connecting 18V battery pack to buck converter

Hello

I have an 18V battery pack from an Old dewalt drill. It puts out 20V DC

When I connect using test leads to battery and to DC buck converter Buck converter

the test lead wire gets hot and burn. They act like a fuse.

What am I doing wrong?

Thanks

What is the spec forthe buck converter?
Polarity?

I have connected a 10w cob led at output and test lead still burn. There is no led lighting up on the buck converter. I am assuming the buck converter is dead. Could this have caused because of first did not have load? or perhaps was connected with inverse polarity in the past?

Polarity is clearly indicated on buck converter input output and checked the polarity on battery pack

Bingo. When connecting test lead incorrectly to test multimeter things falls apart pretty quickly. Thanks for your assistance. :slight_smile: