Basic question 12v

Hi, I have basic knowlege in electicity. I bought a adaptor that clips on a 18v milwakee tool battery that as a port that delivers 12v. The thing is that if i test it , I get 4.4v , but if i touch both polarity it jumps ton 12,3v ,I can let go , it stays at 12.3v. Same with a led strip, plug, nothing, but when I touch both polarity it light up and stay light even when im not touching anything. Either there is something I dont know ( very possible) or the adaptor is not working correctly. I dont really know where to get help, everything is closed where i live. Sorry english is not my first language, hope im clear in my description. Thanks Pascal

by eltarkus
January 13, 2021

I will take a guess and say that there is some smarts built into the adapter that turns on full voltage only after it gets a bit of current at 4.4v. Only guessing

by Foxx
January 15, 2021

There is something not really making sense to me. You say that "but when I touch both polarities", that implies that, before, you didn't ? Then, how do you test 4.4v just touching ... ONE ... polarity (one pole, I assume)? A VOLTAGE is ALWAYS a difference of electrical tension between two points. If you use a voltmeter, one probe on a pole an the other probe hanging in air, you are measuring who knows what. Note that maybe it is just me who does not understand what is evident, though.

by vanderghast
January 16, 2021

No Answers

No answers yet. Contribute your answer below!

Your Answer

You must log in or create an account (free!) to answer a question.

Log in Create an account

Go Ad-Free. Activate your CircuitLab membership. No more ads. Save unlimited circuits. Run unlimited simulations.

Search Questions & Answers

Ask a Question

Anyone can ask a question.

Did you already search (see above) to see if a similar question has already been answered? If you can't find the answer, you may ask a question.

About This Site

CircuitLab's Q&A site is a FREE questions and answers forum for electronics and electrical engineering students, hobbyists, and professionals.

We encourage you to use our built-in schematic & simulation software to add more detail to your questions and answers.

Acceptable Questions:

  • Concept or theory questions
  • Practical engineering questions
  • “Homework” questions
  • Software/hardware intersection
  • Best practices
  • Design choices & component selection
  • Troubleshooting

Unacceptable Questions:

  • Non-English language content
  • Non-question discussion
  • Non-electronics questions
  • Vendor-specific topics
  • Pure software questions
  • CircuitLab software support

Please respect that there are both seasoned experts and total newbies here: please be nice, be constructive, and be specific!

About CircuitLab

CircuitLab is an in-browser schematic capture and circuit simulation software tool to help you rapidly design and analyze analog and digital electronics systems.