[C38] Two Electrical Problems

[Steve Smolinske]

1) voltage drop could be due to bad ground,  your 12v system  is
grounded back to the battery negative terminal, youll  need to  retrace
the entire ground system to see if and where any splices or connections
might be, also your  wire size could be to small for the run (both to
electronics and back to the ground), to small of wire could also result
in a voltage drop.   Blue sea systems has a neat online calculator to
help you determine what size wire you need.   Also your  negative
battery posts could be corroded and need cleaning, typically there
should only be 2 connections to the battery post, after  that you need a
negative terminal to add all the other grounds to.  You may also have a
loose  connection in your grounding bus bar behind the electrical panel.
This is why I rewired my entire boat so I would nt have to chase these
types of  annoying problems. 

2) could be any number of things from a bad voltage regulator, to
undersized wire from the alternator to the batteries,  again check blue
sea systems for wire sizes, also the article Tom and I did, which you
should find on the list serve email for  this year talks about the
charging circuit and efficiency of the old amp meter vs a voltage meter
at  the control panel.   Blue Sea is very helpful with questions and
answers for all things electrical, and they answer their phones.   

-----Original Message-----
From: Listserve [mailto:listserve-bounces at catalina38.org] On Behalf Of
Julian Adams
Sent: Thursday, June 26, 2014 1:09 PM
To: listserve at catalina38.org
Subject: [C38] Two Electrical Problems

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
************************************************
Julian Adams
Department of Molecular, Cellular and Developmental Biology University
of Michigan
 830 N. University, Ann Arbor MI 48109-1048 Tel. (734)-763-3431; Fax
(734)-647-0884; Cell (734)-239-3627 E-mail julian at umich.edu
************************************************



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