With a minimum of parts, let’s create a powerful 45W charger/discharger for 18V Makita tool batteries:
- Output 45W USB PD at up to 20V - enough to power laptops and fast-charge just about anything.
- Charge your Makita tool battery from any USB power supply (including 12V car electric)
Overview
There are plenty of affordable Makita tool battery adapters that provide USB output. While they are nice-looking, they are of limited use.
- 5V Only: cheap electronic components provide only 5V USB output at 1.5A (7.5W).
- No Quick Charge: No support for quick charging protocols, USB PD, or voltage negotiation.
- cannot run devices that require more than 5V (i.e. laptops).
- No Charging: these adapters are one-way and can only output power. You cannot use them to charge your Makita battery.
Modern IP2369 to the Rescue
Modern power management ICs like the IP2369…
- support various battery configurations and chemistries, including the 5S LiIon configuration used by 18V Makita tool batteries. So they are perfectly suited for Makita tool batteries.
- are available on very affordable breakout boards with a small footprint, like the Nouying/DYKB. Breakout boards are flat, have a small foot print (no clumsy coils or capacitors), and are very affordable (€3.80/piece is what I paid).
- work as a buck and boost converter and support all USB PD voltages (including 20V), regardless of battery voltage
Universal Makita Battery Charger
Since IP2360 works both as a discharger and a charger, you get a universal Makita battery charger completely for free: the USB-C port on the breakout board is bidirectional:
- Discharge: full USB PD at a max 45W output
- Charge: full USB PD at up to 45W charging
You can now charge Makita batteries anywhere, a simple USB power supply is all you need.
If you want to charge your Makita batteries from 12V car electric or any other fixed DC voltage, get a simple USB PD converter board.
The Plan
Here are the steps to creating such a device:
- Configure and test the Nouying/DYKB breakout board
- 3D-print a housing that safely slides onto a Makita tool battery
Configuring IP2369 Board
The IP2369 chip can work with a range of different battery configurations and chemistries, so the first crucial step is to configure it for the Makita tool battery.
Such batteries use a 5S LiIon configuration. On the Nouying/DYKB board that I am using, the configuration is done via solder bridges.
Typically, these boards are pre-configured for 4S LiIon. Remove the resistor for 4S, and put a solder blob onto the solder bridge for 5S.
- Careful:
I did not heat up the SMB resistor well enough, so when I removed it, part of the traces were ripped off as well (as you can see in below picture). That’s not an issue if you do not plan to configure the board for 4S later again, but keep in mind that the traces are sensitive. - One Connection Only:
Make sure that you use only one solder bridge at any time. So when you put the blob on the 5S solder bridge, make sure the 4S pads are no longer connected. All solder bridges together form a resistor, and with more than one bridge closed, the total resistance is lower than expected, leading to a lower-S configuration. - Must Configure! Do not use boards with the default 4S configuration. While this would work with Makita batteries and in fact produce USB output, you would not be able to charge the battery. At 4S, even an empty Makita battery voltage would be above the 4S cutoff voltage.
Next, solder two sufficiently thick wires to the + and - pads. These wires later connect to the Makita battery. They must be thick enough to sustain 3.5A, so 18 AWG or lower would be appropriate.
Designing Housing
You can use any of the Makita housing concepts discussed earlier. I chose to design my own 3D-printed housing with external contact plates in snap-in design.
Makita Battery Docker
I designed my own Makita battery docker that safely slides onto the battery:
A standard contact plate can simply be “snapped into” it:
You can download the stl file here.
PCB Mounting Plate
The Nouying/DYKB is mounted on a separate mounting plate:
The plate provides a push button, a hole for the USB-C connector, and openings for the charging LEDs. Simply insert the PCB with the backside on top, then secure the PCB with three M2 screws.
It is recommended to print this part with PETG filament to ensure the material is flexible enough for the push button cover. With more rigid materials like PLA, the button may break off.
You can download the stl file here.
Make sure the push button cover is freely movable. If there are printing residues preventing it from moving on gentle push, carefully remove these.
The mounting plate slides into the battery dock component printed earlier and applies pressure to the snapped in contact plate, providing additional fixation to it.
Heat Sink
The PCB backside shows a silvery designated area. You may want to add an extra heat sink to this area of the back side of the PCB.
During normal operations under load, the PCB can reach temperatures of 60-70C.
Connecting and Testing
Connect the wires from the PCB to the battery.
IMPORTANT: pay attention to the polarities! If you follow my design, then the battery + pole is opposite of the PCB + pad.
In my prototype design, I chose to use crimp connectors. This is not a good idea for production because the connectors are too long and need to be bended. Also, the connection may become loose in rugged environments.
For production adapters I strongly recommend you simply solder the wires to the contact plate pins.
Performing Test
Once the board is connected to the contact plate pins, and you slide the adapter onto a Makita battery, the adapter is ready for a test.
Testing LEDs
The PCB LEDs turn on when you…
- …connect a large-enough load
- …press the push button once
The lights should indicate the current Makita battery state-of-charge.
The PCB LEDs turn off when you…
- …disconnect the load (after a few seconds)
- …double-press the push button
Testing Output
If you own a USB protocol tester, the adapter should support all common USB protocol standards (including USB PD 3.0 at 20V/47.5W).
Testing Charger
When you connect a USB power supply to the adapter, the adapter should start charging the Makita battery: the built-in LEDs lighten up, one of the LEDs is blinking, and the number of lit LEDs indicates charging process.
Add a USB tester to the line if you want to verify the charging power. With modern USB PD power supplies, the adapter uses 20V and charges with up to 45W (depending on battery state-of-charge, the ratings of the USB cables you use, and the USB power supply you use).
Adapter Cover
As a final part, a cover closes the housing and applies pressure to the PCB holder which in turn additionally secures the contact plate.
You can download the stl file here.
While you can add heat-set inserts, this is generally not necessary. The 3D print comes with threaded holes for M3 screws, so you can directly insert M3 screws.
Slow Website?
This website is very fast, and pages should appear instantly. If this site is slow for you, then your routing may be messed up, and this issue does not only affect done.land, but potentially a few other websites and downloads as well. Here are simple steps to speed up your Internet experience and fix issues with slow websites and downloads..
Comments
Please do leave comments below. I am using utteran.ce, an open-source and ad-free light-weight commenting system.
Here is how your comments are stored
Whenever you leave a comment, a new github issue is created on your behalf.
-
All comments become trackable issues in the Github Issues section, and I (and you) can follow up on them.
-
There is no third-party provider, no disrupting ads, and everything remains transparent inside github.
Github Users Yes, Spammers No
To keep spammers out and comments attributable, all you do is log in using your (free) github account and grant utteranc.es the permission to submit issues on your behalf.
If you don’t have a github account yet, go get yourself one - it’s free and simple.
If for any reason you do not feel comfortable with letting the commenting system submit issues for you, then visit Github Issues directly, i.e. by clicking the red button Submit Issue at the bottom of each page, and submit your issue manually. You control everything.
Discussions
For chit-chat and quick questions, feel free to visit and participate in Discussions. They work much like classic forums or bulletin boards. Just keep in mind: your valued input isn’t equally well trackable there.
(content created Oct 10, 2025)