Milwaukee Tools M18 Li-Ion battery adapter for Pinecil/TS100 soldering iron

Design Intent

This adapter includes under-voltage protection. Rechargeable lithium ion batteries can be severely damaged or completely destroyed if allowed to discharge too low. Milwaukee tools have internal electronics that signal the battery to disconnect from the tool when the charge falls below a given voltage. It is very easy to ruin these expensive batteries if used to power non-Milwaukee accessories without any protection. This adapter allows you to use Milwaukee batteries to safely power a Pinecil/TS100 soldering iron but it can be used to power any accessory that can run on 18V DC.

Credits and modifications

The design of this adapter, although a complete remodelling, was inspired by Justin's Power Wheels adapter.

• Redesigned the spade contact block to make it easier to assemble.
•  Added + and - symbols next to the spade terminal block on the top part of the adapter.
• Enlarged the upper part of the adapter and added mounting holes for a power switch and a fuse holder for over-current protection.
• Enlarged the lower part of the adapter to mount an over-discharge protection circuit and output connectors for the soldering iron power cord.
• Created 2 alternate versions of the lower part: one with 2 holes for banana receptacles and one with a rectangular cutout for Anderson Powerpole connectors (BOM and assembly instructions below are for Anderson connectors as it is the best option IMHO).
• Added an optional receptacle for the soldering iron.

Filament and settings used for this project

• Spectrum Smart ABS - Dragon Red
• Polymaker Polylite ABS - Black
• 0.4mm nozzle, 0.2mm layer height, 20% infill

Bill Of Materials

You will need additional items to assemble this adapter. Please note that the source links are provided for reference only. They might not be the best possible source for you.

Hardware

Electronics

Assembly

It is highly recommended to assemble the adapter in the specific sequence illustrated below.

Preparation

• Remove the fuse holder mounting hole supports from the upper part of the adapter by pushing it out with a 2.5mm hex driver/Allen wrench.

• Remove the Anderson Powerpole connector slot support with a pair of pliers. Gently rock the tab back and forth until it gives and pull straight up. The connector pair will be held in place by the tongues on either side of the slot.

• Insert all 16 M3 heat sets in the locations shown below.

Electronic components and wiring

• Insert the fuse holder into its opening and fasten it with 2 M3x8 BHCS + 2 nylocks.

• Insert the rocker switch. Make sure to align the ridge on the side of the switch body with the small slot in the mounting hole. Push it in until it snaps in place.

• Take 4 16AWG ferrules and push out the black insulation with pliers as shown below (A Knipex pliers wrench is ideal for this task).

• Remove the blue insulation off the 2 spade terminals. Solder the first to one end of the red 50mm wire and the second to one end of the black 75mm wire

NOTE:

The wires MUST be soldered to the spade terminals and NOT crimped. The reason for this is that the barrel of of the terminals will not fit in the contact block of the adapter if they are crimped. Care must also be taken to not overfill the barrel with solder as this could also make the terminals difficult to fit in the contact block. This step is critical so take your time.

• Crimp the 4 stripped ferrules on the designated wires and cut about 2-3mm off the end of each the ferrules. This will allow them to be inserted fully into the PCB terminal blocks.

1. One ferrule to the red 70mm wire
2. One ferrule to the red 75mm wire
3. One ferrule to the black 75mm wire (the one with a spade connector at the other end)
4. One ferrule to the black 80mm wire

• Crimp 2 Powerpole 15A terminals to their designated wires:

1. One terminal to the red 40mm wire
2. One terminal to the black 80mm wire (the one with a ferrule at the other end)

• The 6 wires are now ready to connect to the circuitry and should look as shown below:

• Solder the red wires to the switch and fuse holder leads as shown below. Note which wire goes to which lead.

• Insert the ferrule side of the black wires into the PCB terminal blocks as shown below and make sure the screws are tight.

• Place the spade terminals into the contact block as shown below and make sure they are straight and well seated into their slots. Put the contact block cover in place (mind the slot orientation) and make sure everything is properly seated before fastening it with 2 M3x6 SCHS.

• Fasten the red wire from the switch to the Vin+ contact and the red wire to the fuse holder to the Vout+ contact on the PCB. Pay attention to which wire is routed above or below which other. This will make mounting the board into its enclosure much easier.

• Slide the individual Powerpole housings together exactly as shown below. The position of the dovetail male and female slots is crucial to the proper alignment of the assembled connector.

• Weave the bottom part of the adapter around the wires and the board so it's close to its assembled position but don't fasten any screws yet.
• Insert the contacts into the housings with the convex tips facing upwards as show below. Next, push the connector pair into the slot of the bottom part of the adapter.

• Temporarily assemble the upper and lower parts of the adapter with 4 M3x16 SHCS in the corner holes. This will make the next assembly steps easier.

• Carefully bend the wires going to the PCB's terminal blocks and push the board down into the case. Fasten it with 4 M3 x 6 BHCS.

• Remove the fuse holder cap and insert the fuse. Put the cap back in place.

Calibration of the protection circuit

Slide the adapter into a fully charged battery and turn the power switch on. Using a multimeter, measure the voltage on the Vin screw terminals. If the voltage reading on the PCB's LED display is the same as the reading on your multimeter (or within +/- 0.1V), you can move on to the next step. Otherwise you'll have to calibrate it.

To calibrate the LED display, press and hold the + button on the left for 2 seconds, then release it. The display digits will blink. Immediately use the + and - buttons to adjust the displayed voltage until it is equal (or close as you can get it) to the measured voltage.

It should be noted that the display will stop blinking if you do not push any buttons within 2 seconds. This is true for all 4 modes: display calibration, disconnect voltage, hysteresis and reconnect time delay. Only 3 of the 4 modes are used here.

Setting the disconnect voltage level

To set the disconnect voltage, double press the + button. The decimal dot of the LED will blink. Immediately use the + and - buttons to raise or lower the value of the cutoff voltage. I set mine to 14V. YMMV depending on the state of your battery. Higher is safer but the trade-off is less operating time between charges.

Setting the reconnect voltage level

The difference in voltage between the disconnect voltage and the reconnect voltage is called hysteresis. Since I set the disconnect voltage to 14V in this particular example, setting the hysteresis to 2V means that the circuit will only reconnect the battery to the load once it's recharged to a level of 16V or more.

To set the hysteresis, double press the - button. The decimal dot of the LED will blink. Immediately use the + and - buttons to raise or lower the value. Any value between 1V and 2V is OK. I set mine to 2V.

Here's a video showing the entire calibration procedure:

Once you're done, turn off the power switch and remove the adapter from the battery.

Finishing the assembly

• Close the electronics compartment using the cover and 4 M3x6 SHCS.

• Remove the 2 front M3x16 SHCS from the upper half of the adapter.

• Fasten the soldering iron stand to the upper and lower parts using 4 M3x25 SHCS.

Slide the 70mm aluminum tube into the 70mm silicone tube and insert into the soldering iron stand opening. The silicone tube insulates the hot iron tip from the stand.

Soldering iron power cord

• Slide the red and black Powerpole housings together so that they mate properly to the connector on the battery adapter. The left and right position of the red and black housings should be reversed in relation to the ones on the adapter.

• Crimp the Powerpole terminals in the proper orientation to the red and black wires of the DC power cable. The contact “bumps” should be facing upward as shown in the above picture. Insert the Powerpole terminals in their housings.

NOTE:

Some Powerpole connector kits come with PVC covers for 2 contact connectors such as this one. If you don't have those, you can use some ½" heat shrink tubing instead to make a shroud as shown above.

Updates

1. Modified the top part's spade terminal block and the mating spade terminal block cover to improve the fit of the spade terminals in the slots.
2. Deepened the countersink portion of the bottom cover holes so the heads of the socket cap screws are completely recessed.
3. The length of the silicone and aluminum tubes for the iron stand was previously stated as 40mm. This was a mistake, the actual length should be 70mm. Sorry about that.