I am using an IRFZ44N MOSFET (n-type) transistor to regulate the current of a Lithium-ion battery, and I'm trying to use the battery to supply power to both the drain and gate of the transistor. My goal is to allow current to flow from drain to source when I apply voltage to the gate (when I attach the (+) wire to the gate), and stop the current flow when I connect the transistor gate to ground (when I attach the (-) wire to the gate). In my schematic I left the circuit open, but depending on what I want my gate voltage to be I connect either the (+) or the (-) wire momentarily.
My problem is that I don't understand why I'm reading certain values on my ammeter. When I connect the (+) wire to supply voltage, I should see a current of 3.7V/10ohms=370mA, but I'm only reading a value of around 30mA. However, if I use a separate power supply for the gate of the MOSFET with everything else unchanged, I get an ammeter reading of 370mA as expected.
I know the gate-source voltage is the same in both scenarios because I measured it with a voltmeter (measured about 3.5V), and when I use a separate power supply I'm also using a 3.7V battery.
Why does using the same power source to supply the gate voltage only let 30mA through?