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Sometimes, the terminals, terminals or poles of the lead-acid batteries corrode and a kind of white crystals appear around them, which gradually deteriorates the electrical connection until it finally restricts the ignition of the starter motor. Then the popular sound of trac, trac, trac appears, when we pass the suiche to the START position. This sound tells us that there is not enough current from the battery to run our starter motor, and you will see a decrease in the brightness of the indicator lights on the board.
Not necessarily the corrosion indicates that the battery is damaged, this is very important to have it clear and I already explain why this phenomenon appears and how to avoid it.
A battery is composed of lead and sulfuric acid diluted in water, this union of components is called electrolyte. The chemical reaction releases electrical energy and can also store it. Corrosion only occurs when sulfuric acid leaks from the battery's internal electrolyte to the terminals and this can occur for some of these reasons:
Flooded battery: The battery was filled beyond the recommended level. The excess escapes through the ventilation grilles.
Battery reheated: The temperature increases the volume of the electrolyte and raise the levels until it escapes through the grilles or ventilation holes. This is why it is advisable to protect the battery from direct heat from the motor with some shielding if possible.
Over charge of the battery. Voltages above 14.5V increase the electrolyte temperature and volume. This is because already the electrolyte saturated with electrons, can not receive more charge and to compensate, there are internal losses (internal battery resistance) that consume the energy of overload and dissipate in the form of heat and the battery will bubble. It is a very dangerous condition, since hydrogen gas is produced, highly explosive.
Top of dirty battery with a lot of dust: It is normal, the evaporation of water, which carries some sulfuric acid in droplets that escapes through the ventilation of free maintenance batteries, for example. These micro drops are condensed in the dust and dirt on top of the battery and the problem starts when it accumulates.
Cracks or cracks in the electrolyte container or terminal base: It is possible that if there is any crack or defect in the sealing of the battery acid leakage occurs. For this reason it is not advisable to hit the terminals or apply pressure to them so as not to damage the base seal that causes electrolyte leaks.
In the following image you can see some examples of sulfation:
A - Leakage either by evaporated gases or bubbling through the electrolyte container lid, condenses in support.
B - Splash of non-neutralized acid in battery terminal. This could have happened when the battery was filled with fluid, or some overheating or bubbling of the ventilation splashed the terminal.
C - Dirt and leakage on top of the battery. The hydrated copper sulfate is seen in blue, near the battery terminal.
Now, we have already seen how the acid can escape and be deposited in the terminals or terminals of our battery. So now I will explain a little what happens.
Lead itself is a stable metal, its reaction with sulfuric acid is very slow. If contact occurs at the battery terminals, the compound that forms as a result of the reaction is lead sulfate (PbSO4). The chemical reaction between lead and sulfuric acid is, therefore:
Pb (s) + H2SO4 (aq) → PbSO4 (aq) + H2 (g)
The white substance that is seen around the terminals of the battery is lead sulfate made from the reaction explained above.
Also, copper terminals may be used for the connection of the battery terminals. Copper itself is not reactive, even if diluted sulfuric acid is poured on it. But when the electricity passes, it reacts with the sulfuric acid producing copper sulfate (CuSO4) together with water and sulfur dioxide. The equation of this chemical reaction is the following:
Cu (s) + 2 H2SO4 (ℓ) → CuSO4 (aq) + 2 H2O (ℓ) + SO2 (g)
The bluish substance that is seen around corroded copper terminals is hydrated copper sulfate. Copper sulfate is poisonous, you have to be careful with it.
**************************Cleaning is a fairly simple procedure.
1- Corrosion can occur in a dry environment, but is stimulated by moisture and salts present in the water. Therefore, keep the batteries clean, away from moisture and damp places.
2- Always keep the top of the battery dry and free of dust and other contaminants. After pouring water into a flooded lead acid battery, never forget to dry and clean the surface of the battery. Close the caps of the individual cells tightly to avoid accidental leaks.
3.- Do not fill the battery beyond the recommended level.
4- Apply Vaseline or grease to the terminals of the battery to protect them from corrosion. If there is no oxygen from the air, there is no chemical reaction.
5- Use battery terminals made of good quality copper that are also coated with alloy. The alloy layer prevents the terminals from corroding easily by the circulation of electrical energy.
Well, that's all. Soon I will make another article about the internal sulphation of the battery.
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