LED polarity question

Discussion in 'General Electronics Chat' started by Mark48, May 2, 2013.

  1. Mark48

    Thread Starter New Member

    May 2, 2013
    I use LED lighting at a cabin with a 12V battery. I bought a Torchstar MR16 LED (Amazon) that has 4 leds. It just has 2 prongs to plug in and there is no way to tell if one is + and one -. When I hook it up to a small 12V battery (drill driver battery) it works on either polarity. Do I need to worry how I hook it up? I thought LEDs were supposed to only work if hooked up correctly polarity-wise. Thanks
  2. paulktreg

    Distinguished Member

    Jun 2, 2008
    The inclusion of a bridge rectifier would prevent damage caused by wrongly inserted batteries?
    #12 likes this.
  3. GopherT

    AAC Fanatic!

    Nov 23, 2012
    These are "dimmable" bulbs and intended to operate on 12V AC or DC sources. Therefore, you can plug them in either way. They contain internal circuit to sense dimming based on input voltage. This particular model also will not flicker when powered by mains AC because of the internal AC to DC converter and dimmer control.
  4. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    I'm not sure about the "dimmable" part but every 12V LED bulb I've looked at recently has a bridge rectifier so they work equally well for AC or DC. So of course for DC they work with either polarity.

    I've seen some with constant current limiters, some with just resistors. Constant current bulbs are not very dimmable.