Getting rid of noise of car battery/alternator

[Luciano]

Hi,

All depends from where you get the 13.8V.
Ignition key switch? Car battery direct?
Are you using the brown-out detection of the microcontroller?
How much current is drawn by your circuit?

Headlights are not a problem unless your car is like a Christmas tree. (Rooflights).
See picture below. (Starter/battery voltage).

Best regards,

Luciano


(Click to enlarge the picture).

[passion1]

Luciano

Thank you for the graph!
I will be using the ignition key switch to activate the circuit.
My circuit will be driving a load of up to 30A via a mosfet.
In this case, can/should I still add the 4700uf to your circuit as well?

[Luciano]

Hi,

How much current is drawn by your board when the mosfet is not activated?
Are you using the brown-out detection of the microcontroller?

Best regards,

Luciano

[passion1]

Luciano

I have not measured it, but it is very little current.
I am not using the brown out detection.

[Luciano]

Hi,

Build a prototype and try it out.
Enable the brown-out detection.

Best regards,

Luciano

[passion1]

Luciano

Thank you for the advice!

[Darrenmac]

If you are still having trouble ty adding a choke in series with the incomming supply as well as capacitor on input and output of reg. Cars can be so noisey!