Troubleshooting Milwaukee M18 Battery Not Powering Trailer Interior Lights with Adapter

Updated 11/30/2023 | Published 11/29/2023

Question:

Good afternoon, I am attempting to build a convenient method to power 12V interior trailer lights using a Milwaukee M18 battery. This is simply a convenience connection for when I need to do something quick inside the trailer when it is dark out. Trailer is a 2023 Lightning with factory interior lights, electric brakes, and 7-way factory Arctic Blue trailer plug. My intent was to use output from the inverter to a vehicle side 7-way conenctor - so I can just connect to trailer and flip on the lights. The M18 is connected to a fuse-protected inverter to step down/maintain 12V output and I have validated that output is 12V. I have run the positive output 12V + to pin 4 battery/aux 12V on the connector, and the negative output 12 - to pin 1 ground Of course, it doesnt work. Is there something I am missing/misunderstanding ?

asked by: James F

Expert Reply:

It sounds like you've wired your converter/adapter to a vehicle-side 7-Way socket like the Pollak # PK12-707E so you can just plug your Lightening trailer 7-Way into this to power the interior lights.

If this is the case then your power should be connected to the pin in the 1 o'clock position and your ground in the 7 o'clock position when you're looking at the socket directly (see attached photo). Please note that wire coloring doesn't really matter, just as long as the functions match.

If your setup is wired differently then that would explain why your lights aren't working, but if you've matched functions then the only thing I can think of is that your lights are drawing more power than the converter/adapter can output.

expert reply by: Jon G