[Public-List] Bizzare electrical problem

n4lbl alan.schulman at gmail.com
Wed Apr 10 20:54:22 PDT 2013 

Your criticism is on the mark.

thanx,,,
     Alan

On Wed, Apr 10, 2013 at 6:48 PM, Dennis K. Biby <sailor at aweigh.com> wrote:

> Ahoy Glenn,
>
> Sorry for jumping in here but I'm a bit confused by some of the comments.
>  Several folks are tossing around the term "impedance" ...  Just an FYI,
> impedance is basically the AC equivalent of DC resistance.  Not sure why
> impedance is a factor in your DC starter.
>
> Secondly, lightning is a possibility but only if the strike took place
> while you were cranking the engine.  Lightning could very well melt the
> coax insulation but I don't see how it would still be bubbling days later.
>
> My dos centavos is that your VHF coax shield is in contact with a positive
> 12 VDC.  It matters not whether it is contacting an outbound (positive
> voltage) or is on the return ground side of a "hot" source.
>
> Dennis
> s/v Ferrity
>
>
>
>
> On Wed, Apr 10, 2013 at 4:02 PM, Michael Connolly <crufone at comcast.net
> >wrote:
>
> >
> >
> > Glen,
> >
> > You mentioned in an earlier post that you hosed or washed down the engine
> > after doing some fiberglass work last spring. Might you have filled the
> > battery boxes full of wash water?
> >
> > Michael
> >
> >
> >
> > ----- Original Message -----
> >
> >
> > From: "Glennb" <brooks.glenn at comcast.net>
> > To: "alan schulman" <alan.schulman at gmail.com>, "Alberg 30 Public List --
> > open to all" <public-list at lists.alberg30.org>
> > Sent: Tuesday, April 9, 2013 11:55:05 PM
> > Subject: Re: [Public-List] Bizzare electrical problem
> >
> > As followup to my weird electrical problem, today I inspected the
> > batteries and starter system. Interestingly both batteries were wet on
> the
> > outside of their cases, and they were sitting In some small pool of water
> > in their battery cases.   Assume this is due to condensation somehow
> > working its way up from the bilge, although the rest of the FG'd areas in
> > the battery compartment were not wet with condensation.  (I built new
> > battery boxes under the cockpit floor two years ago when I rebuilt the
> > cockpit.  There is no way rain water could have dripped in through the
> > cockpit floor or hatch above.)
> >
> > Q: So, thinking about last weeks earlier comments on the list,  can wet
> > batteries sitting  in smallish pools of water (>1/4 cup) somehow cause
> > sufficient impedance in the electrical system to semi melt coax cable
> > attached to the backof a VHF radio, when the engine is started ???  This
> > seems beyond bizarre!
> >
> > As FYI, my battery ground and positive cables and connections are in good
> > visual shape, some slight corrosion on the engine ground, (such as one
> > would expect from one year of service); look  like new on the battery
> > terminals.  The batteries are new AGM deep cycle I installed last spring.
> >
> > The  battery ground, on the engine, had two or three years normal
> > corrosion on the grounding bolt, not bad looking.
> >
> >  I started the engine once with each battery with no ill effect on any
> > wiring in the general area of the engine, including the radio antenna, so
> > again could not duplicate the overheated wire condition.
> >
> > Verified that The pushpit is not shorted or grounded to any electrical
> > circuit, but is grounded to the emergency VHF antenna via clamps that
> > attach the antenna to the structure.  I am going to find some insulated
> > clamps to,replace the hose clamps I presently use to attach the antenna
> to
> > the stanchion.
> >
> > I guess my next step will be to remove batteries and starter and go have
> > them bench checked.  Also will remove the engine ground, clean and
> > reinstall.
> >
> > A lot of trouble to do this as the starter is mounted on the lower back
> > (port) side of the engine, behind the alternator.  doable, but a major
> pain
> >  unless performed under nice 80 degree sunny weather conditions and
> > preemptively fortified with some high grade of chocolate and dorito
> rancho
> > cheese  snacks to a-swage the usual bursts of rage and doom which broach
> > forth when the alternator bolt or the one usable  wrench  slips out and
> > tumbles into the bilge.
> >
> > Gpb
> >
> > Sent from my iPad
> >
> > On Apr 7, 2013, at 6:16 PM, n4lbl <alan.schulman at gmail.com> wrote:
> >
> > > I'd be really interested in the quality of the starter battery ground.
> > > On Apr 7, 2013 2:09 PM, "Glennb" <brooks.glenn at comcast.net> wrote:
> > >
> > >> Yep, thats kind of what I though.  So far as I know, the hull was dry,
> > >> except for sitting in the water at the slip.  iam going to go check
> for
> > a
> > >> short or ground to,the pushpit tomorrow. Still amazed a heavy gauge
> > >> shielded coax cable would heat up three feet away from the radio as
> > well as
> > >> the back side of the radio, with no damage to any of the much smaller
> > >> ground or positive wires leading to the  radio, or nearby parts of the
> > >> wiring system...
> > >>
> > >> Maybe iam thinking along the wrong lines.  Perhaps the impedance ran
> up
> > >> the radio ground wire from the negative bus to the back of the radio,
> > >> thence started to cook the coax? The radio,itself still works and only
> > the
> > >> heat sink on the back and rear part of the frame was hot.  Maybe had
> > >> nothing to do with the pushpit - which i still believe is isolated
> from
> > the
> > >> electrical system, except for the emergency antenna clamps.
> > >>
> > >> Still Weird!
> > >>
> > >> Glenn
> > >> Dolce 318
> > >>
> > >> Sent from my iPad
> > >>
> > >> On Apr 7, 2013, at 12:23 PM, Gordon Laco <mainstay at csolve.net> wrote:
> > >>
> > >>> The glass in the hull can't carry a current, but moisture on it
> > >> certainly can.
> > >>>
> > >>> On 2013-04-07, at 1:53 PM, Glennb <brooks.glenn at comcast.net> wrote:
> > >>>
> > >>>> I can see stray electrical currents, but can fiberglass hulls
> conduct
> > >> enough electrical energy to heat coax antenna cable to the melting
> > point???
> > >> Never thought that was possible.
> > >>>>
> > >>>> Btw,  i havent looked into the battery compartment yet - under the
> > >> cockpit behind the engine- but everything is new back there this past
> > year.
> > >> Plus I did hose off the engine last spring as part of a serious
> cleanup
> > >> following a lot of FG and wood sanding .
> > >>>>
> > >>>> Gpb
> > >>>>
> > >>>> Sent from my iPad
> > >>>>
> > >>>> On Apr 7, 2013, at 8:54 AM, n4lbl <alan.schulman at gmail.com> wrote:
> > >>>>
> > >>>>> That was true, but,,,,
> > >>>>>
> > >>>>>
> http://www.thebatteryterminal.com/TechTalk_Batteries_on_Concrete.htm
> > >>>>>
> > >>>>> http://www.snopes.com/autos/techno/battery.asp
> > >>>>>
> > >>>>>
> > >>
> >
> http://www.cartalk.com/content/business-batteries-and-concrete-floors-needs-be
> > >>>>>
> > >>>>>
> > >>>>> On Sun, Apr 7, 2013 at 9:19 AM, Don Campbell <
> > dk.campbell at xplornet.ca
> > >>> wrote:
> > >>>>>
> > >>>>>> That is the quickest way to drain a battery that sits without
> being
> > >>>>>> recharged,  and if you set a battery onto concrete,  this is the
> way
> > >> charge
> > >>>>>> is lost to ground, i.e. through condensation between the battery
> and
> > >> the
> > >>>>>> concrete. By setting the battery onto a piece of wood,  that
> breaks
> > >> the
> > >>>>>> continuity of the water film and so maintains the charge in the
> > >> battery.
> > >>>>>>
> > >>>>>> Don
> > >>>>>> On 4/6/2013 2:31 PM, Gordon Laco wrote:
> > >>>>>>
> > >>>>>>> That's good advice.   I once had a shock (pun intended) when I
> > >> casually
> > >>>>>>> touched the probe of a multimeter to the inside skin of my boat
> > >> while the
> > >>>>>>> other probe was touching the SIDE of one of my batteries.
>  There
> > >> was a
> > >>>>>>> slight current.    I noticed everything was damp with
> condensation.
> > >>  I
> > >>>>>>> dried everything I could reach and was able to kill the stray
> > >> current, at
> > >>>>>>> least so far as my meter could detect.   If ever there was a good
> > >> reason
> > >> _______________________________________________
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