COPING WITH ELECTRICAL CORROSION
By David Eidell (02/12)
We've all fallen victim to electrical corrosion: A faint click instead of the whir of a starter motor, darkness where a light bulb should shine, a switch that when flipped does nothing, the possibilities are endless and inevitably frustrating. This is the point where most articles start mentioning electrons, volts and ohms. Nuts to that; theory is good if you want to troubleshoot something, but electrical corrosion is nothing but trouble. Put away the slide rule and get ready for some old-fashioned scraping, soaking and buffing.
Except for spark plug voltage, automotive electricity has to pass through shiny metal. It's when metal is no longer clean and bright is when trouble starts. Take for instance a lead battery post. Freshly buffed lead is silvery, but when exposed to air it quickly dulls to gray. Lead exposed to battery gas and acid fumes starts to turn even darker gray and eventually ends up almost jet black, Somewhere between “darker gray” and “black”, the corroded skin on the battery post will block electricity and that's when the whir of the starter is replaced by an anguished scream from the driver.
Every unprotected terminal in an RV is subject to degradation. From cable as thick as your thumb to threads only a computer could love, every junction, and every terminal is vulnerable to losing its shininess and therefore its electrical integrity.
SHINY COPPER AND LEAD HATES JUST ABOUT EVERYTHING
Well that's not exactly true but if we could keep electrical terminals away from battery acid and fumes, oxygen and salt, it would prevent ninety-nine percent of corrosion problems. Only gold is “noble” enough to resist all forms of corrosion and oxidation (except for a unique blend of several acids called aqua regea); five hundred year old gold treasure emerges from a sunken galleon as lustrous and brilliant as the day it was smelted. If battery posts and terminals were gold plated they would stay shiny forever unless the coating was scuffed off. As unlikely as it may sound a few gold plated terminals are starting to make their appearance in the automotive marketplace. Thunderclap car stereo enthusiasts have created car audio competition events where gold plated hardware garners extra points. Keep in mind however that it does little good to crimp a corrosion-proof terminal onto a vulnerable exposed copper wire. More is needed and I'll talk about that later.
BATTERIES ARE GROUND-ZERO FOR CORROSION
Standard lead acid batteries emit more fumes than an industrial accident. The fumes are a lot more complex than simple “acid fumes” that most people assume is all a battery emits. Sure, there's sulfuric acid, capable of eating solid steel. But then there's hydrogen sulfide, a corrosive gas that seeps through microscopic holes, and hydrogen itself --- capable of penetrating the densest steel alloy. But like those TV infomercials shout “But Wait! There's More!” Of all the insidious things batteries produce, oxygen has to be the biggest surprise. Water just doesn't “evaporate” out of a battery. It is turned (electrolyzed) into it's base components: Hydrogen and Oxygen. You are familiar with the word oxidation right? Well, combined with acid fumes you'll find pure “oxidizing” oxygen. No wonder anything near a battery takes a corrosive beating. Battery terminal manufacturers in fact have addressed this problem by coating diesel truck copper lugs and clamps with (of all things) lead. Many RV'ers have become so frustrated at battery corrosion that they have opted for using valve regulated batteries that eliminate just about all emissions of corrosive gas. But batteries such as Absorbed Glass Mat (AGM) are very expensive and have their own performance and lifespan compromises that must be dealt with.
WAYS TO REDUCE OR EVEN ELIMINATE CORRODED TERMINALS
By now it should be obvious that anything made of metal has to be sealed tight against corrosion. Soldering has been a traditional way to bond a terminal to a copper wire. Many RV'ers shy away from soldering because it involves tools, electricity and a bit of craftsman's panache to pull it off successfully. From personal experience I can brag that there is no better electrical joint than a soldered joint, but as far as corrosion proofing is concerned, soldering is not an absolute must-do. Sealing the parts away from corrosion on the other hand, is vital.
Speaking of soldering, there are nasty rumors floating around that “soldered joints do not belong in an automotive environment”. Supposedly road and engine vibration causes soldered joints to crystallize and fracture. I have soldered more then ten thousand factory joints inside alternators for everything from sports cars to ships and I have yet to see one case of vibration hardening and cracking. Any terminated wire connection should be both strain-relieved (against pullout) and supported so the wire doesn't flap around. Crimped terminals are vulnerable as the terminal tang itself will fatigue and break given enough oscillations. Read more in the section about heat shrink tubing.
Everyone is familiar with the practice of gobbing grease or Vaseline on battery posts and lugs. But two things are required to make this practice effective: The first is that whatever is smeared on must cover everything as thoroughly as a haz-mat suit in an Ebola outbreak. The tiniest most infinitesimal speck of exposed metal will allow corrosive gas to gain a foothold and spread like cancer beneath the greased metal! The gob of grease or petroleum jelly must therefore be meticulously applied in, around, under and through, clamps, bolts, protrusions and other obstacles. Damage occurs in areas hidden from eyesight. Terminals are clamped onto a wire and it is where the terminal is squeezed onto the copper strands lies the problem. Corrosion enters at the tight crack between the end of the wire insulation and the butt of the terminal. Creeping through the tightest crack, corrosive gas goes right to work destroying metal. This phenomenon is true from the largest of battery lugs to thread-size computer pin terminals. This type of opening is difficult to seal using grease or Vaseline and is even more difficult to maintain. Something better is needed. The second point is whatever is smeared on the terminal gas to last a reasonable amount of time. Petroleum jelly worked well until underhood temperatures on newer cars started rising past its melting point. Melted jelly sags and quickly disappears.
ADHESIVE LINED HEAT SHRINK TUBING: As was mentioned above, really damaging corrosion does not occur on the outside of the terminal but rather inside where the terminal and wire strands touch. Special plastic tubing is used to encapsulate terminal to wire junctions. Heat shrinkable tubing that shrinks in diameter but not length anywhere from half it's diameter to a quarter of its original size. This means a half inch diameter 4 to 1 heat shrink tube will shrink down to one eighth of an inch. Heat from a small torch or heat gun is applied to the tubing and it squeezes down over the wire insulation and terminal. Bare heat shrink tubing however is virtually useless to seal a wire joint. Gas and acid creeps in under the tubing no matter how tightly it shrinks. Adhesive sealant is the missing component
Some heat shrink tubing has a meltable inner liner that when heated, and gets sticky so it bonds the plastic tube to wire and terminal. This forms a near impregnable seal against contamination. Different adhesive-sealants are used: some are clear. My favorite tubing is Ico-Rally's HIM tubing with a black sealant. It has a three to one shrink ratio and the black sealant is extremely strong. I've used Harbor Freight's 3 – 1 marine heat shrink tubing and found it to be both effective and very modest in price. It is sold in an assortment of sizes in a small organizer box.
When a piece of heat shrink tubing is applied over a terminal, the part that sticks out onto the wire insulation acts like a big shock absorber – it can just about eliminate vibration weakening and fracture of the terminal.
Online marine electrical supply stores sell larger diameter tubing especially made for battery cable and lugs. You can buy various diameter lengths of very heavy wall tubing in red or black. It really finishes off the battery compartment. Try http://www.genuinedealz.com and root around in their directory for a look at what's available. Three quarter inch tubing will fit battery cable in pickups and motorhomes with gasoline engines (to1 gauge cable) while one inch diameter tubing is great for diesel pickups and large pusher diesel motorhomes with fleet-type engines using up to 0000 cable.
My advice would be for RV'ers to purchase some small size shrink tubing and then play around with it using smaller wire and a lighter to get a feel for how the stuff works. The Harbor Freight marine assortment is a good starter kit for around five dollars. Using heat shrink tubing is fun once you get the hang of it. The biggest challenge is to remember to stick a piece of shrink tubing on a terminal before it is crimped onto the wire. I hate to think how many times I realized with a groan that the shrink tubing lay on the work surface.
Tip: Large sizes of shrink tubing are a challenge to shrink using a propane torch. It's too easy to overheat and char. Harbor Freight sells a very inexpensive electric heat gun that is ideal for this work. When they're on sale they sell for less than a double-burger meal down at the drive-in.
NOTES ABOUT TIN PLATING
You'll notice that some wire and terminals are “tinned”. This means that a tin plate is applied to the bare copper. Tin resists corrosion better than copper but it isn't as good a protection as what the premium cost would suggest. Some tinned wire is twice as expensive as the same wire without plating. Tinned terminals are priced more conservatively. Is it worth it? For terminals I would say yes. But keep in mind If corrosion cannot get in and contact metal, it cannot attack it.
SNEAK ATTACK
Standard batteries leak gas where the battery posts come out of the case. No matter how tight looking the seal, it cannot stop corrosive gas from escaping. The gas will attack the underside of battery terminals and lugs. Smearing sealer around the posts is virtually useless – terminals will still corrode. Felt washers can be placed under the battery lugs, and when the felt is saturated with sealant, it acts as a gasket. I consider felt washer rings like those from NoCo® or Deka® to be indispensable. I have seen packets of these washers on auto parts store counters and hanging on a display hook near the batteries in Wal-Mart stores.
SEALING COMPOUND
Anything that can be gobbed onto exposed metal will greatly reduce corrosion. I've seen chassis grease, insulating spray, WD-40, lanolin, and even more exotic goop. Anything thick enough to smear on without drying out over time will work. Some liquids that dry thick are preferable because they are thin enough to migrate into tight cracks before they harden.
Some lacquer-like anti-corrosion sprays have come and gone over the years. They didn't do a very good job of flowing into tight cracks and joints and I have never had much success with them.
Probably the “friendliest” material I have seen is anhydrous lanolin like you can buy at the pharmacy counter in any drug store. I refer to this stuff as “Sheep Grease”. It is great on battery terminals and hands alike.
LPS offers an excellent aerosol corrosion protector that is specially compounded The company sells different products in near identical looking turquoise colored spray cans. You need to find LPS 3. The 1, and 2 products are lubricants. WD40 lasts about one to four days under severe conditions by the way. LPS 3 on the other hand stays put for years and years. The “WD” in WD-40 stands for “Water Displacement” at which it excels.
Noco, manufacturer of those felt post washers also sells a spray protector, but it is costly and I feel LPS 3 lasts a lot longer. For many years, Noco's battery protector looked exactly like fresh blood – this caused many an anxious moment. Deka's spray protector is too thin for my liking but I like their felt washers.
If you can ferret it out of a General Motors parts department, dealerships sell a spray corrosion compound used in body work to protect inside panels and sheet metal repair. When it dries it forms a very dense, waxy coating that in some instances has lasted more than twenty years on some of my ancient projects!
ELECTRICAL GREASE
Electrical grease is translucent white and is compounded from silicone. This is a great product to seal up headlamp and tail light sockets and electrical plugs on electric door steps. Mechanics have used it for decades to protect ignition spark plug boots.
COMPUTER TERMINAL SPRAY
Because computer signals are so delicate, manufacturers warn against using oil or sealers on computer harness plugs and clips. But that doesn't mean that you cannot apply anything at all. For years I have been successfully using electronic “Tuner Cleaner” that is used in fast-disappearing mechanical radio tuners. Electronic supply stores sell tuner cleaner which has a mild but effective coating action. It's a lot better than nothing.
CLEANING OFF BATTERY CORROSION
Mix baking soda in water and it will bubble and neutralize acid deposits so they can be scraped or flushed off with water. Mix baking soda with boiling water and it will do everything room temperature water does only ten times as fast. Keep dipping the corroded parts into the thin paste, while brushing and scraping until green and brown stains stop bleeding off the parts. Sometimes I have to mix up two or three batches of soda and hot water if there is a lot of corrosion. Chemical cleaning leaves previously corroded copper interesting shades of purple, orange and pink. These areas should be buffed to a bright finish with a stiff wire brush. I use a plumber's copper tubing brushes to help clean battery terminals.
WARNING! Battery corrosion is like a cancer – if you leave the tiniest bit of corrosion behind it will resume its insidious growth and destruction even when buried beneath thick layers of corrosion compound. Take your time when soda washing and buffing terminals to remove every last speck of corrosion.
PROTECTING METAL BATTERY BOXES AND TRAYS
Paint makes a poor coating against corrosive battery acid and fumes. Aerosol undercoating is a much better choice. For years I used a product called “Body Shootz”. Any Wal-Mart or auto parts store carries spray undercoating. Look for paintable undercoating if you don't like black.
SOLDERING SECRETS
Hardware store solder is almost impossible to use on wiring. It doesn't melt well, and won't stick worth a darn. Go to Radio Shack and buy their solder. If you are going to solder old or used wire or terminals, go to the hardware store and buy paste acid flux unless you are working on small electronic circuits. I've used quarts of paste flux over the years on wires as small as 20 gauge and although I have never washed off the flux, thirty-year-old repairs continue to work like new. The acid flux should not be used anywhere near printed circuits or transistors however.
I use a micro butane torch with a heavily throttled-down flame for most incidental repairs. This is a perfect time to practice with Radio Shack solder and acid core flux. You will not believe how easy it is to get really good. Don't worry about toasting terminal or wire insulation, simply pass the flame more briefly across the work area. This is what practice is all about. It is rewarding to see solder wick up into the terminal so precisely that you can make out every strand of wire beneath a thin skin of solder. Practice on some badly corroded copper terminals. Scrape and buff off tiny practice areas, slather on some flux and see for yourself how easy it is to do the job right. Most cases of “humiliating experiences” with solder happened because garbage solder was used. Use Radio Shack or other 60/40 electronic solder, scrape off corrosion until the metal shines, dab on some flux and then prepare to smile – you won't believe how easy it is to get a beautiful soldered joint.
THE WORLD'S MOST EXPENSIVE ELECTRICAL OUTLET?
Remember reading about gold plated terminals above? In the rarefied air of high-end home audio, is an super premium 120 vac receptacle. The same type of “plug-in” as found throughout your home. But the WattGate® 381 “Audio Grade Receptacle” is about 200 times as expensive as a dollar off-the-shelf contractor grade receptacle! The body is made of nylon rather then plastic (similar to what you'd find in Hubbell and Marinco premium receptacles), But unlike unlike seven dollar premium nylon receptacles, the WattGate 381® receptacle manufacturer plates all metal parts, contacts, body and mounting tabs with pure gold! Extravagant? Certainly – but I can envision uses for such a device. I have an RV pad located within yards of the tropical Pacific ocean. Standard receptacles don't last long, especially when the power is switched on, the rainproof flap has been opened and a rig is plugged in. Because rigs come and go their hookup plugs are exposed only for a few weeks at most. It sure would be nice to fit a gold plated receptacle and be done with it. Of course fork terminals would have to be soldered onto the ends of the romex feed wires. Then heat shrink tubing would be applied, and liberal squirts of LPS-3 squirted over and into everything. But I sigh and relegate a dream like this to fit alongside those why I would need to drive a two-million dollar twelve hundred horsepower Bugatti.
DOES OIL AND BATTERIES MIX?
Wouldn't it be nice to add something to battery acid and dramatically reduce corrosion for the life of the battery? The only way this can be done is to reduce the amount electrolysis of the water in the electrolyte. A special battery oil additive has been around for decades and the Canadian invention does indeed eliminate corrosion and water loss. The product is called Thermoil® and you can buy it online. It makes sense to consider using this product in a new or nearly new battery.
SHEEP GREASE?
You can purchase anhydrous lanolin at the pharmacy counter in any drugstore (they will probably have to order it). Its consistency is similar to well chilled petroleum jelly. Mother nature designed lanolin to protect wool. In the process lanolin resists the effects of acids and oxygen – just the thing needed here along with being waterproof. Lanolin is corrosion inhibitor green style. I smear it all over bright surfaces on my rig before parking near the ocean. I have concocted a witches brew of lanolin and liquid LPS-3. I add a pound of lanolin to a gallon of LPS-3 by first heating the lanolin until it turns to liquid in the microwave. The sum total of the two ingredients is a longer lasting better penetrating anti-corrosion inhibitor. I use a commercial hand squirt bottle purchased at Home Depot for applying the compound.
UNBELIEVABLE BUT TRUE
After terminals have been cleaned and shined up, I will prepare the battery posts by first slipping a couple of felt post gaskets over the lead knobs. RV batteries have a weird shaped post so I will glop lanolin or LPS-3 around the base where the post enters the lid. Next I will liberally coat the post itself with corrosion inhibitor then bolt the terminal or clamp onto the post.
I can imagine the steam poring out of some reader's ears “Wait! You can't do that! Corrosion inhibitor is not conductive – it's an insulator and it would be crazy to smear stuff on the post. It should be clean and dry”. Sorry. Sometimes theory clashes with reality and this is one of them. I have greased thousands of battery posts and followed their history for years. Never has one of the terminals caused a problem and furthermore the lead posts stayed brighter than un-coated lead. If the thought of coating the battery post still leaves you queasy you can substitute copper anti-seize paste. I've used both with great success.
The same technique can be used for ground cables that attach to the chassis frame. I scrape off accumulated grime and paint. Shave the metal to a bright luster with 90 grit sandpaper, smear corrosion inhibitor on everything, bolt the lug down and then really gob on more inhibitor. Unless the area is washed with solvent or steam cleaned the connection will last for years.
Is it worth it? I am driving a seventeen year old sedan. The original owner had the car serviced at a garage that believed in applying battery post washers and corrosion inhibitor. According to the car's service records I installed its 3rd battery in May of 2011. The original battery cables are still used and they look like they're brand new. Call it smart, tightwad or green, I have better uses for my time and money than repairing corrosion damage.
© 2012, David Eidell. Reprinted with permission.