[Piwoslaw]

Thanks for the reply, Jacob. Yes, in my neck of the woods headlight bulbs are also 55W. Here is what I was thinking about:



I am concerned about a power drain to the headlight, so maybe the series version is better?



I read recently that the diode is needed to suppress any bad things that may happen to the ciruit after switching the power off, but I've no idea what kind of diode to use.

I understand that a relay labeled as 30A/12V means that that is the current and voltage for the coil, not the contacts, right? Since 55W is about 4.5A @ 12V, then wouldn't a 5A relay be enough? Maybe 10A to be safe? Will the relay in series dim the bulb noticeably?

So many questions...