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.
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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.
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?
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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

In-dash Install - My Setup and Need Info/Advice

So, I have had my Nexus 7 installed in my 2007 Toyota Tacoma for 7 months. I use the Behringer UCA202 DAC($20). I am a cheapo so I preferred $20 over the $76 Fiio E10K that is supposed to be better. I also like that I have a mic input that works on the UCA202. Makes voice search and phone calls possible. Grounded the outside of the rcas to the chassis to help with the electrical noise. Used Premium Monoprice RCA cable to also help with the electrical noise. ($7) Using Alpine KTP-445U($114) to amplify the tablet audio output to the speakers. (Rockford P1675-S in the front and P1675 in the rear, $200) I needed my steering wheel controls to work so I used the Joycon EXR Steering Wheel Interface ($58). Its setup took a couple hours but after I completed the setup I have had ZERO issues with it, LOVE IT! Please note that the Joycon EXR will only work for analog steering wheel controls. You would need the EXC($92) for CAN, IBUS, resistive, and digital steering wheel controls. Used a cheap usb otg charging adapter for allowing usb otg while charging. Be careful with these some cords will allow this, some will not. Pay attention to reviews to get some insight but even then it's a shot in the dark. You also need to make sure that it is a high quality cable so that the wire gauge can handle the current for fast charging. RTL2832U DVB dongle for being able to receive FM stations on the tablet. Also used a cheap 4 port usb hub. Used three of the ports for DAC, EXR, DVB.
Okay, all done with my setup. Now on to getting some advice. I used to use Timurs Kernel for 5.1, cost me $20. It worked okay but it would often freeze when I shut off my truck so the tablet would then reboot after 20ish seconds. 3 months after I bought LP Timur came out with MM. But, he wanted me to pay for that one as well. Hell no. I emailed him, he wouldn't upgrade me without paying. Didn't want to pay for his kernel in the first place so there was no way I was going to pay for it again. So... I decided to take on the setup of the tablet for Fixed install on my own. I installed Cyanogen Mod (13.0-20160827-NIGHTLY) with the Elemental X kernel version 3.16 (last reported version to include working usb otg + fastcharging) Well I get charging + usb otg but its not fast charging. No big deal, I can deal with that for now.
The problem I am having is that I cannot for the life of me figure out how timurs kernel would only lose 1% of batterylife in 12 hours when the truck was turned off. I have tried multiple things, done a ton of research and nothing seems to get close to 1% for 12hrs. The best solution I have found is using the apps Greenify, No Wakelock, and Force Doze as well as disabling Google Sync completely. This has gotten me down to about 8% for 12 hours. When I previously used Tasker as the overall solution I was losing 12% for 12 hours. (disable WiFi and location, enable airplane mode, enable battery saver)
Anyone have any tips to improve the drain while my truck is off?

Nexus 2012 in my car, help with OTG charging and waking up.

First: How do I get my Nexus 7 to charge from the OTG cable? I can connect USB devices to it but connecting the power cable of the Y doesn't seem to do anything.
Second: Is it possible to wake from tapping?
Related threads:
http://forum.xda-developers.com/showthread.php?t=2776308
(references using the Nexus 2013)
All other threads I've found relating to the OTG cable charging reference Timur's ROM which is no longer available. Is there another solution?
I've got a Nexus 2012 Wifi and all the hardware (USB DAC, amp, wiring, etc) to install this in my car. My last 2 hurdles before ripping the dash apart is the charging while connected to a USB hub and how to wake the tablet up. I was afraid of leaving the screen on all the time would burn it out and drain the battery. I wanted the ability to turn the tablet on without having the keys in the ignition. I guess I could forego that requirement and just have the tablet always on and only turn on in the ACC position.
For the wake I am thinking of creating a mechanical switch that activates the button. The power button on the tablet now will be concealed by the bezel once installed in the dash. There is an app that works but it doesn't really wake from sleep but rather creates a black screen that is tappable. I really wanted the thing to go to sleep and then wake with a tap.
I also wanted the newer android version, 6 or greater. I flashed with CM 7.1 and it works great save the two issues I'm having. Even if I had access to Timur's ROM it hasn't been updated since 4.something so I would want it newer anyway.
Any ideas or suggestions?
Thanks in advance.

I installed the BeanStalk 6.19 and I am now able to OTG charge and double-tap to wake device (no extra settings as it was included with the ROM).
My problem now is it seems to only want to OTG charge when I first plug in the OTG cable to the tablet. If it's charging and I turn off the power to the OTG (like disconnect the charging cable connected to the OTG) and then plug that charging cable back in it will not charge until I reconnect the OTG cable to the tablet. I wanted to hide the cable behind the bezel of the dashboard.
I was hoping to switch the power to the USB hub that is connected to the OTG charge cable with the ACC line from the ignition. This way I wouldn't be draining the battery at all when the keys are not in the ignition. It's only 12.5 watts so I guess I could leave it on all the time. It's getting cold here this time of year so I didn't want any type of extra drain on the battery when I didn't need it.
Any suggestions?

Need help getting enough battery power to use MHL adapter with i9506

I need to have an MHL adapter connected to my Samsung Galaxy s4 i9506 which mirrors it's screen to a monitor/info screen indefinitely, but the problem is that an MHL adapter outputs a measly 300mA (Tried lots of chargers but the output never changed) which is nowhere enough. I did some research and found out that I can up that number by installing a custom ROM that enables fast charging so tried that with my other phones doing the same task that are i9505 and SGH-M919. I managed to install a custom ROM that enabled fast charge through STweaks which upped the output all the way to 1000mA, but I haven't been able to find out a ROM that enables the feature for i9506. I tried LineageOS 14.1 which should have fast charge enabled by default, but when I used Ampere to check the charging current the output was 300mA, so I assume that fast charge didn't get enabled.
Does anybody know a ROM, that enables fast charge for i9506, or how I could scrape by with that measly 300mA when the only thing the phone needs to do is to mirror a web page to a monitor. Chrome cast isn't an option, because if the connection drops you need to manually connect it again, and since the phones should be operational for months without rebooting the connection is bound to drop sooner or later.

That's​ a kernel thing. So, unless you find a kernel for the I9506 that supports 1000 mAh USB charging, you're out of luck in this regard.
I guess the only way to survive with 300 mAh would be to turn the screen off, otherwise the phone will use more power than it receives.
Another solution would be wireless charging. I think this is your best bet.

Is there an app that I could use that timers off the screen during the night and then wakes it in the morning? There are a lot of apps that let you time music and other apps, and even turn off the screen, but I haven't found one yet that could also wake the phone up later.

nyoatype said:
Is there an app that I could use that timers off the screen during the night and then wakes it in the morning? There are a lot of apps that let you time music and other apps, and even turn off the screen, but I haven't found one yet that could also wake the phone up later.
Click to expand...
Click to collapse
Maybe Tasker.

@nyoatype
I'm searching for same as you.
Having mhl adapter (which is original as i think, working without power source and resolution is 1080p60). After connecting to AC 1.2A max charging power for phone (I9505) is only 300mAh, on original Samsung charger 2.1A is little bit more - 400mAh but obviously it's still not enough for me. Power output doesn't change even after enabling USB fast charging (700mAh or 1000mAh, doesn't matter).
I was looking to kernel source https://github.com/Slim80/Imperium_...ter/arch/arm/mach-msm/board-fusion3-battery.c
where are defined values of charging for MHL 500/MHL 900/MHL 1500 (phone probably can detect which one is plugged) but after increase charge_current_max and charge_current for every MHL type I do not see any difference unfortunately, so I'm searching still what's is going on and where i can increase power output from MHL to phone.
I'm searching for a way to change resolution of MHL video output too, so if anyone kernel master can follow me a little bit, will be great (maybe here https://github.com/Slim80/Imperium_Kernel_TW_5.0.1/blob/master/drivers/video/msm/external_common.c in line 40 -
HTML:
int hdmi_forced_resolution = - 1 ;
)

PolishVodka said:
@nyoatype
I'm searching for same as you.
Having mhl adapter (which is original as i think, working without power source and resolution is 1080p60). After connecting to AC 1.2A max charging power for phone (I9505) is only 300mAh, on original Samsung charger 2.1A is little bit more - 400mAh but obviously it's still not enough for me. Power output doesn't change even after enabling USB fast charging (700mAh or 1000mAh, doesn't matter).
I was looking to kernel source https://github.com/Slim80/Imperium_...ter/arch/arm/mach-msm/board-fusion3-battery.c
where are defined values of charging for MHL 500/MHL 900/MHL 1500 (phone probably can detect which one is plugged) but after increase charge_current_max and charge_current for every MHL type I do not see any difference unfortunately, so I'm searching still what's is going on and where i can increase power output from MHL to phone.
I'm searching for a way to change resolution of MHL video output too, so if anyone kernel master can follow me a little bit, will be great (maybe here https://github.com/Slim80/Imperium_Kernel_TW_5.0.1/blob/master/drivers/video/msm/external_common.c in line 40 -
HTML:
int hdmi_forced_resolution = - 1 ;
)
Click to expand...
Click to collapse
I used this ROM to up up my numbers with i9505 to 500mAh-640mAh depending on charger and mhl adapter, so if it's of any help to you you can try it. Let me know if you find anything that could be of use : D https://forum.xda-developers.com/ga...dcteam-android-source-project-mra58v-t3251663

Is there any way to wake phone up with a timer? For example make the phone wake up every morning at 8 o'clock? I'm using automate to put the phone to sleep at a fixed time, but waking it up doesn't seem to be as easy (The timer block in automate actually has a checkbox with description "Awake device", but it doesn't actually wake the phone up).

nyoatype said:
Is there any way to wake phone up with a timer? For example make the phone wake up every morning at 8 o'clock? I'm using automate to put the phone to sleep at a fixed time, but waking it up doesn't seem to be as easy (The timer block in automate actually has a checkbox with description "Awake device", but it doesn't actually wake the phone up).
Click to expand...
Click to collapse
I already told you to try Tasker. Did you do it?

Pwnycorn said:
I already told you to try Tasker. Did you do it?
Click to expand...
Click to collapse
I haven't yet added a payment option to Google store (Since this is work related and I'd need to use the companys payment information) so haven't been able to try Tasker. I'll try it when I'm able to get my boss' approval.
I'm also trying to do some physical changes to one of the MHL adapters to bypass it, so that the current would come straight from the charger. This means I'll cut the Power and GND (red and black wires) of the microUSB cable connected to the phone and connect them in parallel with the red and black cables going to the MHL adapter. I'm not sure, but this might cause the MHL adapter get power from the charger, but instead of supplying the power to the phone, the phone would get it's power straight from the charger (although it would still be USB-charging since the data pins are being used, but that wouldn't matter since I usually get 1000mAh when USB charging with computer).
Another possible solution is to use wireless charging pad, because I read that if the USB-connection uses MTP or PTP the wireless charging will take priority, so the data would go through the USB but the power would come from the wireless charger. I'm not sure about this because I read it from another forum post, so if somebody could confirm/deny it I would be seriously grateful!
Thanks for your replies and suggestions so far! This is one heck of a situation I've been put into so I really appreciate the help!

Verify a USB-C issue for me?

Hi,
So I got a new car and I'm testing out all the ways to connect my phone to it to share music, data, and charging. Been having a lot of issues with various parts but this question will pertain to my understanding of USB-C.
I had read that the USB-A ports in this particular car (Mazda 3) are only pinned in a way to provide "dummy" power. If I understand this properly, there isn't data pins hooked up to the port so the phone can decide how much juice to pull so it just outputs at .5 instead of anything higher. Meanwhile, I'm understanding that USB-C can actually push power in two directions kind of like osmosis. And this is why some power banks require a special ritual to make sure power goes from the bank to the phone at some point or you end up discharging your phone into the bank.
What I seem to have run into sounds a bit like this. Under the same conditions of driving into work (half hour) with BT streaming and screen off for the phone. Plugged into the 12V outlet using a Belkin charger, phone fast charges as expected. Plugged into the car's USB-A (tried two different cords too), I was losing 1-3% battery. I just figured the incoming charge wasn't keeping up with the power consumption of the phone.
This morning, I decided to run a control test. Same drive, BT streaming, started with 100% power. Got into work and expected to see at least 1-3% drop. There wasn't any. I still had 100% and did so for at least another half hour of listening with standard headphones plugged in.
My only guess is that the phone is deciding to push power the other way? Any thoughts?