Nope.
The MOSFETs used for reverse-polarity protection normally conduct in the reverse direction, (the direction of the substrate diode) since MOSFETs conduct equally well in both directions when biased ON, and block when the polarity is reversed (MOSFET biased in the normal direction).
Make sense?
Note that as long as the supply voltage is less than the Vgs(max) value (typically 20V), you don't need the Zener from source to drain.
Nope.
The MOSFETs used for reverse-polarity protection normally conduct in the reverse direction, (the direction of the substrate diode) since MOSFETs conduct equally well in both directions when biased ON, and block when the polarity is reversed (MOSFET biased in the normal direction).
Make sense?
Note that as long as the supply voltage is less than the Vgs(max) value (typically 20V), you don't need the Zener from source to drain.
Correct. If the source was connected to the positive rail then the intrinsic body diode of the FET would conduct in the reverse direction and render the reverse-polarity protection useless.
Nope.
The MOSFETs used for reverse-polarity protection normally conduct in the reverse direction, (the direction of the substrate diode) since MOSFETs conduct equally well in both directions when biased ON, and block when the polarity is reversed (MOSFET biased in the normal direction).
Make sense?
Note that as long as the supply voltage is less than the Vgs(max) value (typically 20V), you don't need the Zener from source to drain.
Gophert is correct - the way that circuit is drawn, the anode of the FET body diode is connected (via the load or resistor and zener) to battery positive.
It will never turn anything off, just vary the voltage drop slightly.