Charging method for lead acid battery

Charging method for lead acid battery

The electrode is mainly made of lead and its oxide, and electrolyte is a battery of a sulfuric acid solution. In the discharge state, the main component of positive electrode is lead dioxide, and the main component of negative electrode is lead; in the state of charge, the main components of the positive and negative electrodes are lead sulfate. Divided into exhaust battery and maintenance-free lead-acid battery.

The battery is mainly composed of a tubular positive plate, a negative plate, an electrolyte, a separator, a battery tank, a battery cover, a pole, a liquid injection cover and the like. The electrode of the vented battery is composed of an oxide of lead and lead, and the electrolyte is an aqueous solution of sulfuric acid. The main advantage is that the voltage is stable and the price is cheap; the disadvantage is that the specific energy is low (that is, the energy stored per kilogram of the battery), the service life is short, and the daily maintenance is frequent. Old-fashioned ordinary batteries generally have a life span of about 2 years, and it is necessary to regularly check the height of the electrolyte and add distilled water. However, with the development of technology, the life of lead-acid batteries has become longer and the maintenance is simpler.

Lead-acid battery charging method How to repair lead-acid battery

Lead-acid battery classification

1) Ordinary battery; the plate of an ordinary battery is composed of oxides of lead and lead, and the electrolyte is an aqueous solution of sulfuric acid. Its main advantage is that the voltage is stable and the price is cheap; the disadvantage is that the specific energy is low (that is, the energy stored per kilogram of the battery), the service life is short, and the daily maintenance is frequent.

2) Dry-charged battery: Its full name is dry-charged lead-acid battery. Its main feature is that the negative plate has high storage capacity. In the completely dry state, it can save the obtained power within two years. When you just need to add the electrolyte, wait 20-30 minutes to use.

3) Maintenance-free battery: Maintenance-free battery due to its own structural advantages, the consumption of electrolyte is very small, and it is basically unnecessary to supplement distilled water during the service life. It also has the characteristics of shock resistance, high temperature resistance, small size and small self-discharge. The service life is generally twice that of a normal battery. There are also two kinds of maintenance-free batteries on the market: the first one does not require maintenance (adding replenishing liquid) after the one-time addition of electrolyte at the time of purchase; the other is that the battery itself has been charged with electrolyte and sealed. The user cannot add replenishing liquid at all.

Lead-acid batteries are available in 2-volt, 4-volt, 6-volt, 8-volt, 12-volt, 24 volts, and range from 200 mAh to 3000 amperes. The VRLA battery is a rechargeable battery based on AGM (Aspirating Glass Fiber Board) technology and a calcium grid. It has superior high current discharge characteristics and an extremely long service life. It does not need to add water during use.

Correct lead-acid battery charging method

1. Determine the rated voltage and rated capacity of the battery or battery pack. The rated voltage is used to determine the charging voltage and the rated capacity is used to determine the charging current.

About voltage: The easiest way is to read it from the tag; for example, the rated voltage of the CSB battery shown in Figure 1 below is 12V.

If the label is worn or not at all, it can be judged from the number of vent holes or safety valves that are round holes at the top of the battery that can be opened or opened. To be sure, all lead-acid batteries currently have venting holes. Each vent represents one unit, 2V, so the total voltage of the battery shown in the other figure is 24V because it has 12 vents.

About the capacity: can also be read from the label or calculated; in general, the label will indicate the rated voltage of the battery, as shown in Figure 3 PNP battery is marked as 65Ah, but the UPS battery is usually represented by W, as shown One shows 34W. For this kind of battery, the simple calculation method is the wattage divided by four, that is, 8.5Ah; but when it comes to Figure 2, there is no way, it can only be estimated according to the volume or importance. And the error is large. The 12V100Ah AGM battery weighs 30~35kg. Therefore, if the battery in Figure 2 weighs 500kg, it can be calculated that its capacity is about 700Ah.

Lead-acid battery charging method How to repair lead-acid battery

2. If you only need to charge the battery once using the method described in this article, this step can be skipped; if you need to use it for a long time, it is recommended to perform this step carefully to determine the open circuit voltage when the battery is 100% fully charged. OCV (open circuit voltage) at 100% SOC (stage of charge).

There are several ways to know the value:

First, use a DC voltmeter to measure the voltage of the battery that has been fully charged for more than one hour after being fully charged, and is directly obtained;

Second, get from the file; the value will not be printed on the battery label, but usually can be obtained from the manufacturer's operating instructions or MSDS;

Third, for a flooded battery, it can also be obtained by testing the density of the electrolyte of the battery when fully charged; the method is OCV=SG+0.84, for example, the density of the electrolyte is 1.35 g/mL, and the open circuit voltage of the battery is OCV. =1.35+0.84=2.19V, as shown in the figure below.

It is important to obtain the voltage when the battery is fully charged. It can be used to verify that the battery is fully charged, to determine the battery charge or the depth of discharge.

Lead-acid battery charging method How to repair lead-acid battery

3. Determine the charging voltage.

The charging voltage is divided into a floating charging voltage, a uniform charging voltage, a fast charging voltage, and the like. In general, the floating charge voltage is used for daily floating charge, the lowest; both charges are used for recharging after discharge, which is higher; fast charge is the voltage of rapid full charge under emergency scene, the highest, not commonly used.

The charging voltage referred to herein is the average charging voltage.

Some batteries will be marked with a charging voltage on the label, and will be divided into floating charge and equal charge. For example, as shown in the above figure 1, the float voltage is 13.5V~13.8V, and the charge voltage is 14.4V~15.0V; It is relatively simple, you can use the charging voltage charging directly, you can choose the safer intermediate value or minimum value. The highest value of the average charging voltage can be considered as the fast charging voltage, which is generally considered to have a certain damage to the battery.

If the charging voltage is not indicated on the battery, the reasonable average charging voltage can be estimated according to the open circuit voltage OCV when the battery is fully charged. The open circuit voltage of the 12V battery when fully charged plus 1~1.5V is a reasonable average charging voltage. Other rated voltage batteries and so on.

If you do not know the open circuit voltage when the battery is fully charged, you can occasionally blindly charge with 2.4VPC voltage, but it is more difficult to judge when the battery is full, there may be overcharge, causing certain damage to the battery. The so-called 2.4VPC, that is, 2.4V / cell, 2.4V per unit, if it is 12 units, as shown in Figure 2 above, the average charging voltage can be 28.8V

4. Determine the charging current.

The charging current is related to the rated capacity of the battery. It is generally 0.1C~0.4C, which is one tenth to four tenth of the rated capacity.

If it is a 100Ah battery, it is 10A~40A. It can be measured with a DC ammeter, a clamp meter.

Of course, some of the most advanced manufacturers on the market today use thin plate technology, which has increased the charging current to 1C, which is equal to the rated capacity. This high-current charging method will greatly shorten the charging time, but these high-end batteries are not popular enough. The commonly used 0.1C~0.4C method is still used in this paper.

5, wiring. This is not to say, the positive pole of the charger is connected to the positive pole of the battery, the negative pole of the charger is connected to the negative pole of the battery, then the charger and the mains are turned on, and finally the battery is charged.

It is worth mentioning that for multi-cell battery charging methods, I recommend parallel charging. Because parallel charging can improve the consistency of the battery, and low-voltage charging is also safer.

It should be noted that when charging in parallel, the wiring should adopt the diagonal method to improve the consistency of current shunt. The so-called diagonal connection method is as follows.

Lead-acid battery charging method How to repair lead-acid battery

6. Determine the charging time, or when to stop charging.

If it is not blind charging or charging with an excessive voltage, the charging current is reduced as charging progresses.

If the battery is charged by the manufacturer's recommended charging voltage, in general, the charging current can be fully charged when it is reduced to 0.03C. For example, a 100Ah battery, if using the voltage recommended by the manufacturer, is substantially fully charged when the charging current is less than 3A.

Alternatively, the time required to charge 1.2 times the required amount of power is the charging time. For example, a 100Ah battery, fully discharged, needs to be filled with 100Ah to be full; 1.2 times 120Ah; if the charging current is 0.15C or 15A, then 120÷15=8 hours can be almost fully charged.

7. Determine if it is full.

This do this method if necessary. This is after charging complete, disconnect all lines, leave it for more than one hour, and then measure battery voltage. It can compare with standard curve to determine if it is full.

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