Dead charging circuit? - Nexus 7 Q&A, Help & Troubleshooting

Hi everyone;
I've having an interesting time with my nexus 7 (2012 wifi 32gb).
Before I left on vacation I couldn't get the thing to charge. Looking at the usb port I thought it had become to damaged to make a good connection. So while I was away I ordered a new port assembly. Installed that and still no charging.
Oh the battery cell voltage had gone down to 2.2V so it's in a sleep mode. No problem used a proper lion charger to trickle charge it back to life then further to about 3.8V.
At that point it boots up though the optimization took the charge down to 2% so couldn't do more testing but clearly it worked just fine. However the thing won't charge. Plugging it in to USB it does detect the connection but does not draw any current (as shown by a usb voltage/current monitor). It will show the charge screen, go through 3 cycles of the battery filling animation then shut off.
I check and the voltage is getting from the usb cable into the connector. I traced the ribbon cable from the IO board up to the motherboard and at the other end I also get a nice 5V reading. Clearly the connection from the USB to the device is being made no problem.
At this point I am thinking that maybe I blew the charging circuit. When I was orignally trying to get it to charge before leaving I was applying all kinds of stress to the connector to get it to charge and there was a few times where I think I shorted it (usb monitor showed >3A and the device reset).
Anybody have another theory?
At this point I can't really use it as charging the cell externally is dangerous and not convenient. At this point from what I have seen with my testing and on here if I want to use it I would have to apply 5V to the battery connector (sans battery) which I haven't tried yet.

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..?)

how to charge htc 8125 with no original usb cable and(or) without orig. wall charger

hi there.
shortly-i have this phone with no orig. usb cable and with no wall charger. it was friend of mine phone actualy. given to me with dead battery (i am not sure but i have trouwn it away long time ago)
first I did was to wait until friends of mine from china had sent to me 2 batteries compitable with the phone. what i discovered is that a normal ordinar usb cable cant charge the phone's battery it only can connect to the pc.
second what i did is this: i found my old charger from a very old panasonic cell phone and had a try to make the charging process with the simply contacting corresponding pinouts of the battery to the +&- of this same charger (somehow i dissasembled the plug of that charger and it became more "comfortable" to get in touch to the pinouts of the specific cingular's battery)
that unordinar way i did discovered that i can charge these batteries even not sure how much appropriate that other brand wall charger is. It seems its pretty much the same as a power characteristics.
Meanwhile (as i dont use this phone) i had some free time to search the net and to have better idea about that strange unordinar power charging matter with that model of a phone. The situation is that i cant find a place nearby me to buy a cheap usb and wall charger and become using this nice device finaly.
And also i dont want to buy these cable things before clearly understand why this happens ..
I did try also to charge this phone with a HTC brand wall charger but no sucsess again cause it seems this wall charger is for other htc phone (even same mini usb plug and same characteristics)
What i need is to have answers by someone very informed about that matter and let me know what exactly is the specific power charging matter (need explanations i mean) with this phone. If sharing some good ideas about how to remake others usb cable or wall charger for geting it work along for me in such a case , i will appreciate this very much
thanks
charge
hi ! please forgive me for my bad english! in this case you can charge your phone in 1 way! you need to procure a motorola or any charger with same socket but attention the charger must have 6 volts and no less than 500 mAh(milli amps)! you cut the wires and one wire put on the + of the battery you will see the signs on the battery an one wire at the - no matter which one. and you need stay with the wires 3 - 4 minutes on the battery ! then you put the battery on the phone it will start and then you cand fully charge it with the usb cable ! good luckk ! i hope my inf will help you!
no
no it doesnt work that way.
what i need is the simple answer : what is so special into the pinouts of htc cingular 8125 wall charger?
thats what i need only. Then I might figure out how to proceed
Thanks anyway
I don't know if anyone else has had trouble doing what I have done, but I've got the Cingular 8125 (HTC Wizard 100), which is also known as the HTC 8125.
1. I bought a car charger at a convenience store for $6 that had the mini-USB plug. It worked like a charm. Never any problem there.
2. I also bought a standard USB to mini-USB cable from the local computer store, because I had lost mine, and it also worked fine for both synchronization and for charging.
3. I bought a second wall charger, buying a standard mini-USB wall charger sold pretty much everywhere cellular phone chargers are sold. It's a common charging port, and this generic worked for me as well.
I'd be interested to hear if anyone has had problems with these types of devices not properly charging the unit.
Even my USB cable for my portable USB hard drive will power my unit.
EDIT: About your problem with it not charging. I had that problem about a year ago, when my battery got extremely old. It wouldn't charge even with the original charger. I just needed a new battery. The batteries get old and stop taking a charge after a certain amount of use. How long this takes depends on how heavily the batteries are used. They, like car batteries, do not last forever.
I had this problem when I had my wiz too. The battery died and drained, and my phone refused to charge it. I took it to an AT&T service center, and they had no clue what the problem was, and they wanted to issue me a replacement (it was a G4, I had a G3, I wasn't about to fiddle with that at the time.) So I asked to borrow a demo device they had there to fix it. I charged my battery on their demo device no problem, got it up to 3%, and finished charging it through my USB cable in the car socket.
It appears to be a sort of one-in-every-few-or-so type condition, but I got hit with it.
seems like noone can tell me if something special inside the mini-USB plug.
i realy cant charge. Very nice device, but i cant make it charging up whit cables.
guys, from up there, say that nothing special about the charging cables, but i trust what i see not what i read.
Perhaps there is a problem with your USB port on the device? USB charging has standards, and all devices that need power from a USB port have the same power pin configuration. Otherwise, they can't call it a USB connection. It would have to be called a proprietary connection, and they would have to change the plug size/dimensions and pins.
If there isn't a problem with your battery (which is the most likely source of your problem), then it may be a loose connection on your USB connector. This happens with a number of devices.
If a sync cable connects to the PC but will not charge the battery, then you definitely have an unusual pin detachment of some sort, or a bad battery.
thanks again..
for pity i was writing a lot to make my recent post and finaly it desapeared cause my session was left.. its funny in some case, but now i just dont want to repeat all what was intended to be posted
i give only the link where you might see why i was assuming that this is a kind of a special matter here with that htc 8125 charging
//pinouts.ru/CellularPhones-A-N/razrv3_charger_pinout.shtml
so, any more help will be appreciated a lot
thanks
SOLVED: HTC Wizard (Cingular 8125) Dead Battery Wont Charge
Dozzen said:
hi ! please forgive me for my bad english! in this case you can charge your phone in 1 way! you need to procure a motorola or any charger with same socket but attention the charger must have 6 volts and no less than 500 mAh(milli amps)! you cut the wires and one wire put on the + of the battery you will see the signs on the battery an one wire at the - no matter which one. and you need stay with the wires 3 - 4 minutes on the battery ! then you put the battery on the phone it will start and then you cand fully charge it with the usb cable ! good luckk ! i hope my inf will help you!
Click to expand...
Click to collapse
Hi - Too bad for the OP that asked questions but did not listen to this brilliant post.
I have confirmed that a variation of this method works perfectly! I have an old Cingular 8125 that I have been trying to charge for over a year using various USB chargers and NONE would charge the device.
The reason that this may happen is that the original charger has an output of 1 full amp which is much higher than most chargers. The voltage is the same but you need a charger that can handle such a strong current draw.
Nearly all USB chargers can only handle around 250milliamps - 500milliamps which is about half the power needed to breathe life into a fully discharged battery.
The best solution is to NEVER let the battery fully discharge.
Here are the details of what I did:
1. Find the best match charger of 5-6 DC Volts and ability to put out as close to one amp (1000mA) as possible. I chose an old Sanyo SCP-07ADT that is rated at DC 5.4V at 800mA. The plug can be any type, no need to be USB.
2. Cut the connector off the end of the cable and strip the outer black part up about an inch and then strip the positive and negative (red / black respectively) wires up about a millimeter, just enough to have bare metal ends to touch to a small area.
3. Take your battery out of the phone, look at the back of battery for the + and - marks which correlate to one of the metal connection points on your battery, this is where you will "touch" or "attach" the bare ends of the wires.
4. Plug the charger in making sure not to short your bare leads. Before you do this double check that the OUTPUT of your charger is indeed DC voltage so that you don't hurt yourself. You do not want AC output and it can be dangerous.
Then touch the bare end of the red wire to positive of battery, and black wire to negative terminal of your battery. I held them with my fingers while surfing the web for about five or ten minutes. I had no idea if anything was happening or not but it "felt" like the battery might have gotten just a bit warmer.
5. Unplug the home-made bare wire charger and put battery in your phone. Quickly attach a USB charger or just plug into a USB cable of your computer. I pushed it in and nothing happened at first but finally I heard the standard "bleep" when you plug a USB device in. I knew that I made progress because it never beeped before it took about 30 seconds and several "bleeps" of connecting/disconnecting from USB but eventually the charge light stayed on!
It's been about 30 minutes and I'm up to about 50% charge and been using the phone heavily while charging.
So, in summary... never let your battery discharge below 5% or you can only charge it with an OEM cable rated at 1amp (rare). IF you let it discharge to "dead" then charge for 5-10 minutes with the "wire" method and then charge normally!
Thanks to Dozzen for the original idea!!
Wizard that won't charge
When my Wizard/HTC 8125 goes dead my cure for the battery is to use a 9 volt charger with the wires stripped back also. But, my method is a bit different. I place a standard Christmas Tree light bulb (the newer small ones)in series with the charger wires. Observe the correct polarity. The battery is labeled + and - so that part is easy. By using the small light bulb you are doing 2 things. 1.You can see the slight glow from the bulb and know that proper connection is made. 2. You are limiting the charging current to the battery.
If you get really creative like I did you can solder a couple of small nails or in my case a set of red and black probes to the setup and the points on these nails/probes make for much easier connections. Note.... This method may take a few minutes longer but, is much easier on the battery.
In my experience once the battery is below a certain level NO charger that I plug in will work. I just purchased a used 8125 from eBay and brought it back to life most successfully with this method.
hy there my htc wizard battery whos dead so i charched with a cable with + and - the phone starts but when i try to connect to a usb or a adaptor it doesnt charge anymore it show me the charge icon on the baterry but it doesnt charge the usb works fine it's sync to my pc but it doesnt charge anymore... what sould i do?
So it seems no one touched on what really matters here.
A design flaw, in my opinion. The HTC Wizard cannot recharge via USB unless there is enough power to turn on. The reason is because it requires the OS to charge.
So, what many people already posted are very creative ways to charge your 8125. The easiest and cheapest way, in my opinion, is to use AA batteries.
1) Take two AA batteries and tape together so they are in series. Imagine it like this... [- AA battery #1 +][- AA battery #2 +]
2) Use two wires and tape one to each side of the AA's (one on the + side and another on the other battery's - side since the - of the first battery is connected to the + of the second).
--w-i-r-e--[- AA battery #1 +][- AA battery #2 +]--w-i-r-e--
3) Connect the positive (+) wire to the positive (+) side of the phone. By this I mean the 6 metal pieces that stick out to contact the phone battery. I did it by wrapping the wire around the top most one (or second top most, it's been over a year since I've done this.).
4) Connect the negative (-) wire to the negative (-) side of the phone. Again, bottom most or second bottom most (see #3).
5) Insert phone battery while the wires are still in and connected to the two AAs.
6) Let the power flow for 30 seconds or so and then try turning your phone on. This part is the important part because you cannot use a USB to mini-USB connected to your computer to charge the phone unless the operating system can function. Meaning, it needs to be turned on first.
7) Once the phone is on, plug in the mini-USB part and connect it to a computer. I'd recommend getting at least 5% battery before disconnecting the AAs, seeing as you need to be able to start up your phone long enough for the OS to boot. Once the OS boots, you can fully charge it through a normal USB to mini-USB connection on any computer.
old post but just wanted to say thanks. Used the wire to battery method and got phone turned on after 2 mins of holding wires to battery.

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 ?

NEXUS 7 slow charging problem solved?

Last week, I found that my nexus 7 (16g wifi only) start to charge really slow or even not charging. This happen after I upgrade my tablet to android 4.4.2(no root, no mod). I tried all the ways I could found on internet such as disconnect the battery and reconnect after few minutes, downgrade to android 4.3 or 4.2, changing to different type of charger and so on but failed.
After tried for few days, I was frustrated and decided to throw away the tablet. But 2 days ago, when I tried to charge the tablet with samsung galaxy tab2 7.0 charger, I manage to charge from 0% to 50% in two hour. I thought my tablet was back to alive but the tablet stop charging after 50% battery. I tried with oem 2A charger or cheapo china ipad charger and the charging starts but slow and sometimes not charging. I search online and found out that the samsung tab2 7.0 charger has 1.2V at both data pins and both data pins was shorted. I checked my asus oem charger and found out that both data pin was shorted but no voltage supplied.
I take a usb cable, strip and cut both data wire and short both data wire at micro usb side. I connect the tablet to the samsung charger and the tablet start charging and charge at normal speed to 100%. I thought that was the solution but yesterday, when I tried to charge the tablet which has 10% battery remains with samsung charger and my modified usb cable, the tablet charge, but in slow rate. I take half a day to charge to 50%. i exchange the moded usb cable with a normal usb cable and this time the tablet charge to around 80% in one hour. I was confused. Does my tablet need voltage of 1.2V at both data pins for the tablet to recognize as normal charger?
I start to do my experiment by using the oem charger. I apply around 1.2V by using resistors connect to the +5v and gnd. My tablet start to charge at normal rate that i can get the increment in battery % after 1 or 2 minutes in screen off mode. After charge to around 25% my tablet stop charging. I checked the data pins voltage and found out to be around 1.8V. 1.8V??? not 1.2V??? I check the resistors connection and disconnect my tablet from the usb cable. The data pins is now 1.2V. I connect my tablet back to the usb cable, wait for the tablet to start charging at normal rate and disconnect the data wires from the resistor. I tested with multimeter and found out that there was a voltage of 3.1V at data pins (shorted together) from the tablet when charging.
After a few tries by changing the resistors with different values to increase or decrease the data pins voltage, I manage to get a combinations that works well with my charger and my tablet charge normally. With the resistor combination, I get a voltage of 0.5V when no tablet connected and around 1.2V when tablet connected and start charging by using a resistor of 1Kohm connect from the +5V pin to the data pin and 100ohm connect from the data pin to the ground. Actually my tablet shows sign of normal charging when I apply 1V to 1.5V to the data pins that I choose 1.2V for full charging testing. I manage to charge my tablet from 0% to around 30% by using the samsung charger, 30% to 60% using the cheap ipad charger and 60% to 100% using the oem charger. No sign of stop charging or slow charging during the charging process. Maybe this is the solution to the charging problem?
I hope that someone which is more professional in this fields will try my way and give me the final results of the most suitable resistor combination or is my way of solution, or is this just an coincidence or my solution can only be applied onto my tablet? Warning: Try at your own risk.
fix foe nexus 7 slow charging
samuraiman said:
Last week, I found that my nexus 7 (16g wifi only) start to charge really slow or even not charging. This happen after I upgrade my tablet to android 4.4.2(no root, no mod). I tried all the ways I could found on internet such as disconnect the battery and reconnect after few minutes, downgrade to android 4.3 or 4.2, changing to different type of charger and so on but failed.
After tried for few days, I was frustrated and decided to throw away the tablet. But 2 days ago, when I tried to charge the tablet with samsung galaxy tab2 7.0 charger, I manage to charge from 0% to 50% in two hour. I thought my tablet was back to alive but the tablet stop charging after 50% battery. I tried with oem 2A charger or cheapo china ipad charger and the charging starts but slow and sometimes not charging. I search online and found out that the samsung tab2 7.0 charger has 1.2V at both data pins and both data pins was shorted. I checked my asus oem charger and found out that both data pin was shorted but no voltage supplied.
I take a usb cable, strip and cut both data wire and short both data wire at micro usb side. I connect the tablet to the samsung charger and the tablet start charging and charge at normal speed to 100%. I thought that was the solution but yesterday, when I tried to charge the tablet which has 10% battery remains with samsung charger and my modified usb cable, the tablet charge, but in slow rate. I take half a day to charge to 50%. i exchange the moded usb cable with a normal usb cable and this time the tablet charge to around 80% in one hour. I was confused. Does my tablet need voltage of 1.2V at both data pins for the tablet to recognize as normal charger?
I start to do my experiment by using the oem charger. I apply around 1.2V by using resistors connect to the +5v and gnd. My tablet start to charge at normal rate that i can get the increment in battery % after 1 or 2 minutes in screen off mode. After charge to around 25% my tablet stop charging. I checked the data pins voltage and found out to be around 1.8V. 1.8V??? not 1.2V??? I check the resistors connection and disconnect my tablet from the usb cable. The data pins is now 1.2V. I connect my tablet back to the usb cable, wait for the tablet to start charging at normal rate and disconnect the data wires from the resistor. I tested with multimeter and found out that there was a voltage of 3.1V at data pins (shorted together) from the tablet when charging.
After a few tries by changing the resistors with different values to increase or decrease the data pins voltage, I manage to get a combinations that works well with my charger and my tablet charge normally. With the resistor combination, I get a voltage of 0.5V when no tablet connected and around 1.2V when tablet connected and start charging by using a resistor of 1Kohm connect from the +5V pin to the data pin and 100ohm connect from the data pin to the ground. Actually my tablet shows sign of normal charging when I apply 1V to 1.5V to the data pins that I choose 1.2V for full charging testing. I manage to charge my tablet from 0% to around 30% by using the samsung charger, 30% to 60% using the cheap ipad charger and 60% to 100% using the oem charger. No sign of stop charging or slow charging during the charging process. Maybe this is the solution to the charging problem?
I hope that someone which is more professional in this fields will try my way and give me the final results of the most suitable resistor combination or is my way of solution, or is this just an coincidence or my solution can only be applied onto my tablet? Warning: Try at your own risk.
Click to expand...
Click to collapse
here's what i posted at google forums. hope it helps you
FIXED!!!
and i didnt wait for google to solve it. they take ages.
as one of the pioneers of this thread, trust me i have tried everything, and started solutions you can see if you back track a bit.
what does not work/or temporary works but not permanent:
>OS downgrading
>bootloader upgrading
>plug unplug with battery monitor (temporary)
>reseating battery cable
>changing chargers/cables/using OEM
>all else above
what works:
>dock
from what i observe, some symptoms of failure started prior to kitkat, as to some of the nexus' handled to me. and some kitkat dont have it.
and the dock works. led me to conclude it might be hardware, probably with the USB
THE FIX:
OPEN YOUR NEXUS 7 AND RESEAT THE USB CHARGING PORT FROM THE INSIDE. if you do not know how, this video will guide you:
(cannot post link) go to youtube and watch?v=m5FagzLdbbM
as you can see the 4:07 in the video is the most important, remove the usb port/audio port completely and reseat it, place it back tightly.
my tab was left at 0% charge, unable to charge anymore, so i was left with the option to tinker it. which to my delight, it charges now at 500-900mah. i tried to drain it and charge again charging-recharging 3 times before posting it here to make sure it was not sheer luck, and so it did.
its a hardware problem guys. i just wish google/asus had the courage to admit it rather than we find it ourselves. go ahead try it. post if it works
for you. it worked for me.
emanlee said:
here's what i posted at google forums. hope it helps you
FIXED!!!
and i didnt wait for google to solve it. they take ages.
as one of the pioneers of this thread, trust me i have tried everything, and started solutions you can see if you back track a bit.
what does not work/or temporary works but not permanent:
>OS downgrading
>bootloader upgrading
>plug unplug with battery monitor (temporary)
>reseating battery cable
>changing chargers/cables/using OEM
>all else above
what works:
>dock
from what i observe, some symptoms of failure started prior to kitkat, as to some of the nexus' handled to me. and some kitkat dont have it.
and the dock works. led me to conclude it might be hardware, probably with the USB
THE FIX:
OPEN YOUR NEXUS 7 AND RESEAT THE USB CHARGING PORT FROM THE INSIDE. if you do not know how, this video will guide you:
(cannot post link) go to youtube and watch?v=m5FagzLdbbM
as you can see the 4:07 in the video is the most important, remove the usb port/audio port completely and reseat it, place it back tightly.
my tab was left at 0% charge, unable to charge anymore, so i was left with the option to tinker it. which to my delight, it charges now at 500-900mah. i tried to drain it and charge again charging-recharging 3 times before posting it here to make sure it was not sheer luck, and so it did.
its a hardware problem guys. i just wish google/asus had the courage to admit it rather than we find it ourselves. go ahead try it. post if it works
for you. it worked for me.
Click to expand...
Click to collapse
thx mate .. how do you know what the actual charge rate is? on my Galaxy S3 there is an app for that, but can't find anything that works on this unit. thx
jj92942000 said:
thx mate .. how do you know what the actual charge rate is? on my Galaxy S3 there is an app for that, but can't find anything that works on this unit. thx
Click to expand...
Click to collapse
https://play.google.com/store/apps/details?id=ccc71.bmw
Nexus 7 slow charging problem
Thanks emanlee, worked for me. I thought my battery was weak. Made my day.
emanlee said:
here's what i posted at google forums. hope it helps you
FIXED!!!
and i didnt wait for google to solve it. they take ages.
as one of the pioneers of this thread, trust me i have tried everything, and started solutions you can see if you back track a bit.
what does not work/or temporary works but not permanent:
>OS downgrading
>bootloader upgrading
>plug unplug with battery monitor (temporary)
>reseating battery cable
>changing chargers/cables/using OEM
>all else above
what works:
>dock
from what i observe, some symptoms of failure started prior to kitkat, as to some of the nexus' handled to me. and some kitkat dont have it.
and the dock works. led me to conclude it might be hardware, probably with the USB
THE FIX:
OPEN YOUR NEXUS 7 AND RESEAT THE USB CHARGING PORT FROM THE INSIDE. if you do not know how, this video will guide you:
(cannot post link) go to youtube and watch?v=m5FagzLdbbM
as you can see the 4:07 in the video is the most important, remove the usb port/audio port completely and reseat it, place it back tightly.
my tab was left at 0% charge, unable to charge anymore, so i was left with the option to tinker it. which to my delight, it charges now at 500-900mah. i tried to drain it and charge again charging-recharging 3 times before posting it here to make sure it was not sheer luck, and so it did.
its a hardware problem guys. i just wish google/asus had the courage to admit it rather than we find it ourselves. go ahead try it. post if it works
for you. it worked for me.
Click to expand...
Click to collapse
emanlee said:
here's what i posted at google forums. hope it helps you
FIXED!!!
and i didnt wait for google to solve it. they take ages.
as one of the pioneers of this thread, trust me i have tried everything, and started solutions you can see if you back track a bit.
what does not work/or temporary works but not permanent:
>OS downgrading
>bootloader upgrading
>plug unplug with battery monitor (temporary)
>reseating battery cable
>changing chargers/cables/using OEM
>all else above
what works:
>dock
from what i observe, some symptoms of failure started prior to kitkat, as to some of the nexus' handled to me. and some kitkat dont have it.
and the dock works. led me to conclude it might be hardware, probably with the USB
THE FIX:
OPEN YOUR NEXUS 7 AND RESEAT THE USB CHARGING PORT FROM THE INSIDE. if you do not know how, this video will guide you:
(cannot post link) go to youtube and watch?v=m5FagzLdbbM
as you can see the 4:07 in the video is the most important, remove the usb port/audio port completely and reseat it, place it back tightly.
my tab was left at 0% charge, unable to charge anymore, so i was left with the option to tinker it. which to my delight, it charges now at 500-900mah. i tried to drain it and charge again charging-recharging 3 times before posting it here to make sure it was not sheer luck, and so it did.
its a hardware problem guys. i just wish google/asus had the courage to admit it rather than we find it ourselves. go ahead try it. post if it works
for you. it worked for me.
Click to expand...
Click to collapse
I have an old Nexus 7 and was about to toss it out because it wouldn't charge, this took 20 minutes and now it charges as it did when new - great.
Thanks.
emanlee said:
fix foe nexus 7 slow charging
here's what i posted at google forums. hope it helps you
FIXED!!!
and i didnt wait for google to solve it. they take ages.
as one of the pioneers of this thread, trust me i have tried everything, and started solutions you can see if you back track a bit.
what does not work/or temporary works but not permanent:
>OS downgrading
>bootloader upgrading
>plug unplug with battery monitor (temporary)
>reseating battery cable
>changing chargers/cables/using OEM
>all else above
what works:
>dock
from what i observe, some symptoms of failure started prior to kitkat, as to some of the nexus' handled to me. and some kitkat dont have it.
and the dock works. led me to conclude it might be hardware, probably with the USB
THE FIX:
OPEN YOUR NEXUS 7 AND RESEAT THE USB CHARGING PORT FROM THE INSIDE. if you do not know how, this video will guide you:
(cannot post link) go to youtube and watch?v=m5FagzLdbbM
as you can see the 4:07 in the video is the most important, remove the usb port/audio port completely and reseat it, place it back tightly.
my tab was left at 0% charge, unable to charge anymore, so i was left with the option to tinker it. which to my delight, it charges now at 500-900mah. i tried to drain it and charge again charging-recharging 3 times before posting it here to make sure it was not sheer luck, and so it did.
its a hardware problem guys. i just wish google/asus had the courage to admit it rather than we find it ourselves. go ahead try it. post if it works
for you. it worked for me.
Click to expand...
Click to collapse
Thank you very much, it has also fixed the issue to me. The tablet is not ready yet to become e-waste. Genius!

[Q] Samsung Galaxy S5 Won't charge?

I've had my S5 for about 2 months now. and i've been having charging problems? My phone only charges when it's turned off. And does it at a very slow pace. When i turn it own, it indicate it's charging but it's going down.. Now it's not charging at all..... I check my usb voltage and the max was 1800 and it would switch from 300 to 1100?
This makes me believe it's the usb cord. Because i haven't dropped it, bent the ports. no water damages. nothing it just stop.. making me think its the usb or the battery. What is your insights on this? I am always on business trips and don't have time to send it in for repairs. please tell me its the usb cord or battery not the port or hardware?
I've also done 2 factorys resets so it's no hardware issue. i don't know how much this helps but someone told me to take the battery out to see if it would turn on. it didn't. this is a new phone that shouldn't behaving issues.
Have you tried to use your USB cord to charge other phone? Did it charge correctly? If it's yes, then try to buy a new battery.
Xx_Evlo_xX said:
I've had my S5 for about 2 months now. and i've been having charging problems? My phone only charges when it's turned off. And does it at a very slow pace. When i turn it own, it indicate it's charging but it's going down.. Now it's not charging at all..... I check my usb voltage and the max was 1800 and it would switch from 300 to 1100?
This makes me believe it's the usb cord. Because i haven't dropped it, bent the ports. no water damages. nothing it just stop.. making me think its the usb or the battery. What is your insights on this? I am always on business trips and don't have time to send it in for repairs. please tell me its the usb cord or battery not the port or hardware?
I've also done 2 factorys resets so it's no hardware issue. i don't know how much this helps but someone told me to take the battery out to see if it would turn on. it didn't. this is a new phone that shouldn't behaving issues.
Click to expand...
Click to collapse
Your description of the situation is murky. Are you charging from a wall adapter or from a computer USB port? It sounds like the latter and the problem may well be on your PC end or a bad cable e.g. have an intermittent connection. Or you may simply have a high app draw e.g. high screen brightness, processor use, gaming, etc that exceeds the current available from your USB port.
Your statement about USB voltages doesn't make sense. The nominal USB voltage is 5 volts. If it was anything near 300 - 1800, something would be on fire. Possibly you are referring to current draw in mA. But even with that assumption it's unclear what you are describing.
It's almost certainly the USB port, cable or battery. Perhaps a damaged USB port if it has been abused. It's unlikely to be the actual power circuit inside the phone. You haven't provided enough detail to really narrow anything down. Try charging from a wall charger or at least a different computer. If it works, then your port has an issue. Next try a different cable to see if the cable is obviously bad. Testing the battery without proper equipment is harder, but if your battery life is notably short or erratic then suspect the battery. Perhaps borrow a battery from a friend to try and rule out a bad battery.
.
.
It's got to be software.
My son and I have the same phone. My S5 will only charge powered off. So I'm constantly swapping batteries with him which obviously rules out the battery or any powering cords because his is fine with either battery and cords. Time to upgrade

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