In this article we will talk about why the battery can boil and what this "phenomenon" means.
Main reasons
Battery boiling usually occurs when the battery is almost fully charged. Various instructions for charging batteries state that the battery is charged when it is the density does not grow for several hours and at the same time gases are released abundantly, that is, there is abundant gas release.
Boiling of the battery can also be observed when the battery is recharging, when the relay-regulator or charger outputs a voltage of more than 14.4 volts, that is, the battery is being recharged.
The formation of bubbles on the plates is also observed during self-discharge of the battery, when the battery has the phenomenon of self-discharge, if you look in the bank - from time to time you can see how they rise from the plates bubbles.
Also, the battery immediately boils when charging with strong sulfation. That is, you connected a sulfated battery to a charge - it immediately begins to boil, gas evolution occurs and the temperature of the electrolyte rises.
So, from the above, I will summarize the main reasons for the battery boiling:
- The battery is charged;
- Recharge the battery;
- Self-charging of the battery;
- Sulfation.
Why is that? Now we will deal with this!
Understanding the essence of the battery boiling process
Understanding the essence of this process is very important if you want to understand what is going on inside the battery.
So, what is this process called "battery boiling", what is it connected with, how to deal with it and what leads to what?
So, everyone knows perfectly well that from time to time it is necessary to add distilled water to the serviced battery.
Where does it go? It has two ways: either in hot weather it evaporates through the ventilation system, or the very process that we will talk about now takes place.
So where does the distilled water from the battery go? As a result of the loss of distilled water by the battery, the density of the electrolyte in it increases, which in turn leads to sulfation of the plates.
Where did the water go? And the water goes to such a thing as water electrolysis. What is electrolysis? Electrolysis is an electrochemical process that occurs through two electrodes placed in the electrolyte: a positive anode (in our case, this is positive plate) and a negative cathode (we have these negative plates in the battery) and through these two electrodes a constant current.
It is under these conditions that the phenomenon of water electrolysis occurs. To put it simply, the decomposition of water into hydrogen and oxygen. In this case, pure oxygen is formed on the positive plates, and hydrogen is formed on the negative plates. This process produces twice as much hydrogen as oxygen.
That is, the bubbles in the negative plates emit twice as many bubbles as the bubbles in the positive plates.
Whoever remembers chemistry lessons from school knows that hydrogen is also called differently - namely, explosive gas. Why it has such a name is easy to guess, because in a certain proportion of mixing hydrogen and oxygen, it explodes very wonderfully at the slightest spark or open fire.
It is due to the boiling of the battery, that is, the phenomenon of electrolysis of water in the battery in which ventilation is faulty from time to time this explosive mixture is collected, which sometimes leads to the fact that your battery is blown away at the slightest malfunction, hitting an open fire.
That is, the battery explodes, the entire hood is in electrolyte, the entire motor is in electrolyte, plastic in pieces, and so on.
That is why, so that it does not explode, the battery has a spark arrestor in the ventilation holes. This is a little white pill that stands in the ventilation window and called a flame arrester (see the picture below). It just saves your battery from being blown over the engine compartment.
As everyone knows, at the beginning of charging, a discharged battery does not boil. Why isn't it boiling? Because the current that you supply to the battery from the rectifier is spent to ensure that electrochemical reaction - decomposition of sulfate and its conversion into liquid acid, that is, dissolution of sulfate from plates.
As long as the direct current supplied by you is used for the course of this electrochemical reaction, the battery does not boil! Everything is spent on dissolving sulfate. When the battery is almost fully charged and there is little sulfate left on the plates, then some of the current that you supply to the battery terminals will be superfluous.
Where does this extra current go? Everything is correct! The battery begins to make an electrolysis reaction, that is, to decompose water, and here the battery starts what they say to boil and that is why it does not a charged battery does not boil on charging, but a charged battery begins to boil, and this is one of the signs that the battery charged.