Few days after Jasmina’s Sony Xperia Z charger broke, I had another unpleasant surprise. I woke up to a dead phone and no amount of charging, trying to turn it on, putting the battery in and out, helped…
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How do I revive my phone’s dead battery?
Things to try before you jump start your battery
- Turn the phone on by pressing/long-pressing the power button
- Take the battery out. Press and hold the power button for at least 30s.
- Try a new battery. Borrow from a friend who has the same phone.
Why this can help
First point is self explanatory. If your phone turned off because of a glitch or something, this turns it back on, voila!
Second point might seem a bit weird to most. You obviously won’t turn on the phone while it has no power supply. Good thing this isn’t the point here. This step discharges residue charge from your phone’s electronic components. This also works for laptops and I used it to revive quite a few of them inspiring statements like “It didn’t work before, I swear!”. I know, I believe you 🙂
Third point, tried after second, makes sure it’s a problem with battery and not the phone. You can also try your battery in your friend’s phone.
I didn’t have a spare battery to try with, so I used the cable described later in article and connected the red and black directly to the appropriate pins inside of the phone. My Samsung S3 turned right on, so that ruled out problems with the phone itself.
If you’re in the similar situation be careful, the right pins will depend on the phone you have. My battery’s plus and minus pads were marked so I just followed and saw witch pins in the phone they touch. You can follow the same idea to figure out where your phone’s plus and minus pins are.
Why your battery plays dead
I’m talking about lithium-ion battery (sometimes called Li-ion battery or LIB), which are most common batteries in phones these days.
They can go unstable and “boom” if they get too discharged. To prevent that doodoo, engineers put electronics in place with some smarts in them. If the battery voltage drops below a certain point, to prevent further discharge, they disconnect the cells from the battery pads completely. Thumbs up for safety!
So why can’t you charge it?
Your phone has a battery charger or else you’d have to take your battery out every time to charge it. Convenient!
In order for that charger to work, it needs electricity. It gets its electricity from the battery, which currently puts out 0V.
The Hack (this is what you’re here for)
All you need is a spare USB cable and a charger (or a laptop, play station, smart TV…).
Tools (recommended, yet optional)
While you can probably do with tools you find in you kitchen, some of these tools will help a lot if you have access to them. If you don’t, they are very general tools and you can find many other uses once you get them.
- Wire stripper pliers
- Recommended for cutting and skinning the cable
- can do both, cut and skin the cable
- Regular pliers
- can cut the cable
- with a little technique, such as not applying full force, or using the top of the pliers, you can skin the wires as well
- Utility knife
- although you could cut some wires with a utility knife, I wouldn’t recommend it
- you can use it to skin the wires by applying little force to cut through insulation and then pulling it off with your fingers.
Threads in the black and red wire are often very thin to make the cable more flexible. Unfortunately, this also makes them very easy to cut with a utility knife once they are exposed, be careful.
- Checking the battery.
You can test your battery voltage and polarity and get the idea if battery is the culprit. If the voltage is a lot bellow what you expect (usually 5V), it probably is and this hack might help.
- Checking wire polarity.
When you cut and skin the wire, their colors usually indicate what they are used for, like in the picture below.
Sometimes that’s not the case.
You can use a multimeter to detect plus and minus polarity of the wires.
To do that, plug in the cut cable into the power supply (be careful that your bare wires don’t touch), put the multimeter in a voltage measuring setting and try different combinations until you get a positive reading around 5 volts. Wire that’s on COM of multimeter will be minus and the other one will be plus.
- Checking the battery.
- USB charging cable
- In case you don’t have an extra USB charging cable lying around, you will need to get a replacement once you fix your battery to charge your phone the usual way.
- USB charger
- Depending on your access to USB charging ports, you might not need this, however, if you’re planning on using some electronic device such as laptop or TV as a power source, keep in mind you might cause damage to that device if you do something wrong.
- It’s also a nice to have even if everything goes well and it goes along nicely with the charging cable from the previous point.
Ready to get your hands dirty?
- Cut the USB cable.
- Skin 5mm (quarter of an inch) of red and black wires.
- Twist the exposed end of each wire.
- Plug the cable into charger.
- Place the black wire (-) to the minus of the battery.
- Place the red wire (+) to the plus of the battery.
- Hold in place manually for a couple of minutes.
- Put the battery back into the phone.
- Plug the phone into the charger.
Your phone should soon start charging. If it doesn’t, try again, make step 7 longer.
Why this works
USB gives 5V which is above the normal Li-ion battery voltage (3.7V or 4.2V). This charges the battery enough to be briefly above the cut-off voltage. That’s just enough to start your phone’s charger and allow it to continue charging the battery until full.
I’ve been using and charging my phone normally since then. I also don’t allow my phone to die from empty battery. Lesson learned 🙂
If all else fails…
…and you are really 100% sure the problem is the battery and not the phone or anything else, you may need to, sigh, get a replacement battery.
Questions from comments
Could a universal charger work instead?
Yes, if it provides 5V of the correct polarity on the battery pads, as explained in “Why this works” section.
I’m struggling to get results, what else can I do?
You can trying boosting it, as described in step 7 of “The Hack” section, longer. Try couple of minutes or more, depending on the state of the battery, or even to a full charge. It needs enough juice to be able to take care of its charging process when you use original charger. You can also try upping the voltage/current a bit.
What about in-built batteries?
How can I revive built-in batteries? Devices with built-in batteries don’t normally give direct access to battery (why would they) and you access the battery only through the charging system you’re trying to circumvent.
Solution for that would be to open the device to get to the battery. There’s a whole new set of things to watch out there, it depends on the individual device and it’s much riskier since you can break the device. Good news is the same principle applies once you have the battery in your hands.
There are plenty of phone fixing kits available and you can order them online.
If your device is bricked and you can’t take it to the shop, you might as well have a little fun with it and have a chance of fixing it, but be careful and don’t do anything you’re not comfortable with.
What if the wires are not the same colors as here in the picture when I cut the cord?
As mentioned in the Tools section, the best way would be to use a multimeter to determine polarity (to find out where’s the plus and where’s the minus.)
If you don’t have a multimeter, you could use an LED with a resistor in series to determine polarity.
Can the mobile battery explode while jumping it?
It’s highly unlikely, but I can’t rule it out. Likelihood goes up if battery is physically damaged.
Also, remember Galaxy Note 7? So, sure, but I wouldn’t bet on it.
What’s the difference between this reviving phone battery by jump-starting it, and charging it normally?
The goal here is not to replace your phone charger (although you could). The difference is bypassing phone’s charging system which refuses to charge the battery if it’s bellow a certain threshold.
Charging it by wires will briefly boost the voltage (revive the battery) which will enable phone to detect it and continue charging it to full.
You don’t really need to charge the battery all the way on the wires, merely boost it enough to get over the voltage that allows the phone to detect it and charge it.