I have a string of BigW led lights that is 30m long (600 leds). It currently runs on a 24v AC transformer. I am planning on cutting of the multi function controller and running the string on 27V DC through one of Alan's 2811DC15 controllers. My question is can I cut the string in half and turn it into two 15m strings (300 leds each). I understand that I have to work out where to cut it as the leds are in groups. What I want to know is do I have to add some extra resistance to each string to stop the current going up. My thinking is V=IR, I have halved the resistance so one of the other two variables has to change. Or doesn't it matter if current goes up. This now has got me thinking. Are leds voltage dependent or current dependent. If it is current then maybe their is the potential to drop the voltage instead of adding resistance. I realise this is not as practical as all the other strings on the controller will still need 27V to run. Now if I do need to add a resistor, is this as simple as measuring the resistance through the existing full length string (with multimeter) and then measuring the resistance through the shortened string and adding the required amount (with a resistor) to get back to the original total.