Database Users

[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
Click to expand...
Click to collapse
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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Click to collapse
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
Click to expand...
Click to collapse
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.
Click to expand...
Click to collapse
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.
Click to expand...
Click to collapse
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?
Click to expand...
Click to collapse
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.
Click to expand...
Click to collapse
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

[q] otg cable causes total shutdown

I got an OTG cable off ebay and it said it was good for nexus7.
PROBLEM IS...
When i plug it in nexus7 Instantly, totally shuts off.
Will NOT turn back on no matter how much i push POWER....
UNLESS i plug my nexus 7 back into it's wall charger.
Anyone ever have this problem with an OTG cable?

Are you plugging in just the cable, or are you connecting something to it? I had my N7 reboot when I was screwing with USB power and a hard drive.

Hi. First I tried it with nothing at all. I thought it killed my N7.
Than I tried it with it plugged into my six axis gamepad.
Same thing.
No matter how much I would push the power button it wouldn't go on.
Plug in my Ac adapter and it boots.
I'm using stock, unrooted.
Any setting that can cause this?
Im thinking some wires that are not supposed to be touching inside the connector are shorted.

EBay merchandise is always questionable quality. Yours is shorted - send it back to the seller. He will sell it to the next guy in line...
Sent from my Nexus 7 using xda app-developers app

...or get a new one, it probably cost less then shipping.
Check out dx.com, I got 2 adapters and one cable (all OTG) from there, and everything works.

Thank you. I'll get another. I'll let you know how it goes.
Oh, I have a question.
Is there an otg cable that allows charging of N7 while using with a gamepad?

OTG charging cable
brantgoose said:
Thank you. I'll get another. I'll let you know how it goes.
Oh, I have a question.
Is there an otg cable that allows charging of N7 while using with a gamepad?
Click to expand...
Click to collapse
With stock kernel OTG charging will not work.
If your Nexus is rooted, you can flash custom kernel (Timur's latest mobile kernel from http://rootzwiki.com/topic/37755-timurs-kernel-usb-host-power-management-usb-audio/). The one from faux123 (013) will also work, but charging mode must be enabled/disabled via script. In Timur's kernel it's automatic.
Then something like this will work (I use the first one, but ordered the second now):
http://www.ebay.com/itm/Micro-USB-Host-OTG-Cable-w-USB-power-Male-Female-Samsung-S2-i9100-S3-i9300-9220-/261161262679?pt=PDA_Accessories&hash=item3cce6c9e57
or
http://www.ebay.com/itm/Left-angled-Micro-USB-OTG-Cable-With-USB-power-for-i9100-i9300-i9220-i9250-N7100-/380553042368?pt=PDA_Accessories&hash=item589aba99c0
Hope it helps.

OK. .I guess i will need to Root than. The reason i wanted to use the OTG cable was to not Root. But since i can't charge while playing. (without rooting anyway)
I'll root and than i'll be able to run the controller off of bluetooth and charge.
Thank you.

brantgoose said:
OK. .I guess i will need to Root than. The reason i wanted to use the OTG cable was to not Root. But since i can't charge while playing. (without rooting anyway)
I'll root and than i'll be able to run the controller off of bluetooth and charge.
Thank you.
Click to expand...
Click to collapse
does anyone know if a mouse using an otg cable will work in recovery mode. cracked my screen looking for a way to flash new roms but not dont want to restart my tab because im afraid i wont be able to get out of recovery. im running m-kernel 32a with multiboot.

I don't know but if you start a new thread your bound to get way more hits and maybe someone who knows would see it.

The CABLE was the culprit. Got a new one. It works. Thanks.

bringing this one back from the dead. i have a KNOWN GOOD usb otg adapter that works flawlessly in my nexus 5 but has the exact same symptoms as the OP, it powers fully off and wont turn back on without a wall charger or battery pull.
sincei know its not the adapter what other options do we have

Is there a kernel\rom to allow USB host + charging for the N10

Is there a kernel\rom to allow USB host + charging for the N10

siviog1 said:
Is there a kernel\rom to allow USB host + charging for the N10
Click to expand...
Click to collapse
No, not with an OTG Y Cable and/or Pogo plug. I did read that there is work being done on the Nexus 7 to add that capability but at the time I read that (a week or so ago) it had not been accomplished. Be aware that if a OTG device is attached at the same time the pogo plug is connected the charge notification will display. Unfortunately that is a false indicator.

3DSammy said:
No, not with an OTG Y Cable and/or Pogo plug. I did read that there is work being done on the Nexus 7 to add that capability but at the time I read that (a week or so ago) it had not been accomplished. Be aware that if a OTG device is attached at the same time the pogo plug is connected the charge notification will display. Unfortunately that is a false indicator.
Click to expand...
Click to collapse
I thought that the Timur Kernel solved exactly that issue for the Nexus 7. Or did I overlook something?

ArrowHood said:
I thought that the Timur Kernel solved exactly that issue for the Nexus 7. Or did I overlook something?
Click to expand...
Click to collapse
You maybe right, I have not kept up as I have a N10 and only really watch development of its related custom ROM/Kernels.

Charge while OTG

Hi.Is there any kernel for Nexus 10 to charge while OTG ? I really need it,my nexus 10 will be connected to a printer most of the time so i need to be able to charge it thru the pogo or thru a USB hub.
Thanks in advance and have a good day !

There's nothing in the kernel that should stop the device from charging via Pogo if you're connected via OTG to something else, so long as the incoming source outweighs power output (which it should in basically every instance).

Rirere said:
There's nothing in the kernel that should stop the device from charging via Pogo if you're connected via OTG to something else, so long as the incoming source outweighs power output (which it should in basically every instance).
Click to expand...
Click to collapse
I see.I'll wait till my Pogo arrives but from what i've read,there are problems when using OTG and trying to charge the device as well.
Also,is there a way to connect my nexus 10 to the pc(for app developing) and also connect it to the printer(Star micronics tsp100/143USB-to test if my app is printing right).It really sucks that i need to connect it to the pc,run my app from eclipse and then plug it to the printer.
.This would mean i need to use the tablet as a host and as a slave/client at the same time,is that possible ?

Rirere said:
There's nothing in the kernel that should stop the device from charging via Pogo if you're connected via OTG to something else, so long as the incoming source outweighs power output (which it should in basically every instance).
Click to expand...
Click to collapse
You cannot charge with the pogo plug while any OTG device is connected period. This limitation has only been resolved with the Nexus 7. The limitation extends to all Roms stock or otherwise.
This topic has been covered in the accessories forum and I can personally confirm it. What fools a lot of people is that the notifications menu shows charging but the indicator is bogus.
Maybe with Android 4.3 but I am not holding out hope for that fix. It seems Google has abandoned any plans they once had for the pogo connector despite its potential (dock, audio, charging, fasters device I/O ... etc). Charging through the pogo plug has only been enabled through a 3rd party.
I love my N10 but Google dropped the ball on the pogo connector.

3DSammy said:
You cannot charge with the pogo plug while any OTG device is connected period. This limitation has only been resolved with the Nexus 7. The limitation extends to all Roms stock or otherwise.
This topic has been covered in the accessories forum and I can personally confirm it. What fools a lot of people is that the notifications menu shows charging but the indicator is bogus.
Maybe with Android 4.3 but I am not holding out hope for that fix. It seems Google has abandoned any plans they once had for the pogo connector despite its potential (dock, audio, charging, fasters device I/O ... etc). Charging through the pogo plug has only been enabled through a 3rd party.
I love my N10 but Google dropped the ball on the pogo connector.
Click to expand...
Click to collapse
Damn,really bad news for me.. What do you mean by "Charging through the pogo plug has only been enabled through a 3rd party."
Are you talking about the nexus 7 or about some hardware modifications ?
And what you're saying is that there are no mods,roms or kernels for nexus 10 that can modifiy this,like the nexus 7 timurs kernel(if i got it right) ?

gehaste said:
... Are you talking about the nexus 7 or about some hardware modifications ? And what you're saying is that there are no mods,roms or kernels for nexus 10 that can modifiy this,like the nexus 7 timurs kernel(if i got it right) ?
Click to expand...
Click to collapse
Just to be clear the Nexus 7 (only) has the "Timur Kernel" as an option. While the Nexus 10 "no mods,roms or kernels" or even any hardware mods as far as I am aware.
To me this lack of functionality is a flaw in Google's kernel/ROM implementation considering they added the pogo plug connector allowing charging but never anticipated/implemented concurrent use of the USB and pogo connector.
From what I have read the pogo plug was originally supposed to be included with the Nexus 10 but that was changed just before the product was released. I never heard exactly why but I now suspect that it has to do with the stock kernel/ROM limitation.

[Q] USB OTG + pogo charging

I've seen this question pop up a while ago but it doesn't appear to have been solved. Someone mentioned that the KTManta kernal might have solved this but I couldn't find that answered anywhere in that thread (here). I am using the USB OTG cable to control an IR Droid USB transmitter in a permanent kiosk installation and I need the pogo connector to supply power so this can run 24/7.
Any help is much appreciated!
UPDATE:
Wooo!!! Just thought I'd give the kernel a shot and see what happens... it works! I have a separate USB voltage meter that confirms, as well as seeing the battery % increase while being used, and my IR Droid is also working.
Just install the above mentioned kernel, plug in the USB Y OTG cable into tablet, external power supply to the male USB end of Y adapter, and external device (mine being the IR Droid device) to female USB end. Plug second power supply (I used the 2.4a (12w) iPad charger) into pogo connector. Win.
Ktoonsez, your next few beers are on me, good sir!!

UPDATE: The latest KTManta kernel (04-06-2014) breaks root (SuperSU) with the stock rom. In my case that is v4.4.4 so I've had to revert to my nandroid backup. The issue has been known for a long while but it seems the dev is prioritizing his kernel on other devices. Obviously this means I'll not be testing any time soon.
Interesting, I've wanted this solution for a long time as I use an USB Ethernet adapter from a room with poor WiFi reception. I'll see if it makes any difference if the OTG USB device is attached to a powered USB hub or not and report back.
Sent from my Nexus 10 using XDA Premium HD app

3DSammy said:
UPDATE: The latest KTManta kernel (04-06-2014) breaks root (SuperSU) with the stock rom. In my case that is v4.4.4 so I've had to revert to my nandroid backup. The issue has been known for a long while but it seems the dev is prioritizing his kernel on other devices. Obviously this means I'll not be testing any time soon.
Interesting, I've wanted this solution for a long time as I use an USB Ethernet adapter from a room with poor WiFi reception. I'll see if it makes any difference if the OTG USB device is attached to a powered USB hub or not and report back.
Sent from my Nexus 10 using XDA Premium HD app
Click to expand...
Click to collapse
Oh man, I wish I knew about it breaking root before installing!! I was wondering why it was saying I wasn't rooted... Is there a way to fix root while on this kernel?
I'm having some issues with the tablets now that I didn't have before - the most basic seems that it won't boot (won't even start the Google logo) if I have both OTG device and Pogo connected at same time when the tablet is off. I did solder my own right angle tip onto the OTG Y cable though, so I may have messed something up... I'm going to be doing some more testing over the next couple days and I'll keep this up to date.

"Is there a way to fix root while on this kernel?"
The root issue with KTManta's latest release is specifically with the stock ROM from what I've read in the N10 KTManta thread. So it would seem that installing a non-stock ROM then installing the KTManta kernel would be the only way to get this kernel and root. I'm unwilling to do that for this single feature. There were comments that root was still working on an older KTManta release which if I can remember is from Dec 2013. I've no idea if that release has the charging features you see with the latest release.
If you go the custom ROM route then read the KTManta thread to find out which custom ROM's are working. Don't quote me but I thought the OMNI ROM was one that worked, please confirm that for yourself.
From my experience stock with the XPosed framework is more stable than any custom ROM and I've tried many.
Sent from my Nexus 10 using XDA Premium HD app

So there were a few other issues that I found out while testing...
If you have USB plugged in, then reboot, the tablet freezes while trying to boot. It doesn't even get to the loading screen.
It seems a bit buggy as to when it wants to work and when it doesn't, and all the while the tablet says that it's charging so it is hard to test, but I was using a USB volt meter to see if the pogo was actually taking power or not.

The next thing I want to test is using a powered USB hub, instead of a Y cable. Has anybody done this successfully? Does it need the modified kernel? Does it ACTUALLY charge, or just say that it is?

SupremeTaco said:
The next thing I want to test is using a powered USB hub, instead of a Y cable. Has anybody done this successfully? Does it need the modified kernel? Does it ACTUALLY charge, or just say that it is?
Click to expand...
Click to collapse
I use a powered hub to access an Ethernet adapter while concurrently having the pogo plug attached. The result is that the tablet drains slower as the Ethernet adapter is drawing power from USB Hub rather than the tablet. The tablet does not get charged in anyway despite the false charging icon indicator. This is why your post was so interesting to me until I discovered that root was lost. I can live the charging and OTG limitations but I can't loose root.
Sent from my Nexus 10 using XDA Premium HD app

I tried this the same way as SupremeTaco described.
My nexus 10 runs the latest Omnirom 4.4.4 with latest KTManta kernel.
I plugged in the OTG Y Cable, which was connected to a charger and a usb SD-card reader. Then I plugged in the Pogo charger and to my surprise, the Nexus 10 charges yay! (I saw the battery percentage increase as I was using device with screen on)
SupremeTaco thank you for this great tip, I have been looking for a solution for a long time. I can now charge my Nexus 10 16GB while using a Meenova reader with 64GB microSD card - which is extremely useful :good: :good:

xIsei said:
I tried this the same way as SupremeTaco described.
My nexus 10 runs the latest Omnirom 4.4.4 with latest KTManta kernel.
I plugged in the OTG Y Cable, which was connected to a charger and a usb SD-card reader. Then I plugged in the Pogo charger and to my surprise, the Nexus 10 charges yay! (I saw the battery percentage increase as I was using device with screen on)
SupremeTaco thank you for this great tip, I have been looking for a solution for a long time. I can now charge my Nexus 10 16GB while using a Meenova reader with 64GB microSD card - which is extremely useful :good: :good:
Click to expand...
Click to collapse
I'm glad it helped! But be careful as you may have issues booting with the USB plugged in. Let me know if this does happen to you... it may just be the version of the kernel I was using but I gave up and am looking for another solution at this point, since I must leave the USB plugged in 24/7

Pogo works great
Should have bought one earliar

Pogo works great
Should have bought one earliar

SupremeTaco said:
I'm glad it helped! But be careful as you may have issues booting with the USB plugged in. Let me know if this does happen to you... it may just be the version of the kernel I was using but I gave up and am looking for another solution at this point, since I must leave the USB plugged in 24/7
Click to expand...
Click to collapse
Sorry for the slow response,
I did some testing with both KTManta kernel and the stock Omnirom kernel and indeed booting with USB plugged in does not work. The culprit seems to be the OTG Y-Cable and specifically the power supply part. If you disconnect power from the Y cable but leave everything else plugged into the tablet, the tablet will boot. Perhaps you could have a power switch for the Y-cable and switch it off only when booting?
Also, I have discovered that Pogo charging with Y-cable also works on stock Omnirom kernel. So it seems that the kernel does not affect the charging capability with this setup in anyway, so we are not limited to using KTManta. However the booting issue does not seem to be a kernel-related problem.
Edit: I also confirmed charging in this way works with franco kernel r16 (so it will probably work with all other franco kernels and any other custom kernel)