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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Click to collapse
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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Click to collapse
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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Click to collapse
I think 3.7 won't be enough. Coz usb giving ~5V. So phone won't charge at smaller voltage.
Can someone verify that the Nexus 7 can operates perfectly fine with the battery removed and only powered by the USB cable? I've read some threads eluding to this, but no one has confirmed. Mine is in the dash of my car so i cant verify this myself. If someone can. that would be amazing! Thank you.
look at the thread right below yours.
Old Guy said:
look at the thread right below yours.
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I saw that thread, i was still a bit confused as they were talking about USB DAC and other devices hooked up to me.
I want to make sure data can still be transferred from the same USB cable and such.
Yes, it's possible, but has some side-effects
Yes, it's possible to power the Nexus 7 without battery from a USB-cable, but it involves sending power directly to the battery connection inside the Nexus 7, and it seems to have some side-effects.
The battery is a one-cell lithium polymer, which has a max charge of 4.23 V. I hoped the Nexus wouldn't fry when connecting 5 V, and it has worked fine the few minutes I've tested it. No smell of burnt electronics
Here is what I did:
Tear off the tape around the battery cable. You'll see it's soldered to a pcb-board, and the two black and two red wires are soldered together. The two wires in the middle is probably some kind of data-connection to the battery. Will investigate this further later.
Then I soldered loose the cables, so I could use the battery-connector, and soldered both red and black wires to red and black wires in a USB-cable. Drilled a hole in the back-cover right below the NFC-antenna. The back-cover is filled with all sorts of antennas, so scratch carefully with a knife before drilling. Attached some pictures of the process.
Side-effects I've noticed so far:
- It thinks the battery is at 0% and not charging.
- The clock is reset when you turn off the power. But if you have internet it will update from NTP within a minute or so.
- My computer (OS X) can't detect it anymore. So I suspect it doesn't work in USB device-mode anymore, but I'm able to connect a USB-keyboard with an OTG-cable, so it seems to work in host-mode.
Does anyone else have any experience with this, or any ideas why it doesn't work in device-mode? I'm considering adding a small connector so I can use the two extra wires from the battery to the data-wires of the USB-cable (and disconnect when not in use), and then solder a USB female cable to the original battery. That way I can (hopefully) connect the Nexus 7 to my computer when needed, and possibly analyze what the two extra wires is actually used for.
I have CM for Android 4.2, and Timur's USB-rom, but it's probably not needed for this hack, and I will probably install a stock rom if I get this working properly.
Be careful, and don't blame me if you fry your Nexus (or anything else). Be sure to turn off any fast-charge hacks when the battery is disconnected.
Old Guy - look at the thread right below yours
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Threads are sorted by last post in each thread, so it's impossible to find which one you are referring to. Do you have an url?
Theory worked
I managed to connect the Nexus 7 to my computer again
I'm considering adding a small connector so I can use the two extra wires from the battery to the data-wires of the USB-cable (and disconnect when not in use), and then solder a USB female cable to the original battery. That way I can (hopefully) connect the Nexus 7 to my computer when needed, and possibly analyze what the two extra wires is actually used for.
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Click to collapse
Can confirm that this works. I didn't have any small connectors, so I hot-glued one header-pin and a female connector for a header pin on the data-wires in the USB-cable. Doesn't look good, but it works
When I have it in the car, I disconnect the header-pins on the USB-cable, and connect it to an USB power-source. When I need to connect it to the computer, I connect the header-pins and connect the battery (with the female USB-cable), and a regular USB-cable to the computer.
Sorry to bring up an older thread, but it sounds like the White and Yellow wires of the battery are for data?
if so, if I applied 3.7-4.2 volts on the battery connection and then still had a 5v connection on the USB would this work?
I would like to use Timur's ROM, and have power applied when my car is off (fixed install) for deep sleep and then apply the 5v when the car is on to bring it from the deep sleep. the issues would be faking it to not charge which I am guessing would mean to set the battery input to 4.23 volts to show as being fully charged. then when key on, the 5v would take over and you would still have the 4.23 applied at the battery connection ( probably have a diode on the + side to keep from injecting voltage to that supply
Has any one completed something like this?
The problematic usb port finally gave up on my Nexus 7 (2012). I've opened up it up, connected the black and red wires from a cut usb cable to the 1st and 4th pogo pins without removing the battery. Now charging's fast and stable..
Added: Tried 5v2a charging, it doesn't melt anything.. Fully charged in just slightly over1 hour.
This thread has been great help and a motivator for wiring my Nexus 7 to do a (permanent) dash install.
I've just removed the battery and wired it to a Pico-Box X5-ATX-180 carputer PSU with an adjustable voltage converter in-between to get around 3.9 volts to the tablet. Works great, but I found another drawback.
Like mentioned in a post before me, the battery status will show 0% which I thought wouldn't be too big of a problem. However, at the moment there is an Android update (4.4.3) available and when I try to update it first tells that the battery is too low and that I should connect a charger. So I did, but then it tells me too "wait for the battery to charge sufficiently".
So for anyone reading this wanting to do the same, know that you won't be able to update Android without a battery connected.
I have attached a photo of the tablet running without a battery for those interested.
Rutjes said:
This thread has been great help and a motivator for wiring my Nexus 7 to do a (permanent) dash install.
I've just removed the battery and wired it to a Pico-Box X5-ATX-180 carputer PSU with an adjustable voltage converter in-between to get around 3.9 volts to the tablet. Works great, but I found another drawback.
Like mentioned in a post before me, the battery status will show 0% which I thought wouldn't be too big of a problem. However, at the moment there is an Android update (4.4.3) available and when I try to update it first tells that the battery is too low and that I should connect a charger. So I did, but then it tells me too "wait for the battery to charge sufficiently".
So for anyone reading this wanting to do the same, know that you won't be able to update Android without a battery connected.
I have attached a photo of the tablet running without a battery for those interested.
Click to expand...
Click to collapse
You could use the factory image to update your nexus 7. It's just a bit more work.
Rutjes said:
This thread has been great help and a motivator for wiring my Nexus 7 to do a (permanent) dash install.
I've just removed the battery and wired it to a Pico-Box X5-ATX-180 carputer PSU with an adjustable voltage converter in-between to get around 3.9 volts to the tablet. Works great, but I found another drawback.
Like mentioned in a post before me, the battery status will show 0% which I thought wouldn't be too big of a problem. However, at the moment there is an Android update (4.4.3) available and when I try to update it first tells that the battery is too low and that I should connect a charger. So I did, but then it tells me too "wait for the battery to charge sufficiently".
So for anyone reading this wanting to do the same, know that you won't be able to update Android without a battery connected.
I have attached a photo of the tablet running without a battery for those interested.
Click to expand...
Click to collapse
What did you use to get the voltage down to 3.9 volts?
the exact thread I've been searching for.
Just completed by initial installation and now troubleshooting various problems.
The biggest being this battery scenario. So from what I've read in this thread is to use a DC-DC power switcher PICO for carputers and run that to the battery leads. How is the boot time though?
I've read that with a low battery, the kernal during bootup takes longer for checks to occur?
I have an idea.....:
If we can switch 12VDC to 5VDC during switched (Key On Accesory) with a regulator.....
we should be able to do the same with a sepearate regulator to switch 12VDC to5VDC during constant (Key off) when the switch voltage is lost.
This would retain the time you mentioned gets lost. Also, how much mAh (current) do you get out of that PICO regulator to the battery leads? The TIMUR kernal for FI-mode wants 1800mAh at least. Currently I'm using a cigarette lighter DC-DC adapter that has 2 ports. (2.1A, and 1A). The Nexus 7 is currently connected to the 2.1A and my HUB is connected to the 1A.
any advice?
Thanks
rezmax said:
Just completed by initial installation and now troubleshooting various problems.
The biggest being this battery scenario. So from what I've read in this thread is to use a DC-DC power switcher PICO for carputers and run that to the battery leads. How is the boot time though?
I've read that with a low battery, the kernal during bootup takes longer for checks to occur?
I have an idea.....:
If we can switch 12VDC to 5VDC during switched (Key On Accesory) with a regulator.....
we should be able to do the same with a sepearate regulator to switch 12VDC to5VDC during constant (Key off) when the switch voltage is lost.
This would retain the time you mentioned gets lost. Also, how much mAh (current) do you get out of that PICO regulator to the battery leads? The TIMUR kernal for FI-mode wants 1800mAh at least. Currently I'm using a cigarette lighter DC-DC adapter that has 2 ports. (2.1A, and 1A). The Nexus 7 is currently connected to the 2.1A and my HUB is connected to the 1A.
any advice?
Thanks
Click to expand...
Click to collapse
Why go through all the trouble? Just snip off any USB cable and connect to the pogo pins.. This way, you can charge at pogo's speed with any wall charger and still bring your tablet anywhere.
Hi guys just wanted to report i used your trick on my nexus 7 and it worked perfectly!
I used this method to check if the problem was the battery or if the screen was dead and it turned out to be the battery!
Now i have another battery on the way from Ebay.
Thanks again good job!
Hi guys me again,
I want to update the software but it wont let me because battery is on 1% for ever.
BUT i was wondering, what would happend if i simultaneously plug in the mini usb to another usb charger?
would that create some sort of an insane weird circut and burn my tablet?
any thoughts?
thanks!
Im thinking to use the Nexus 7 in car without the original battery. Constant 4.2V from car battery via converter to nexus battery pins and using the usb with ignition to switch the tablet between sleep and normal state. One thing i would want to reuse is the temperature sensor in the Li-ion pack. Has anyone some idea if the two extra wires are directly connected to temp sensor or there is a circuit for it on the battery controller? If so how it could be reproduced so i could use this to monitor the temp in car for example or if anyone knows any usb dongles that i could use for monitoring external temp with android.
So now i hav tryed the nexus without the battery aswell. At first i applyed 5v directly to the little black battery connector. tablet worked but showed 0%. Then tryed desoldering the batteryback from the little circuit and applyed 5v to the actual battery connectors on the circuit. It shows 100% battery and works and also the temperature sensor is working. One issue is that i need to plug in the charger before connecting the circuit to the motherboard, maybe the charger im using is just too weak that cant get the voltage up or something. And another thing is that i left it plugged in for the night and now the percentage goes down slowly as it would be discharging. havent figured out why that is. Maybe someone has tackled this before also?
freakadell said:
So now i hav tryed the nexus without the battery aswell. At first i applyed 5v directly to the little black battery connector. tablet worked but showed 0%. Then tryed desoldering the batteryback from the little circuit and applyed 5v to the actual battery connectors on the circuit. It shows 100% battery and works and also the temperature sensor is working. One issue is that i need to plug in the charger before connecting the circuit to the motherboard, maybe the charger im using is just too weak that cant get the voltage up or something. And another thing is that i left it plugged in for the night and now the percentage goes down slowly as it would be discharging. havent figured out why that is. Maybe someone has tackled this before also?
Click to expand...
Click to collapse
You supplied power to the protection circuit? I'm surprised that worked.
The battery is probably going down because the protection circuit is designed to prevent over and under voltage. Since you're feeding it 5V and a lithium battery is supposed to max out at about 4.2V it must be trying to lower the voltage somehow. The percentage going down is probably nothing to worry about, but I'd strongly recommend connecting to the battery connector instead, and only connecting it like this when you need to have a certain percentage to do a system update etc. Also be careful with the bare battery, if the two pins short it could catch fire.
Hi i tried that works ,however it doesn't boot when powered i have to turn it on pressing power button,any idea why?
As a car dash its pretty useless now
Just a quick message that I have managed to power my nexus 7 2012 from a USB cable connected to the circuit board that was attached to my dead battery. Battery level indicator is permanently at 100%.
Sort of like the above it involves using the battery circuit board but it is disconnected from the battery.
Step 1: Strip back battery wrapping revealing the board attached to the connector cables (that connects to Nexus 7)
Step 2: Cut the metal strips going from the circuit board to the actual battery part
Step 3: Solder USB cable Positive wire to board pad labelled VP and Negative to pad VG(? not 100% on last one, but it's the other pad)
Step 4: Solder short wire from VP pad to other side of the board onto the ++ pad (that goes to the red wires then connector)
Step 5: Wrap board up with elec/other tape to avoid shorts
Step 6: Connect up and power on
Not sure why the last wire is needed but it didn't work for me without it.
Next step for me is to wire it to the onboard micro-usb
Where is the ++ pad ??
dribbleboy said:
Step 4: Solder short wire from VP pad to other side of the board onto the ++ pad (that goes to the red wires then connector)
Not sure why the last wire is needed but it didn't work for me without it.
Next step for me is to wire it to the onboard micro-usb
Click to expand...
Click to collapse
Where is the ++ pad mentioned in step 4 ? Can you post some pictures ?
So, I apparently did something very stupid with my new Nexus 7.
I have a few 1 TB external hard drives, which don't get enough power via an OTG adapter from the Nexus 7 to run. So, I purchased a two into one cable -- that is, a cable that combines two male USB A plugs into one Micro USB B plug so that a USB 3.0 hard drive can use two USB 2.0 ports to have enough power. I had planned to use this to enable use of the hard drives with the Nexus 7 while traveling by plugging one cable in the tablet and the other into a charger.
When I got the cable I tested it by plugging one of the USB A plugs into my Nexus 7, and then I plugged the other into my computer's USB port. The Nexus 7 promptly shut down, the computer complained of a power surge on the USB port, and a distinct smell of melted plastic came from the computer's USB port. I guess the combining cable didn't combine so much as it just acted like a double headed male A USB cable and shorted things out?
The Nexus 7 refused to restart afterwards until I it plugged it into its charger. It works now, mostly. However, if its battery charge is above about eighty-seven percent then it always reports that it is charging, regardless if it is plugged in or not. And if I plug it into a computer while it is reporting that it is charging I have to restart the tablet to get it to connect to the computer -- I guess it thinks it is connected to a charger and doesn't bother checking for a data connection unless restarted.
The level where it stops thinking it's charging varies somewhat -- I've had it still claim to be charging all the way down to eighty-two percent charge, and by repeatedly opening the battery app over and over again I have been able to get it to notice that it's really not charging all the way up to ninety-one percent, but no higher, and I have to open and close the battery app an increasing number of times for every percent that it goes up over eighty-seven before it will notice it's not charging.
Any idea what kind of damage I'm looking at? How to fix it? Whether I can get the warranty people to fix it free of charge? If yes, whether they will send me a new one or just fix the one I have? Whether it's worth getting fixed since it mostly still works, and doesn't really bother me as long as it doesn't get worse?
Nothing?
Nothing from anyone?
Try replacing the internal USB plug? About $25. Easy to do your self.
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?
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.