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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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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
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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.
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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.
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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?
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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.
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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
Hi, I have recently installed my Nexus 7 (running CM10.2 on 4.3.1 and leanKernel) in the dashboard of my car. I installed a cigarette socket behind that dash that provides power to the device when the vehicle is running. When the vehicle turns on i have tasker set to lock the display on, start my music and torque. The problem I am having is when the N7 is one and receiving a charge the battery is still discharging (approx. .8%/h according to battery stats app). I have used 3 different charges, two which are 2.1A and the third is 150w dc 12v to 110v ac power inverter which i have used 2 different usb chargers in, but i am still seeing the battery discharge while I am using the tablet. i can rewire the cigarette socket so it is constantly charging the device but since I am not able to reach the power button on the tablet i dont know how ill be able to toggle the screen. i have tried to under-clock the cpu and gpu (currently have the device running on 1 core) but still havent seen an improvement. Any idea what i may be able to do to rectify the problem?
I was also going to try to upgrade the tablet to 4.4.2 but adb and fastboot cannot see the tablet anymore. i updated the usb drives and it was working perfectly fine up until a week ago so i am not sure what is happening.
Thanks for the help.
Ted_rivers said:
Hi, I have recently installed my Nexus 7 (running CM10.2 on 4.3.1 and leanKernel) in the dashboard of my car. I installed a cigarette socket behind that dash that provides power to the device when the vehicle is running. When the vehicle turns on i have tasker set to lock the display on, start my music and torque. The problem I am having is when the N7 is one and receiving a charge the battery is still discharging (approx. .8%/h according to battery stats app). I have used 3 different charges, two which are 2.1A and the third is 150w dc 12v to 110v ac power inverter which i have used 2 different usb chargers in, but i am still seeing the battery discharge while I am using the tablet. i can rewire the cigarette socket so it is constantly charging the device but since I am not able to reach the power button on the tablet i dont know how ill be able to toggle the screen. i have tried to under-clock the cpu and gpu (currently have the device running on 1 core) but still havent seen an improvement. Any idea what i may be able to do to rectify the problem?
I was also going to try to upgrade the tablet to 4.4.2 but adb and fastboot cannot see the tablet anymore. i updated the usb drives and it was working perfectly fine up until a week ago so i am not sure what is happening.
Thanks for the help.
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Click to collapse
Hi, do you have a dcdc-usb? I know Who did your work (n7 in dash car) normaly have that, with a otg-y cable and normaly use USB ROM with Timur's kernel, which is a dedicated rom for car 's installation. Try to search info about that.
Unfortunatelly development is stopped to android 4.2 (the release before 4.3) But it' s very good rom.
If your installation is fixed, in the night u will lost about 1-2 %
Ps can you upload some photoes about your dash ?
Inviato dal mio Nexus 7 utilizzando Tapatalk
furious84 said:
Hi, do you have a dcdc-usb? I know Who did your work (n7 in dash car) normaly have that, with a otg-y cable and normaly use USB ROM with Timur's kernel, which is a dedicated rom for car 's installation. Try to search info about that.
Unfortunatelly development is stopped to android 4.2 (the release before 4.3) But it' s very good rom.
If your installation is fixed, in the night u will lost about 1-2 %
Ps can you upload some photoes about your dash ?
Inviato dal mio Nexus 7 utilizzando Tapatalk
Click to expand...
Click to collapse
I dont have a dcdc-usb as the power to the tablet is coming from 2.1A car charger or a 150w power inverter. i dont have a otg-y cable but i do have the means to easily install one if i ever need it. I never knew about USB rom and Timur's kernel. ill flash those asap and hopefully that will fix the battery drain. As for pictures i only have this one from when i first installed the the tablet but know i have my dashboard disassembled. hopefully this will hold you over for now .
Uhm i can say to u try the USB ROM,i haven't other idea
Ps nice work
Inviato dal mio Nexus 7 utilizzando Tapatalk
Ted, you need to flash a kernel that supports fast charge and enable it. I have the same issue, after flashing a 4.4 rom I lost my fast charge and over the duration of a long drive the battery is discharged. Apps such as fanco kernel updater have the option to enable fastcharge, if the kernel supports it. Great setup BTW, I have mine mounted on the dash.
ryar said:
Ted, you need to flash a kernel that supports fast charge and enable it. I have the same issue, after flashing a 4.4 rom I lost my fast charge and over the duration of a long drive the battery is discharged. Apps such as fanco kernel updater have the option to enable fastcharge, if the kernel supports it. Great setup BTW, I have mine mounted on the dash.
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Click to collapse
Hi ryar,
Thanks for the help. I've flashed a few different kernels that have fast charging enabled. The latest is Timur's kernel which says fast charging is enabled. Sadly my tablet is still discharging when its in use so I've decided I'm going to have it set to charge at all time and use a magnet to switch the screen on when I need it.
Ted_rivers said:
Hi ryar,
Thanks for the help. I've flashed a few different kernels that have fast charging enabled. The latest is Timur's kernel which says fast charging is enabled. Sadly my tablet is still discharging when its in use so I've decided I'm going to have it set to charge at all time and use a magnet to switch the screen on when I need it.
Click to expand...
Click to collapse
Are you trying to charge in host mode or just using the USB came that came with the nexus 7? I could help you solder power and volume to some switches so you can toggle screen on off that way? I bought a Samsung branded car charger and it works great for car charging. I made a y cable that you can turn host mode on and off with a switch. I could help talk you through it or do it for u if you buy the stuff its pretty cheap fairly simple to do if u have patients. Most of Those 2.1 amp dual port chargers only supply 1 amp to android devices, this could be your problem.
b3ltazar said:
Are you trying to charge in host mode or just using the USB came that came with the nexus 7? I could help you solder power and volume to some switches so you can toggle screen on off that way? I bought a Samsung branded car charger and it works great for car charging. I made a y cable that you can turn host mode on and off with a switch. I could help talk you through it or do it for u if you buy the stuff its pretty cheap fairly simple to do if u have patients. Most of Those 2.1 amp dual port chargers only supply 1 amp to android devices, this could be your problem.
Click to expand...
Click to collapse
I am just charging the tablet straight up no host mode. ive used a variety of chargers: two different branded 2.1a chargers and both the stock nexus 7 wall charger and another tablet wall charger plugged into a 150w power inverter. Thank you for the offers! If its fairly simple to solder the power switch I would prefer to do that regardless of the discharging problem so that i can hard reset the tablet if i ever need to.
Thank you for the help!
Ted_rivers said:
Hi ryar,
Thanks for the help. I've flashed a few different kernels that have fast charging enabled. The latest is Timur's kernel which says fast charging is enabled. Sadly my tablet is still discharging when its in use so I've decided I'm going to have it set to charge at all time and use a magnet to switch the screen on when I need it.
Click to expand...
Click to collapse
Fast charging on Timur's rom work with otg Y Cable
Inviato dal mio Nexus 7 utilizzando Tapatalk
Ted_rivers said:
The problem I am having is when the N7 is one and receiving a charge the battery is still discharging (approx. .8%/h according to battery stats app). I have used 3 different charges, two which are 2.1A and the third is 150w dc 12v to 110v ac power inverter which i have used 2 different usb chargers in, but i am still seeing the battery discharge...
Click to expand...
Click to collapse
I've had my Nexus 7 "in my truck since last year. I at first had it sleep via Tasker, but I was having issues if I left my car for awhile. The batterywwould be low and if I didn't have long drives, I could never rechargeit to ssufficient battery fullness.
I changed my setup to have the tablet power on upon receiving AC ignitionpower using this adb command:
there is a Fastboot command that you can issue to the bootloader to make the tablet power on once plugged it.* “fastboot oem off-mode-charge 0” makes the unit power on the instant its connected to AC. “fastboot oem off-mode-charge 1” returns to normal state,* so fitting an external switch isn’t 100% necessary, but i decided i wanted one anyway. I’m using Tasker to switch the unit on and off* with the ignition, but having the external switch is a handy addition.
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Click to collapse
Then I have Tasker turn it off after minute not being used. I'm sure it's not good for the Nexus 7 to always be at 100% power, but I don't care about the batter health because I purchased this for my truck only.
My only concern now, is the safety of the battery in AZ summer heat. I don'twant it to explode, and iI'm wondering if the tablet will function with AC power only, then I could remove the battery and not worry about it.
Poi25 said:
I've had my Nexus 7 "in my truck since last year. I at first had it sleep via Tasker, but I was having issues if I left my car for awhile. The batterywwould be low and if I didn't have long drives, I could never rechargeit to ssufficient battery fullness.
I changed my setup to have the tablet power on upon receiving AC ignitionpower using this adb command:
Then I have Tasker turn it off after minute not being used. I'm sure it's not good for the Nexus 7 to always be at 100% power, but I don't care about the batter health because I purchased this for my truck only.
My only concern now, is the safety of the battery in AZ summer heat. I don'twant it to explode, and iI'm wondering if the tablet will function with AC power only, then I could remove the battery and not worry about it.
Click to expand...
Click to collapse
How are about temperature there? How is your setup into truck? I mean n7 is into the Dash? Or You have some support? Anyway maybe your technical questions will be better answering on developer forum (If You have installed usb rom by timur)
Inviato dal mio Nexus 7 utilizzando Tapatalk
furious84 said:
How are about temperature there? How is your setup into truck? I mean n7 is into the Dash? Or You have some support? Anyway maybe your technical questions will be better answering on developer forum (If You have installed usb rom by timur)
Inviato dal mio Nexus 7 utilizzando Tapatalk
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Click to collapse
The temperature gets to almost 120F (48.8C) in the summer, and that's outside the vehicle. I took a dremel to my dash and modified it to mount the nexus 7. It's clean and looks just about stock. I made a wooden box to the dimensions of double DIN, and put the mounting brackets on either side. I used sticky tape to mount a nexus 7 matte black case to the front of the box, so when I slide the box into the double din area it lines it up perfectly. Then I just snapped the dash back into place over the top of the Nexus 7. So, the tablet is basically built into my truck.
Poi25 said:
The temperature gets to almost 120F (48.8C) in the summer, and that's outside the vehicle. I took a dremel to my dash and modified it to mount the nexus 7. It's clean and looks just about stock. I made a wooden box to the dimensions of double DIN, and put the mounting brackets on either side. I used sticky tape to mount a nexus 7 matte black case to the front of the box, so when I slide the box into the double din area it lines it up perfectly. Then I just snapped the dash back into place over the top of the Nexus 7. So, the tablet is basically built into my truck.
Click to expand...
Click to collapse
I saw photoes after i posted .
48C wow.... In italy it s hard when there are 35...
Inviato dal mio Nexus 7 utilizzando Tapatalk
hi. i need some help with my hardware modification. i successfully was able to run/power up my tegra note 7 (zotac variant) with no internal battery. power is supplied from a buck converter outputting 4.2V. power is supplied to the internal battery power board (battery itself is removed). the intention of this modification is to use my tablet as multimedia player and provide general android functionality to my car.
what i want to happen with this modification is the tablet to boot up once power has been supplied to the buck converter thus the tablet. i have to press the power on switch of the tablet to boot it up. i do not mind the boot time at every car start.
how can i or what do i need to do so that the tablet boots up automatically once powered has been supplied from the buck converter.
any kind of help would very much be appreciated.
PS: i have an option to leave the internal battery and do with all of the automation from the usb port but it doesnt work anymore (the usb port).
I use the 7inch Galaxy A6 (SM-T280) in a few applications that need USB communication. Unfortunately the electronics that the device is plugged into cannot also tell it to draw more current at the moment. When it is connected like this there is a red cross over the battery symbol and it loses charge over time.
For the time being I have used a modified USB cable with the data lines shorted together and communicated over Bluetooth, but that is also presenting issues. This makes the tablet charge properly, but I'd like to remove the reliance on Bluetooth.
What I want is for the tablet to know that it is capable of drawing more current (the power to the USB ports on the electronics are rated for over 2A). The tablets are already rooted to enable boot on charge which was done by modifying the lpm file in system/bin to start the boot sequence once power is applied to the USB port. I was hoping there was another file or line I could modify to enable the tablet to always fast charge. I'm not concerned about this "breaking the rules" on USB devices, so even if it means this happens all the time, then I'm ok with that.
Thanks!
Hello all,
First thread here and hoping you guys and girls with more experience can help.
Basically I am fitting my nexus 7 2012 in my car but its got the common charging problem where my battery drains faster than I can charge it.
I have ordered a new USB port strip as I've read that can fix it and fingers crossed with that.
My problem/requirement:
1. I want to charge the tablet via the usb port using a hardwired 5V 2A device this will be plugged into a otg y splitter which is then plugged into the tablet.
2. The USB A side of the splitter I want to connect to my cars ECU (it has a USB port) so I can read the data on that (basically a very expensive memory stick)
I wanted to confirm that this would work and id be able to read data at the same time as charging it.
I also wanted to double check I'm not somehow going to send my 5v 2a power down into my ECU and set it on fire
On a side note, if my new USB port replacement doesn't solve the issue of charging the tablet i will have to remove the battery and hardwire it in, will i still be ok with using the USB port for the ecu while charging hardwired with no battery?
Kind Regards
Tim
Getting any USB 2.0 device to take current while hosting is tricky.
Usually it involves talking directly to the PMIC (power management IC).
If it's a fixed installation, why not remove the battery?
It will avoid the grief of the battery swelling up, which is not too unusual for things plugged in all the time.
I've been using a Nexus 7 (2013) for a few years, but just charging on USB.
It started falling out of its nice holder.
That's when I realized that the battery was all puffed up making the back convex.
I cut off the battery cell itself on the metal tabs and soldered in wires to a 4 V 2 A supply.
I found out that the BMS is a bit balky, it refused to turn on.
So I connected it to USB to "charge" it for about 10 seconds.
Then I could turn it on (without the USB).
Ok, I could have bypassed the BMS entirely but that can be a whole 'nother can of worms too.