Corrosion on Negative Terminal

[CFranks]

Hello all. At the end of my first short driving season I noticed some significant corrosion on the negative terminal of my battery. The attached picture is after only a few hundred miles. I have some theories but wanted to throw it out to this group to get your thoughts. Here is some relevant info:

-Brand new Yellowtop Battery (everyone’s favorite :) )
-Negative battery wire is gauge 4 and pre-fabbed from Del City
-No exotic electrical components that would draw excessive power
-1 wire alternator - note, I have been having problems with this guy. The charging post was loose, so I had to take it apart to get inside to the nut to tighten. After putting it back together it seemed to function as normal and operate at 14+v after initially revving the engine up as designed and continuing whenever I look at the gauge. It could be bouncing though when I’m not looking at it.
-Engine Ground (see photos). A normal gauge 4 wire connected to the block and then bolted directly to the 4” tube and then running to the solenoid.

Any thoughts? Could it be the alternator? Would my ground setup drive this? Any other ideas?

https://live.staticflickr.com/65535/49529889373_276deb857c.jpg (https://flic.kr/p/2isMCvT)

https://live.staticflickr.com/65535/49529888818_676a4b6ac2.jpg (https://flic.kr/p/2isMCmj)

https://live.staticflickr.com/65535/49530393051_578bfa81be.jpg (https://flic.kr/p/2isQdeZ)


Thanks,
Craig

[Papa]

Corrosion on the negative terminal can be caused by under charging. The other case is out gassing, which shouldn't be an issue with a sealed AGM battery.

[grluisi150]

Clean the connections and reassemble with dielectric grease. This will keep moisture and air out of connection.
Gary

[frankeeski]

Dielectric grease is a NON-Conductive, silicone-based grease that's designed to seal out moisture and prevent corrosion on electrical connectors. It also DISRUPTS the flow of electrical current, which makes it good for lubricating and sealing the rubber parts of electrical connectors.

Back to the OP's question. Any draw on the battery as the car is stored for even short periods of time may cause the corrosion you are seeing on the negative battery cable connection. Best practice is to clean it using a battery terminal cleaning spray and also applying a light cost of battery cable protector.

https://www.amazon.com/CRC-05046-Battery-Terminal-Protector/dp/B000CIPUNC/ref=sr_1_3?dchild=1&keywords=battery+cable+protector&qid=1581621061&sr=8-3

[Nigel Allen]

I work with UPS systems and diesel generators, as such, we deal with thousands of batteries. The corrosion problem is a result of electrolyte / vapour making its way through the seal between the terminal and the casing of the battery. Depending on the construction, this seal is sometimes an oring, sometimes just a press fit through the lid of the battery. Gary is right on the money with using grease. You just need terminal jointing grease (conductive) that is used in the electrical industry. Ensure all connecting surfaces are nice and shiny. Apply a bead of grease around the base of the terminal, then attach the clamp. Put a light smear of grease over the connections. Not super pretty but will be covered by the rubber boot. The gease will prevent oxygen getting in thereby preventing corrosion. we experimented with a number of spray on solutions but none of them work as well as the grease. Most have some level of porosity. Best of all this solution is permanent and will need no maintenance.

Hope this helps.

Cheers, Nigel in South Oz

[Nigel Allen]

oh, I forgot to mention we use Utilux H2397/1 jointing compound. A slight variation on its intended application, but 21years of use has proved it works.

Cheers, Nigel

[CFranks]

I work with UPS systems and diesel generators, as such, we deal with thousands of batteries. The corrosion problem is a result of electrolyte / vapour making its way through the seal between the terminal and the casing of the battery. Depending on the construction, this seal is sometimes an oring, sometimes just a press fit through the lid of the battery. Gary is right on the money with using grease. You just need terminal jointing grease (conductive) that is used in the electrical industry. Ensure all connecting surfaces are nice and shiny. Apply a bead of grease around the base of the terminal, then attach the clamp. Put a light smear of grease over the connections. Not super pretty but will be covered by the rubber boot. The gease will prevent oxygen getting in thereby preventing corrosion. we experimented with a number of spray on solutions but none of them work as well as the grease. Most have some level of porosity. Best of all this solution is permanent and will need no maintenance.

Hope this helps.

Cheers, Nigel in South Oz

Thanks. Is this all still the case with an AGM battery?

[Avalanche325]

Dielectric grease is a NON-Conductive, silicone-based grease that's designed to seal out moisture and prevent corrosion on electrical connectors. It also DISRUPTS the flow of electrical current, which makes it good for lubricating and sealing the rubber parts of electrical connectors.

https://www.amazon.com/CRC-05046-Battery-Terminal-Protector/dp/B000CIPUNC/ref=sr_1_3?dchild=1&keywords=battery+cable+protector&qid=1581621061&sr=8-3

Yes it is non-conductive. It is actually designed for protecting contacts and is designed to be smeared right on them. The secondary use is rubber boots. Clean the terminal and post, Put it back on, and coat the whole thing with dielectric grease. You can actually coat the terminals, it won't stop the physical connection. You just shouldn't load up a low voltage connector to the brim so it can stop connections.

The CRC spray is paraffin wax based, which is also NON-conductive.

[FF33rod]

What Nigel said, this has nothing to do with your alternator. It is kinda weird though for an AGM battery as it has to do with battery electrolyte being around. Perhaps left over from a previous battery?

Steve

[CFranks]

What Nigel said, this has nothing to do with your alternator. It is kinda weird though for an AGM battery as it has to do with battery electrolyte being around. Perhaps left over from a previous battery?

Steve
Thanks. So I did just replace another battery because the negative post was damaged and corrosion had formed and it wouldn’t hold a charge (some idiot accidentally shorted it with the positive side when putting it in the front battery box previously - that idiot is a.k.a “me”). It was another yellow top though so still agm. This is the same cable (I had cleaned it) though, I have another cable so maybe will swap it out.

[frankeeski]

Yes it is non-conductive. It is actually designed for protecting contacts and is designed to be smeared right on them. The secondary use is rubber boots. Clean the terminal and post, Put it back on, and coat the whole thing with dielectric grease. You can actually coat the terminals, it won't stop the physical connection. You just shouldn't load up a low voltage connector to the brim so it can stop connections.

The CRC spray is paraffin wax based, which is also NON-conductive.

It's always amazing to me, 30+ years in the electrical trade and someone thinks they are going to school me on the use of dielectric grease. You can smear poop on the connection for all I care. Dielectric grease is used to keep water/moisture out. You want to slather it inside and outside the connection be my guest. An insulator make it harder for the electricity to flow (resistance).

And the Battery protectant spray is used after the connection has been made, not during the assembly. Just like dielectric grease should be used.

Have a wonderful day. :)

[CraigS]

I have used wheel bearing grease. The sole purpose here is keeping air/gas from the terminal. Dang near anything that won't dry out or melt away will work. I keep a small tub of synthetic bearing grease w/ a small hole in the top and a small brush in the hole in the cabinet. Really handy to brush a little grease on things when assembling.

[mike223]

I have used wheel bearing grease. The sole purpose here is keeping air/gas from the terminal. Dang near anything that won't dry out or melt away will work.



+1

My UPS / generator expert says it's caused by acid / vapor leaching through the lead terminal(s).

Not significantly different than leaching through the plastic to lead junction (just a slightly different theory).

I've seen them where one battery terminal eventually became a noticeably different shade of gray from the other (one terminal ended up more porous than the other? - my theory).


Bear in mind that the only reason it works is because of an ongoing chemical reaction between lead plates and acid...


Doesn't matter - clean + grease.

[Avalanche325]

It's always amazing to me, 30+ years in the electrical trade and someone thinks they are going to school me on the use of dielectric grease. You can smear poop on the connection for all I care. Dielectric grease is used to keep water/moisture out. You want to slather it inside and outside the connection be my guest. An insulator make it harder for the electricity to flow (resistance).

And the Battery protectant spray is used after the connection has been made, not during the assembly. Just like dielectric grease should be used.

Have a wonderful day. :)

I am having a wonderful day! Thank you.

Nuclear submarine electrician, shipboard and nuclear power plant control systems and data acquisition systems specialist are all on my resume.

Note that I said this - "Put it back on, and coat the whole thing with dielectric grease." Which is what I tend to do. So we are in agreement.
However, you can put it on battery posts. Which is what the manufacturer actually says to do. It is hardly going to stop the mechanical / electrical connection. What it is going to do is fill any little moisture trapping gaps.

One thing I have learned is that there is always more to learn, no matter how long you have been doing a job. So, what does the manufacturer say?

https://www.permatex.com/products/specialized-maintenance-repair/electrical-system-maintenance/permatex-dielectric-tune-up-grease-2/

Which says:

"Connectors and Battery Terminals:

Make sure ignition system is off.
Clean surface with Permatex® Battery Cleaner.
Coat both parts of terminal contact with Dielectric Grease.
Reassemble maintaining metal to-metal contact."

[CFranks]

Thanks all, seems the consensus is to clean and put on some grease. I’ll start with that!