help with 12 V relay for controlling a car head light.

Hi everyone!

Great forum.

I hope anyone of you could spare some time helping me with som unclear stuff about working with relays for my latest experiment.

My idea is to control a cars head light running on 12V with a draw of around 3A with a relay. The relay would be controlled with a microcontroller type arduino.
I will use a digital output on the arduino supplying 5V.

What is still unclear for me is how to calculate which relay to use.

If the relay is rated 12V for controlling and with a max of 10A at 120 -230V

Would this relay be able to pass 3A at 12V?.

I understand how to trigger the relay the only thing where im totally lost is how the be sure that the relay may handle 3A at only 12V:

would this work in my setup or is it only able to handle 10A at 120-230V?

SparkFun Electronics - Relay SPDT Sealed

Hope i made my self clear.

Best regards Niklas

Use a proper car relay, they are designed for high current DC, mains relays are intended mainly for AC - and derate drastically for DC.

3A also sounds rather puny for a car hedlight?.

Hi Nigel!

Thanks for responding!

And clearing this out for me. I was heading towards the same conclusion so thanks again for confirming it to me

I was looking at these relays. Will any of these will do the job?

Board Relays from AEI Components

Best regards Niklas

Ps. What does puny mean? ds: