Often people don’t use anything on their car battery terminals to protect them, which is fine when everything is working as it should.
Since corrosion is one of the biggest car battery terminals enemy, I will address some important things.
Do car battery terminals need grease?
Car battery terminals need grease to protect them from corrosion. One of the main reasons for this is caused by battery overcharging, making gas escape, passing by terminals, and react with the metal creating oxidation.
Should you put grease on car battery terminals?
Do you need to put grease on terminals depends on many factors?
You should put grease on terminals to prevent corrosion formation, but it is not necessary.
The battery will work either way, as long as terminals and clamps are clean out of the corrosion and they are connected and well tight together.
There are two reasons why corrosion will form over the terminals.
The first is when the battery getting overcharge to the point that sulfuric acid starts to boil.
Boiling acid will make hydrogen gas vent out of the battery.
Eventually, gas will find a way to escape due to high-pressure buildup inside a battery through terminal seals making terminals corrode.
A bad alternator or a bad charger will cause the battery to overcharge. Both of them will pump more Voltage than is required for charging a battery safely. Due to excessive heat terminals will get hot. This is especially important if you trying to charge a new car battery, if you damage it by overcharging it, you will void warranty by doing so.
The second is if you live in a cold and humid climate. This kind of weather will for sure make terminals oxidize.
And if terminals oxidize a new problem might occur, which is heat. Read this article to learn more about why terminals might get hot.
So, the best way to prevent corrosion buildup is to put grease over the terminals.
Grease types for car battery terminals
There are several types of grease out there you might consider when it comes to greasing terminals to prevent corrosion.
And there are pros and cons to all of them.
We can classify them into two groups. The one of which will conduct electricity and the other which will not.
Non-conductive are:
- Silicone-based
- White Lithium grease
- Copper grease
- Teflon based
- Oil-Based
- Wax-based
Conductive is:
- Graphite grease
The main purpose of all of them is to prevent oxidation formation. They are doing that by repelling water and humid air.
Which grease do you put on car battery terminals depends on who you ask. Most of the battery manufacturers will not give such an informations, if you compare car battery brands from manuals, you will not find any recomendations about should you put grease on terminals or not.
And it’s more important to grease terminals of a lead-acid car battery types independently from Lithium based types batteries because the Lithium ones will not vent out harsh acid vapours to make terminals corrode.
But the main decision will be either what you already have in the garage or what you prefer so that you will buy it.
Non-conductive or dielectric grease
You can often hear that you should put dielectric grease on battery terminals. But wait, dielectric means non-conductive, and terminals and clamps are electrical connections.
If you think logically, you really shouldn’t put an electrical insulator between electrical connections.
And you are right, to a certain extent.
When you put dielectric grease on terminals and clamps and bolt them together, what will really happen is when you tighten them, a clamp will squeeze out the majority of grease, making a good connection.
Grease that will stay inside will fill out micro gaps making air and water unable to get trapped.
Not all dielectric greases are the same.
Let’s compare them and see pros and cons:
Silicone grease
Silicone-based grease is an excellent choice for protecting terminals from corrosion.
The main characteristics of a silicone-based grease are that it has very good resistance to hot vapors and can withstand temperatures from -40 °C (-40 °F) all the way to +150 °C (302 °F).
The downside is that you need to maintain it routinely in order to keep on the protective layer.
White lithium grease
White lithium lubricant is great all-purpose grease. It can withstand extreme temperatures.
They are mainly used in metal-to-metal applications where there is a rubbing to each other.
Examples might be garage doors, springs, car door hinges, sliding doors, bolts, hinges, chains, etc.
It also has great hydrophobic properties.
As such, it can be used to protect terminals from corrosion well.
But, it’s advisable first to clean terminals and clamps, bolt them together, and after that apply white lithium grease.
White lithium grease can dry, so it needs to be reapplied regularly.
Copper grease
Copper grease has a very wide temperature range. It works the best from -40 °C (-40 °F) to 1,150 °C (2,102 °F).
It is also called anti-seize because it’s very good for preventing corrosion.
Because it can withstand high temperatures and prevent seizing, it is recommended for flanges, wheels, nuts, bolts, exhaust brackets, studs.
It’s commonly recommended for preventing corrosion on battery terminals.
Oil-based grease
Oil-based greases are not commonly suggested for protecting terminals from corrosion.
They are used in a situation where you have to protect surfaces from rubbing against each other. They are high viscosity fluids that will increase when temperatures go up.
So, they are not recommended to protect terminals.
They can be used in winter times where temperatures are low and also in emergencies where you don’t have any other choice.
Wax-based grease
Compared to oil-based grease, wax-based has better viscosity. It can stay longer.
This lubricant is not commonly recommended for protecting terminals, but it can be used in emergency situations.
Wax-based grease is used in applications where parts are moving and rubbing to each other, especially in the bicycle industry to lube chains.
Wax lube has a very impressive temperature range in which operates the best. It can go from -30 °C (-22 °F) to +130 °C (266 °F).
PTFE or Teflon based grease
Teflon lubricants have very high penetration ability, and they are not electrically conductive.
Because of that, you should never use them on battery terminals.
It’s better off not to protect terminals with anything than with PTFE grease, until you buy the suitable one.
This type of grease is used to lube chains and cables. It is also used to lube cabinet hinges and drawers.
Conductive grease for protecting terminals
Conductive types of grease are the best when it comes to protecting terminals from corrosion and also making sure that the connection is strong.
They conduct electricity, so they are an excellent choice for terminal connections.
Due to this property, you will have a minimal amount of resistance between terminals and clamps, which is negligible.
They are also very good at repelling water and have a very good temperature range where they work best.
This type of grease is also used in applications other than protecting terminals from corrosion.
Graphite grease
Graphite grease is an excellent choice for metal-to-metal connections. Also, it’s suitable for moving parts rubbing to each other.
It’s a good water repellent and also very good for conducting electricity.
Because of that, it can also be used for battery terminals to protects them against corrosion.
It’s recommended for using on hinges, sliding surfaces, spark plugs, chains, lathes, and electrical connections.
Because this grease is made out of graphite does not lose electrical property over time, so it’s a very good long-term solution for protection. It also can withstand temperatures from -20 °C (-4 °F) to +70 °C (158 °F).
Is it OK to put Vaseline on battery terminals?
Vaseline is also known as petroleum jelly. It has a wide range of applications in medicine and for cosmetic purposes.
It does not conduct electricity, but it’s a good water repellent.
The melting point of petroleum jelly is between 40 °C (105 °F) to 70 °C (160 °F).
It is not flammable as such. When it’s melted to a liquid, fumes will light, making flames.
Can you use Vaseline instead of dielectric grease?
Many people are already using Vaseline to protect battery terminals from corrosion.
It has similar properties to dielectric grease. It can be used as a replacement for emergency situations.
Because it’s not commercially recommended for this application, I strongly recommend using some sort of dielectric grease instead of petroleum jelly.
And use Vaseline only if you don’t have any other choice at your hand.
Electrical conductivity comparison of grease
If we want to compare the resistance of different greases, we need to make sure to measure them first.
Every type of grease has some amount of resistance. Some of them are higher or lower than others.
In our situation, with car battery terminals, we need as little resistance as possible to maintain a solid electrical connection.
I recommend watching this video below to see the resistance difference of several greases measured in Ohms:
He demonstrates resistance between two copper bars lying down, one on top of the other, with several greases between them.
He is measuring resistance expressed in Ohms, applying Voltage on them.
The results are very interesting.
What is the best thing to put on battery terminals?
The best and the most recommended grease to put on battery terminals to protect them from corrosion is silicone dielectric grease.
Dielectric grease prevents acid vapors and water from getting inside contacts making them corrode.
By sealing gaps between contacts corrosion won’t form, and the final result is low resistance, which is good for electrical connections.
How do you grease car battery terminals?
First of all, whether your terminals are corroded or not, it is a good idea to clean the connections, before grease them.
When terminals are clean put a thin coat of dielectric grease over the terminals.
Put a clamp over the terminal and bolt them tight together.
Excess of grease will be squeezed out and you will have nice sealed, strong connection.
Helpful Sources
Here you can find more about dielectric grease vs conductive grease, and how their application compares to each other on car battery terminals.
And be sure to read Wikipedia article about silicone grease (dielectric grease).