What to do if the battery terminals are oxidized
Useful tips for motorists

What to do if the battery terminals are oxidized

Car batteries contain a very aggressive substance - sulfuric acid in the composition of the electrolyte. Therefore, the safety of output terminals, which are usually made of lead alloys, is not enough to ensure on a general basis, as they protect all other vehicle wiring from atmospheric influences.

What to do if the battery terminals are oxidized

It is important to take into account the effect of the electrolyte and some other products of electrochemical reactions in batteries. Sealed and maintenance-free batteries do little to help with long service life.

What causes battery terminal oxidation?

For the appearance of oxides, the presence of:

  • metal;
  • oxygen;
  • substances that serve as catalysts for the process;
  • elevated temperature, which increases the rate of all chemical reactions.

It is also good to have an electric current flowing through the surface of a metal object, which turns the chemical process into an electrochemical one, that is, many times more productive. From the point of view of oxidation, not just any part of the car, but the battery terminal, where it is important to take into account the fact that any reaction on the surface of the lead terminal is called oxidation. It has nothing to do with oxidation.

Lead sulfates can hardly be called oxides, like copper sulphate, that is, copper sulfate, as well as many other substances of mineral and organic origin. It is important that they all degrade the properties of the external battery circuit, lead to electrical failures, so they need to be dealt with effectively, and not an accurate chemical analysis.

Hydrogen gas leak

During charging and even intense discharge of a lead-acid battery, hydrogen, as the main reaction product, is not formed. There is a transformation of pure lead and its combination with oxygen to sulfate and vice versa. The acid in the electrolyte during these reactions is consumed and then replenished, but hydrogen does not emit in large quantities.

What to do if the battery terminals are oxidized

However, when the reaction proceeds with high intensity, mainly at high charging currents, the hydrogen involved in intermediate chemical transformations does not have time to recombine with oxygen and turn into water.

In this mode, it will be intensively released in the form of a gas, forming a characteristic "boiling" of the electrolyte. In fact, this is not boiling, the solution will not boil at such low temperatures. This is the release of gaseous hydrogen and oxygen.

An additional share of gases is supplied by the water electrolysis process. The current is large, there is enough potential difference, water molecules begin to decompose into hydrogen and oxygen. There are no conditions for the reverse transformation, gases begin to accumulate inside the battery case. If it is sealed, as is done in maintenance-free batteries, then the pressure rises.

The path will be freer for a battery that has worked a lot with loosened external fittings. The gases will go out, flowing around the metal of the terminals and entering into chemical reactions.

electrolyte leakage

It is not necessary to expect that under the conditions of the passage of gas in vapors of sulfuric acid and water through leaks into the atmosphere, things will do without capturing part of the electrolyte.

Molecules of sulfuric acid will fall on down conductors and terminal lugs in abundance. In addition, they are heated by significant currents. Immediately, the above substances will begin to form. Terminals literally bloom with a lush bloom, usually white, but there are other colors.

Electrolyte leakage from under the battery cover

The electrolyte can also pass through defects in the filling of the case, as well as through ventilation, which can be free or with a protective valve. But at high pressures, this does not matter.

The result is always the same - sulfuric acid that appears on metal surfaces will very quickly turn them into what, for simplicity, is called oxide. That is, substances with a large volume, causing souring of all compounds, but at the same time disgustingly conducting electric current.

What gives an increase in transient resistance, an increase in temperature, an acceleration of reactions and, at the end, a failure of the terminal connection. This is usually expressed in the form of starter silence when the key is turned to start. The maximum that occurs is a loud crackling of the retractor relay.

Clamp corrosion

Against such a powerful background, you can already forget about ordinary corrosion. But when the battery is absolutely sealed and in good condition, and all modes are normal, then its role comes to the fore.

Corrosion proceeds rather slowly, but inevitably. After a few years, the surface of the terminals will oxidize so much that the contact resistance will not allow the desired current to be delivered. The behavior of the starter in such cases has already been described.

What to do if the battery terminals are oxidized

Not only the battery terminals are subject to corrosion, but also their counterparts on the cables. It does not matter what they are made of, lead, copper, any alloys tinned with tin or other protective metals. Sooner or later, everything oxidizes except gold. But these parts are not made from it.

Battery recharge

Especially intensely aggressive substances are torn out due to overcharging. The energy of an external source can no longer be spent on useful reactions of converting lead sulfates into the active mass of electrodes, they simply ended, the plates were restored.

What to do if the battery terminals are oxidized

It remains to overheat the electrolyte and cause abundant gas formation. Therefore, it is necessary to carefully monitor the stability of the charging voltage, avoiding its dangerous excesses.

What can oxides on contacts lead to?

The main problem that oxides create is the increase in transient resistance. When current flows through it, a voltage drop occurs.

Not only does it get less to consumers, and sometimes it doesn’t get it at all, so heat begins to be released on this resistance with a power proportional to its value multiplied by the square of the current strength, that is, very large.

With such heating, all contacts will be destroyed quickly, if not physically, the voltage is still limited, then in the electrical sense. Electrical equipment failures will begin in the car, sometimes inexplicable at first glance.

Is there a difference between the oxidation of bipolar terminals

There are many legends and myths about the various reasons for the oxidation of bipolar terminals. In fact, these are all products of thoughtful observation of the process by numerous victims of wear and tear of equipment and their own lack of knowledge.

There is no difference between damage to the terminal tips of the anode and cathode, it is the same metal under the same conditions, and the direction of current flow can only affect the galvanic effects between the parts of the connector.

Against the background of the loss of contact for the reasons already stated, this can be neglected, the phenomena are of purely theoretical interest to science enthusiasts.

How and how to clean the battery terminals

Cleaning is carried out mechanically, depending on the degree of contamination, metal brushes, coarse rags, knives and files can be used.

It is important to remove the reaction products, while minimizing the consumption of the metal of the terminal. Otherwise, over time, the conclusions become thinner, it is more difficult to fix the tips on them.

What to do if the battery terminals are oxidized

The cable part of the connector must also be cleaned. Similar tools. You can also use a rough skin, but this is undesirable due to the introduction of detached parts of the abrasive into the metal. But usually nothing bad happens, after cleaning with sandpaper, the terminals work fine.

How to avoid battery terminal oxidation in the future

After cleaning, the terminals must be protected. This is done by lubricating them with any universal grease compositions. For example, technical petroleum jelly, although any other similar product will do.

What to do if the battery terminals are oxidized

It is not even the quality of the lubricant that is important, but its regular renewal, rinsing with a solvent and applying fresh. Without access to oxygen and aggressive vapors, the metal will live much longer.

There is no need to worry about contact failure due to the use of lubricant. When the terminal is tightened, the protection layer will easily be pressed through until metal-to-metal contact, while the remaining areas will remain lubricated and preserved.

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