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From: jhs@druco.ATT.COM (J H Shore)
Newsgroups: sci.electronics,rec.autos.tech
Subject: Re: parasitic anodes for rust prevention ???
Message-ID: <4345@druco.ATT.COM>
Date: 9 Jun 89 14:04:04 GMT
References: <11854@bloom-beacon.MIT.EDU>
Organization: AT&T, Denver, CO
Lines: 25

in article <11854@bloom-beacon.MIT.EDU>, wolfgang@mgm.mit.edu (Wolfgang Rupprecht) says:
> Has anyone tried playing with parasitic anodes for rust prevention of
> automobiles?  I have seen several likely gimmics that you "bolt-on"
> and forget.  
> 
> I was wondering if there is any simple way to make a system that
> *really* works for protecting some of the parts that tend to collect
> water, such as on the bottom insides of the doors.  I was going to try
> a long of cloth-wrapped zinc wire attached to +12v (through a several
> k-ohm resistor).  Anyone have any other pointers or insight?

I would suggest making your parasitic anodes passive, so to speak, 
rather than  using +12vdc.  I suspect that some unanticipated 
results will occur, not the least of which would be relatively
rapid reduction of your zinc wire. Power experts--comments?

Naval ships--and probably merchant marine ones as well--use large 
zinc bars bolted in strategic places both within and external to the
hull to minimize electrolytic action associated with prolonged 
exposure to sea water.  None use an active potential (that I know of).

Again, even if you only use zinc wire, you'll likely have to replace
them fairly frequently. And I suspect you'd have to try out various 
types and locations of the anodes to know how effective it would be
anyway.  Good luck--keep us posted.