Intro: Bypass Iphone 5S Charging Circuit, Directly Charge Battery.
I have an iphone 5S, there is some problem with the motherboard due to which newly replaced charging flex/cable stops working and gets corrupt. I tried 2 seperate charging flex from IFIXIT, both of them got corrupt and stopped working. I knew that the problem was with the iphone motherboard, most likely the U2 IC and/or the tiny capacitors near the battery connector. It isn't my main phone, I HATE APPLE PRODUCTS. This iphone belonged to my mom and I got her a new Google PIXEL. I myself use a NEXUS 6P. This was the first and last apple phone I ever bought.
Now I didn't like the idea of spending a fortune on that iphone, I decided to use it as a spare phone and to charge the battery directly. First I tried to provide current directly to the motherboard, but that doesn't work, the iphone needs battery data from the battery's pcb to start and function properly. Hence, I removed the pcb from a cheap spare battery and connected an android charger's (5v 1amp) +ve and -ve wires directly to the battery pcb THEN connected the pcb connectors on the motherboard. VOILA! The iphone started functioning as if nothing's out of order.
Now you can't provide 5v directly to the battery, it needs around 4.2v for proper, risk-free charging. I decided to buy a universal battery charger and join the wires directly to the battery terminals/tabs.
First the wires from the battery terminals go to the charging port. I desoldered (or just pull it off) the iphone charging port to make space. Then I put an ANDROID CHARGING PORT in its place. Now I HAVE AN IPHONE WITH ANDROID CHARGING PORT. How cool is that!
This universal charger is quite cheap, but of a good brand, it has a green LED indicator, it keeps blinking when the battery is charging and glows solid when it's fully charged. I have this exact one:
My project is working better than I expected. This charger provides 0.4 amps only, hence it takes a long time to charge if I am using the charger while using the iphone in LTE network. I have to put the phone in airplane or 2G mode, then charge it. Even better, once the battery is 100% full, I start using the iphone with the charger still connected, I even turn on the personal hotspot with LTE data mode. I have even left it for charging overnight, the battery was fully charged, the charger's green led was lit solid. There was no heating at all, the battery was cool to touch. So I concluded that (at least) this charger trickle charges the battery once it's full.
(If you can buy such charger with 700-1000 mA ratings, you will get faster charging times, I don't need it so much so as to further search or buy one.) You can also buy expensive universal chargers with 1 amps ratings and led screen etc, but don't buy very cheap ones as that would be risky.
The iphone reports DECREASE in battery percentage when it's on, NOT THE INCREASE. So while the charger is connected and phone is on, it will either show the same percentage or declining value, but not the increase. If I need the updated charge percentage, I need to reboot the phone.
Who needs to follow this project? People like me who are PEEVED with iphone parts & repairing costs, and just want a working iphone and are ok with long charging times, without worrying about expensive IC's and capacitors.
I didn't have time to take pictures while doing so, and I don't wanna risk anything by opening it up again to show the connections. Credits for the battery pics go to szoter.com and Luke Hines from bottleofcode.com. The pics of universal charger and the iphone are mine.
Step 1: Open the Iphone and Remove the Battery
There are millions of tutorial videos on youtube, just follow the videos and open up the iphone to remove the battery completely out of the case.
You will see a thin, discreet tape near the top. Peel that tape carefully, if possible we will use the same tape for repacking. There are multiple layers of this tape. Preserve all the pieces.
Alternatively, you can use electrical tape in place of this, but that will be a little wider and may cause a bugle in the screen after closing the phone.
Step 2: Pull Up the Pcb Tab Gently and Solder Two Wires.
When you see and exposed pcb circuit, try to gently lift it up. You will feel that the pcb only moves upwards from a particular angle, as it's soldered to the battery terminals. Don't put excessive force or you might end up ripping the battery terminals, do it slowly and gradually.
Now I won't tell you which one is +ve and -ve terminal, it's better if you find it yourself using a multimeter. You can use any cheap multimeter, we just need to check the voltage at the terminals. If you connected the red multimeter lead to the right terminal and the multimeter shows +ve voltage, it's obvious that the right one is the battery's +ve terminal.
Solder very thin wires, around 1.5 inches long to these terminals. Use very little soldering wire, if you make a thick solder, the pcb will not fold back into original position. Then fold the pcb back into original position gently and gradually, taking around 20-30 seconds to do so.
Bring the wires out from the left and right sides and tape it back as tightly as possible. You can use a final layer of electrical tape to be extra cautious, but don't make it too thick.
Step 3: Solder the Other Ends to Android Charging Female Jack.
Now solder the other ends of those wires to a female android charging jack, I acquired it from a spare useless phone lying around. To be sure about polarity, first insert a charging usb type B (aka android charger) into the jack, then measure the voltage on the outermost, corner pins.
Suppose the right one shows as +ve, then you have to solder the +ve terminal of the battery to the right pin of the jack. (BTW this isn't necessary in my case, this universal charger is smart enough, I can connect the battery in either polarity, it will automatically detect it and charge accordingly.)
The charging port hole is too small for android charging pin and jack. There is a ring on the inside of the charging port, wiggle it and remove it entirely. Now you have a bigger hole, it's sufficient for the android female jack.
Remember when you removed the original apple charging port from it's original position? There was a strip of metal encasing that charging port, with two strips on either side for the screws. Remove this strip forcefully, using pliers from that charging port. Then position this strip around the android female jack and compress it a little so that it sits tightly, place it in position inside the iphone's body so that the charging jack protrudes out a little, then screw back the strip in position. Now pour a little super-glue on the strip to glue it to the metal strip.
Step 4: Connect Thin Wires to the Charger's Connectors and Join a Female Usb Type-B Jack on Other End.
I opened up the universal charger and soldered two wires to the pcb directly at the location of the charging pins, and brought the wires out from under the charger.
I joined a female usb type-B jack to the other end. I could directly solder a usb to micro-usb cable to the charger, but I wanted to keep an option open to charge the iphone directly from other 5v 1amp chargers in rare occasions.
Step 5: Connect the Charger to the Battery Via the Usb Type-B Jack and Test It, Then Assemble the Phone Back.
Connect the charger to the iphone's android female jack, via a usb to micro usb cable. Turn on the charger and test the polarity, voltage at the android female jack's terminals. You can also verify that the battery is charging as the universal charger will start indicating via its LED, or led display etc.
Now position the battery inside the iphone, and adjust the wires so that they don't interfere with other components, don't worry you can't break anything with just pressing the wires around. The position of the wires need to be okay enough so as to close the iphone screen back without any bulge under the home button.
Now perform a quick review, test the battery charging status again, connect the home button connector again and assemble the screen back.