Thursday, 3 December 2015

Another Failure

Well another of those bright ideas hasn’t worked out.  Like Edison I’m not disillusioned and will persevere. This time it was the Christmas lights.  I suddenly had a bright idea.  What if I could convert them to operate off the boat 12V system?  They have a transformer and provided the required voltage was 12V or higher I had a spare DC to DC converter.  The Christmas lights box was dragged from long term storage and I checked the transformer to check the secondary voltage.


An input voltage of 240V and an output of 24V.  Good news, I could use the spare DC to DC converter to raise the boat 12V to 24V and run the lights off the domestic battery bank.

xmas lights

In the above photo you can see the original transformer, the DC to DC converter, the lights and the 12V cigarette socket.  I cut the cable connecting the lights to the transformer and wired them to the converter adding the cigarette plug to the primary side.


The cigarette plug was connected to the boat 12V system and I adjusted the output voltage on the DC to DC converter to 24V.


There’s nothing wrong with the wiring and the output voltage is correct.  My guess is the transformer 24V output is AC and the boat is DC.  I’ve reconnected the transformer and the lights are back to working off the 240V system.


Jenny and Robin said...

Tom looking at the top picture after the sec voltage of 24v there is a wavey line, does this not denote AC current?


Tom and Jan said...


I had to use a magnifying glass to read the numbers. Yes, I think it's an AC output!

Davidss said...

I hesitate to say this, but did you try reversing the potential of the 24vDC feed into the lights?

Tom and Jan said...

Yes I did that David!

Sean Wiltshire said...

Just put a cheap bridge rec inline?

Tom and Jan said...

Sean I don't think a bridge rectifier will convert DC to AC?