Arduino Nano on 12v bettery in a running car? its ok?

Projects General Guidance
21

If you've got 5v 80mA relays, just add a series resistor (100 ohms?) to +12, and drive with a transistor - eg BC337. A 470 ohm base resistor would be fine .

Don't forget the flyback diode across the relay.

Allan

22

allanhurst:
If you've got 5v 80mA relays, just add a series resistor (100 ohms?) to +12, and drive with a transistor - eg BC337. A 470 ohm base resistor would be fine .
Don't forget the flyback diode across the relay.

If you look at OP's pictures, you see that he uses 4-relay modules.
The modules have all the supporting parts (transistors/resistors/diodes).
But one common VCC for the four relays, so the resistor dropper won't work here.
As said, he should have bought 12volt relay modules.
Leo..

23

Wawa:
If you look at OP's pictures, you see that he uses 4-relay modules.
The modules have all the supporting parts (transistors/resistors/diodes).
But one common VCC for the four relays, so the resistor dropper won't work here.
As said, he should have bought 12volt relay modules.
Leo..

Where can I but 12v relays to Arduino? I dont find it on Ebay

24

Knutarn:
I dont find it on Ebay

These tiny buck converters can be used for the Nano itself.
https://www.ebay.com/itm/DC-DC-Buck-Step-down-Regulator-Converter-4-2-40v-to-3V-3-3V-5V-9V-12V-24V-Module/112472493337?hash=item1a2fe20d19:g:8qUAAOSwbUtZppBa
Leo..

25

Thx :smiley:

26

But if you have a step down, 12v to 5 v, you can power the relays and the duino from that step down right? No need to power the relays via the arduino?

27

Bringamosa:
But if you have a step down, 12v to 5 v, you can power the relays and the duino from that step down right?
No need to power the relays via the arduino?

True.

28

Just make sure your step down can supply the amps, make sure you read the specs before you buy.

29

Wawa:
You might just be able to power ONE relay from the Nano's 5volt pin at that voltage, but not four.
Why do you think that.
If you need 5volt, and you have 9volt, you need to get rid of four volts.

but Nano has a regulator, and the 5V pin power depends only on the input of the regulator.

30

Juraj:
but Nano has a regulator, and the 5V pin power depends only on the input of the regulator.

A very tiny regulator.