Lead-acid battery-conventional charging technology and floating charging technology
2022 May 25 By admin 0 comment
  1. Lead-acid battery conventional charging technology

1.1. Characteristics and requirements of conventional charging
Conventional charging, also known as regular charging or frequent charging, is a work that is often done in the use and maintenance of batteries. It is different from the requirements for the initial charge of a new battery. When the lead-acid battery is used until the single cell voltage drops to 1.8V, it should be charged in time. When the battery is not used after being charged, it should also be routinely charged once a month to make up for the power loss caused by its self-discharge.
When the lead-acid battery is conventionally charged, the charged power should be 1.3 times the discharged power.
The conventional charging of lead-acid batteries should be carried out with a standard current of C/10. Conventional charging can use a constant voltage charging method or a staged charging method. (For more knowledge on battery charging, please visit Tycorun Battery where professionals will answer your questions)

1.2. Constant voltage charging method of conventional charging
The method steps of using constant voltage charging for lead-acid batteries are as follows:
(1) Clean the surface of the battery.
(2) Check and adjust the height of the liquid level so that the liquid level is 10mm-15mm higher than the pole plate. If the liquid level is too low, and it is not caused by leakage, only distilled water can be added instead of electrolyte.
(3) Connect the battery to the charger and charge it with a standard current of C/10 for about 12h-16h
(4) During the charging process, if the temperature of the electrolyte exceeds 45°C, the charging should be stopped or the charging current should be reduced, and then continue charging after cooling down.
(5) A constant voltage charger should be used for constant voltage charging of the battery to ensure that the charging voltage remains constant throughout the charging process.

1.3. Conventional staged charging method
In normal use, the battery can also be regularly charged by staged charging. The first stage is charged with a standard current of C/10 for 10h-12h, and the second stage is charged with a small current of C/20 for 3h-Sh. Finish. Table 1 lists the technical parameters of several types of motorcycle start-up lead-acid batteries for conventional staged charging for readers’ reference.

Table 1 - Technical parameter table of conventional staged charging of lead-acid batteries for starting several motorcycles
Table 1 – Technical parameter table of conventional staged charging of lead-acid batteries for starting several motorcycles

1.4. Judgment criteria for the completion of conventional charging
When the battery is normally charged, if one of the following characteristics occurs at the end of the charging period, it can be judged that it is fully charged.
(1) A large number of bubbles are produced in the electrolyte of the battery;
(2) The voltage of the single cell rises to 2.5V and remains unchanged for one hour;
(3) The electrolyte reaches the specified density value.
That is to say, the charging time of the battery is only a reference data. In practice, the battery should reflect the above characteristics as the standard.

1.5. General charging precautions
(1) In the process of constant voltage charging or staged charging, the charging current should not be greater than the standard value, otherwise it will easily cause the battery to heat up, which is harmful to the plates. If the battery has been used for many years, it should be charged with a small current, which can prevent the active material on the plate from falling off.
(2) The charging current should not be lower than 1/2 of the standard value. If the charging current is too low due to the low charging voltage, the voltage at the end of charging of the single battery will not reach 2.5v, which will directly lead to insufficient charging of the battery.
(3) If the temperature of the battery is too high during charging, the charging current can be reduced or the charging can be suspended. Continue charging when the temperature drops to the allowable value.
(4) The battery should be prevented from overcharging during the charging process to avoid damage to the battery.

  1. Lead-acid battery floating charging technology

2.1. Uninterruptible power supply system
Communication equipment in the telecommunications sector needs to work 24 hours a day, which requires uninterrupted supply of DC power. Usually, the regulated power supply, charger (or charger), battery and controller are connected together to form an uninterrupted power supply system to continuously supply power to communication equipment.
When the mains is normal, the regulated power supply converts the mains into direct current to supply power to the communication equipment, and the charger also floats the battery with a small current.

When the mains power fails, both the regulated power supply and the charger stop working. The communication equipment is controlled by the controller and automatically switched to emergency power supply by the battery, which ensures the normal operation of the communication equipment and smooth communication. In addition, when the mains is normal, when the load of the power supply system suddenly increases for some reason (called the impact load). ), which will lead to insufficient power supply and low voltage of the regulated power supply. At this time, the battery will briefly supply power to the communication equipment to help the regulated power supply meet the needs of the temporarily increased load. When the impact load passes or the mains returns to normal, the communication equipment is mainly powered by the regulated power supply, and the battery is always in a floating charge state.

2.2. Characteristics of floating charging method
The above shows that the battery used by the telecommunications sector is only a backup power source, and lead-acid batteries are generally used. Once the battery for this purpose is installed, the position will not be changed frequently, and it is often called a fixed battery. The battery used as a backup power source must always maintain sufficient power. In order to achieve this, the battery is often charged by floating charging.

Float charging is an operation mode of the battery. Briefly, its essence is to use a small current to charge the battery for a long time. Because the battery is charged for a long time after being fully charged at one time, it will often cause the battery to self-discharge due to the purity of the electrolyte, the purity of the effective material of the plate, the insulation condition of the separator, and the service life of the battery. exhausted. In this way, when the mains power fails, the battery cannot supply power to the communication equipment in an emergency.

For battery self-discharge power loss, the state stipulates that the capacity lost by mobile batteries in 28 days shall not be greater than 20% of the rated value; the capacity lost by stationary batteries in 7 days shall not be greater than 10% of the rated value. Generally speaking, the power lost by battery self-discharge is about 1% of the rated capacity per day on average, so it must be ensured that the backup battery is always in the running state of floating charge to supplement the power loss caused by self-discharge of the battery. Otherwise, the normal operation of the communication equipment after a power failure cannot be reliably guaranteed.

There are the following technical requirements for the floating charge of the battery.

2.3. Technical requirements for floating charging.
(1) The density of the electrolyte should be checked and measured frequently or regularly. Only when the density of the electrolyte is kept in the range of 1.20g/cm³-1.21g/cm³ can it indicate that the battery is always in a fully charged state. In order to ensure the reliability of the safe work of telecommunications equipment.

(2) Always check the voltage of the battery to keep the voltage of each single cell within the range of 2.1V-2.2V, the minimum should not be lower than 2.1V, and the maximum should not be higher than 2.2V, otherwise, the battery is not in a floating charge state, On the contrary, it is easy to cause over-discharge or over-charge, which is harmful to the plates of the battery.

(3) When the DC load supplied by the regulated power supply suddenly increases, 95% of the load current is actually provided by the battery. This also requires that when the fixed battery is used as a backup power supply, it must be operated in a floating charging mode. Only in this way can the communication equipment be reliably guaranteed to work continuously without electricity.

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