Power ground

[Clarence L.Snyder]

Jim Davies wrote:
> 
> On Sat, 2 Jan 1999, Clarence L.Snyder wrote:
> 
> > > Anyone have time to explain the difference between 'ground' and
> > > 'powerground'?
> > > TIA
> > > Geoff
> > I'll give it a crack.
> > In a DC power system on a car, the negative(usually) terminal uses a
> > "chassis ground" for power "return".This is your "power ground". It can
> > have a voltage drop of up to .1 volt across it for accessory and
> > charging loads, and up to one volt for starter loads.
> > For signal circuits, such as sensors, sometimes the .1 volt drop across
> > the frame ground could cause calibration errors, so a "signal ground" is
> > provided. Sometimes the signal can even "float" above chassis ground, as
> > through a protection diode with a, say, .6 volt forward voltage drop.
> > Can't use chassis ground return for such a signal.
> > Hope this helps understand it.
> >
> 
> So in other words, high amperage and low amperage devices should have
> seperate ground paths to the battery??
Not necessarily:
but devices that are VOLTAGE SENSITIVE, particularly at low voltages,
should have their own ground circuit.