TS100 Power Adapter for Makita Batteries

DISCLAIMER: All you do in life is at your own risk. So... You know... Stay safe.

After getting my TS100 soldering iron, I soon discovered that this was the perfect every-day-carry soldering iron.

One of its major advantages is its very flexible requirement in regards to its power supply.

Therefor instead of carrying a large power supply for the TS100 I instead decided to make a bunch of small light-weight adapters so that I could use the soldering iron with whatever power source I have available: DC adapter, labtop power supply and drone batteries (XT60 3S+)

But since I have a bunch of high capacity Makita batteries, I wanted to make a simple XT60 snap-on adapter that can interface with this silicone power cable for the TS100 which has an XT60 plug.

There are multiple properties of these batteries that makes them particularly suited for these kind of custom uses:

• They have build in over discharge protection, which is a must, to make sure that you don't just drain the battery and thereby permanently damaging it.
• Its relatively high voltage and capacity
• Additional protection features
• Easy to interface with using either the 644808 8 replacement part or by making you own e.g.: Makita 18v battery terminal connector (I scavenge mine from old broken tools)
• Build in battery charge level indicator

NB: The Makita batteries themselves do not cut power when discharged, so you will need to handle that.
I have made a Instructable showing how this can be done here: Making a Over Discharge Protection for Makita Batteries

Tools

• Access to a 3D printer (Download prints from here: https://www.prusaprinters.org)
• Soldering iron
• Crimping tool

Supplies

• 1 x Makita 644808 8 battery connector
• 1 x Male XT60 plug
• 2 x Right angled 6.6mm cable terminals
• 1 x 2.8mm cable terminal
• 1 x IRFP3006 MOSFET
• 1 x TO-247 Heatsink
• 1 x M3 TO-247 plastic insulator
• 1 x TO-247 Silicone pad
• 4 x M4 nuts
• 4 x M4 x 28mm countersunk screw
• 1 x M3 square nut
• 1 x M3 x 8mm screw
• Some shrink tubing
• Miscellaneous wire
• Epoxy
• a Makita battery, One of the STAR protection variety

Before I started to model the adapter, I wanted to define the requirements/design goals for the project to guide me through the modelling process.

Design Requirements:

• Needed to accept the Makita 644808 8 part
• Output to an XT60 plug
• Be as small as practically possible
• Be printable on an FFF 3D printer
• Easy to assemble

I used Fusion 360 for modelling and started by making the 644808 8 part (terminal connector) so that I could use this to validate the actual adapter up against.

There is also another terminal connector: 643852 2 (The yellow) connector, which is slightly different from the black connector. I modified the base adapter so that it accepts the 643852 2 but I haven't tested it more then making sure that it fits.
So if you use it please share your results in the comments.

Afterwards I started designing the adapter base using a cordless Makita drill as a reference. This was then simplified and had some of the features smoothed out to make it more universally usable and easier to print. This is also why I attempted to restrict the model to be within the bounds of the battery itself and having it no larger then absolutely necessary to facilitate this. The key to the base model was that it needed to have a ridged connection to the battery, so that it locks in tight.

I designed the adapter base so that it would be easy to adapt into future project without having to heavily modify it, but instead could just expand upon it.

The base adapter took me around 5 tries to get right, fine-tuning the interface with the battery so that it was easy to connect and disconnect but without rattling when attached.
Once the base adapter had the right "fit" with the battery, I needed to add a way for the lid to connect to it. I made two interchangeable versions, one which uses a nut that is added during printed and another the uses thread inserts.

The version I used for mine was the one with the captive nut.

To make sure that the terminal connector is securely seated in the adapter I next designed a small terminal lock, which keeps the terminal connector pressed in place once the parts are screwed together.
The lock is simply an outline of the terminal connector which then sandwiches the terminal connector in place.

The final part that I needed was the adapter lid.

I had originally, before I learned that the Makita batteries themselves didn't cut power, made a adapter lid design that was much smaller and just made the 3 third pin available through a 3.5mm audio jack.
I will include the model for it, but cannot recommend using it unless you have something that uses the audio jack to switch off the power. Not doing so could break your battery.

The adapter lid has three key features which I designed around:

1. It needed to have a hole were the XT60 plug could be seated.
2. Enough room and mount point for the MOSFET, heatsink and headroom for wiring.
3. Four screw holes that line up with the nuts/inserts in the base adapter.

I started the assembly by preparing all the different parts, starting by printing the three pieces.

All the parts can be found here: https://www.prusaprinters.org/prints/67118-ts100-power-adapter-for-makita-batteries

The adapter base and the connector lock I printed in a black PETG and the adapter lid in a orange PETG

Depending on use, the MOSFET could get quite hot. I would therefor recommend printing the parts in something more heat resistant then PLA, at least PETG but better yet ASA or ABS since the model doesn't have any vents for cooling.
I am not going to be pulling a lot of power through mine, so PETG is fine for my use case.

There are two important things to remember when printing.

1. The adapter base needs to be printed with supports everywhere as the "arms" that connect with the battery is printed mid air.
2. When printing the adapter lid, you need to pause the print at around 5.2 mm to add the locking nuts.

The next part is for the over-discharge protection, THIS IS VERY IMPORTANT, I am however not going to go into much detail with it here as I made another Instructable which goes into more detail: Making a Over Discharge Protection for Makita Batteries

I started by adding all the crimp connectors to the wires, and pre-soldered the black and yellow wire to the MOSFET and the red and black wire to the XT60 plug.

It is a pain to crimp and solder the parts once they are installed, so doing these preparations worth it.

The wires I used was scavenged from an old ATX power supply, which means that they aren't as thick as I would have liked, but enough for my use case. As for getting the right length of wire, I simply pressed the parts in place and used that to measure it out directly.

When choosing the wire thickness, make sure it is thick enough to match your use case.

Once I had confirmed that the protection circuit worked as intended, I glued the XT60 plug in place using a two part epoxy.
After the glue had dried the only thing left was to mount the rest of the components.
Starting with the MOSFET, insulator, silicon pad, heatsink, all screwed together using a M3 screw and a M3 square nut inserted into the mount column in the adapter lid.

Then the adapter itself could be assembled.
First step was connecting the crimp connectors to the terminal connector. It is important that the terminal lock is put over the wires IN THE CORRECT ORIENTATION, before connecting the crimp connectors.
Then I simply screwed in the four M4 screws in the adapter lid to the base and did a final test to confirm that it still worked.

If you have any questions, constructive feedback or comments, fell free to post them, and I will do my best to answer them.