Milwaukee M18 or Makita 18v Regulated DC Power Supply

I needed a regulated DC power supply for automotive and power sports troubleshooting and I got sick of using 12v and 5v batteries to do the job. I drew up a M18 compatible power supply that uses an inexpensive dc to dc buck boost converter power supply module to get the job done. I also added some low voltage protection since the Milwaukee batteries lack that feature. I've included the CAD files if needed for tweaks. Unfortunately i'm limited to what fusion will export.

Wiring is straight forward, glue in some spade terminals to the m18 housing, hot glue works fine, positive goes first to a 10amp fuse, then the switch and finally to the low voltage board, from the low voltage board wire output to the power supply module. From power supply module to the terminals. When the low voltage board cuts off the power switch will stay lit to remind you to turn it off. You can still over discharge the batteries if you leave it on after use.

I set the low voltage board to kill power at 16.8 volts. Its a very safe range for the lipo cells and doesn't irritate the m18 batteries

For Makita 18v, there are 4 stl's the power supply top, midplate, battery mount and cap. The Makita unit uses a terminal block from Makita to connect to the battery. It fits in the slot on the batty mount. I advice using some glue to keep it in place, but it is a snug fit. I have printed and tested, but I don't not have one to photograph since they were made from a friend.

Parts list:

I used a 30amp rated switch for my main switch but anything will work.

16g wire and terminals

Power Supply Module - https://www.aliexpress.com/item/4000424191711.html?spm=a2g0s.9042311.0.0.1e184c4dNntEnN

Low voltage cut off - https://www.amazon.com/gp/product/B093V5VG2C/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1

Terminals - https://www.amazon.com/gp/product/B07CQSCK9J/ref=ppx_yo_dt_b_asin_title_o06_s00?ie=UTF8&psc=1

Fuse Holder - https://www.aliexpress.com/item/32799694132.html?spm=a2g0s.9042311.0.0.1e184c4dNntEnN

Makita Only additional part-

Makita part #643852-2 terminal block

misc screws, nuts to attach the base to the top. 

Print Settings

Printer Brand:

Prusa

Printer: 

I3 MK3S

Rafts:

No

Supports: 

Yes

Resolution:

0.2

Infill: 

15

Filament: prusamemt PETG gray

Notes:

There will be a lot of work required post print. Remove all supports, clean out holes, and some file fitting may be needed depending on how calibrated your printer is. I've made 4 of these and they take about 45 mins to clean up.

You will need supports on both items.

Category: Tools