That chalky gunk on your battery is probably corrosion. This greenish or whitish residue often forms on battery posts and cable terminals and can cause issues.
While battery corrosion is fairly common, the great news is you can easily remove it yourself in just minutes and simple tools. Read about what causes corrosive battery deposits and then follow step-by-step instructions to safely clean them away.
How to Clean Corroded Battery Terminals?
The next six steps will yield your battery’s posts and terminals a cleaning that will restore integrity to your electrical systems.
Gather Your Supplies: Before cleaning can begin, you will need to get all the supplies that you will require. They are:
- Battery Terminal Cleaner or Homemade Alternative (baking soda/water)
- Battery Terminal Brush or Old Toothbrush
- Corrosion Inhibitor or Petroleum Jelly
- Rag or Paper Towel
- Rubber Gloves
- Basic Set of Hand Tools
Step 1: Remove Battery Cables.
You will now remove your battery cables. Remove the negative cable first, then the positive. Each of these cables should be long enough to allow its terminals to be cleaned properly.
If either terminal is corroded through or otherwise of questionable structural integrity, replacement is the better option.
Step 2: Clean Each Terminal
Next, get ready to clean each terminal. If using a store-bought product like CRC battery cleaner, spray this solution onto each terminal at this time.
If you’ve decided to make your own solution, mix a tablespoon of baking soda into a cup of water. Differently, some motorists choose to use vinegar in a similar way. Stir that mixture until all of the baking soda dissolves and apply it to your battery cable terminals.
With your cleaning solution on, vigorously scrub each terminal with a battery terminal cleaning brush like this Schumacher one (good and cheap) until all corrosion is gone. An old toothbrush with considerable effort will also work.
It’s also a good idea to re-examine each terminal for damage after all corrosion has been removed.
Step 3: Clean Battery Posts.
You will now clean each post in much the same way as you just did with each terminal. Apply your cleaning solution to each battery post, and scrub vigorously, with the aid of the same brush as above.
Make sure no corrosion remains when you are finished.
Step 4: Wipe All Residue Away.
With corroded material having been cleaned off both of your battery’s posts and terminals, all remaining residue must be wiped clean.
Using a rag, wipe away all remaining corrosion or cleaning material until each terminal shines up metallic.
Step 5: Coat With Corrosion Inhibitor.
You will now coat each battery post with a corrosion inhibitor to avoid experiencing the same issue again sometime in the future. You can choose store-bought inhibitor products or use petroleum jelly, both of which are generally equally effective.
Step 6: Reattach Battery Terminals.
With everything having been cleaned, examined, and treated, it is time to reconnect your terminals to their respective battery posts. Tighten each down securely, and make sure they are not loose to any extent.
What Causes Car Battery Corrosion?
There are actually three different types of battery corrosion, each caused by a different reason. While the cause of each can differ, all are capable of causing the motorist headaches should they not be dealt with in a quick manner.
Corrosion through the normal venting of hydrogen gas from within a battery: the most common type of corrosion. Hydrogen gas is produced when the battery acid heats and cools, and this gas, created by the battery, is expelled from vents in an automotive battery, and this gas reacts with the lead of the posts, creating corrosion.
Corrosion from a reaction with the battery copper terminal clamps and the posts. This typically only happens when the posts are exposed to moisture, and is recognized by the buildup of corrosion, which is green in color.
Battery corrosion occurs through a process called sulfation. All automotive batteries contain a chemical substance known as sulfuric acid which can crystallize with age, especially in batteries not regularly put on charge. Sulfuric acid is what you see on the rare occasions a car battery is leaking.
This type of corrosion is also common in batteries nearing the end of their service, or used in little-run vehicles.
How Corrosion Affects Your Vehicle
Battery terminal corrosion can interfere with your vehicle’s ability to function correctly, regardless of how bad it is. The corrosion creates resistance within a vehicle’s electrical circuitry, and that resistance stifles the free movement of electricity through a vehicle’s electric circuits.
Virtually all automotive electrical systems are designed to operate off of a certain preset voltage. Too much resistance from battery terminal corrosion can stifle flow to the point that the voltage will drop below a certain circuit’s effective level.
As a result, this causes lots of systems in your vehicle to be affected, particularly those concerning starting and charging. Indeed, one of the symptoms you’re most likely to run into due to battery terminal corrosion is a no-crank, or slow crank condition. You may hear a click, or a series of clicks, if you try to crank your car.
Your vehicle’s battery is its sole source of electrical energy during cranking. If the battery is unable to transmit peak voltage and amperage through its proper cables, a lot of the time, a car won’t crank at all.
How to Prevent Car Battery Corrosion
If corrosion hasn’t already developed on your battery posts or terminals, there are several steps you can take to stop the progression of this condition.
Taking these measures can fortify your vehicle’s electrical system and insulate you from many of the operational issues that typically accompany battery corrosion.
Use Corrosion Inhibiting Sprays
A number of corrosion inhibitors are available on the market today, which can be easily sprayed onto your battery posts and terminals to avoid the formation of corrosion. These products function because of their ability to seal a battery’s connections from water intrusion.
If terminal spray isn’t available, WD-40 can also be used in much the same fashion.
Use Corrosion Inhibiting Oil/Gel
Much like the previously mentioned corrosion inhibitor treatment of a spray form, oils and gels work to seal a battery’s posts and terminals from the intrusion of water.
Products of this nature are used to thoroughly coat the outer exterior of battery-related connections, where they remain for a period of time. Many motorists use petroleum jelly in a similar fashion.
Use Corrosion Inhibiting Pads
Corrosion-inhibiting battery post pads can be used by themselves or in conjunction with a chemical-derived corrosion inhibitor to prevent such a build-up from taking place.
These pads are most generally soaked in a corrosion-resistant compound, intended to keep hydrogen gas from escaping between a battery’s casing and posts.
Keep an Eye on Charging System Health
Closely watching your vehicle’s charging system can also prevent battery corrosion. This system uses a belt-driven alternator to provide a steady stream of power to your car’s battery while in operation.
An under or overcharging alternator can lead to a host of corrosion-creating conditions, including sulfation.
Cleaning Battery Terminals Vs Replacing
Almost every corroded battery terminal can be cleaned satisfactorily. In extreme cases, this simply cannot be accomplished. When this happens, terminal replacement is the only option.
Cleaning battery terminals takes just minutes, and can be done by anyone of modest mechanical aptitude. When a battery’s terminals are in adequate condition, this is the most inexpensive solution.
Corrosion can become severe enough to corrode a battery’s terminals beyond the structural integrity of the battery. Terminals can corrode to the extent of actually pitting on the face of their contact surface, or they may become difficult to tighten securely in place. When this happens, replacement is in order.
Can I clean car battery terminals without disconnecting?
No, you cannot properly clean battery terminals without first disconnecting them.
In order to clean corrosion from your battery’s connections, both terminals must be disconnected from their posts. Failing to do so makes it impossible to reach the contact surface between the battery’s post and the terminals with whatever cleaning substances are to be used on them.
As a result, cleaning your battery’s terminals without first disconnecting them does little more than to remove surface corrosion. This can leave you facing many of the same symptoms, since the proper terminal-to-post connection was not restored.
By disconnecting your battery cable’s terminals from their respective battery posts, you can remove corrosion in its entirety, while also helping yourself determine a terminal’s structural integrity. In the process, you are better able to make a sound judgment as to whether or not terminal replacement is called for.