[Q][tilapia] Battery discharges with no Battery? - Nexus 7 Q&A, Help & Troubleshooting

Hello,
i had resently installed a Nexus 7 Tilapia in my Car.
I had removed the Battery from his own Circuit Board and conntected it to a DC-DC Step Down Converter (10A) with a Output Voltage of 4.25 Volt.
After some time of Useage the percent of the Battery slowly decreases, but the Voltage stays Stable.
Does someone know how to fix that?
I want to Keep that board because of the Battery Display (100%) and the Clock.
Thanks.

Hello there .were you able to fix this issue?i am facing the same thing right now in grouper.it was drawing battery,so I connected the tablet directly to my car battery with dc dc hoping to solve the problem but instead the percentage keeps dropping and I have to disconnect the pcb board (battery board) and restart the tablet.i see 100% and then it starts dropping ?

hello, no i dont. that peace of shi* broke down, so i trashed the whole project. sry

Related

battery won't charge

my wizard battery won't charge.
i have tried another battery and another rom with no change.
wehn i plug in the sync cord, the izard reognizes that it is on external power but just won't charge the battery.
any ideas.
thanks
...try to find out, by measuring, if the ±5Volt DC is present on the pins on the inside of the ppc which is needed to charge the battery. Probably your charging circuit is busted and the ppc should brought back for repairs...
thanks for the response
what is ppc
where do i measure the voltage.
when i first connect the sync cable, it starts to charge for one or two seconds and then stops and reverts to a normal non charging screen.
thanks
PPC stands for Pocket PC
What you speak of, I had the same problem on my wizard.
My battery finally died and I couldnt re-vive my phone.
I bought a new battery off of ebay, put it in, plugged it into the charger that came with my phone, let it charge overnight and I havent had a charging problem yet.
My advice, as well as alot of others on this board, dont use any other charger other than the one that the phone came with. I know I wont be.
...inside your ppc,when you remove your battery, you'll see different connection pins which are normally connected to the battery. With power attached (and without battery) you measure between 2 pins at a time. WATCH OUT for shortcircuiting, be careful!!!. You can use an analog or digital voltagemeter. I don't know which pins, so you have to try it yourself.
You should measure ±5 Volt DC which's delivered by your adapter. If there's no power then your charging circuit is defect and you'll have to let it repair...
reading about a volt on the internal pins that connect to the battery.
so it's the charging circuit.
damn
I had the same problem twice with 2 different batteries. it seems if the batterie dies completely, the device can not recharge itself. something like a car, you need to have enough juice to start the car so you can recharge the battery.
I took 2 paper clips that i used to connect the charger directly to the battery( bypassing the phone). you need to be careful with that, make sure you connect the right battery pins. I left my battery like this for 15min, just enough to have aniough power to start the phone and continue the charging process regularly.
As mlarif said the battery can fail to charge if totally discharged. So if you are not absolutely certain your circuit is faulty there are at least two threads here describing how to butcher a usb cable to jump start the battery.
Sorry I can't remember the colours of the wires off the top of my head. But a search may find the relavent posts.
...you can also use a 9 VDC battery to give the ppc batteries a boost for a few seconds. But indeed be sure to use the right pins
(btw did you measure any VDC on the batteries..?)

Battery dead ? red led blinking after charger plugin

Hello,
I have problem,
My MDA was shuting down about 40 / 50 % of power left !.
So i'm so stupid to get idea " help discharge battery manual to 0 % ".
I get light bulb, connect wires and wait about 15 minutes until light went down.
When light goes down, fast connect pda to charger (i don't want to destroy battery Li don't want to be discharged for long time).
But, it don't want to charge it... it's blinking red led about 30 minutes, and wont power on...
Grrrr
I'm so stupid to kill this battery ?
Do you have any idea ?
regards
seba22 said:
Hello,
I have problem,
My MDA was shuting down about 40 / 50 % of power left !.
So i'm so stupid to get idea " help discharge battery manual to 0 % ".
I get light bulb, connect wires and wait about 15 minutes until light went down.
When light goes down, fast connect pda to charger (i don't want to destroy battery Li don't want to be discharged for long time).
But, it don't want to charge it... it's blinking red led about 30 minutes, and wont power on...
Grrrr
I'm so stupid to kill this battery ?
Do you have any idea ?
regards
Click to expand...
Click to collapse
1.- Buy another battery
2.- READ here: http://wiki.xda-developers.com/index.php?pagename=UniversalSmallBattery and here: http://wiki.xda-developers.com/index.php?pagename=UniversalBatteryIssue
Good luck,
it appears that your battery can no longer hold enough power (ampacity) to sustain the needs of the unit, the reason why it shuts down although the power level shows that 40% or more was remaining. in short, it is no longer in its optimum state.
i made such conclusion as this was confirmed when you said that you drained it manually but your charger can no longer drive it back to normal charging state (just red led blinking). this happens when one of the cells of your battery, if not all, is in near open state and the current (A-amperes) can no longer normally pass through it due to large resistance (ohms), hence, not charging at all.
if you want to revive the battery, nonetheless, i would suggest to intermittently charge it manually using a more powerful charger, that is, the same voltage (V) but more power (VA-VoltAmpere) or ampere rating (take note, i strongly advise not to do the charging conventionally through the unit, it would certainly destroy the power circuit or the unit itself) until such time that it can be charged by the usual wall charger. Likewise, extra caution must be taken since prolonged charging using a more powerful charger may lead to battery explosion, thou i'm bit sure its not in such magnitude to kill . just joking..
seriously, even assuming you can drive it back, your battery will be most likely in the same state as it was before although there were rare occasions that boost-charging may revive the cells and will thereafter perform normally (fingers crossed), otherwise, sad to say you have to replace the battery with a new one to have a working uni once more hope this would help, regards..
Hi,
Thank you for reply.
What i do ?
I have problem with my computer, so i shut it down, and go in to bios.
I leave my PDA pluged in.
After 30 minutes, i started linux, and then i saw red led don't blinking !
I press power, and it's started ;>
I charged to 100 %, then discharge and charge again.
Now it's shuting down on 20 % !!
Previously it's going down about 50 %/ 60 %.
Now 20 %
I wan't to thow this battery to trash but now it's alive... i'm realy happy...
seba22 said:
Hi,
Thank you for reply.
What i do ?
I have problem with my computer, so i shut it down, and go in to bios.
I leave my PDA pluged in.
After 30 minutes, i started linux, and then i saw red led don't blinking !
I press power, and it's started ;>
I charged to 100 %, then discharge and charge again.
Now it's shuting down on 20 % !!
Previously it's going down about 50 %/ 60 %.
Now 20 %
I wan't to thow this battery to trash but now it's alive... i'm realy happy...
Click to expand...
Click to collapse
that calls for celebration.. cheers :
Actually we should never ever discharge lithium battery unless you have voltage meters and know what you are doing, if A (that is one with ONE Cell) lithium battery's voltage gets lower than 3.6V it already started to damage the chemical make up of the battery and cases the battery's size to reduce greatly
And fast charging actually reduces the battery life, because the fast charging generate heat, and the heat will create gas inside the sealed battery and causes the battery to expend, and it changes the pressure of the chemical make up inside the battery and will greatly reduces the current and size of the battery... that is why sometimes you can see the lithium battery actually expend when you View it from the side....
I had maybe over 100 lithium battery from all the phones, and the electronic powered helicopter I have.... so I would say I know it pretty well
SOG said:
Actually we should never ever discharge lithium battery unless you have voltage meters and know what you are doing, if A (that is one with ONE Cell) lithium battery's voltage gets lower than 3.6V it already started to damage the chemical make up of the battery and cases the battery's size to reduce greatly
And fast charging actually reduces the battery life, because the fast charging generate heat, and the heat will create gas inside the sealed battery and causes the battery to expend, and it changes the pressure of the chemical make up inside the battery and will greatly reduces the current and size of the battery... that is why sometimes you can see the lithium battery actually expend when you View it from the side....
I had maybe over 100 lithium battery from all the phones, and the electronic powered helicopter I have.... so I would say I know it pretty well
Click to expand...
Click to collapse
well said, cheers mate

Charging Problem with Navigation turned on

Hi,
I have a navigation software on my x10. everything works fine but it seems that this programm needs so much battery that the charger can´t charger the battery.
With navigation turned on and charging the battery is still getting lower and lower.
I have a self build car charger in my car with 1000mA but it seems, that it´s not enough.
Have you any suggestions, how to solve the problem? Is there an app to change the cpu usage for the navigation to e.g. 60% instead of 100%? Or is this only possible with rooted phones?
Thanks.
Same Problem over here.
My only solution --> 2G instead of 3G and turning off W-Lan.
In that way (with GPS and Bluetooth active), the phone at least charges very slowly and doesn't drain the battery.
I had turned WLAN, BT, 3G off. But my battery was still not loading... Maybe I have to switch from 100% Screen brightness to automatic. I will try it the next time...
UserX10 said:
...But my battery was still not loading...
Click to expand...
Click to collapse
But the charging symbol shows up?
Did you shorten the Data+ and Data- Lines on your selfmade car charger?
I guess, you build it, like i did:
I took a 12V cigarette lighter to USB adapter.
Then I broke that thing apart and soldered a (micro) USB cable directly do the USB jack.
To make it working, I had to shorten the inner two lines.
Otherwise, the phone didn't charge at all.
Then I glued / taped / bubblegummed the whole thing an threw it behind my radio
Or did you build an other solution?
I build it myself, not broken a charger, and yes, it´s working (data is shorten), but it´s not enough to load the battery during navigation. If I turn navigation off, my battery is charging as usual.
UserX10 said:
I build it myself.
Click to expand...
Click to collapse
Nice one
Uhm.. what about rising mA a little further?
I've no clue what max. should be.
Probably you know?
I've also seen USB Chargers with 1500mA.
But I dunno, if its a good idea.
Phone + Battery would also heat up a little further...
Another Idea:
Maybe there is a couple of Apps running at full load in the background?
Take a look around in this forum.
Especially at the "helix launcher" and the "battery life issues" threads.
You can also download the App "SystemPanelLite".
With that one you can search and monitor the running Apps and their CPU consumption and so on.
With "Task Manger" (the one made by Rhythm Software) you can set up a auto kill rule.
Hope, that helps...
I have also tried to charge my phone with my car charger left from Omnia HD and the phone is not charging ??? HTC Desire is charging but X10 is not. Can someone tell me what could be the problem ??
Tnx
@damirbusic
The Problem is, that the two Data Pins (2 & 3 - the two middle ones)) must be shorten. Then the X10 is loading...
@McKebapp
I´m tried it with helix launcher and have some applications auto killed and all tasks closed. But it's still not enough.
It´s possible to charge the Li-Ion Batteries with 1500 mA. That will be my last solution. Don´t want to charge it with 1500mA due to overheating, specially in the summertime...
I don't have this issue at all, weird
,
-------------------------------------
..
@UserX10:
Uhm... that is strange after all...
Which Navi-SW do u use?
I use "Sygic" for onboard navigation.
Normaly I use Sygic, too.
I tried Navigon, too, but the same result.
Both Apps draining the battery more then the charger is loading...
UserX10 said:
Normaly I use Sygic, too.
I tried Navigon, too, but the same result.
Both Apps draining the battery more then the charger is loading...
Click to expand...
Click to collapse
Really Strange...
Which temperatures do you have to deal with?
My last Idea: Maybe some overheat protection, that limits the charging rate?
By my one is the problem defently the temparatur... when i hold me phone in to the airstream from the aircooling then does the phone charging works. If i let the phone just on the right side of me on seat the it doesnt charged. But the symbol on the phone say the is currently charging... with the tool batterygraph can i see, thats isnt true...
aso i can reconized that the phone is hot.. realy hot.. extremly when the sun does shine on the phone.. the only solution is for me, to hold the phone from time to time at the airstream or i let the phone down in to the footweel, where does the sun not shine and a airstream flow around...
The akku is the warmest thing. without the cover, it works better.. i thnk the akku has around 45°... when is hot..
tested with navigon..
Hm... that´s possible. I will try it the next time with holding it in the airstream... Maybe that´s the solution.
I've got an windshield holder (dunno the correct English word).
While I'm driving open with my convertible, I set the airstream to the windshield (demister setting, but without heat), to cool the Phone a little down.
(If the Car is closed, I usually drive with activated A/C at 19°C - 23°C depending on my mood and the frozen girl on my side )
My Phone never exceeded 40°C.
So, this really may be the solution.
BY shorten the middle 2 pins... do you mean "short circuit" by joining the pins together in some way.
I have the same issue - I have the car charger from my old samsung omnia but it doesn't charge the phone and using any navigation software drains the battery very quickly
Jepp, short circuit the both two middle pins, then it will work.
For information: I tested today the charging with power supply.
780 mA is the maximum what the X10 takes. Tested with empty Battery (in Idle Mode and Apps running + WLAN + BT + GPS). Same result.
So a 1000 mA charger is fully sufficient.
UserX10 said:
For information: I tested today the charging with power supply.
780 mA is the maximum what the X10 takes. Tested with empty Battery (in Idle Mode and Apps running + WLAN + BT + GPS). Same result.
So a 1000 mA charger is fully sufficient.
Click to expand...
Click to collapse
i had bought an FM transmitter for the iphone for like 10bucks... the charger is USB so i just use the sony's charger cable and plug it in and it works great for me when i use NAV....no problems here
UserX10 said:
For information: I tested today the charging with power supply.
780 mA is the maximum what the X10 takes. Tested with empty Battery (in Idle Mode and Apps running + WLAN + BT + GPS). Same result.
So a 1000 mA charger is fully sufficient.
Click to expand...
Click to collapse
Thanks for sharing your knowledge.
Great work!
What's your opinion about your battery drainage?
Do you really think that the phone, running at full load, will suck more than 780mA to prevent charging?
Or is it really an overheating prevention?
Something I realized today:
I drove around for about an hour today.
We had 31,5°C today.
The phone was placed in its windscreen holder directly facing with its backside to the sun.
I drove with closed top A/C at 23°C.
At the end, when I was at home, the App "TempMonitor" showed me 56°C at the battery, that still was charging.
On weekend I'll try pushing the limits a little higher.
Empty battery + Navigation + open top without any A/C.
I hope my phone doesn't melt away

Nexus 7 Running without Battery

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

Completely dead and unresponsive Nexus 4 after voltage spike while charging in car

So yesterday, my old car's voltage regulator went haywire, and blew the car's main fuses after a couple of seconds.
I was charging my N4 during this incident with a cigarette lighter thingy and was holding aprox. 10% batttery charge.
The N4 is now 100% unresponsive. No amount of pressing any key combination for any amount of time does anything at all.
I have also tried charging it with a generic USB charger for a couple of hours, to no effect.
After that, I tried charging it with my computer's USB3 port for a couple of hours. This warmed up the phone a bit on the back, so it seems the ingoing current is doing something in there.
I am not getting a red LED indicator as most other people seem to be getting.
i fear something important was simply fried inside the phone, but I don't want to give up yet!
- Does anyone have any ideas what else I could try out?
- Are there maybe some small fuses inside the N4 that might be burned due to the voltage spike? Could I maybe replace or bridge them?
- could replacing the battery maybe revive the phone? If so, how could I test if getting a replacement battery will be worth it? Maybe temporarily wiring a compatible voltage to board?
http://www.reddit.com/r/nexus4/comments/29gkfj/usb_power_surge_killed_nexus_4/
Does this help?
LooieENG said:
http://www.reddit.com/r/nexus4/comments/29gkfj/usb_power_surge_killed_nexus_4/
Does this help?
Click to expand...
Click to collapse
Cool! I must have missed that the USB charging stuff is on a seperate board when i stepped through the N4 teardown!
Do you know if wireless charging goes through this board, too, or would it be using a separate circuit - i.e. should I head over to a friend's and test if I get SOME reaction from the phone when wirelessly charging?
Also: what worries me is that, as i mentioned, the phone's back is getting quite warm when charging it via USB3, so I am afraid that the charge is actually getting to the battery (vs. being stopped at a burnt fuse)

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