Headlight Turn On Delay

If you use the automatic headlights function, you'll find that the headlights come on as soon as you turn the key and stay on while the engine cranks. This isn't the best setup because the headlights are drawing power during the start, when all power available should go to the starter (on my wife's VW for example, the headlights turn off while cranking). This is especially bad if you have HID's, and one of my ballasts would sometimes cut off because of the drop in voltage while cranking. So simple solution is to delay the headlights from turning on by a few seconds. You can actually buy time delay relays, but if you already have a relay harness, it's much cheaper to add a delay timer.
You need to pick up an NE555 relay circuit such as this: https://www.ebay.com (commissions earned)
Note that the little relay in the board does not have enough amp rating to directly drive the headlights, so I use it to drive another relay (which I already had in my HID relay harness kit).
The board you get is just that - a board. I sliced up a harness adapter to make a plug and play unit like this:

The black female plug goes to the car's headlight power, the male yellow plug goes to the relay harness for the HID's.

Close up of the wiring:


Wrapped it all up tightly with electrical tape to finish and plugged in. Result is headlights turn on after a 6 second delay (adjustable using the little pot on the board).

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Cool. I was playing with this relay for a different reason.
So far on my car saw no reason for it, even with HID, but an interesting mod. Will add to the list.

@Vasy You're right, with good HID ballasts they should start despite the voltage drop. One of mine was borderline and would cut out maybe a third of the time. But regardless, I think it's good to have maximum power to the starter. Thinking cold winter starts.

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jetstreamblue said:

@Vasy You're right, with good HID ballasts they should start despite the voltage drop. One of mine was borderline and would cut out maybe a third of the time. But regardless, I think it's good to have maximum power to the starter. Thinking cold winter starts.

Click to expand...

Actually my friend wanted to add HID to his bike and did not do it for this exact reason.
I'll let him know about the delay he can add.

What is this "cold winter" start you speak of?

Did you weather proof the board in any way? Just having it exposed like that doesn't seem very durable, it's going to get contaminated with moisture or debris at some point underhood...

That's a cool, nice little mod though.

Your batteries don't have as much power in sub zero temperature, thus the term "Cold Cranking Amps" (CCA) for automotive batteries. I live in Canada, it gets cold sometimes.
The picture I took isn't the final product, just wanted to show the innards before wrapping it up.

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