Reasons of explosion of lead-acid batteries and preventive ways

Reasons of explosion of lead-acid batteries and preventive ways

Since its invention in 1859 by Plant, lead-acid battery has a history of more than 150 years and is mature. It is the most widely used chemical power source in the world. Although other batteries such as nickel-cadmium batteries, nickel-hydrogen batteries, and lithium-ion batteries have been introduced and applied, lead-acid batteries are still strong in their high-current discharge performance, wide in temperature range, large in single-cell batteries, and high in safety. A wide range of advantages, such as abundant raw materials, renewable and low prices, occupy a strong position in most traditional fields and some emerging applications. Batteries are very common in our lives, but because people do not know much about proper batteries use, there are some misunderstandings. Especially in recent years, the application of electric vehicles has become more and more extensive, but due to the improper use of lead-acid batteries, explosion accidents have occurred, causing great losses to people's lives and property safety. This article will analyze the root cause of battery explosion from the working principle of lead-acid battery for your reference.

1. The working principle of lead-acid battery

The positive electrode active material of the lead-acid battery is PbO 2, the negative electrode active material is spongy metal Pb, and the conductive medium is dilute sulfuric acid (electrolyte). During the charging and discharging process of the battery, the following reactions will occur on the positive and negative plates to convert the electrical energy into chemical energy stored in the battery or convert the chemical energy into electrical energy for supply to the load.

The composition of the precipitated gas when the lead-bismuth alloy battery charged with the change of voltage shown in Table 1. During the charging process of the battery, a combustible mixed gas easily formed inside and around the battery. If the exhaust hole is not smooth, a high voltage easily formed in the battery.

During the charging and discharging process of the battery, the internal resistance generates heat, which causes the temperature of the electrolyte to rise, thereby causing some of the water to become water vapor. If the battery vent hole is unblocked, the water vapor will discharged outside the battery. In the end, the battery will dehydrated; otherwise, a certain internal pressure will formed in the battery.

2. Three cases of lead-acid battery explosion

2.1 The internal pressure is too high and causes an explosion

At the end of the lead-acid battery charging, water decomposes into hydrogen and oxygen. At the same time, short circuit, severe sulfurization and a sharp rise in electrolyte temperature will cause a large amount of water to evaporate. If the vent hole is blocked, the internal gas of the battery will be too much to overflow. As a result, the internal pressure and temperature of the battery are too high, which first causes deformation of the battery case. When the internal pressure is concentrated to a certain extent, it will burst from the junction of the battery cover or other weak places, which is a physical process.

2.2 Hydrogen encounters battery explosion caused by open flame

The explosion limit of the H2 and O2 mixed gas is 4% to 96% of the volume of the mixed gas, and the explosion limit of the H2 and air mixed gas is 4% to 74% of the volume of the mixed gas. When the hydrogen content generated by the battery accumulates to the explosion limit, an explosion occurs when exposed to an open flame, which is a chemical reaction. It found that the explosion of the battery belongs to the branch explosion reaction. Most of the explosions occur under overcharge conditions. If there are virtual solder joints in the internal poles and through-wall welding of the battery, the explosion probability of the battery is high. A qualified battery will not undergo a self-heating explosion reaction under normal conditions of use.

2.3 First burst after the explosion

Due to the clogging of the battery vent, the battery first bursts, the battery causes the battery to vibrate, and the pole column wiring does not produce a spark, which forms an explosion.

3. Preventive measures

It known from the above explosion mechanism of the lead-acid battery that the explosion of the battery should prevented from the prevention of the formation of the explosive mixed gas and the elimination of the open flame during use. The specific measures are as follows:

a) The battery charging room well ventilated and has no open flame;

b) Use a matching charging device, but charge;

c) The cable connection should be firm and reliable to avoid sparking due to looseness;

d) The vents of the battery remain unobstructed;

e) Whether the output voltage of the regulator (or integral alternator) is within the specified range, generally, the gasoline vehicle does not exceed 14.4V, and the diesel vehicle does not exceed 28.8V.

The explosion of lead-acid batteries is horrible, but if we can pay more attention batteries in our life, we can certainly eliminate the potential dangers in advance. The lead-acid battery protector developed by Beijing Dacheng Luchuan Technology Co., Ltd. (DACEEN) directly installed on positive and negative poles of battery to realize on-line repair. The protector uses battery itself to generate continuous pulse to remove sulfide crystal of the plate while preventing new vulcanization. Generate, reduce the internal resistance of battery, and achieve battery charging voltage equalization. With this, you will have a safe, high-quality, worry-free green DC power supply.

The page contains the contents of the machine translation.