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Introduction

Use this guide to replace a worn out or dead battery in your Bose Quiet Comfort 35.

If your battery is swollen, take appropriate precautions. For your safety, discharge your battery below 25% before disassembling your headphones. This reduces the risk of a dangerous thermal event if the battery is accidentally damaged during the repair.

For this guide we recommend the use of a hairdryer or a heat gun. It’s manageable to disassemble your headphones with the use of an iOpener however the disassembly gets way more difficult.

You’ll need replacement adhesive and a soldering iron to loosen components during disassembly and and to reattach them when reassembling the device.

Your replacement battery may be a different size or capacity than your original battery. As far as we know all QuietComfort 35 replacement batteries will work with both the QuietComfort 35 I and QuietComfort 35 II.

  1. The earcup cushions of the Bose QC 35 are held in place by small plastic clips. Grab the cushion of the left earcup and gently pull it to the center of the earcup to free it from the plastic clip holding it in place. Repeat this procedure for all clips that hold the cushion in place.
    • The earcup cushions of the Bose QC 35 are held in place by small plastic clips.

    • Grab the cushion of the left earcup and gently pull it to the center of the earcup to free it from the plastic clip holding it in place.

    • Repeat this procedure for all clips that hold the cushion in place.

    • Remove the left earcup cushion.

  2. Carefully peel off the protective cloth which covers the inside of the earcup. The protective cloth is held in place by mild adhesive. If the cloth starts to rip during the removal, apply an heated iOpener to the cloth or use a hairdryer/heatgun at the lowest setting to loosen the adhesive. The protective cloth is held in place by mild adhesive. If the cloth starts to rip during the removal, apply an heated iOpener to the cloth or use a hairdryer/heatgun at the lowest setting to loosen the adhesive.
    • Carefully peel off the protective cloth which covers the inside of the earcup.

    • The protective cloth is held in place by mild adhesive. If the cloth starts to rip during the removal, apply an heated iOpener to the cloth or use a hairdryer/heatgun at the lowest setting to loosen the adhesive.

  3. Remove the two Phillips #00 screws (6.2 mm length).
    • Remove the two Phillips #00 screws (6.2 mm length).

  4. Turn the headphones over. Insert an opening pick into the gap between the plastic cover and the earcup frame. Use the opening pick to pry up the plastic cover of the left earcup.
    • Turn the headphones over.

    • Insert an opening pick into the gap between the plastic cover and the earcup frame.

    • Use the opening pick to pry up the plastic cover of the left earcup.

    • Remove the plastic cover.

  5. To avoid melting the speaker diaphragm by exposing it to too much heat in the next steps we advise preparing a protection. Cut a cardboard as shown in the pictures so it covers everything inside the earcup but the battery cover. Place the cover inside the left earcup.
    • To avoid melting the speaker diaphragm by exposing it to too much heat in the next steps we advise preparing a protection.

    • Cut a cardboard as shown in the pictures so it covers everything inside the earcup but the battery cover.

    • Place the cover inside the left earcup.

  6. Even with a heat protector in use we highly recommend to start with low heat to loosen the adhesive of the battery cover and to raise it slowly (maximum of 100°C) if the adhesive doesn't soften.
    • Even with a heat protector in use we highly recommend to start with low heat to loosen the adhesive of the battery cover and to raise it slowly (maximum of 100°C) if the adhesive doesn't soften.

    • Do not aim your heat gun vertically onto the battery cover but only in a flat angle facing the straight edge of it.

    • Use your heat gun to loosen the adhesive underneath the edge of the battery cover.

  7. Avoid puncturing the battery during the following process. Do not use metal tools or excessive force when working near the battery. Insert the edge of an opening tool underneath the bottom corner of the battery cover. This requires some force.
    • Avoid puncturing the battery during the following process. Do not use metal tools or excessive force when working near the battery.

    • Insert the edge of an opening tool underneath the bottom corner of the battery cover. This requires some force.

  8. Slide the opening tool along the edge of the battery cover to loosen the adhesive underneath and create a small gap. Slide the opening tool along the edge of the battery cover to loosen the adhesive underneath and create a small gap.
    • Slide the opening tool along the edge of the battery cover to loosen the adhesive underneath and create a small gap.

  9. Insert the flat end of a spudger between the battery cover and the battery. Avoid to use the spudger as a lever when working close to the battery. Use to spudger to carefully separate the  plastic cover from the earcup. Avoid excessive force to the battery.
    • Insert the flat end of a spudger between the battery cover and the battery.

    • Avoid to use the spudger as a lever when working close to the battery.

    • Use to spudger to carefully separate the plastic cover from the earcup. Avoid excessive force to the battery.

  10. Remove the plastic cover from the left earpiece. Remove the plastic cover from the left earpiece.
    • Remove the plastic cover from the left earpiece.

  11. In the next step you will desolder the battery cables.
    • In the next step you will desolder the battery cables.

    • Use this picture as reference for resoldering during re-assembly or make your own photo if the cable order differs in your model.

  12. Use a soldering iron to desolder the three battery cables from the circuitboard. Use a soldering iron to desolder the three battery cables from the circuitboard. Use a soldering iron to desolder the three battery cables from the circuitboard.
    • Use a soldering iron to desolder the three battery cables from the circuitboard.

  13. Try not to deform or puncture the battery during the following removal process. Soft-shell lithium-ion batteries can leak dangerous chemicals, catch fire, or even explode if damaged. Insert the flat end of a spudger between the battery and the battery well. Carefully pry the battery out of its recess.
    • Try not to deform or puncture the battery during the following removal process. Soft-shell lithium-ion batteries can leak dangerous chemicals, catch fire, or even explode if damaged.

    • Insert the flat end of a spudger between the battery and the battery well.

    • Carefully pry the battery out of its recess.

    • You might want to change the position of the spudger a couple of times during this process to avoid excessive force to a single point of the battery.

  14. Remove the battery. Do not reinstall a damaged or deformed battery, as doing so is a potential safety hazard. Replace it with a new battery. Before installing a new battery remove any remaining adhesive from the headphones, and clean the glued areas with isopropyl alcohol and a lint-free cloth.
    • Remove the battery.

    • Do not reinstall a damaged or deformed battery, as doing so is a potential safety hazard. Replace it with a new battery.

    • Before installing a new battery remove any remaining adhesive from the headphones, and clean the glued areas with isopropyl alcohol and a lint-free cloth.

    • Make sure the battery cables are long enough to solder them onto the circuit board before installing new adhesive into the battery well.

Conclusion

If possible, turn on your device and test your repair before installing new adhesive and resealing.

To reassemble your device, follow these instructions in reverse order.

For optimal performance, calibrate your newly installed battery: Charge it to 100%, and keep charging it for at least two more hours. Then, use it until it shuts off due to low battery. Finally, charge it uninterrupted to 100%

Take your e-waste to an R2 or e-Stewards certified recycler.

Repair didn’t go as planned? Check out our Answers community for troubleshooting help.

20 other people completed this guide.

Dominik Schnabelrauch

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17 Comments

спасибо ! будет полезно на будующее

Komar - Reply

Hallo, tolle Beschreibung. Vielen Dank dafür.

kann man bei den Bose 700 NC auch den Akku tauschen ?

Würde mich sehr freuen, wenn das so wäre. Hat da jemand evtl bereits schon Erfahrungen gemacht. Könnte mir vorstellen, dass viele 700 NC jetzt auch in das Alter kommen, in dem der Akku schwach wird.

Jens Nußbaum - Reply

Fk Bose for making it so difficult! They all care about the environment so much, don’t they?!

Batteries should be easily replaceable by any customer by themselves! Ear pads as well. Bose makes it harder so you would throw away your $300 headphones when battery dies. So much waste, plastic and other harmful stuff.

EU mandated to use USB-C on all devices to reduce the waste. Batteries are more harmful. They should make it mandatory for batteries to be user replaceable on tech like headphones. Manufacturers are making disposable headphones in purpose, obviously. Like AirPods and other similar earbuds. 18-24 months and you’re forced to throw them away. They should offer cheap battery replacement for AirPods and like earbuds as well. Maybe trade in deals. $70-$90 a bud isn’t cheap replacement.

Companies are lying about the love for the environment to make us buy more and add more harmful waste to it.

Usern@me - Reply

Thanks. Replaced my bose qc35 headphone battery. Works perfectly!

Thomas Maher - Reply

Wastage and ‘the environment’ are not quite the same thing. Most, if not all, of the material used to make the device is recyclable. It’s not an issue of damage to the environment for companies to make it difficult, or really, to not make it easy to replace a battery. You’ll find many companies do this in order to make their devices more water-resistant and dust-resistant. It’s not just because the big bad rich guys hate the planet.

If you’ve an issue with waste, contribute your waste to recycling. It’s your fault, not the company who made the product’s fault, if you don’t.

Great guide.

Harry Grade - Reply

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