I am new to all this and I am sure this is a very basic question, but wanted to ask before I fry some pumps up. enter image description here

I have a relay, which is controlled by my raspberry pi, switching the pump on and off. However, I would like the pump to pump 3 times more, can I just connect the other two in a serial fashion? So I do not want to control them individually, but basically treat them as one.

The pumps are 3.6w, 12V DC and pull roughly 0.4Amps. Power adapter outputs 12, 2 A. Max power is 24W.

Here are the links to the components:

Power: https://www.amazon.de/gp/product/B019IHQND8/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1

Pump: https://www.amazon.de/gp/product/B07KJK6S4H/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1





Thanks for the reply, every little helps, even just pointing out how basic this is:D . I did a search, but nothing with this exact example, so I wanted to make sure.

I did consider a more powerful pump, but I am uneasy with having a powerful AC device submerged in water in the house without me there.

Thanks again!!! Happy Weekend :D

  • 3
    \$\begingroup\$ Those are in series. Connect them in parallel not series - each one needs 12V, not 4V. If the power adapter isn't up to starting 3 pumps at once under load, give each its own relay and have the R-Pi start them a few seconds apart. \$\endgroup\$ – user_1818839 Feb 28 '20 at 15:44
  • \$\begingroup\$ I’m sure you can get a 15 watt to 20 watt DC pump if you looked harder. \$\endgroup\$ – Andy aka Feb 28 '20 at 15:58
  • \$\begingroup\$ Question is your diagram a flow diagram or strictly an electrical one? Are you looking for 3 times the volume or 3 times the pressure? If it is three times the volume the above is correct, but if it is 3 times the pressure then your first diagram is correct for plumbing but wire them as the answer. \$\endgroup\$ – Laurin Cavender Feb 28 '20 at 16:52
  • \$\begingroup\$ @icaGuzz: Tip: there's a hyperlink button on the editor toolbar that lets you put in proper hyperlinks rather than just pasting in the URL which breaks the flow of your post. Welcome to EE.SE. \$\endgroup\$ – Transistor Feb 28 '20 at 17:18

Assuming the power supply can handle all 3 pumps turning on at once, this is what your circuit should look like:


simulate this circuit – Schematic created using CircuitLab

(Please ignore the "bulb" element, CircuitLab doesn't have a good motor/pump element)

Make sure that you pick a switch that can handle the load through the contacts.

If the pumps all pull from the same liquid and empty into the same container, they should pump 3 times as much in this configuration. They don't have to be plumbed in series for this to happen.

  • \$\begingroup\$ These are reciprocating diaphragm pumps, with a solenoid fed (typically) a square wave generated by an internal timer board, so they don't have a starting current significantly larger than the operating value. \$\endgroup\$ – Phil G Feb 28 '20 at 16:04
  • \$\begingroup\$ @PhilG I didn't realize they were those kinds of pumps, I removed that reference, thanks. \$\endgroup\$ – Ron Beyer Feb 28 '20 at 16:05
  • \$\begingroup\$ @PhilG Cheers for the reply. What formula would I use to calculate the load these pumps would generate when in parallel? The power supply is 24W max and 12v 2A. The assumption from me is you add them up, so 10.8 in this case (each pump is 3.6w). The relay specs are these: 30 V DC/10 A \$\endgroup\$ – icaGuzz Feb 28 '20 at 17:56
  • \$\begingroup\$ Correct, so the supply is adequate, and the relay more than adequate. \$\endgroup\$ – Phil G Feb 28 '20 at 19:30

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