't work on 4.4 volt.
Throw in a silicon diode and you're down a further 0.7 volts.
Ok, you could make it a Schottky diode if you want.
You're still going to have to disconnect both data lines to get this to work,
unless you are planning to only use the external USB connector for charging.
Using host mode, the power should be coming out of the USB interface.
As mentioned, if you don't have it there, it's not working.
Here's a sequence of a Kindle Fire teardown: http://www.ifixit.com/Teardown/Kindle-Fire-Teardown/7099/1
Click to expand...
Click to collapse
Taking power straight from the battery is only a temporary solution, the devs working on the 3.0 kernel is working on fixing the OTG issues and trying to remove the kernel limit of 3v. Also, from what I understand there are other issues that the KF is having regulating the voltage out, people report that below 50% battery USB host stops working.
So, if the issues get fixed i'll just disconnect the battery, or, as I said before, it may have just been my Kindle. I got it used & broken and fixed it myself, so it may have been damaged more than I was aware. I would be able to provide more definitive answers if I had something to experiment with, but I won't have the other Kindle for a few days.
Also, since i'll have a second battery now, i'm not as worried about the battery being damaged.
I do realize that the diodes drop the voltage by .7v, but people who have USB host working report that the KF is putting out 3.3v, and some people have gotten certain flash drives and other devices to work off of that. I believe the microsd adapter I have will work off of that lower voltage.
I only charge using a wall adapter, and charging did work for me as long as the ID and GND cables were separated. My main concern is that adb and fastboot work since i'll just be transferring files to the Kindle and the sdcard with FTP. Which, if adb works so will mass storage, so...
Without using the battery it's just and internal OTG USB host set up with a switch/es, so in theory it should work.
I also don't need and diodes if it's not connected to the battery. I was just hooking it up to the battery cause I wasn't getting any power from the Kindle.
As for the reed switches not working reliably, I did read something before that said that they might screw each other up if they were all right next to each other. What if they were lined up end to end, would they interfere with each other like that? If they do work properly end to end all I need is a custom, long, slender, and rectangular neodymium magnet.
Again, I didn't really have much time to experiment since gravity and I screwed up my motherboard. I had just done some physical modding to the housing and framing to make space for everything, and done some testing on the voltages that it was putting out.
Also, thanks for the help and advice

Ok, here's what I was planning on doing without the battery, any problems now, besides the potential issues with the reed switches?

Ok, the TWL6030 used in the KF uses an LDO regulator for VBUS on USB for OTG
and is speced for 3.3V at 35 mA
http://www.ti.com/lit/ds/symlink/twl6030.pdf
The Nook Touch that I have uses a TPS65921 (a/k/a TWL4030) which uses a charge pump
and is speced for 5.0V and guaranteed for 50 to 100 mA depending on battery voltage.
http://www.ti.com/lit/ds/swcs048f/swcs048f.pdf page 16
I've seen some devices that won't even work at 4.5V
Keyboards generally draw about 5mA.
I've seen audio adapters at 25 mA.
Some thumb drives take a lot of current.
Keeping the red connected all the time may or may not be a problem.
An inactive USB device should not be drawing much (any?) current, but you can never tell.
Bottom line, I don't think that the KF is a very good candidate for stand-alone OTG.
I'd use a powered (and back-powering) hub if I owned a KF.

I don't know what's going on here.. but I corrected your power supply in the schematic above.

Renate NST said:
Ok, the TWL6030 used in the KF uses an LDO regulator for VBUS on USB for OTG
and is speced for 3.3V at 35 mA
http://www.ti.com/lit/ds/symlink/twl6030.pdf
The Nook Touch that I have uses a TPS65921 (a/k/a TWL4030) which uses a charge pump
and is speced for 5.0V and guaranteed for 50 to 100 mA depending on battery voltage.
http://www.ti.com/lit/ds/swcs048f/swcs048f.pdf page 16
I've seen some devices that won't even work at 4.5V
Keyboards generally draw about 5mA.
I've seen audio adapters at 25 mA.
Some thumb drives take a lot of current.
Keeping the red connected all the time may or may not be a problem.
An inactive USB device should not be drawing much (any?) current, but you can never tell.
Bottom line, I don't think that the KF is a very good candidate for stand-alone OTG.
I'd use a powered (and back-powering) hub if I owned a KF.
Click to expand...
Click to collapse
Thanks for the info, I cut open a cable and plugged it into my computer with a resistor hooked up to it and got the voltage down to about 3.4v and the adapter that i'm using still ran and was recognized. I'm unsure about the current though.
It's not really OTG if it has to be hooked up to a separate power supply :/
AdamOutler said:
I don't know what's going on here.. but I corrected your power supply in the schematic above.
Click to expand...
Click to collapse
I don't understand why i'd need a 5v regulator on the battery when it's only putting out 4.4v? (Again, current-wise i'm unsure)
Also, the ID wire(blue) needs to be connected to the GND to activate USB host mode, it tells the device that it's a master and not a slave.
And I don't know if you read my previous posts, but I may not even be using the battery if I can get USB host working like everyone else. And the diodes were there cause I didn't want power going directly to the battery since it could mess it up.

Well, your circuit is wrong in a bunch of different ways so I redesigned it.
0. USB requires 5V regulated power.
1. the ground diodes are pointing the wrong way so the power would not flow.
2. When charging the battery you'd kill your device
3. zener diodes breakover at a certain voltage, not regulate. Those zener would just prevent any voltage from flowing. You'd want a Silicone Controlled Rectifier.
4. The 2 extra diodes do nothing at all in your circuit.
5. Each diode drops .7V. Your circuit effectively uses 4 of them between power and ground from the battery. so, by the end of your circuit, the microSD adapter gets 1.6 volts.... no where near what's required to run the device.
So, I corrected the circuit.
Didn't read that you were using any other method, still havn't.. Just wanted to correct the circuit in case someone else tries to do it.

I built my own car charger using a similar circuit. It's the same thing you'll find in a powered usb hub, although they may use diodes to prevent a backflow of power into the computer.

AdamOutler said:
Well, your circuit is wrong in a bunch of different ways so I redesigned it.
0. USB requires 5V regulated power.
1. the ground diodes are pointing the wrong way so the power would not flow.
2. When charging the battery you'd kill your device
3. zener diodes breakover at a certain voltage, not regulate. Those zener would just prevent any voltage from flowing. You'd want a Silicone Controlled Rectifier.
4. The 2 extra diodes do nothing at all in your circuit.
5. Each diode drops .7V. Your circuit effectively uses 4 of them between power and ground from the battery. so, by the end of your circuit, the microSD adapter gets 1.6 volts.... no where near what's required to run the device.
So, I corrected the circuit.
Didn't read that you were using any other method, still havn't.. Just wanted to correct the circuit in case someone else tries to do it.
Click to expand...
Click to collapse
AdamOutler said:
I built my own car charger using a similar circuit. It's the same thing you'll find in a powered usb hub, although they may use diodes to prevent a backflow of power into the computer.
Click to expand...
Click to collapse
*If it requires 5v then how do devices run with less with USB host on other people's KFs?
*I'm aware that the ground diodes are the wrong way, I asked in my og diagram, and mentioned in a previous post that I know how they go on physically, just not in a diagram.
*That's why I had the diodes, to prevent messing up the battery and device
*I still don't understand how/why it needs to be regulated when it's only 4.4v, it's not over 5v.
I know what zener diodes are, all I would need is to prevent power going straight into the battery, and that's what the diodes would do.
*I wasn't going to use those extra two diodes on each battery line unless someone said that it did something, it was suggested to me by someone who has less electronical knowledge than me and I figured it doesn't hurt to ask.
*And with the 3.3v from the Kindle and 4.4v from the battery minus the 2.8v required for four diodes it equals 4.9v, which should work, but hopefully I don't have to use the battery.
Also, if you look at the picture in my post here it shows exactly what a OTG USB host cable does minus the switches. All I did was add the battery and diodes to prevent power from the charger going into the battery and power from the battery going into the charge port. In theory that should work out. And like I said before, hopefully I don't need to use the battery at all.
I removed the picture in the first post since it was incorrect; while I doubt anyone is going to try it at this point, I understand your sentiment.

Look, im not saying my way is totally up to standards, but it comes much closer than yours with fewer parts, less work and i gaurantee it will work. The proper way is to buy a powered hub and connect to that. If you dont want feedback, dont post in a discussion forum.
Im done wasting my time on this thread. Youre doing it wrong.

AdamOutler said:
Look, im not saying my way is totally up to standards, but it comes much closer than yours with fewer parts, less work and i gaurantee it will work. The proper way is to buy a powered hub and connect to that. If you dont want feedback, dont post in a discussion forum.
Im done wasting my time on this thread. Youre doing it wrong.
Click to expand...
Click to collapse
No need to get all upset bro, i'm just replying to what you've said(Like you said, discussion forum). You said you didn't read any previous posts, and it was obvious, you kept saying things that had already been brought up. And you say things like "Those zener would just prevent any voltage from flowing" when I was saying that was what I was trying to do anyways. Your comment implies that you think that I shouldn't use them, but with no explanation as to why not.
It's not that I don't want feedback, but you keep saying i'm doing it wrong, but you're not answering the questions that I ask. You're just saying "My way is right, your way is wrong," basically.
I repeatedly asked why it needs to be regulated when it's already less than 5v.
I also asked "If it requires 5v then how do devices run with less with USB host on other people's KFs?"
And I realize I didn't post this, but my next question was going to be, with the regulator there I would still need to put the diodes in to prevent power from the battery from going into the charge port and power from the charger going directly into the battery, correct?
Tl;dr:
You're right, you're wasting your and my time because you're not answering my questions, you're not explaining why your way is correct, and you keep bringing up things that were already discussed that I know about.

aaricchavez said:
If it requires 5v then how do devices run with less with USB host on other people's KFs?
Click to expand...
Click to collapse
Um, luck? Sure, a lot of devices are not picky about power.
The specification for USB is 5.0 V
Some devices may not have enough voltage to run at 3.3 V
Some devices may not have enough current to run at 35 mA
Some may simply not detect the presence until it rises over a threshold of 4.5 V
An SD card all by itself uses a nominal 3.3 V
The USB interface circuit is a separate issue.
aaricchavez said:
And with the 3.3v from the Kindle and 4.4v from the battery minus the 2.8v required for four diodes it equals 4.9v
Click to expand...
Click to collapse
The math may be correct, but unfortunately the circuit is not in series.
The voltages just don't add up that way.
You'd need a "floating" battery (not the built-in one) to make the voltages add.
Getting a higher voltage from somewhere and using a 5 V voltage regulator would work.
However, you might need up to 7 V input because your garden-variety regulator has a "dropout voltage" of about 2.0 at full current.
That's why there are special "low dropout" (LDO) regulators designed for such cases.
Still, they can't make more voltage than what they take in.
For that we use charge pumps or boost regulators.
Both of those are active switching devices.

aaricchavez said:
I repeatedly asked why it needs to be regulated when it's already less than 5v.
I also asked "If it requires 5v then how do devices run with less with USB host on other people's KFs?"
Click to expand...
Click to collapse
Sorry didnt read all of the posts, butfor this you can use simple step-up converter.
I have solar charger also with li-ion battery which can provide max 4,22 V and I need 5 Volts.
I bought this module on ebay:
http://www.ebay.com/itm/DC-DC-Conve...175?pt=LH_DefaultDomain_0&hash=item4165891a1f
Works great, provides nice clean 5V output, max is about 2 Amps, even they are telling more... Could also post my complete solution photo if you want

Renate NST said:
The math may be correct, but unfortunately the circuit is not in series.
The voltages just don't add up that way.
You'd need a "floating" battery (not the built-in one) to make the voltages add.
Getting a higher voltage from somewhere and using a 5 V voltage regulator would work.
However, you might need up to 7 V input because your garden-variety regulator has a "dropout voltage" of about 2.0 at full current.
That's why there are special "low dropout" (LDO) regulators designed for such cases.
Still, they can't make more voltage than what they take in.
For that we use charge pumps or boost regulators.
Both of those are active switching devices.
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What's the difference between the built in battery vs an outside battery that would make it add up?
Adding another power source would basically end up being the same as getting a powered hub.
So what Helium, the poster below you, said should work with the 3.3v that the KF already puts out?
HeliumX10 said:
Sorry didnt read all of the posts, butfor this you can use simple step-up converter.
I have solar charger also with li-ion battery which can provide max 4,22 V and I need 5 Volts.
I bought this module on ebay:
http://www.ebay.com/itm/DC-DC-Conve...175?pt=LH_DefaultDomain_0&hash=item4165891a1f
Works great, provides nice clean 5V output, max is about 2 Amps, even they are telling more... Could also post my complete solution photo if you want
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I would like to see the photo, if you don't mind.
This one should work as well, correct? http://www.ebay.com/itm/DC-DC-3V-to...932?pt=LH_DefaultDomain_0&hash=item3a722f7ccc

aaricchavez said:
What's the difference between the built in battery vs an outside battery that would make it add up?
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Many many ..
Power outputs form every mobile devices are not designed to provide big current. It is many times about 50-100 mA, which is sufficient for flash sticks,keyboards or mouses but not for e .g. hard drives.
If you connect step-up converter to for example 3,3V and 100mA, on output you will get 5V 50mA - this is really not sufficien for even mouse...
But if you use battery insted, it can provide huge current - normally 2000mA max. So if you connect battery to converter you will get 3,7V 2000mA and on output 5V 1400mA. Which could be usable even for low power 2,5" hard driver. Also battery has bigger voltage, so it means, that efficiency will rise up a little.
aaricchavez said:
So what Helium, the poster below you, said should work with the 3.3v that the KF already puts out?
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Yes, look up in this post
aaricchavez said:
I would like to see the photo, if you don't mind.
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Here there are - as you can see. I am charging my phone from standart li-ion battery from GPS with standart 5V USB
aaricchavez said:
This one should work as well, correct?
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Yes, could. But I recommend that I posted before - it has bigger mosfet package, which allows about 0,5W thermal dissipation. On your module are SMD transistors, which can dissipate only 0,1W and are very sensitive to aḿbient temperature. I dont trust SMD components in power solutions.

I'd actually recommend keeping the boost regulator on the smaller side.
Besides the space consideration, it would be nice if there were some current limiting.
I just measured the current draw on a 4GB microSD in a IOGear USB adapter and it was 45 mA.
The wireless mouse dongle that I measured was 15 mA.
I don't have any wired mice to measure, but I'd guess that they would all be around that.

Renate NST said:
I'd actually recommend keeping the boost regulator on the smaller side.
Besides the space consideration, it would be nice if there were some current limiting.
I just measured the current draw on a 4GB microSD in a IOGear USB adapter and it was 45 mA.
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Sure, but you wrote, that his device provides 35 mA max, so it wont be enought for most flash drives. Besides that - you measured in low power (3,3V) or high power (5V) USB mode? Because I expect 5V mode so it means than in 3,3V will be much more miliamps...
Anyway, with boost module it will enable him to use almost everything which has drivers. Not only tiny consumption devices, it will be full equipped active host hub also could be connected with switch as emergency charger...

[Q] Battery Connection Voltage/Amperage

ok here's what I want to do.
Permanently integrate a nexus 7 in my car dashboard in the double din radio opening
Remove the battery from the nexus 7 and hardwire to always on power from the car battery
Hardwire the power button to a button installed in the dash
Dashmount a usb port connected via otg for hotswapping media
Hardwire a potentiometer into the dash for volume control
all of the above is fairly simple except for power supply, otg+charging is a possible solution but a car battery wired solution is far better so what i need is information on what the battery pins supply in terms voltage/amperage so i can create a 12v to direct power converter or a device that already does this. any help is appreciated TIA

bump, if someone knows i could really use this info

b22ri22an said:
ok here's what I want to do.
Permanently integrate a nexus 7 in my car dashboard in the double din radio opening
Remove the battery from the nexus 7 and hardwire to always on power from the car battery
Hardwire the power button to a button installed in the dash
Dashmount a usb port connected via otg for hotswapping media
Hardwire a potentiometer into the dash for volume control
all of the above is fairly simple except for power supply, otg+charging is a possible solution but a car battery wired solution is far better so what i need is information on what the battery pins supply in terms voltage/amperage so i can create a 12v to direct power converter or a device that already does this. any help is appreciated TIA
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Can't you just use the USB port to charge it? it takes 5V, and 2A. With a car battery it should have enough amps, the voltage is what you'd need to regulate.
But if you really want to take out the battery instead...can't you just use a volt meter to see what the N7 draws from the battery? I'd guess it's 3.7v lithium ion but I'm not positive. I couldn't find the specs on google either..

As far as I have read there are some major difficulties getting otg+charging to work at the same time and I need the storage space provided by external storage. Having the car power source replacing the nexus 7 battery would eliminate that problem altogether.
I was hoping that someone here had known the voltages since I don't currently own or have access to a multimeter to test for myself. Knowing the voltages in advance would give me the opportunity to see what would be entailed financially to build the project and determine if its its financially acceptable to me, if the project isn't viable the money spent on the multimeter to do the tests would be wasted as it's not something I need for anything other than this particular project. So in the interest of trying to save $20 I figured I would ask here first and that there was a good chance that someone might have the information I needed.

b22ri22an said:
As far as I have read there are some major difficulties getting otg+charging to work at the same time and I need the storage space provided by external storage. Having the car power source replacing the nexus 7 battery would eliminate that problem altogether.
I was hoping that someone here had known the voltages since I don't currently own or have access to a multimeter to test for myself. Knowing the voltages in advance would give me the opportunity to see what would be entailed financially to build the project and determine if its its financially acceptable to me, if the project isn't viable the money spent on the multimeter to do the tests would be wasted as it's not something I need for anything other than this particular project. So in the interest of trying to save $20 I figured I would ask here first and that there was a good chance that someone might have the information I needed.
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oh ok..well have you taken a look at the battery? It should just be 3.7v, I don't think it would be too hard to find which pins it is. Maybe take a LED and test it across the pins?
Also, I have heard reports OTG + charging is working fine on CM10 with a patched kernel. you might want to check this thread: http://forum.xda-developers.com/showthread.php?t=1934722

mvmacd said:
oh ok..well have you taken a look at the battery? It should just be 3.7v, I don't think it would be too hard to find which pins it is. Maybe take a LED and test it across the pins?
Also, I have heard reports OTG + charging is working fine on CM10 with a patched kernel. you might want to check this thread: http://forum.xda-developers.com/showthread.php?t=1934722
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I've been participating heavily in the arena of OTG + charging simultaneously, as well as using USB audio.
To answer the OP's question directly: I have demonstrated (to myself) that I can power down my Nexus 7, disconnect the battery connector, plug in my y-splitting OTG cable with power in one plug, and an unpowered USB hub in the other plug. [Plugged into the USB hub is a flash drive, USB DAC, and I'm sure a keyboard would also be an option.] Then I turn on my Nexus 7, and in the OS it shows the battery at 0%, but charging (obviously it's not actually charging without the battery present...).
I even booted up the Nexus 7 normally, with all the same stuff connected to USB, and then disconnected the battery connector... and the Nexus 7 remained on!
I've thought about integrating some sort of tactile switch that essentially disconnects the battery whenever the switch is depressed. So then part of the car mount could be a little protrusion that presses this switch whenever the tablet is inserted into the car mount. That way whenever the tablet is removed from the car mount, the battery will take over without removing power from the motherboard.

MetalMan2 said:
I've been participating heavily in the arena of OTG + charging simultaneously, as well as using USB audio.
To answer the OP's question directly: I have demonstrated (to myself) that I can power down my Nexus 7, disconnect the battery connector, plug in my y-splitting OTG cable with power in one plug, and an unpowered USB hub in the other plug. [Plugged into the USB hub is a flash drive, USB DAC, and I'm sure a keyboard would also be an option.] Then I turn on my Nexus 7, and in the OS it shows the battery at 0%, but charging (obviously it's not actually charging without the battery present...).
I even booted up the Nexus 7 normally, with all the same stuff connected to USB, and then disconnected the battery connector... and the Nexus 7 remained on!
I've thought about integrating some sort of tactile switch that essentially disconnects the battery whenever the switch is depressed. So then part of the car mount could be a little protrusion that presses this switch whenever the tablet is inserted into the car mount. That way whenever the tablet is removed from the car mount, the battery will take over without removing power from the motherboard.
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Lol, yes, I think I had you in mind when I said that.. I'm still waiting for my Y cable. I won't get it till at least 1.5 weeks..

MetalMan2 said:
I've been participating heavily in the arena of OTG + charging simultaneously, as well as using USB audio.
To answer the OP's question directly: I have demonstrated (to myself) that I can power down my Nexus 7, disconnect the battery connector, plug in my y-splitting OTG cable with power in one plug, and an unpowered USB hub in the other plug. [Plugged into the USB hub is a flash drive, USB DAC, and I'm sure a keyboard would also be an option.] Then I turn on my Nexus 7, and in the OS it shows the battery at 0%, but charging (obviously it's not actually charging without the battery present...).
I even booted up the Nexus 7 normally, with all the same stuff connected to USB, and then disconnected the battery connector... and the Nexus 7 remained on!
I've thought about integrating some sort of tactile switch that essentially disconnects the battery whenever the switch is depressed. So then part of the car mount could be a little protrusion that presses this switch whenever the tablet is inserted into the car mount. That way whenever the tablet is removed from the car mount, the battery will take over without removing power from the motherboard.
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Am i understanding you correctly? If i unplug the battery, and just have the OTG cable plug into the charger, it would be able to power on and off and run just fine?

ho9984 said:
Am i understanding you correctly? If i unplug the battery, and just have the OTG cable plug into the charger, it would be able to power on and off and run just fine?
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This was how it worked while the N7 was running Jelly Bean 4.1.2. I can't guarantee it would operate the same on 4.2.2.

MetalMan2 said:
This was how it worked while the N7 was running Jelly Bean 4.1.2. I can't guarantee it would operate the same on 4.2.2.
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Someone tried it on Reddit. Removed the battery and tried powering it on with only OEM charger. The screen just flickered. They were on 4.2.2

I am curious about removing the battery and hardwiring as well as I am gathering parts to put my Nexus 7 in my car dash. The problem w/ the OTG route - it gets pretty hot down here and I'm afraid the battery will have some long term issues (ie...could leak/explode). So, hardwiring it would be preferred.
Any ideas for hardwiring?

with the new nexus 7 coming out I am just going to mount the wireless charger behind the tablet dock, now I just hope otg is supported with the slimport on the new nexus 7

Shorting the USB Port?

I bought a Nexus One with the infamous broken power button issue, and I am curious what would the effect be if I short the VCC and GND line in the charging port? Has anyone tried that? I am thinking that it will either fry the board or trick the phone to think that it is charging.
The reason I want to do this is because I travel a lot and I might not have access to USB charging if I want to swap the SIM card. I am familiar with the other tricks regarding remapping the trackball_center and I am going to install a version of CWM that doesn't support charging (that way the phone boots when I plug a charging cable).
So long story short... what do you think about attempting to short the micro USB charging/data port?

dcalpha said:
what do you think about attempting to short the micro USB charging/data port?
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Not much.
Unless the unit is in USB host mode there will be no voltage on the Vcc line.
Even in USB host mode it should be current limited and do no damage.
Still, I wouldn't do it.
I don't know why you think that shorting it will do something useful.

Renate NST said:
Not much.
Unless the unit is in USB host mode there will be no voltage on the Vcc line.
Even in USB host mode it should be current limited and do no damage.
Still, I wouldn't do it.
I don't know why you think that shorting it will do something useful.
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I actually do not know, thus I asked... just trying to think outside the box about a way to trick the phone to think it is charging short of carrying a portable battery charger with me (which can be problematic on carry-on luggage).

Another idea I am thinking about is building a small flex cable using a conductive ink pen that permanently connect to the phone's battery on one side and a cut down male micro-usb on the other side (to slim it down). Such cable would be small enough to fold under the battery cover and allow it to close.
My question is: Will the ~3.7v be enough to get the phone to start charging? and do you foresee any issues with feeding power from the battery right back into the phone's charge port?

dcalpha said:
Another idea I am thinking about is building a small flex cable using a conductive ink pen that permanently connect to the phone's battery on one side and a cut down male micro-usb on the other side (to slim it down). Such cable would be small enough to fold under the battery cover and allow it to close.
My question is: Will the ~3.7v be enough to get the phone to start charging? and do you foresee any issues with feeding power from the battery right back into the phone's charge port?
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I think 3.7 won't be enough. Coz usb giving ~5V. So phone won't charge at smaller voltage.