5V DC Mini Water Pump needs something??

Well hello again!! Let me summarize the situtation. I am using arduino mega 2560 and a 4-channel relay. I have a 5v two wired fan and a 5v two wired mini water pump. I am using different 6V batteries for each of them.

Here comes the problem: I made their connections the same way. And 5V two wired fan is working without a problem with my code. So, my code and my wiring is correct. But i am using the same wiring as fan and also same code with only changing the pin. And if i don't connect the last wire, i mean any wire about pump, not only red wire, to my breadboard i can see the relay is working as expected. The led of that channel, 4th channel turns on and i hear the clicking sound. However, when i connect the last wire about pump, it goes crazy. By crazy, i mean that, channel 4th's led starts blinking repeatedly and quickly, and pump doesn't work.

There is not a problem with the battery i use or wires i use. Because when i connect the pump directly to 6v battery, my pump works just well. And as i told, my wiring is also fine, because it works with fan. So, why my fan works greatly without a problem, but my pump doesnt work even though everything is exactly same?? Is there something special about water pumps, like i need to put a resistor or something?

Thanks in advance!!

The special may be from the limitations of current capacity of the breadboard. Are you using an engineering prototyping breadboard or an other? You'd know by the price and current ratings of the breadboard.

I have two breadboards and i am using fan with one and mini water pump with the other. Both of them are same with this breadboard here: https://www.amazon.com/BB400-Solderless-Plug-BreadBoard-tie-points/dp/B0040Z1ERO

OK, here's how you do it.

Read the instructions.

When you understand them, post

  • A photograph (or many) of your setup, including all parts taken in bright light, preferably outdoors but not in the sun.
  • A schematic diagram of all parts of your setup, showing where each wire goes.
  • Your complete code, in "code" tags according to the instructions.

I am sorry but it is not possible. And all i was asking is should i do anything different than starting a fan, when i want to start a mini water pump. Both needs 5V, both has same connections. Fan working, pump isn't. Fan's working is a proof of my connections are correct, so no need for a schematic. Fan is working with respect to my arduino code, so my code is also correct.

My question is, should i do anything different than fan for pump? Either code-wise or connection-wise? Like adding a resistor or capacitor? (even though i think my arduino compatible relay module includes them)

I am sorry but it is not possible.

OK, no problem then.

And I mean just that. :sunglasses:

How are you connecting the pump and its 6v battery? You stated that the fan and pump each have their own separate 6v battery, so unless you have some type of sensor or other feedback element on the pump, the only connections should be to the relay contacts, which should have to effect whatsoever on the rest of the circuitry. Even if you burn the relay contacts, or weld them together, that wouldn't effect the drive circuitry, and there is no need at all for a common ground connection, or any other connections to any part of the rest of the circuitry.

Yes they both have their own separate 6v batteries and they also have their own breadboards. At the moment, i am not using any sensors or other feedback elements. Yes, only arduino+relay contact+battery connections, exactly the same way that works with fan.

And for your information, without using arduino, i can make the pump work well either only using the 6v battery or using battery+Normally Closed of relay contacted pump. The problem is about Normally Open, and i need to use my pump with normally open later on, because i will add a soil moisture sensor and some code to integrate them.

But at the moment, i am only testing to use pump with simplest code, the same code that works with fan.

Sounds like you are using a "low true" relay module, try switching the output pin direction from HIGH to LOW: