How To Jump-Start Phone Battery (No-Budget Hack)

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

  1. Turn the phone on by pressing/long-pressing the power button
  2. Take the battery out. Press and hold the power button for at least 30s.
  3. 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.

  1. Wire stripper pliers
    • Recommended for cutting and skinning the cable
    • can do both, cut and skin the cable
  2. 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
  3. 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.
  4. Multimeter
    • 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.
  5. 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.
  6. 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?

Steps

  1. Cut the USB cable.
  2. Skin 5mm (quarter of an inch) of red and black wires.
    USB cable wires
  3. Twist the exposed end of each wire.
  4. Plug the cable into charger.
  5. Place the black wire (-) to the minus of the battery.
  6. Place the red wire (+) to the plus of the battery.
  7. Hold in place manually for a couple of minutes.
  8. Put the battery back into the phone.
  9. Plug the phone into the charger.

Your phone should soon start charging. If it doesn’t, try again, make step 7 longer.

Jump starting a phone battery

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.

Have you ever tried this? Do you have any other ways to revive dead batteries?

68 thoughts on “How To Jump-Start Phone Battery (No-Budget Hack)

        1. Hi Alex,

          I’m not exactly sure what you mean by “cable strip”. What this does is, it charges the battery a little bit “forcibly” to (temporarily) raise the voltage enough so phones charger can recognize it and continue charging it.

          If your battery has the same problem, you should be able to boost it the same way. Be cautious and happy hacking 🙂

  1. hey bro i am gonna use this trick with my canvas 2 and just hope that it works and one more thing that my phones upper part gets hot i there i any current in the phone. i u can help me or the same!!!

    1. Hi Dev,

      There is more than one reason why phone might be getting hot.
      When it’s charging, there is electrical current flowing from the wall outlet through your phone to the battery.
      Another case is when you’re using it heavily, your processor uses more power and more current flows through it. That’s why your phone depletes faster and gets hotter.

      These are both normal use cases and unless it gets too hot, it doesn’t represent a concern.

      As explained in the article, jump-starting a phone battery might be needed if you can’t get your phone to charge the battery.
      If your phone battery charges, just gets hot, jump-starting is not going to help.
      Charging with lower current might help, but your battery will take more time to charge.

      I hope this helps.

      Cheers, Zvonimir

  2. I’m sorry to be too late but I actually have a phone in which the battery can’t be removed. How can i jump start this one?

    1. That’s a tough one and might not be possible without opening the phone.
      How did you identify that battery is the problem?
      What’s the model of the phone?

    1. iPod 5g has a lithium ion battery and if you get to it, it should perform as the article explains. Exercise caution and don’t do anything you’re not prepared to take responsibility for 😉

      Good luck!

  3. Hi! I can see that my handphone has been fully charged. But i can’t turn in on again. It just shown fully charge , and that’s it all. What should i do?

  4. Wow! Used it for an old Nokia I had lying around. Can’t believe I didn’t think of this considering I’m usually pretty good at this stuff! Great hack dude! You’re smart!

    1. There are 2 red wire and 2 black, are they both connected ? I inserted the small wire at 2nd red and the 5th black, Im guessing with connection but with volt meter they both have 7:13pm 3.92 v reading from 3.46 v 4pm, I connect all the black wiring 3 and then battery, press the power and volume down for 1 minute while charging with 2.1 amp battery pack using the port, still off, until what voltage will it works 5 volts ?

    1. There should be no difference. You can trying boosting it for longer (couple of minutes or more, depends on the state of the battery; it needs enough juice to be able to take care of its charging process when you use original charger) and/or upping the voltage/current a bit.

    1. Hey Peter!

      To my knowledge devices with built-in batteries don’t 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’s depending on the 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.

      I don’t have any links right now (I’m not on my computer) but ifixit should have the tools you need to get in 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.

    1. Well, best way then would be to use a voltmeter to determine polarity (where’s the plus and where’s the minus.)
      If you don’t have a voltmeter, you could use an LED with a resistor in series to determine polarity.
      What other electronic components do you have around?

    1. Depends. 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.

  5. using LG my phone can’t turn on when I power it on don’t no if the battery fault or phone but the battery have power unable to turn it on plss help

    1. If you’re sure your battery is full, then it’s probably something wrong with the phone or phone’s connection to the battery.

      If you’re not sure, then it might mean that your battery is overdepleted and steps in this article might help you.

      Steps here won’t work if you can’t remove the battery from the phone.

  6. I had remove my battery to charge with universal charger cuz my charging system not working when it finish charging n I plug it in my phone it can’t power on again that how the problem start

    1. It’s possible that your battery didn’t actually charge, or that something’s wrong with getting the power from the battery to the phone, or that something’s wrong with the phone itself.

      I can’t really tell based on the information you provided.

      If you’re really, really sure that the battery is charged, then it’s probably one or both of the latter two.

        1. I assume by terminal you mean contacts/connectors?
          You’ll have to find where plus and minus connectors for that specific battery are if it’s not obvious.

  7. Whats the difference cutting of the micro-usb connector and charge by wires, than keeping the connector and charge a phone as usual, same voltage?

    1. Hi Johan,

      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.

      Cheers, Zvonimir

  8. I have Samsung galaxy tab 2 found off in the morning, left on before I sleep and when I charge first it keep cir ling now its dead and I already tried the press On for 10 sec,1min with up button,remove the battery terminal and the 3 other pressing the power button thing and didn’t work, I’ve seen the 2 red wire and 2 black, I will try this, before buying and replacing the P5100 battery for 599 pesos /$12 and charging port – 240 pesos/$ 5, i just use the volt meter, I wish it wont damage the battery by connecting the 2 red together and the 2 black, will post back for my result , thanks Zvonimir

      1. Presently charging my samsung tab 2 battery 4:10pm, Philippine time, there are 2 black and 2 red, I start with the outer black and red Im not sure if the 1st red is connected with the 4th black, it seems ,the wire in my usb cable is so thin enough to insert to the plug, I have photos I wish to share

      2. Sir Until what volts will I charge 5 volts ? Is there a voltage check circuit. were I can put my red probe ? Im looking at galaxy tab circuit diagram for specific point , thank you sir for any help

        1. Hi William,
          Based on your comments across the comment section, if I understood them correctly, it sounds like you’re making progress as the voltage went up over time.
          It all sounds a little bit confusing without an image with multiple back and red wires so I’ll try to reiterate the main points.

          The cable you cut has 4 wires. When plugged into the standard USB port, between two of those four wires, there will be a voltage of about 5V. It’s usually between a red and a black, red being positive. Depending on the manufacturer, that can differ. That’s where voltmeter comes in handy.

          If polarity is not marked on the battery, you can use voltmeter to determine that too.
          Then connect the powered wires to the battery pads according to the picture in the article.

          This only needs to be going on for long enough for the battery to go over a threshold. You don’t need to fully charge the battery like this.

          After you boost the battery for a while, you can try quickly putting it back into the phone and try charging the phone with its charger. Don’t try to turn the phone on until it says the battery is full.
          If the phone doesn’t show it’s charging after 15 min, try taking the battery out and boosting it longer.

          It is possible to deplete the battery completely beyond the repair if the polarities are reversed and the battery doesn’t have inner circuits that protect it from that.

          Good luck and I hope you make it!

  9. 4:10 pm 3.46 volts
    7:10pm 3.92 volts
    I tried and attached the 3 black wire and then the battery then charge and press the power and volume down still nothing happened, Im charging it again at 3.92 volts, I want this to work, while waiting I’ll try to make cable charger with resistor thing the 100k, and look for possible in circuit voltage check diagram

  10. Yes! Thanks! Magic! Have a Samsung XCover2, battery was dead so couldn’t be charged with computer or charger. I took an old Nokia 5V phone charger, cut the wires (has only 2 cables with exactly red and black cables inside as described here), and simply took the phone battery with its + and – contacts clearly visible and held the wires correctly (IMPORTANT! You have to be 100% sure about the + and -) on the battery contact surfaces for about 30s to begin with – no result. Then I continued with 2 mins. Plugged the battery into the phone and phone with USB cable to computer for charging – incredible! It woke up and started charging normally again!

  11. Thanks for the info. Can I make a full charging (of like 2 to 3 hours)with this wire method? My phone’s charging terminal is faulty.

    1. Hi Bello! You can. Be aware that with this method, there are no charging protections, unless the battery has some built in, so the battery can overcharge if charged for too long.
      Proceed with caution!

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