Discussion on Several Problems of Storage Battery in UPS

by:Power Kingdom     2021-07-07

  1 Introduction

   At present, UPS has been widely used in various economic fields, playing an important role in communications, e-commerce, finance, medical treatment, petrochemical, industrial automation and other fields , Not only to protect the load carried by the UPS itself, but more importantly to protect the products produced by the load, such as the data in the computer. As an important part of UPS, storage battery generally accounts for about 1/4 of the total cost of UPS power supply for standard time machines. For long-term UPS power supply, the cost of storage battery may exceed the cost of the UPS power supply host. Due to the battery itself or battery management reasons, there are currently many UPS power failures caused by the battery (1/3). Therefore, it is necessary to strengthen the understanding of the battery characteristics, correctly select and use the battery, and extend the service life of the battery as much as possible. At the same time, how to manage batteries has become a key research issue for various UPS manufacturers.

  2Characteristics of battery

  2.1 Working principle of lead-acid battery

   Most of the batteries in UPS use lead-acid batteries (the same below). The battery is a device that converts chemical energy and electrical energy. The battery needs to be charged with a DC power supply to convert electrical energy into chemical energy. When stored, the active material of the battery anode is lead dioxide (PbO2), the active material of the cathode is lead (Pb), and the electrolyte is dilute sulfuric acid (H2SO4).

  The battery is composed of a single 'primary batteryp>  The battery is composed of 6 primary cells.

  2.2 maintenance-free

   sealed maintenance-free lead-acid battery, which has all the advantages of open-type lead-acid battery , The so-called maintenance-free is in terms of the need for frequent water addition to open-type batteries. The entire battery is fully enclosed (the redox reaction of the battery is cyclically carried out inside the closed casing), so the maintenance-free battery does not have 'harmful gas' overflow. No need for daily operation and maintenance such as adding water. It can be installed in the host room, suitable for unattended computer room.

  2.3 The relationship between battery capacity and discharge rate

  The capacity of a battery refers to its power storage capacity. It is a fully charged battery that discharges to a specified end voltage. Standard YD/T799-2002 stipulates that the rated capacity of 2V, 6V, and 12V sealed batteries are the capacity of 10 hours discharge rate (Iu003d0.1C10A) at standard temperature (25℃). The standard clearly states that the capacity of 6V and 12V batteries is based on a 10h discharge rate. However, the old industry practice and the current majority of manufacturers are: for 2V batteries, the capacity is defined by a 10-hour discharge rate (Iu003d0.1C10A), and for 6V and 12V batteries, the capacity is defined by a 20-hour discharge rate (Iu003d0.05). C20A) capacity.

The relationship between    discharge rate and capacity: The capacity discharged by the battery decreases with the increase of the discharge current. The high-discharge process is a forced change of the effective substances on the surface of the electrode plate. The generated lead sulfate can easily block the small holes on the electrode plate, and the effective substances in the deep layer of the electrode plate do not participate in the chemical reaction. In this way, the internal resistance of the battery increases, and the voltage drops quickly, so that the battery cannot discharge all the capacity.

   10h discharge rate discharge capacity is 100%, 20h discharge rate discharge capacity is 105%, 3h discharge rate discharge capacity is 75%, 1h discharge rate discharge capacity is 52% . The relationship between discharge current and capacity can be determined by the following formula:


Where Q——I capacity at discharge current (Ah)

  Q0——Rated capacity at 10h discharge rate (Ah)

  I0——Rated discharge current of 10h discharge rate (A)

  I——Discharge current of non-10h discharge rate (A)

  n——battery discharge capacity index, its value is I/I0<3nu003d1.313;I/I0≥3,nu003d'1'.414

   above means that a battery with a capacity defined by a discharge rate of 10h has more capacity than a battery with a capacity defined by a discharge rate of 20h. If other conditions are the same, the cost of the former is higher.

  2.4 The relationship between temperature and capacity

   Generally, the relationship between capacity and temperature is as follows:

  C25--the discharge capacity of the battery at -25℃ (Ah)

  Ct---the discharge capacity of the battery at t℃ (Ah )

  t---the average temperature of the electrolyte (℃)

  The above formula adapts to the electrolyte temperature of -15 ℃~35℃. If the temperature is lower than, the capacity decrease is more significant, and when the temperature exceeds 35°C, the capacity decreases instead.

   Especially for batteries used in outdoor UPS, if the capacity of the battery needs to be fully utilized as much as possible, the temperature of the battery case must be improved.

  2.5 The relationship between electrolyte quantity and concentration and capacity

   appropriately increase the electrolyte quantity and increase the electrolyte concentration, The capacity of the battery can be increased, but it must be within the allowable range, otherwise it will accelerate the corrosion of the electrode plate and shorten the life of the battery.

  2.6 The relationship between plate area and capacity

These sealed lead acid battery top lead acid battery manufacturers are meant to serve as a guide for business owners on how to both identify potential opportunities for transformative innovation and how to adapt to the constantly changing technologies of today.
Shenzhen Power Kingdom Co., Ltd. seeks to lead the industry by instilling pride in our customers, creating value for the market and sharing responsibility around the world.
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