Protecting low voltage connections from corrosion in marine environment - Page 1
Forum section: electronics / general

author: Lomax
author_rank: Frequent Contributor
timestamp: February 18, 2018, 03:45:25 pm
content: I'm about to start making up the battery cabling for my boat, which will be done using hexagonal crimp ring terminals covered by heat shrink tubing. For long term corrosion protection I would like to put some kind of "gunk" in the seam between the terminals and the (PVC) cable sheath, butwhat kind of gunkexactly? Similarly, I would like to coat the terminal posts and ring terminals with something to stop these from corroding. I see people mentioning silicone grease as suitable for this but would like to confirm before I make any (costly) mistakes - I am concerned that silicone, being an excellent insulator, might actually degrade the connections? I am also concerned about the long-term effects of silicone on the PVC cable insulation, and the heat shrink tubing.

author: SeanB
author_rank: Super Contributor
timestamp: February 18, 2018, 04:10:56 pm
content: Use heat shrink with a conformal inner low melting point glue, which melts before the outer fully shrinks and then provides a good seal. Make sure the cable sheath and the connector are clean before shrinking, cleaning with a scotchbrite pad and wiping down with some IPA as well to ensure the best clean surface for the glue to bond to. then over the outside by the connector side some dielectric grease, available at your boating supplier, to keep the connection corrosion free. the grease is non conductive, but as the tightening of the connector to the lugs displaces the grease and provides metal to metal contact, it will not have an effect on the connection, but will keep it free from corrosion for a long time.

author: Lomax
author_rank: Frequent Contributor
timestamp: February 19, 2018, 12:56:56 am
content: Thank you, now I know what to do. After posting I also foundthis, detailed, discussionof the pros & cons of "dielectric grease" use on high/low voltage high/low frequency connectors - from which I quote:Quote

author: GerryBags
author_rank: Frequent Contributor
timestamp: February 19, 2018, 01:05:14 am
content: You could use resorcinol which is an excellent dielectric, but not very common. I had some that I got to repair the cascover on my old Grand Banks woody I used to live on. Much less hazardous would be to melt some ABS or styrene (evergreen rod, for example) in either DCM - dichloromethane, or MEK - methyl-ethyl-ketone. Apply the resultant goo to your exposed metal area and wait a couple of minutes for it to cure and then apply more. Build it up like this and it will be better than the PVC insulation on the rest of the cables and you'll get no corrosion. The solvent has no effect on the PVC by the way.

author: rhb
author_rank: Super Contributor
timestamp: February 19, 2018, 02:14:31 am
content: I reworked the mast connections for a friend using silicone grease and a couple of layers of heatshrink. I also slathered silicone grease on all the power panel connections which had corroded from salt air.. I chose the silicone grease because it had a 400 F melting point. Not much help if the grease oozes out over time.Unfortunately my friend is deceased and I don't know where the boat is. It's a documented vessel and I've been meaning to get in touch with his son to see if he knows the vessel number.Glue has the problem that it is stiff and a gap can develop between the glue and the connectors.

author: gildasd
author_rank: Frequent Contributor
timestamp: February 19, 2018, 08:13:47 am
content: I work offshore, so this is my daily Lot!For short term, low exposure, or simply something that needs to be regularly checked: clean with WD40 and cover with Vaseline.For moderate exposure, storage and medium exposure, clean with WD40, two coats of Tectyl. Note, if you need to tighten a bolt or scratch the Tectyl, apply a new coat. If outside, add aluminium backed grease tape over sensitive stuff like connectors.For stuff that can get exposed to sea water (not just spray) but not immersed. Take apart, clean with WD40 then with a heavy duty degreaser, paint with conductive Zinc paint, assemble, Tectyl, fill voids with thick high temp grease (that does not go soft or liquid in direct sunlight) and aluminium backed grease tape.Wavy lines...But, if at all possible, we use watertight connections boxes (on the cabling and closure) because it’s less of a long term hassle.

author: tautech
author_rank: Super Contributor
timestamp: February 19, 2018, 08:23:26 am
content: Historically here, the power co's used self amalgamating tape and/or Denso tape.On copper overheads (now mostly obsolete here), the joints when uncovered some decades later looked as the day they were made and although we're not right at the coast, we do get significantly more corrosion than those further inland.

author: BravoV
author_rank: Super Contributor
timestamp: February 19, 2018, 08:40:26 am
content: Another interesting long term (years) characteristic of this hot snot glue exposed for "years" in salt water and sun, from another forum fellow (Rufus), read carefully this particular ->POSTand subsequently the ->Proofs, quite interesting imo.

author: BradC
author_rank: Super Contributor
timestamp: February 19, 2018, 11:23:46 am
content: Quote from: tautech on February 19, 2018, 08:23:26 am+1 for denso tape on anything thicker than your little finger. Pretty much anything subject to corrosion. Amazing stuff.Silicone grease and self amalgamating tape are my favourite marine treatments for anything passing electrons, but just keeping them dry and away from salt wins. Good quality boxes with quality glands make life easy if you need serviceability.

author: Electro Detective
author_rank: Super Contributor
timestamp: February 20, 2018, 09:55:53 am
content: Brush on regular WD40 sprayed into a container, and keep a check every few weeks and re- apply if necessarySealing stuff up also seals up any chance of spotting corrosion problems and creep-age, YMMV