voltage drop on resistor if no current

[John Parker]

How can I calculate the voltage drop on a resistor if no current? I use an N-channel MOSFET and I want to put a resistor between the gate and the positive terminal of the battery but max. Vgs is 20V and my battery bank is 45V.

 

[JimB]

How can I calculate the voltage drop on a resistor if no current?

Quite easily, using the accepted expression:

V = I x R

When I = 0, then V = 0.
Does not matter what the resistance is, no current, no volt drop.

Maybe what you need is a voltage divider, two resistors in series and take the output from the junction of the two resistors.

JimB

 

[crutschow]

If you connect a 10k ohm resistor to the 45V in series with 3.65K ohm resistor to ground, then the junction of the two, connected to the MOSFET gate, will be at about 12V.