Repair Dead Laptop Battery

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Introduction: Repair Dead Laptop Battery

About: A lover of nature, astronomy and cozy evenings in front of the wood stove.

We all know it. Suddenly, your laptop battery stops working. It won't charge and the moment you pull out the charger the laptop turns off. You have a dead battery. I have a fix that will revive it.

Please notice, that we are only reviving a dead battery. If you have a "bad" battery that only holds smaller charges for a few minutes worth of work, then this is not the right instructable for you. If your battery is completely dead then read on!
Oh, and by the way.. I cannot be held responsible for any problems you may run into, like damaged battery cells, fires, explosions and any other damage. Continue on your own risk.

People are suing like crazy these days, I have to say that. Anyway, next step!

Step 1: The Theory

A laptop battery typically consists of three battery pairs. Each pair is two battery cells soldered together in parallel. When you connect battery cells in parallel the voltage stays the same but you increase the capacity of the entire package (you can "pull more amps" out of them, more electrons).

Typically each battery cell (and thus pair) is 3.7 V. Now, when you connect them in series (be it individual cells or aforementioned pairs), you increase the voltage, thus getting 3. 7 x 3 = 11.1 V.

Too long, didn't read: each pack has to be 3.7 V.

Now, why isn't it charging? That's because one of the pairs does not have the same voltage as the others, making it impossible for the computer to charge them all at the same time.

Step 2: The Battleplan

We are going to open the laptop battery and examine each of the three "pairs". They need to have the same voltage. If not, we are going to recharge the pair with the low voltage back to 3.7 V.

Step 3: Tools

  • Multimeter (cheap and useful)
  • Charger, around 4-5 V

You may also need

  • Small cutter, to remove the paper on the battery.
  • Screwdriver to pop open the battery

Step 4: Remove the Battery

Unplug charger, turn over your laptop and locate the battery on the backside of the laptop.

It may have two buttons like mine. One is a lock, push it away from the battery. Now push the other button away and pull out the battery.

Step 5: Remove Paper

Now flip it over again. You will see a side with text. What you are looking at is a thick piece of special paper. We can safely peel that off with a small cutter or any sharp object. You really just need to start the peeling with the cutter and continue with your fingers.

Step 6: Pop Open the Lid

Now you are looking at this. That is actually a lid that is popped on.

You may need to use your screwdriver to put in the "crevice", turn it around and make it pop open that way. Once it has popped up, just remove it with your fingers as shown.

Step 7: Out Comes the Batteries

Gently lift the batteries from one end, then the other to make sure, that they are not sticking. Now turn it over and let the batteries fall out into your hand. Make sure that the circuit board also comes out together with the batteries.

Step 8: Seperate the Cells

Seperate the three pairs of cells just a bit so we can do some measuring on them. Also, get your multimeter.

As you can see, they are soldered together in pairs, so it doesn't matter where you put your multimeter tip. You will be measuring the voltage of the pair.

Step 9: Start Measuring

The voltage has to be 3.7 V. With that in mind, start measuring.

As you can see, the middle pair is bad here.

Step 10: Get Your Charger

Now we start the fixing process!

Get your charger. Determine which wire is the positive and which is the negative. Often there is a white or grey line on one of the wires. If not, just use a bit of tape. Now measure with your multimeter. If the voltage displayed is a positive number, then the red tip is touching the positive and the black tip the negative.
If the voltage displayed is negative, then it's the other way around.

Yes, I am measuring 11.9 V. That's because I didn't have a low voltage charger laying around, but if you do this, you may damage your cells. I didn't care a whole lot, though, and I haven't noticed any damage even though I've done this twice now.

Step 11: Help It Back to Life

Put your positive wire on the positive end of the battery and the negative on the negative. Recharge for a minute. Then wait 10-20 seconds before measuring. That is because the voltage in the cells will fall when you stop charging them. Here, I have already increased the voltage quite a bit.

When you think you have finally hit the correct voltage, wait half a minute and remeasure to make sure that it doesn't need a little more.

Step 12: Put It Back

Push the cells back together and put them down the battery cover as shown. Make sure, that the circuit board is all the way in (you can't do it wrong).

Put back the lid, it will pop in. Put back the sticker and if it doesn't stick (it really should), just use some transparent tape or glue.

Step 13: Back to Its Natural Habitat

Push it back in the laptop and push the lock into the locked position, which is towards the battery.

Step 14: Return of the Battery

Oh boy! Is it going to work (is anyone even doubting?!)?

Let it charge for one minute, then unplug it and try turning it on.

It is alive! I mean, of course it is.

Now let it recharge completely before using the laptop without the charger.

Step 15: Extra: If You Do Not Have a Charger Like Mine

Don't be discouraged! We'll just make one.

Grab your old 4-5 V charger, that you don't use anymore. Get a pair of electric pliers.

Cut off the plug. Seperate the wires (c'mon, you don't need instructions for that).

Now, grab one of the wires and close the pliers on them, but don't cut. Sort of pull away the insulation. You may need to use your fingers to pull it off completely. Twist the cable. Repeat for the other cable and you´re good to go!

Step 16: Final Words

That is how you fix your laptop battery for no money at all and in only half an hour! You may consider changing the cells, though, as dying this
way is an indicator of a bad cell. There are great instructables for that. But for now, just enjoy that you're awesome and could fix this yourself (and save some $50)! And who knows, maybe it will keep working forever?
Mine kept working for half a year before it needed a new treatment but hey, how else would one spend a Saturday evening, am I right?

Leave comments if you have questions or, well, comments!
Thanks for reading!

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    35 Comments

    0
    Amir-H- Masoud
    Amir-H- Masoud

    Question 3 months ago on Step 12

    So sorry,i spread all six batteries instead of what you're did , I been told that they must be bunch together again and I can't attach them by soldering and ... I think it'll be more chipper if I buy a new one ? I'm a bit confused, I want to build a battery for My drill (14.4v) with 4 batteries in series but I am afraid to break this one too and it's much expensive than the laptops , I'll be grateful if you say to do it or not . thanks

    162576574959864746508.jpg1625766261860-370615523.jpg
    0
    Gelfling6
    Gelfling6

    3 years ago

    There's also one more thing.... 18650 cells have an internal breaker that opens when the temp gets too high (usually off-gasses the battery as well.) this is where it gets dangerous unless you know exactly what you're doing.

    Notice on the "+" end of each cell, the point is surrounded by a paper gasket, with a little space of the O-shape of this, and the point. if you carefully press down around the gasket, You'll see the vents in the point. take a small, BLUNT point small enough to fit through the vent, and lift upward only slightly. remove the instrument, and check the cell for voltage. You might find it's at full voltage.

    the breaker opens when charging the cell, and it becomes too warm. You might also get some crystalized electrolyte that holds it open. the pressing down (when you lift up on the blunt instrument) pushes the breaker shut..

    Sounds simple, right? rememeber that I said Dangerous. for two reasons.

    #1, you can puncture the seal on the cell, and the electrolyte will leak when you start charging. the other danger, shorting the center point to the outer canister lip. LIion cells dump their full mAh amperage into a dead short. I had one cell burn a 17-AWG solid brass pin in half.(and my fingertip that was against it when it shorted.)

    0
    Amir-H- Masoud
    Amir-H- Masoud

    Reply 3 months ago

    I already broke it badly with my finger in it , I was thinking about making or buying a new one, now I have already sixteen li--ion battery's , what sould I do ? Thanks and thanks about your article

    0
    mdtechtechone
    mdtechtechone

    Reply 7 months ago

    I have done all thous step before view this but the problem is after returned the battery it can't power the system and started warming what is the next thing to do. Thanks

    0
    Protriton
    Protriton

    Reply 3 years ago

    This is good to know, thanks for sharing!

    0
    mabotha1970
    mabotha1970

    Question 8 months ago

    Hi everyone ive just joined. Can anyone probide me with circuit diagram for my laptop battery supply, its an acer travelmate, the battery cover states as follows:AS10D51 (31CR18/65-2) Rating 10.8v 4400mAh/48wh . I disconnected the batteries without sketching. Mark

    0
    tytower
    tytower

    3 years ago

    Its a temporary fix and a good starting point . Lithium ion cells should be charged into their upper knees (4.2Volts) then all connected in parallel for 24 hours . This is called top balancing It should only need to be done once in a blue moon if the cells get out of balance.

    This is needed because each cell will now discharge with use down to its lower knee of (around 3.0 Volts) .So each cell will contain so much energy to release until one cell gets too low for the BMS and it will disconnect all of them.

    My suggestion would be to buy new cells and make up the pack again or buy a new battery complete. You can disconnect each cell and charge it separately on some chargers and thats what I do .

    0
    eduardo.u.monteiro
    eduardo.u.monteiro

    Reply 8 months ago

    Great input, many thanks.
    To help increase the lifespan we should use something like 90% down to 20% max 10%
    Max Voltage 4.2v = 100%
    Stop Charging 4.08v = 90%
    Nominal 3.7v = 75%
    Stop using 3.2v = 20%
    Cut-Off 3.0v = 0%

    0
    Protriton
    Protriton

    Reply 3 years ago

    Thank you for this valuable information. Yes, it is temporary fix, that will help the battery go for another half year or, hopefully, more. I am planning to replace the faulty cells (or maybe the entire package) with some others I have in an old laptop I'm not using. The battery there is surprisingly good.

    0
    Protriton
    Protriton

    Reply 3 years ago

    Looks awesome, thanks for sharing!

    0
    Thompson Josiah
    Thompson Josiah

    2 years ago

    Thanks sir for the information but my battery have been dead for more than a year now.
    If i follow this method will i still recover its life back?
    Sir thank you again but can i use a laptop charger to boost the cells up because i don't have any adapter that is similar to your own

    0
    Protriton
    Protriton

    Reply 2 years ago

    You have to be careful that the batteries look completely healthy, no leaking etc otherwise it may be dangerous.
    About the adapter: it is safest to use a voltage that is just slightly higher than the battery voltage, but I used one that is much higher but I only put it on the battery a few seconds a time until it recharged.

    0
    eduardo.u.monteiro
    eduardo.u.monteiro

    Reply 8 months ago

    Agree, BTW an USB charger could help to do the trick
    5V 1A

    You could add it to this instructable (how to use a USB charger and cable)

    0
    zikirlah
    zikirlah

    Reply 2 years ago

    those it work for yo

    0
    AthaariqA
    AthaariqA

    Question 2 years ago

    How if I add more 3 more batteries to increase capacity twice and 3D print the new battery case. Is that possible?

    0
    Protriton
    Protriton

    Answer 2 years ago

    I don't know to be honest. I don't know if the printboard is designed to handle more batteries.

    0
    eduardo.u.monteiro
    eduardo.u.monteiro

    Reply 8 months ago

    I believe yes, cause the circuit board only checks the voltage.
    3.7v nominal
    3.0v cutt off
    4.2v max (charge)
    knowing this you can use more time and also take more time to charge (A)

    Some brands have 3, 6, 9 or 2, 4, 6 cells
    We must have the follow in mind
    Cells always in pairs and all balanced to the voltage and also with the same capacity. (9 cell 2500mah = 83,25wh or 9 Cell 3000mah = 99,9wh)

    You will have a powerbank + UPS for extra battery lifetime.

    BTW share the 3D

    0
    Ptplopes
    Ptplopes

    Question 10 months ago

    Hi !
    I have just changed the 3 x18650 batteries of the BTY-S11 pack, from my LG netbook.
    I used an external source to charge the batteries prior to install them.
    I mounted the pack but no voltage at the connector. I have the negative at pin 9 but no positive at pin 1!
    Need some help to have it fixed.

    Regards,
    Paulo de Tarso