I need to control a 12V water pump (like this) to a Raspberry PI zero W.

Can I control it from the 5V power out port using a this relay? I heard that when switching off the relay there could be current coming back damaging my board, do I need to put some components between Raspberry and Realy to prevent it?


  • 2
    \$\begingroup\$ 12 V or 5 V? You meant 5 W in the question, didn't you? \$\endgroup\$ – Bence Kaulics Aug 16 '17 at 11:14
  • \$\begingroup\$ @BenceKaulics Nice catch. I've assumed the following setting: pump powered from independent 12V power supply; relay module powered from 5V from RPi. Signal from 3.3V RPi output. But it would be nice if OP could clarify his setting. \$\endgroup\$ – Mark Aug 16 '17 at 11:19
  • \$\begingroup\$ I meant 12 V, I edited it. \$\endgroup\$ – Gusepo Aug 16 '17 at 11:22
  • \$\begingroup\$ I have a 12 V power source for the pump, my next step (after making the pump work) will be to power RPi from the same source converting it at 5.5V I thought I can connect the relay to the 5V RPi port, but I guess I cannot control its state from it, is that right? \$\endgroup\$ – Gusepo Aug 16 '17 at 11:24
  • \$\begingroup\$ @Gusepo please provide drawing how would you like to connect everything. \$\endgroup\$ – Mark Aug 16 '17 at 11:46

The relay board you have linked to has optocoupler, so your Raspberry Pi should be safe. I'm using similar design myself and it works good. What you should be aware of is the pump generating noise which could appear on long, unshielded inputs (eg. switch).

  • \$\begingroup\$ Thanks @mark, can you explain what's the pump noise and how to solve it? I haven't got much experience with electrical components. \$\endgroup\$ – Gusepo Aug 16 '17 at 11:26
  • \$\begingroup\$ @Gusepo unfortunatelly this is quite a complex task. Please see electronics.stackexchange.com/questions/4640/… . I experienced this with much more powerful pump (1.5kW) made by Grundfos, so decent brand, not China made. And it still caused my inputs to trigger when it turned on or off. There is no simple way to fix this. \$\endgroup\$ – Mark Aug 16 '17 at 11:45

The description fpr your linked relais module says

Segnale di controllo TTL 5V-12V

so the 3.3V from your RPi might not be sufficient to drive the opto-coupler. Without having a proper datasheet it's difficult to say...

But for you initial question: from the image above it looks like there already is a snubber for the coil and your RPi is save.


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