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In the acidic aqueous solution as a electrolyte battery are collectively referred to as acid battery, One of the most typical is lead-acid battery . The main advantages of acid batteries are high operating voltage, wide use temperature, good high and low rate discharge performance, rich source of raw materials, and low price. Its disadvantage is that the energy density is low, which makes its volume and weight larger.
Lead-acid batteries, having a positive lead dioxide and a negative spongy lead, with an electrolyte of sulfuric acid solution, separator (diaphragm) using microporous rubber separator , microporous plastic separator or other materials, depending on the type of lead-acid battery, , Battery shell use hard rubber, engineering plastics , glass fiber reinforced plastic materials, etc.
a, tectonic
& have spent The acid battery is mainly composed of three parts: container, plate and separator. The container of the acid battery is used to store the electrolyte and support the plate, so it must have the characteristics of preventing acid leakage, corrosion resistance, robustness and high temperature resistance. According to different materials, commonly used lead-acid battery have glass tank, lead lining containers made of wood, plastic and hard rubber trough is four.
Generally the offshore oil engineering using acid battery plate lead antimony alloy to make grid type, grid medium voltage into the active material. Positive plate of the active material is lead dioxide (PbO 2 ), negative plate of the active material is spongy pure lead. In order to increase the capacity, the positive and negative plates of the battery are made of many pieces, which are connected together in parallel and connected into two groups to form the positive and negative terminals of the battery. Each group of positive and negative plates composed of a single battery voltage of about 2V, in practical applications often 3 or 6 of the same single battery series together into a group. The negative plate of the battery is always more than one positive plate, and each positive plate is sandwiching between two negative plates, so that both sides of the positive plate react chemically, resulting in the same expansion and contraction, reducing the chance of plate bending, thus extending the service life of the plate, because the negative plate is much less telescopic than the positive plate during the charge and discharge process. It is also thinner than the positive plate
, and only one side of the two outermost negative plates interacts with the positive electrode, so its thickness is thinner than the negative plate in the middle.
the role of partition is to make the battery positive and negative plate insulation, each other can use wood, hard rubber, plastic, etc. In order to allow the electrolyte to flow freely, the structure of the separator should be porous, but the shed active material cannot be in contact with the adjacent plate through the separator.
second, the principle of discharge
& have spent A voltage is generated by a chemical change in the two plates of a lead-acid battery inserted into a dilute sulfuric acid solution. When the direct current is applied (charged), the lead oxide on the positive plate becomes a tan lead dioxide (PbO2), and the lead oxide on the negative plate becomes a gray velvet lead (Pb, also known as spongy lead). When the lead battery is discharged, the active substances on the positive and negative plates absorb sulfuric acid and change chemically, gradually becoming lead sulfate (PbSO4), when the active substances on the positive and negative plates become the same lead sulfate, the voltage of the battery drops to no longer discharge. At this time, the battery needs to be charged to restore it to the original lead dioxide and velvet lead, so that the battery can continue to discharge. The chemical changes that occur in the battery are reversible and expressed by the equation as follows: [2]
to charge and discharge chemical expression
{{13 7}} It can be seen from the above formula that the density of dilute sulfuric acid in the electrolyte will increase during charging; When discharging, the density decreases due to the formation of water. Acid battery electromotive force , mainly related to electrolyte density. Higher density, higher electromotive force. In empirical formula has the following relationship:
type:
E -- electromotive force of a battery, V;
d - density of electrolyte.
, internal resistance and capacity
& nbsp; The internal resistance of the acid battery is composed of plate resistance, electrolyte resistance and the resistance of the plate connection part.
When the battery is charged, the density of the electrolysis changes, and the effective substance on the plate changes, so the internal resistance of the battery also changes. The internal resistance of a battery is minimal after charging and increases when discharging. For the battery used, its internal resistance can be calculated by the following formula:
type:
R -- internal resistance of the battery, Ω;
E -- open circuit voltage, V;
U -- terminal voltage at operation, V;
I -- discharge current, A.
The capacity of the battery indicates the capacity of the battery to store electrical energy, and the capacity of the Marine battery is generally measured in ampere-hours at a 10-hour discharge rate. For example, a 250 amp hour battery can discharge for 10 hours at a current of 25 amps. However, the same battery cannot give a 250 amp hour capacity at a 1 hour discharge rate, and will, in fact, be less than 250 amp hours. If the discharge rate is not 10 hours, multiply it by an appropriate capacity coefficient, as shown in Table 2-58. [2]
acid battery capacity coefficient of
{{2 39}}
four, use
charging method
Initial charge. A new or long-term storage battery needs to be discharged for the first time before use. The steps are as follows:
① Pull out the water cover first, remove the seal of the small hole on the cover, and make the air smooth.
② Add the prepared electrolyte, its density is 1.285(note that when preparing the electrolyte, sulfuric acid should be slowly injected into the distilled water), add 10 ~ 15mm above the partition.
③ After the electrolyte is added, the battery can stand for 2 to 3 hours to connect the positive and negative terminals of the battery to the positive and negative terminals of the power supply, ready to discharge.
(4) the initial charge according to the specified in table 2 to 59 of the current and time. The first stage of current charging increases the terminal voltage of each small battery to 2.4V, and then switches to the second stage of current charging until the voltage and electrolyte ratio is basically no longer changed within 3h. [2]
battery discharge main parameters
{{2 90}} Recurrent charging method. Regular charging of acid batteries is performed in two stages. Table 2-59 lists the charging current and time. The first stage of charging, so that the battery voltage rises to about 2.4V per battery, and then transfer to the second stage of charging, until the electrolyte density reaches 1.285 and is uniform up and down, the charging is complete.
& have spent In the process of charging the battery, due to the occurrence of gas, the water in the electrolyte is reduced and the liquid level is reduced. Although sulfuric acid also has a little splash, but the loss is very little, so when the liquid level is added to the original height, only water is allowed, and acid must not be added. If the electrolyte density is lower than the original value after charging, it should be adjusted by adding dilute sulfuric acid with a density of 1.35 ~ 1.40 according to the requirements of the manufacturer, and if the density is higher than the original value, distilled water can be added to adjust.
to adjust the electrolyte density of work shall be carried out in the normal charge. Then use half of the ordinary charging current, and then charge for 30 minutes or 1 hour, so that the electrolyte is mixed evenly, if the measured density is still different, it should be repeated according to the above method until the density of battery set reaches the specified level.
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