Electrical – How to determine the correct 12v relay


I have a two filament turn signal/parking lamp on my car (3157A bulb).
When the parking lights are on, the turn signal is not very noticeable, so I am trying to get the parking filament to turn off when turn signal is on.
I understand I can achieve this by using a normally closed 12V relay.
The 3157 bulb draws about 0.6amps for the parking lamp filament.
I have two questions:
1) Since this is a very low current circuit would it be ok to use a generic automotive relay ie: bosch 30 or 40amp? Or should I use a smaller rated like 10amp or 5amp PC relay like this one https://www.e-sonic.com/ds/505330.pdf?p=45319483
2)Do I need to install a flyback diode in parallel with the coil to prevent damage, if so what size does it need to be?

Thanks in advance.

Best Answer

It's okay if you use a car relay as long as it handles more current than your load, you'll have the advantage of having terminals to easily connect all the wiring but it will cost you some more current when the relay is on, car relays can draw up to 2amps from your battery, so that is something you should keep in mind considering your load only draws 600mA.

Using pcb relays will work as well and draw much less current, but they're hard to connect if they're not soldered on a PCB