I've a 9v battery and I'm trying to get 9v through my IRLZ44, to power an solenoid. It's a seperate system from my arduino who's sending a 5v signal to the IRLZ44 in order to activate it.

For some reason i can not get more than 4.5v through my IRLZ44? What am I gonna doo???


simulate this circuit – Schematic created using CircuitLab

Tried drawing it as correctly as possible, but I'm super new to this. I'm sorry if i screwed up.

  • \$\begingroup\$ What is Vgs, Vgs and 9V reading? What Id do you expect? Id=9V/DCR \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 May 12 '18 at 0:17
  • \$\begingroup\$ @TonyStewartolderthandirt I'm sorry, I don't know what VGS means, I'm trying to get atleast 9v through the IRLZ44N but i'm maximum getting out 4.5v off it. \$\endgroup\$ – Artonn May 12 '18 at 0:22
  • \$\begingroup\$ Connect the 9V battery directly to the solenoid and measure the voltage across the solenoid. What do you get? ... Does the solenoid activate?... do not connect any other components. \$\endgroup\$ – jsotola May 12 '18 at 0:42
  • \$\begingroup\$ @jsotola my batteries output 8,24v. When I connect the solenoid directly to the battery the multimeter says 7,48v. \$\endgroup\$ – Artonn May 12 '18 at 0:57
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    \$\begingroup\$ @TonyStewartolderthandirt Going to take some time, but I had hoped I would figure these things out as I worked with them. But you can also be fair to a newcommer. If you simply would had said voltage gate to source, our communication would have been a lot more productive, it's fine you don't feel like dealing with a newcommer, but no reason to make it more difficult. :) To answer your question, i'm sending 9v or 7.2v through the source and only around 4.5v comes out of the drain whenever i send a 5v signal to the gate. \$\endgroup\$ – Artonn May 13 '18 at 21:13

What do you mean "4.5v through my IRLZ44"? Do you mean "4.5V across the drain and source? When the mosfet is switched on, the drain to source voltage should be extremely low (millivolts). When off, the drain to source voltage should be 7.2V. If it is less than 7.2V when off, the mosfet may already be fried, and the drain to source may be partially shorted.

Check the gate voltage. It should be above 2V (peferably above 4V) for the mosfet to work properly. Also, there needs to be a high value resistor from gate to ground, for the mosfet gate capacitance to discharge when it is switched off (otherwise it will not switch off).

Decrease the value of the 1K resistor to the minimum required to not go over the arduino pin current limit. Operating the mosfet in the linear region with a lower gate voltage may shorten it's life.

  • \$\begingroup\$ Hi Indraneel. I have my two 18650 batteries ground connected to the source, while the drain is connected to the solenoid ground. The positive wire is connected directly to the battery. The Arduino nano sends a 5v signal to the gate, and the arduino nano ground is also connected to the ground of the battery. When measuring the voltage between the drain and the positive voltage of the battery, while activating my switch to send a 5v signal to the IRLZ44 gate it reads around 4.5v between the drain and my multimeter ground. \$\endgroup\$ – Artonn May 13 '18 at 20:29
  • \$\begingroup\$ I'll check the voltage to the gate, to make sure it's 5v. It should be, but haven't actually checked it. I believe I might not be able to go lower than the 1k resistor, as far as I've been told. EDIT: BTW, When I deactivate the switch, the voltage reads 0. \$\endgroup\$ – Artonn May 13 '18 at 20:34
  • \$\begingroup\$ Voltage is a potential difference between two points. Please specify both the points when you are measuring the voltage, otherwise it becomes difficult to understand what you are reporting. \$\endgroup\$ – Indraneel May 14 '18 at 17:35
  • \$\begingroup\$ Okay I think I might have found the problem, I took my multimeter and connected it to ground and to the digital pin 11. It says that there's being outputted 1.6V... \$\endgroup\$ – Artonn May 17 '18 at 22:27

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