Leakage hazards and preventive measures of high-power lead-acid batteries in data room

In recent years, with the rapid development of information and computer network, the scale of data center construction in China is increasing. The smooth operation of data center can not be separated from the guarantee of UPS system. UPS system is also called "uninterrupted power supply", which protects the uninterrupted power supply of network equipment in computer data center and provides continuous power guarantee for computer and its network system.

At present, in the construction of data center in our country, most UPS systems use valve-controlled sealed lead-acid batteries as backup emergency power supply. Valve-regulated sealed lead-acid batteries are characterized by mature technology, high cost performance, convenient use and maintenance, mature production process, environmentally friendly and renewable. Among them, high-power lead-acid batteries are widely used because of their advantages of high current output performance and high specific energy. As a key component of UPS system, high-power lead-acid batteries directly affect the reliability of UPS system. Among many factors affecting the stability and reliability of UPS, battery leakage is the most fatal hidden danger that can not be ignored. Once the battery leaks, resulting in the short circuit of the battery, it will inevitably cause the output voltage of UPS DC power supply system to drop instantaneously, resulting in power failure of load equipment, resulting in network interruption, affecting the transmission of information and communication. If the power supply can not be found and cut off in time, it will cause the engine room fire accident.

Analysis of Leakage Reasons of 1 High Power Lead-acid Battery

During the long-term use of batteries in the data room, no matter what type of batteries, there are more or less potential safety problems, such as battery deformation and leakage caused by improper manufacturing, handling, transportation, maintenance, long use time, poor installation and other problems. Battery leakage is a common potential safety problem. Through many years of research and analysis, mainly the following reasons lead to leakage.

Electrolyte

High-power lead-acid batteries need no electrolyte for maintenance-free batteries. In the production process, the lean-liquid technology is generally used. The oxygen generated by the positive electrode reaches the negative electrode through the ultra-fine glass fiber partition channel for compound absorption. If the excessive amount of electrolyte in the battery and the increase of pressure lead to the blockage of the composite channel, the internal gas pressure of the battery will be increased, and the leakage of the battery will occur where the seal is not good. 。

Safety valve

Safety valve is the "metronome" of the storage battery to regulate the gas pressure. It can seal the battery under certain pressure and prevent the electrolyte from overflowing to the outside world. When the battery exceeds the prescribed pressure, the relief valve opens automatically to deflate, which generally causes two reasons for the leakage of the relief valve:

First, the excessive acidification of the battery and the rich liquid state of the battery result in the obstruction of the gas passage of the O2 regeneration, the gas generated by the battery can not be compounded, and the increase of internal pressure leads to the frequent opening of the safety valve. After the gas overflows the safety valve, it is cooled outside the battery and condenses into acid around the safety valve.

Secondly, the aging of rubber pad around the safety valve and the change of battery sealing performance result in the decrease of opening pressure, the long time opening of the safety valve, and the leakage of acid fog after condensation into liquid.

(3) Polar terminal

The leakage of pole terminals is common in data centers. After one year of battery operation, the leakage of individual pole terminals will occur. Often after five years of operation, the leakage of pole terminals is very serious. The key reason for battery leakage is that pole metal does not cooperate well with battery cover sealant, pole terminals are corroded by oxygen in acidic environment, and electrolyte flows along the corrosive path to the sub-surface under the action of internal pressure to produce leakage, which is commonly known as acid creeping phenomenon.

(4) Battery cell cover

At present, there are two ways to seal the battery tank cover: epoxy resin seal and heat seal.

The leakage of epoxy resin sealant is mainly due to the strict control conditions of the sealant, which requires that the formulation and curing conditions of epoxy resin be well controlled. Otherwise, it will result in poor bonding between the sealant and the shell, forming a leakage channel and causing battery leakage.

Battery heat seal is to melt the plastic of battery tank cover at a specific temperature and time. If the heating temperature and time are well controlled, and the sealing place is clean and pollution-free, the sealing is very reliable. According to anatomical analysis, there are honeycomb trachoma in the hot melt layer of the cell cover. Under the internal gas pressure, acid mist will leak through the trachoma with the passage of O2.

Preventive Measures for Leakage of High Power Lead-acid Batteries

In order to solve the leakage problem of lead-acid batteries, the most important thing is to ensure the quality of lead-acid batteries, such as ensuring the quantity of electrolyte in a reasonable range, ensuring the sealing of battery shell, and ensuring the effectiveness of battery cover sealing. Controlling leakage at source is the most important way and the most basic responsibility of battery manufacturers.

Of course, any product is difficult to achieve 100% of the good rate, so some additional methods to prevent battery leakage caused by harm also has a certain practical significance. Usually, data center users prevent short circuit damage caused by battery leakage, mainly take the following measures.

Insulation pad

The insulation pad installed in data center is the simplest and most effective way to prevent the short circuit of high-power lead-acid battery. It is generally placed in the middle of the battery and the bearing beam of the battery rack. By adding the insulation pad at the bottom of the battery, the electrolyte generated by the battery leakage is stacked on the insulation pad instead of the battery rack to prevent the battery leakage. Electricity is caused by conduction between the corrosive liquid and the metal rack at the bottom of the battery.