Painted battery terminal

showcrop · Sep 8, 2021

The positive post of the battery and the + terminal of my '67 Datsun is getting coated with a black coating that looks just like paint. It gets all over the terminal except for the nut and bolt that tighten the clamp, and the screws and plate that holds the cable. It is also uniformly all over the post including the contact surfaces of both. The terminal was new six weeks ago. The old terminal never did this.

Note that it is uniform like paint. It insulates the terminal from the post. When it first happened I cleaned it from the mating surfaces and put the terminal back on and it worked well for another 250 miles and then it was coated again. the material is liquid like paint. There is no unusual heat.

johnofnewhaven · Sep 8, 2021

I think your battery is the culprit
and it's going bad. I think it's
releasing gases and that's what's
causing it.

Stephen Newell · Sep 8, 2021

https://www.yourmechanic.com/question/what-causes-my-pos-battery-terminal-to-turn-black-by-clyde-w#:~:text=The%20black%20colored%20surface%20on,not%20to%20transmit%20power%20properly.

SVcummins · Sep 8, 2021

Thats where the battery washers come in handy and some
dielectric grease

K in Iowa · Sep 8, 2021

That would be lead oxide. Likely leaking from around the battery post.

rustred · Sep 8, 2021

quite a normal situation with old battery's. put some grease around the post and on the clamp. on of the oldest fixes around.

Crazy Horse · Sep 9, 2021

Interesting question Showcrop BUT what is even more interesting is your '67 Datsun.
Can you post a pic for us?

Geo-TH,In · Sep 9, 2021

SV
I use a dielectric grease that electricians put on the big Aluminum wires going to load center.
AGM batteries are less likely to have oxidation on terminals, no battery acid gasses.

Geo-TH,In · Sep 9, 2021

Didn't Datson make a 280z? My nephew had one. Only lasted 10 years in Indian's rust belt before the sub frame was gone. It was a neat looking sports car.

Crazy Horse · Sep 9, 2021

Yes they did, and the Nissan name was used in Japan I believe while it was Datsun elsewhere. I remember a Jeep-type vehicle called the Nissan Patrol back in the day while Datsun sedans were being sold in North America. Eventually the Datsun name disappeared for whatever reason, all Nissan now. Here's some info fro Wikipedia on your nephew's car .... very collectible these days and I'm sure the rust was an issue ......

The Nissan S30 was sold in Japan as the Nissan Fairlady Z and in other markets as the Datsun 240Z, then later as the 260Z and 280Z. It was the first generation of Z GT 3-door two-seat coups, produced by Nissan Motors, Ltd. of Japan from 1969 to 1978.

Hobo,NC · Sep 9, 2021

I attended a interstate podcast and asked WHY it does this they said its a deflective battery I hope you are not seeing this on our battery's. Yes I see this from time to time on batteries I did not install.

I coat the terminals and the base of the terminals with silicon dielectric grease so I don't see that on my installs. Those worthless felt washers give the most trouble I throw all I see AWAY. It does not take long before they loose their effect then they become a trap a sponge that holds the corrosive material.

Either way the issue is the battery its defective it will haunt you till death do you part.

showcrop · Sep 9, 2021

Well that makes sense but it sucks because it is only two years old. I bought it at my local independent auto supply so I know that they will give me the prorated warrantee on it. I am currently prepping the barn in the background for paint. I am having to replace a lot of clapboards.

Here are a couple of pics:

The woman in the second is my sister. The odd looking seats were from a Miata. I picked them up as a short cut and last spring I rebuilt the originals.

DoubleO7 · Sep 9, 2021

That is a beautiful car.
It deserves better battery terminals!
Either full factory made with the cable molded into the battery terminal end or some ends like these.

showcrop · Sep 9, 2021

(quoted from post at 06:16:09 09/09/21)
That is a beautiful car.
It deserves better battery terminals!
Either full factory made with the cable molded into the battery terminal end or some ends like these.

Thanks Double07, I have never seen that type. I will look for them.

DoubleO7 · Sep 9, 2021

Compression battery terminal.
One source is NAPA at $12 +/- depending on cable size needed.

Hobo,NC · Sep 9, 2021

That's not a permeant repair either : ( Tho better (maybe) it will comeback to haunt you.

Hdonly · Sep 9, 2021

I go around and spray mine with WD-40 once a month. No problems.

1948CaseVAI · Sep 9, 2021

(quoted from post at 05:48:26 09/09/21) SV
I use a dielectric grease that electricians put on the big Aluminum wires going to load center.
AGM batteries are less likely to have oxidation on terminals, no battery acid gasses.

Dielectric is a very poor protector of aluminum wiring plus it is an insulator. You should use Noalox on aluminum wiring to protect it from the corrosion that can cause poor connections. Noalox is conductive so facilitates good connections. Look up the difference - they are different products for different uses.

BarnyardEngineering · Sep 9, 2021

(quoted from post at 06:56:38 09/09/21)
Compression battery terminal.
One source is NAPA at $12 +/- depending on cable size needed.

Walmart has them as well. I keep a supply in my battery cable toolbox.

showcrop · Sep 9, 2021

I took the battery and got it tested and it showed only 225 out of rated 700 CCA so I got it replaced at 50% cost under the prorated warrantee. I will be monitoring my voltmeter to see how much it is charging.

Painted battery terminal

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