PAX 2 Battery replacement guide

Stop throwing shit out…. I never bought into the “Disposable” society that discards technology as soon as the next best thing comes out. This guide will show you how to repair your perfectly good PAX 2 with a new battery and breathe new life into an already outstanding product.

The PAX 2 is an outstanding example of brilliant product design

Let me start by saying that PAX is a phenomenal company that has shown with each iteration of the PAX vaporizer that they can innovate. How good of a design is the PAX? At one point I thought to myself “I should get into the vaporizer industry.” One day shortly after that thought my fiance came home with a PAX 1 and I was so impressed with the overall design and functionality that I changed my mind about making a splash in that industry.

TLDR; The PAX is one of the most well designed pieces of vaporizing equipment around. Highly recommended.

But the one Achilles heel of even the most well engineered product is always the lifespan of their battery. In the case of the PAX this comes from the internal lithium cylindrical cell, which generally can be charged to around 500 cycles before you see degradation of the capacity (it will store around 70% of the original capacity at 500ish charges). As time goes on the cell will hold less of a charge, heat up slower due to decreased current output, and generally cause the end user to be frustrated.

This is a great tear-down of the PAX 2 so you can ogle at the guts of the device. This is however destructive and we can’t take the milling machine approach since we want to keep using our PAX 2.

This article will walk you through the process of changing the 18650 sized lithium cell and effectively double the life of the product.

DISCLAIMER

This process will require you to be proficient with several types of tools including power tools, soldering equipment, and a firm grasp of common sense. You are performing this repair at your own risk, it WILL void your warranty; however this warranty does not cover the battery so if you want to revive your device this is the only way to do it. PERFORM THIS PROCESS AT YOUR OWN RISK, I assume NO responsibility for personal injury or damage to your device.

With that said here is the list of parts you will need:

  1. NCR18650B protected Lithium cell — $8ea
  2. Solder braid or small battery tabs

And the tools you will need:

  1. Soldering Iron — I have the older version of this Hakko, going on 6 years it hasn’t failed me yet.
  2. PCB Endmill or small drillbit — something around 1/16" in diameter
  3. Dental Pick or Small Flathead screwdriver
  4. Double sided tape
  5. Spudger or similar prying tool

Alright so if you watched the teardown video linked above you will know that the guts of your PAX 2 are held in with a clever key that also holds the pogo-pin targets for the charger. We need to remove this in order to access the battery compartment:

This is the most difficult part of the repair, take your time

STEP 1 — Drill baby Drill

Take your endmill/drillbit and drill a small hole in the plastic key to give us a place to start prying it out. Unfortunately I choose to start prying on the very end and in the wrong direction and fractured the key, I have a 3D model that you can 3D print to replace the key entirely posted at the bottom of the article in case you completely demolish yours.

Drill your hole so that you can pry ALONG the long edge instead of from the short edge and it should pop out much easier.

STEP 2 — Slide the guts out

At this point we can now remove the internals and get to work, put the key aside so we can repair it later. As you slide out the internals there are 2 heating chamber magnets (Cylindrical) and 2 charger mount magnets (Rectangular) that can fall out. It’s a good idea to mark the magnets with a magic marker so you know which direction to put them back in once we start reassembly.

Now that the PAX internals have been removed we can see that the battery wrapping has been torn from repeated temperature cycles.

STEP 3 — Disconnect the battery

The battery I choose as a replacement is a NCR18650B which has a capacity of 3400 mAh, an additional 400 mAh over the stock cell. This cell has built in protection circuitry and it is important you choose a battery that has this feature if you choose to use a different cell than I did. Next we need to find the points where the battery connects and de-solder them.

Notice the “B+” and “B-” on the silk screen of the PCBA. They are on the bottom edge of the board, one on each end.

De-solder the tabs and make sure to bend the battery tab so it no longer makes contact with the board.

Tab successfully de-soldered

STEP 4 — Remove the bad cell

Now that we have de-soldered both battery tabs we can star prying out the old battery, which is held to the frame using double sided tape. Use a spudger to carefully pry the battery away, taking caution not to crack any of the plastic housing. Once you have the battery out go ahead and tear out all of the tape as well, save the two red end-cap stickers for the new cell.

Battery removed, take your time.

STEP 5 — prepare the new cell

This can be a tricky step if you have never worked with cylindrical cells before. First we will sand both battery terminals so that the solder will adhere better. Then we will place a small dab of solder on each terminal, make sure to mount both tabs OFF-CENTER to the same side on both ends so they will line up with the housing when re-assembly occurs. You can choose to use some heat-shrink on the tabs if you wish. Then place the red end-caps back onto the cell using some double sided tape.

Sand both sides with fine grit paper, then place a small dab of solder on the terminal.
Solder your new tab onto the battery, you can make the lead extra long and trim it to the correct length after assembly. Insulate with heat-shrink or Kapton tape.
Replace the red insulating stickers and get ready to put your PAX 2 back together.

STEP 6 — Connect the new cell

Getting closer, if you made it this far you are a few steps away from the finish line. Put a piece of double sided tape down into the bottom of the battery well and fish your leads back through the plastic housing with a pair of tweezers (or tiny fingers). Trim the leads so that a few millimeters stick up past the PCBA to give us something to solder to the board.

Trim the lead so you have enough to solder to the board, we don’t want too much however; that could potentially create a short with the aluminum shell if there is too much. Solder down to the board using tweezers to make sure it lays as flat as possible. Repeat on the other end.

STEP 6 — Re-install the outer shell

Now we can slide the outer shell back onto the PAX 2 guts, make sure the mouthpiece area is pressed down properly and the O-ring near the heating chamber isn’t twisted. I inserted it from the bottom of the pack and applied steady pressure to slide the unit back together, MAKE SURE TO PUT YOUR MAGNETS BACK before finishing up. Test the charger and heating chamber door to ensure you replaced the magnets in the correct orientation. Once you verify that the magnets are all in and that it powers on go ahead and re-install the key that locks it in place.

Back together, notice the small steel clips inside the housing. Test the PAX and make sure it turns on, you might need to put it in the charger first.

STEP 7 — Cry a little

So hopefully you were smart and learned from my mistake when removing the key lock. If you did you can re-install the key and it should snap in place without a problem. If you however fractured your key like mine (Which is very possible since the material is VERY brittle) you will need to do one of 2 things:

  1. If there is enough of the key left you can re-install the remains, ensure that the pogo-pins line up, and then put some 5 minute epoxy where the fractured bits are missing to keep it in place. Obviously this will mean you cannot repair the unit again, but since this battery will last you another 2 years that might not be an issue.
  2. You can 3D print a replacement part, I’m going to post the file here once I get the prototypes tested to ensure they fit. Just 3D print the file, push the pogo-pins into it, and install just like the original key.

I hope this was helpful, if you would like to see more guides like this please comment below.

FILE COMING SOON

MEDIUM TEAM — It would be a great feature if you wanted to add the ability to draw on photos that you place in your articles, it would dramatically improve the clarity for tutorials like this.

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