Inductive kick from switching a starter motor off does not get
transmitted to the electronics. The inductive kick comes from the
induction of the windings in the starter motor when the current is
interrupted. But if the current has been interrupted it is no longer
connected to the battery so the spike is restricted to the starter
motor side of the switch.
Ah, but what about the inductive kick that happens when the starter is
running and the commutator brushes in it kick like hell switching
windings on their way around? This kick, working against the normal
corroded up terminals, wiring, connections in a boat can, indeed, be
substantial.
Just leave it until the damned radio won't transmit any more.....It's too
much trouble to flip the breakers off....
Oh, by the way folks, turning electronics OFF with the switch on them
doesn't turn electronics OFF, for the last 30 years or so. When you turn
off any VHF transceiver, for instance, you are switching off the low-
level electronics...receiver, transmitter exciter, PARTS of the synthesis
electronics. Other parts, notably MEMORY for channel scanning and that
big RF power brick that makes 25 watts bolted to the heat sink are
CONNECTED TO THE DC ALL THE TIME! So, my suggestion to turn off the
electronics at the source....
Aboard Lionheart is a continuous-duty master contactor. The contactor is
controlled by a panel push-pull marine switch that simply turns the
contactors coil on and off and lights a big red pilot light so my captain
doesn't go off for 3 weeks and leave it all running. This contactor
controls the "Electronics DC Bus" throughout the boat. The only radio
that's not on it is the emergency VHF, an Icom M59, that has its own
breaker. All the other electronics operates from the bus. Disabling the
bus, disables all those continuously-connected devices NMEA doesn't want
to waste money on switches to shut down.
A few years ago, a little seawater made it way around the chinzy speaker
seal of a Standard Eclipse Plus VHF radio, ran across the main PC board
behind it and puddled up against the back heat sink on top of the board
right under the power amp brick pins, driving the power amp control
circuit into a continuous conduction state. This did NOT blow the
radio's manufacturer fuse as the brick was only pulling 3 amps, all
converted to 36 watts of heat that discolored the metal surface of the
radio's heat sink in back, we later found. The boat was on a trailer and
not hooked to a charger, so the radio simply killed the boat battery
REALLY dead, so dead it would never recover. Since figuring out that
one, all electronics needs to be hooked to some kind of disconnect device
that totally disconnects all electronics on the boat from DC power before
the boat is put away from use.
I found another phenomenon that took me a while to comprehend. The boat
had been put up for a month and a half while I was on Lionheart in
Florida, dealing with engine flooding in Daytona Beach. The next time I
went to use the portable GPS, I noticed the plastic plug on the dash had
gotten really hard and brittle, so brittle it crumbled in my hand! The
plug was the power/data plug for a Garmin handheld GPS. It simply
disintegrated! This was caused by 12 volts DC and a little humidity
caused by rain making it under the cover. Evidently, the 12VDC conducted
around, and maybe through, the plastic the plug was made of, completely
changing the chemistry of the plastic by electrolysis. The most damage
was nearest the +12V pin near the surface of the hole the +12V was in.
That pin simply fell out in my hand. This is another reason to secure
all 12V power from all electronics, even electronics plugs just left
open!
How DO they engineer plugs so cheap 12 volts DESTROYS them?!
