Step 1: Disassembly

Remove a single T4 Torx screw from the back of the unit.

Step 2: Disassembly, Cont.

Slide the cover toward the mouthpiece. The cover is very tight and may require some force to slip off the unit. Be careful not to loose 2 little bowl magnets as shown in the image.

Step 3: Disassembly, Cont.

Once the cover is off, you will see the internal circuitry and a single battery cell taped to the unit.

Step 4: Battery Removal

Carefully cut the tape, remove it from the battery and slide the battery out of its compartment.

Step 5: Disconnecting Battery

Simply rip the weld tabs off the battery.

Step 6: Insulation Removal

Using a knife, cut and remove the shrink tube insulation from the weld tabs and wires. After shrink tubing is off, the solder joints will be visible. Use a soldering iron to desolder tabs from the wires.

Step 7: Prepare the Wires

Slip new shrink tubing over the wires. You can also use electrical tape in the later steps if you don't have shrink tubing.

Step 8: Connect New Battery

For a replacement, I used Panasonic NCR18650B 3400 mAh battery. This cell had the solder tabs spot welded on in our shop. The tabs are thinner and narrower than standard weld tabs in order to match the original.

Solder the wires to the terminal tabs only.

Do not solder directly to the battery!!!

Step 9: Complete the Insulation

Slide the shrink tubing over the terminal tabs and solder joints leaving as little of the tabs exposed, as possible. Heat them up with a hair dryer or a heat gun to shrink in place.

Step 10: Re-assembly

Insert the battery back into its compartment and replace the tape that was cut during the disassembly, any electrical tape will do. Slide the cover back over the unit, replace the torx screw.

Your Pax will not turn on. Don't worry, you just need to "unlock" the internal protection circuit. Simple place your Pax on its charging base and make sure that it is plugged in. Watch that light come to life!