In article ContestID67 writes:
Frank,

Intermittents can be FRUSTRATING! From your symptoms it would appear
that something is giving you a high resistance path from your battery
to your 302. This *CAN* be a dangerous thing because high resistance
can mean high wattage which leads to high temperatures and smoke. You
don't report any smoke or "hot smells" so this seems unlikely in your
case.

Actually, a high resistance in the power lead to equipment reduces
the current, and is unlikely to result in smoke -- the current is already
limited by the needs of the 302, and further limited by any resistance
in the line. It is not impossible (the resistance may be in a small wire
with poor thermal conductivity, and concentrated hot spot), but it would
seem less likely.

Another possibily that would seem worth considering is that the ground
path is good. If it is through the mechanical mounting to the panel, and
the panel is painted, there might be a poor ground connection causing the
voltage drop in the return path. This can be extra nasty if there are
connections to other equipment that are connected to the grounded case
of the 302, causing ground current out other wires not intended for it,
or causing ground voltage to rise on connections to other equipment.

Alan