I'm going bad to worse. Last week I posted that I forgot to disconnect my house battery on class c then we took off snowbirding for 7 months in our trailer. Came back and after charging only got 0.97 volt. Batteries are shot. Yesterday I took out the batteries, to go get new. First cable I undid had a red collar on the cable. Thinking to myself great, that's the pos side its marker red. Then after pulling all the way out, discover both cables have a red collar on them. I think red collars are what somebody used to make cables. So I can't tell difference of pos and neg (they both have red collar) So before I hook up new batteries and screw something else up...Is this test right to determine pos and neg?Neg side should be grounded to frame? So just follow cable back and look. Then to confirm, start motor (so alt puts out some juice), put one volt meter probe on cable that is not grounded (which should be pos) and the other probe, ground out to frame. This would complete a connection and will show up on volt meter.Do I have this right or going to mess something up?Elec is my biggest short fall on RV's. Thanks

path1 wrote:Neg side should be grounded to frame? So just follow cable back and look. Yes, whichever cables eventually connects to the frame is going to be negative. You can also use your volt meter in OHMS mode, one lead on a battery cable, one lead on a screw head or bolt on the frame. The negative side will have a very low / 0 reading, the positive cable will have a higher reading.I wouldn't start the engine to test, instead, plug into shore power. Your on board converter will put 12v on the battery leads and you can check the polarity with your volt meter.Wrap the negative lead with green or white tape... as black also can mean positive in the land of RV wiring (black = hot, white = neutral)edit: fixed a typo

When you have successfully finished, and cables assembled and tightened, SPRAY PAINT the positive terminal and post red, and the negative post and cable black. Then slime everything with protective coating.Works every time.With 3 cell batteries, I paint the series connections, green.

What is or what makes a good protective coating? A forklift place behind where I retired from used "Noco NCP-2 Battery corrosion preventative spray" I still have about 1/2 can left but over 5 years old, will use it up, but will still need more. This stuff any good? Or what do you folks recommend? https://www.amazon.com/NOCO-A202S-Battery-Corrosion-Preventative/dp/B001DKRGLM

What is or what makes a good protective coating? Grease

Please understand...Chassis grease contains sulfurNot the ideal mix-n-match with copperDielectric silicone grease is light years better especially when it comes to very high temps. But even more important is sealing the junction between the lead battery post and plastic jar lid. The grease has to be applied meticulously to the underside of the battery lug as well as to the morphodite shaped "RV" lead post. Getting -under- the flat section is a chore. The terminals should be outright banned and a 3/8" + 5/16" stainless steel stud used. Anyway arguing will bring forth images of my 100 amp bussbar that was smeared with chassis grease then stored by a friend. "Chocolate" does not quite describe the patina. Sulfur and chlorine are both found in lubes and both are detrimental to shiny brass or copper. Pb does not seem to care.If thoughts of Kumbayah enter the picture sheep grease, anhydrous lanolin can be used. It works great but has a low melting thresh hold.

Doing stupid things to my elec system...question

westend
Explorer
Jul 15, 2016
Don't forget the penny under each clamp, lol.

I've used a variety of battery cleaners and terminal sealants. Grease is greasy, it will get on my shirt, my hands, and others. I lived with a shirt spotted or soaked in petroleum products for years. Grease won't kill 'ya but I don't need any more than is necessary on me now. Dielectric grease is expensive.

I am using the same can of Napa battery terminal spray that I first used 15 years ago. It sprays a red, rubbery spray onto the terminal and I may have to renew it when I clean terminals over the years.

If it was just air that caused corrosion on a battery terminal, we would be living in a sea of rust. The emitting of H2SO4 and sulfur dioxides is principally what causes corrosion. The acidic vapors need to come into contact with the metal terminal. So, yes, your solution of an "air tight" coating is correct.
path1
Explorer
Jul 15, 2016
Op here...After seeing some of the responses to

"What is or what makes a good protective coating"

(Just thinking) I assume that corrosion, like other things needs air to grow?

So I also assume a "good protective coating" is something that doesn't conduct elec and is air tight.

(I know assume...gets one into trouble)
MEXICOWANDERER
Explorer
Jul 15, 2016
No matter. fast-on terminals, clamp battery posts, lugs, whatever, silicone dielectric grease will only prevent contact if a connection is laid atop another with gravity holding it there. I am not arguing the dielectric integrity of the substance, merely dispelling the notion that if it is applied, conductivity will be lost in automotive electrical applications.

Terminal washers are excellent if if if if they are properly saturated with oil or preservative. NoCo terminal washers are good. DEKA brand washers are almost useless right out of the can. Saturate almost dry DEKA felt washers will oil or silicone grease and they will then work fine. When I run out of washers, a thick smear of silicone grease around the battery post to case, seal circumference works just as good.
GordonThree
Explorer
Jul 15, 2016
use AGM batteries, and keep them indoors :) the terminals on my duracells look just as clean as they did three years ago
rvten
Explorer
Jul 15, 2016
Spray paint works good on battery terminals also. Just a lite coat. Does not at tracked dirt and dust like grease.
RAS43
Explorer III
Jul 15, 2016
I have never been one to slop grease all over battery terminals as it leaves a mess over time. There are spray products that can be used after the terminals are tightened but I have had a good experience with those green and red felt terminal pads that slide over the post before the terminals. They seal the post to case seam, have a chemical acid neutralizer, and can be easily replaced without a lot of cleanup.
mkirsch
Nomad II
Jul 14, 2016
That is because the dielectric grease is getting SCRAPED AWAY where the electrical contact is made. The layer of grease on the direct contact surfaces is so thin as to be irrelevant, or completely nonexistent.

The grease itself will not pass current. It prevents corrosion because it's smeared all over everything else besides where the electrical contact is made.
MEXICOWANDERER
Explorer
Jul 14, 2016
Almost, this is being written with all smiles :) and salutations :)

Disconnect a battery cable, any battery cable...

chunk on the dielectric grease. Throw gobs and gobs on...

reassemble then throw a tremendous load on the connection...

SUR...

PRISE!

Reality is sometimes weird as hell ain't it?
Almot
Explorer III
Jul 14, 2016
Corroded metal shelve probably has nothing to do with the cause of death. Acid evaporates, and so does any liquid. Though old battery casing can develop cracks and leaks sometimes.
Ava
Explorer
Jul 14, 2016
The positive terminal on any normal battery is larger than the negative terminal, if that helps as well.

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