Philips AirFloss Battery Replacement Guide

In this guide we show you how to open up the Philips Sonicare AirFloss dental flosser to replace the internal battery.


This disassembly and repair tutorial is based on the HX8240 AirFloss as shown in the photo above, but is applicable to the other AirFloss flosser models in the Philips Sonicare range including those listed below. You can find the HX number of your Philips AirFloss interdental cleaner marked on the bottom of the handle, as shown in the example arrowed below.


This guide applies to Philips Sonicare AirFloss models with the following HX numbers, amongst others:

  • HX8100 series, including HX8110, HX8111, HX8120, HX8130, HX8140 and others starting HX81
  • HX8200 series, including HX8210, HX8211, HX8212, HX8220, HX8222, HX8230, HX8240, HX8241, HX8260, HX8261 and others starting HX82
  • HX8300 series, including Airfloss Pro/Ultra, HX8310, HX8311, HX8312, HX8315, HX8316, HX8330, HX8331, HX8332, HX8340, HX8341, HX8350 and others starting HX83
  • HX8400 series, including Airfloss Pro/Ultra, HX8410, HX8420, HX8430, HX8438, HX8440, HX8460, HX8462 and others starting HX84

The basic battery replacement method is:

  • Open and dismantle your Philips AirFloss flosser
  • Remove the old rechargeable battery
  • Fit the replacement battery and solder the wires for the new battery
  • Reassemble the AirFloss and recharge the new battery

The AirFloss battery replacement process is documented in detail below along with lots of pictures. Click on any photo to enlarge it.



Any damage to yourself, your device or anything else is entirely your responsibility. This guide is for professional, educational purposes only and is offered without guarantee or liability. Lithium-ion (Li-ion) batteries are dangerous if short-circuited and can go into thermal runaway and self-ignite if you do not observe all handling precautions. Always wear safety glasses when soldering and cutting.

Tools / Parts / Equipment

  • Philips Sonicare AirFloss flosser (interdental cleaner)
  • Compatible charger
  • Soldering iron: Electronics grade (about 18-25 watt)
  • Solder: Lead-free silver solder is great for this
  • Wire cutters
  • Wire strippers
  • Insulation tape or heatshrink
  • Double-sided tape
  • Replacement 3.7V Li-ion battery. Support us by buying yours from here


To start with, remove the spray nozzle from your AirFloss and empty the water reservoir.


The AirFloss comes apart around a seam in the middle of the handle. Gradually pull and work the two halves apart while bending the AirFloss back and forth along its seam. Go slowly so you do not end up ripping the casing apart as you might end up breaking wires or knocking components off the PCB. If you have trouble grip the top half at the sides and squeeze the lower half front to back. This can help release the internal catches while you pull the casing open. If you come up with a better technique please let us know in the comments below!


Slide the lower casing off the inner workings while leaving the internal mechanism in the upper casing.


Time to get your soldering iron warmed up!

Locate the two ACT wire connections on the PCB, arrowed below. These are for the activation button.


You can mark the PCB and one wire if you want to make sure you reconnect them to the same holes later. Desolder the two ACT wires and pull them down through the PCB.

Locate the B+ and B- connections on the PCB, arrowed below. B+ is the red (positive) battery wire, and B- is the black (negative) battery wire.


Desolder each battery wire in turn, and wrap the end of the first one in a piece of insulation tape to prevent short circuits.


Locate the reservoir pipe as arrowed below, and pull it off the reservoir outlet to disconnect it.


Push the internal assembly up and away from the front edge of the upper casing to unclip it. The gap arrowed below should widen.


Untape the battery and activation switch wires then slide the internal assembly out of the upper casing. This should leave the battery and the switch wires in the upper casing.


Check that the two black rubber grommets for connecting the pipework are fully located either in the upper casing or on the end of the internal assembly. Make sure these are both still properly seated for later reassembly.


You can see the original battery inside the upper casing. It might be secured with double-sided tape.


Unstick the original battery and remove it from the casing.


Compare the original battery to the new battery. This new battery is 500mAh capacity giving you a great upgrade in running time over the original battery. Please support us in writing these guides by buying your replacement battery from us here at – Replacement AirFloss batteries.


Measure the length of the wires on the original battery. In this case they are almost 10cm long.


Measure the length of the wires on the replacement battery. These are just over 4cm long.


Starting with the black negative wire on the old battery, cut off enough to extend the black wire on the new battery, plus a bit extra just in case!

Solder the wire extension to the black wire on the new battery.


Insulate the solder joint by wrapping it with insulation tape or a piece of heatshrink. If using tape you can slightly melt the outer layer of the tape in one place by momentarily touching it with the side of your soldering iron tip. This stops the tape undoing itself in the future.


Do the same with the red wire. You can solder the old wire to the new battery before cutting it if you like.


Strip and tin the end of the black wire.


Temporarily wrap the tinned end in insulation tape to prevent accidental short circuits. Strip and tin the red wire.


Add a piece of double-sided tape to the back of the new battery. Make sure the wires are pointing in the direction shown so you can determine which surface is the ‘back’.


Slide the new battery to the far end of the casing and stick it in place as shown below, with its wires on the right.


Tuck the activation switch wires between the battery and the right hand side of the casing.


Check that the black grommets are still fully seated in either the upper casing or on the end of the internal assembly.


Turn over the upper casing so the battery is uppermost. Then, keeping the wires tucked to the left, slide the mechanism into the upper casing.


Keep the wires above the plastic tab (arrowed below) as you slide the mechanism into the casing.


Guide the flexible pipe towards the fixed connector outlet, and connect it up.


Once the mechanism is pushed fully home, engage the clip in the upper casing by moving the mechanism downwards inside the casing. This will close up the gap arrowed below.


Solder the red B+ and black B- wires into their PCB holes.


Route the two ACT wires under the charging coil and solder them back into their PCB holes.


You can now plug in your charger and hold the exposed assembly on the charger. Make sure the charging LED on the PCB lights up (arrowed below).


Tape the loose wires onto the metal plate that supports the gearbox so they can’t get tangled in the gears.


You can now try powering on your AirFloss by pressing SW1 on the PCB (arrowed below). The LED should come on. Press SW1 again to switch the flosser off off.


Slide the lower casing over the internals and clip the AirFloss back together.


You now have a fully reassembled Philips Sonicare AirFloss!


Test the AirFloss by switching it on and pressing the activation button on the top. You should hear it working as normal.

Put your AirFloss on for a full charge then it’s ready to use. Happy flossing!


Please recycle your old flosser battery. It is safest to tape over the exposed wire ends to avoid short-circuits. You can then take it to your local supermarket battery collection point or civic recycling facility.

Please leave any questions, tips or suggestions about Philips Sonicare AirFloss battery replacement below.

7 thoughts on “Philips AirFloss Battery Replacement Guide

  1. An excellent tutorial resulting in my successful replacement of a battery. Thanks indeed to the creator and all.

  2. The easiest way to get it apart.
    Twist the two sections in opposite directions until a small gap appears. Pour a very small amount of fairy liquid into the joint and work the two half back and forth. Then rinse in warm water and the fairy liquid will release the rubber seal and the two halves will come apart.

    1. Thanks for the tip Roger!

  3. Could you cut the existing battery wires and join/graft/solder the new battery wires to the cut ends to save a bit of soldering?

    1. That’s the way to do it!

  4. I found if you soak a flannel in hot water and wrap the lower casing in the fannel for a couple of minutes. Dry off the casing and pull apart, it comes apart alot easier.

    1. Thanks for the tip Neal!

Leave a Reply
Your email address will not be published. Any comments containing links are automatically deleted. Email us instead.