[C38] Two Electrical Problems

[Les Howell]

Hi, Julian,
	The GPS issue could be a number of things.  If you have the old fuse
panel still in place, the fuse and holder could be corroded.  The C38
are not spring chickens any more, and things get moldy...
	Also when Nancy and I got JACE (formerly Infinity, and now Knee Deep
or ???) There were a number of the three way rivited terminal splices in
the wires.  These things are like 3 eye terminals riveted together.
Every one of them was corroded and intermittant or high resistance.  I
took them all out.  My trick was a barrel connector with the input side
being a single wire doubled back on itself, twisted and then crimped, to
the two wires  in a bit of heat shrink longer than the barrel connector,
twisted and crimped on the other side, and the whole shebang covered
with that bit of heatshrink and shrunk.  At least where I could put the
heatshrink on (some were located where I couldn't apply the heatshrink
or heat it properly.)  Another place was the fuse panel fuse sockets
were really corroded.  I used some 300 grit wet/dry sand paper and
burnished the fuses and the socket bits to get a better connection prior
to my replacing the whole panel with circuit breakers.

	Also, prior owner/catalina/various shops had used several balls worth
of electrical tape splicing bits of wire together for many of the
electrical connections.  I did my best to find and eliminate them.  Good
luck on that one.

The alternator controller is a way to boost the charge current.  It is
pretty abusive in some cases, but you can use it to set the charge
current.  When the motor is running, check the voltage at the battery.
If everything is good and the battery is full, it will be between 13.6
and 14.2 volts.  This voltage is due to the internal drop of the battery
and the current coursing through the wires.  The regulator monitors the
current and the voltage.  To get faster charging, some one thought up a
way to change the comparator to the voltage regulator to make it run a
bit hotter, and also to step up the current supply by causing the field
to get more excitation in the alternator.  This little trick has some
tradeoffs though.  
	Pros: 
	1.  can charge the battery faster and/or at a lower rpm
	2.  gives you more current available when running the engine to both
charge the batteries and run the house.

	Cons:
	1.  hard on the battery and alternator.  Most of the commercial units
will have some kind of limit on how far you can push the alternator, but
this only works for a specific alternator, as the current limits and
cooling of alternators vary quite a bit.
	2.  has to be monitored to prevent boiling the batteries.  If a battery
is charged with too high a current it out gasses and the plates break
down.  A limited version of this is sometimes called equalizing a
battery, but that is very tightly controlled and time limited.  When a
battery is abused this way, its life will be shorter, and if too badly
abused can produce an explosive situation due to the output of both
hydrogen and oxygen in what is called out-gassing.
	3.  Alternator may catch fire if the current is pushed too high while
the alternator is turning slowly because the only cooling is provided by
the fan that is part of the spindle where the pully is mounted.  slow
fan, hot alternator, burnt insulation, maybe fire.

Read up on the  alternator controller.  I found a reference:
http://forum.ssca.org/viewtopic.php?f=6&t=10915

and if  you read down a bit, one of the responses indicates it is in
"The 12Volt Doctor's Practical Handbook".  That is a pretty useful book
for other reasons as well.

Regards,
Les H
On Thu, 2014-06-26 at 16:08 -0400, Julian Adams wrote:
> I have two electrical problems that have been resistant to my tinkering.
> 
> 1. Low voltage at the helm.  I mounted a Garmin GPS unit (4308, I think
> the number is) ate the helm.   Every so often (typically when I need it
> the most) the screen goes blank.  I sent it back to Garmin for service at
> a cost of $500 only to receive a reply that there was nothing wrong.  A
> Garmin rep. told me that it was likely low voltage at the unit and sure
> enough when II measured the voltage it was 8-9 volts.   He suggested that
> it may be a bad ground. I replaced the cord and resoldered connections to
> no effect.   So if it is a bad ground where do I start looking?  I thought
> everything was grounded though the keel.   OK, maybe I am just showing my
> ignorance here?
> 
> 2. This problem is unconnected to the first.   At the dock I can charge
> the batteries to the usual 13-14 volts (through shore power), but when we
> are cruising, and on the hook for several days the battery voltage
> steadily goes down to 10 to 10.5 volts (over say 3 -4 days) irrespective
> of how long I run the engine to top off the batteries.  I have removed the
> alternator and had it serviced.   I also have a unit called an alternator
> controller, made by a company named called "Spa Creek".   I have no manual
> for it; the company no longer exists so I can find nothing on the web
> about the unit.  It has a switch and a dial but no idea what the switch
> and the dial do.
> 
> I would greatly appreciate some tips from on how to solve them
> 
> Julian