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Serious 12v battery corrosion. Normal?

Back in August when I had a service appointment for the acoustic blanket we noticed some serious corrosion on the negative port of the 12v battery. The tech cleaned if off and said it was no big deal. Today I wanted to check again and it looks basically the same as back then. Is this normal?
battery12v.jpg
 
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It all depends on your environment. For me in DFW (much drier than Orlando), I would find this troubling.

I would install oil impregnated felt rings (auto parts store) on both of the battery posts, and then coat the lug/post with a protective oil.
yes, I was going to say something similar. That corrosion sure looks worse than anything I've seen. Do I remember correctly.... doesn't it help to put petroleum jelly on those things, or did I just dream that up?
 
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jcanoe

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Oct 2, 2020
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This is caused by the 12V battery electrolyte leaking at the battery terminal post. The battery may test ok but the continued corrosion will eventually destroy the battery cable harness. Replacing the battery cable harness can be expensive.

You can clean up the battery terminal and battery cable corrosion with a wire brush, baking soda and water. Then flush with more water.

You can also use the Coke hack where you soak the battery cable connectors in a solution of not too cold Coca Cola. The phosphoric acid in Coke will dissolve away the corrosion. It really does work! Rinse off the cola after 5 or 10 minutes and dry the terminals. You will probably see where the corrosive action of the battery electrolyte has removed the zinc plating from the battery cable exposing the copper metal. The battery cable is still ok but you can see how this would eventually destroy the battery cable if not addressed.

To properly clean the battery terminal post you need to remove the battery terminal cable from the battery post. A battery post brush tool is handy for this operation. Dry off the clean post and cable harness before reconnecting. Avoid using any type of grease as this will seep into the connection and can interfere with the battery connection.

There are battery post rings sold at auto parts stores. These are color coded Red and Green. The rings are pretreated with grease that can help keep the electrolyte from working past the rings and contacting the battery cable.

I had this happen after 3 years with a 2011 Ford Fusion and the OE Duracraft battery. Ford would not cover under the warranty as the battery still tested good. I ended up replacing the Duracraft battery.
 
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jcanoe

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Oct 2, 2020
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jcanoe: So this could be indicative of a cracked battery case, at the base of the post? On a new vehicle, wouldn't that be covered under warranty?
Not a cracked case; just seepage of the battery electrolyte at the battery terminal post. You can ask Tesla to replace the battery, see what they say. Based on my experience with Ford as long as the battery passes whatever test Tesla performs that Tesla may not replace the battery under the warranty.
 

MY-Y

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Mar 4, 2020
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That's a sealed flooded cell battery. Clearly, it is leaking acid. Replace.

If you really don't want to replace it, a felt pad under the wire (sold at auto stores) will delay the corrosion, as will grease. Tesla should have replaced that battery when they saw that much corrosion.
 
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This is pretty common with any flooded/sealed lead acid battery and may be considered to be ‘within spec’ for this reason.

The best product to prevent this type of corrosion is dielectric grease, aka silicone grease. This should be applied after the connections have been mated together since this kind of grease does not conduct electricity.
 
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The argument would be, while it’s not pleasant to look at, it’s still functioning and doing its job ‘within spec.’

Don’t get me wrong, I would want to replace it as well... but personally, I would be going with a different chemistry (Li instead of Pb) so I can avoid this problem entirely and get some benefits in longevity at the same time.
 

jcanoe

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Oct 2, 2020
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At one time you could apply a small amount of dielectric grease, petroleum jelly, etc. to the battery terminals of a automotive 12V battery to prevent moisture and corrosion from ruining the connection however modern vehicles are very sensitive to 12V system voltage variations.

Today these products should not be used on the battery posts and terminal connections as the vehicle may incorrectly sense problems with the 12V system. The best thing to do is ensure there is a clean, tight connection at the battery post. Inspect the battery terminals regularly for signs of corrosion.

Battery post protectors are felt rings that are treated with waterproof grease. The rings install below the part of the battery posts where the battery cable connection is made so the grease in the ring should not interfere with the battery connection. This may provide some protection from corrosion if there is a small battery electrolyte leak around the base of the battery post. If the corrosion recurs the 12V battery should be replaced.
 
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jcanoe

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Oct 2, 2020
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Just got off the phone with service and they want to replace the battery. They even offered to do it today (in home service). They will determine if the terminal needs to be replaced as well. Thanks for al the input.
If the Mobile Service technician wants to reuse the existing battery cable, once the battery cable has been disconnected from the 12V battery you can quickly clean off the corrosion on the cable connector by dunking the end of the 12V battery cable in a small container or cup of Coca Cola for 5 or so minutes. Then just rinse the connector cable in fresh water. This works because Coca Cola contains dilute phosphoric acid; just imagine what it does to your teeth over time.

Here is a video:
 

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