A quick test method for water loss of lead-acid battery

Abstract

The application discloses a quick testing method for water loss of a lead-acid storage battery, which comprises the following steps: testing the 20h rate capacity of the battery and fully charging; selecting a corresponding gas collecting mode according to different battery exhaust structures and reaction heat effects, installing a gas collecting device, placing the battery with the gas collecting device in a 40 DEG C + / -2 DEG C water bath tank, and immersing the battery in water to a height of more than 80% of the total height of the battery; after temperature balancing for 24h, pre-charging at a constant voltage of 14.4V + / -0.05V for 12h, and then entering the gas collecting stage, recording the gas collecting amount V na , n is the serial number of the gas collecting mode, n=1, 2, 3 or 4, calculating the gas collecting amount V a of the whole battery; calculating the gas volume V n under the standard state V=0.936Va, calculating the gas collecting amount V of the battery for 500h, and calculating the water loss G.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of lead-acid battery water loss quantity fast test method, belong to battery detection technical field. BACKGROUND

[0002] With the increasing performance requirements of lead-acid battery, water loss performance becomes more and more an important performance indicator for measuring lead-acid battery, especially the wide application of high specific surface area carbon material in lead-carbon battery and stationary air conditioning battery, while improving the charge acceptance, the water loss rate of battery also increases accordingly, there is the risk of electrolyte reduction, cycle life reduction in use, and water loss performance is an important indicator for carbon material selection and evaluation.

[0003] In GB / T 5008.1-2013 and various types of battery standards, water loss performance is expressed by the water loss of the battery. The smaller the water loss, the less likely the battery will lose water. According to GB / T 5008.1-2013 standard, the water loss test method is as follows: weigh the mass W1 of the fully charged battery (weighing accuracy ±0.05%), then charge at 14.4V±0.05V constant voltage for 500h at 40℃±2℃ environment temperature, then weigh the mass W2 (weighing accuracy ±0.05%). Water loss W=(W1-W2) / Cn, Cn is the rated capacity of the battery.

[0004] According to the above method, the standard requires that the mass loss of micro-water loss battery is not more than 1g / Ah. For example, to test the water loss of a 6-QFLZ-220 battery for stationary air conditioning, the battery mass is about 66kg, and the mass loss during water loss should be less than 220g, so the laboratory needs to be equipped with a large range, high precision electronic scale; and the test time is as long as 500h, which is difficult to meet the needs in some cases where results are needed as soon as possible. SUMMARY

[0005] The present application overcomes the drawbacks of the prior art and provides a fast test method for the water loss of a lead-acid battery. The gas discharged during charging of the battery is collected, and the water loss of the battery is calculated using the gas collection amount. The test period is shortened to 24h, and the equipment is simple, without the need for a large range, high precision electronic scale.

[0006] The technical solution adopted by the present application to solve its technical problems is:

[0007] A fast test method for the water loss of a lead-acid battery, which calculates the water loss of the battery by the volume of gas generated by the battery. The test method comprises the following steps:

[0008] a. Test the 20h rate capacity of the battery and fully charge it;

[0009] b. Selecting corresponding gas collecting mode according to different battery exhaust structure and reaction heat effect, installing gas collecting device, and placing the battery with gas collecting device in 40℃±2℃ water bath, with the height of battery immersed in water being more than 80% of the total height of the battery;

[0010] c. After temperature balance for 24h, pre-charging at constant voltage of 14.4V±0.05V for 12h to eliminate the error caused by too large initial current, then entering gas collecting stage, and recording the gas collecting volume V na , n is the serial number of gas collecting mode, n=1, 2, 3 or 4, and the gas collecting volume V of the whole battery is calculated a ;

[0011] d. Calculating the gas volume V n under standard state a , and bringing V a into ideal gas state equation (I):

[0012]

[0013] In the formula, V n is the corrected gas volume (mL);

[0014] V a is the collected gas volume (mL);

[0015] T r is the standard temperature (293) (K);

[0016] T a is the environmental temperature (℃), which is 40℃;

[0017] P a is the environmental atmospheric pressure (kPa), and the atmospheric pressure in laboratory environment is close to the standard atmospheric pressure, thus P a =P r ;

[0018] P r is the standard atmospheric pressure (101.3kPa);

[0019] After calculation, Vn=0.936Va;

[0020] e. Calculating the gas collecting volume V of battery in 500h and water loss volume:

[0021] During the test, the gas collecting time is t, the gas collecting volume under the gas collecting time t is converted into the gas collecting volume V in 500h, which is calculated by formula (II) to obtain the gas collecting volume V in 500h:

[0022]

[0023] According to the gas collecting volume V in 500h, the mass G of electrolytic water is calculated by formula (III):

[0024]

[0025] 0.336: the electrochemical equivalent of water calculated by Faraday's law of electrolysis, unit g / Ah;

[0026] 684: the theoretical gas evolution amount of water electrolysis when the battery is charged with 1 Ah of electricity under standard conditions, unit mL / Ah;

[0027] According to the obtained mass G of electrolytic water, the water loss value W is calculated by the following formula (four), unit g / Ah,

[0028]

[0029] In formula (four), C n is the rated capacity of the battery.

[0030] The above-mentioned rapid test method for water loss of lead-acid battery, in step e, when the test battery is a valve-regulated battery with AGM separator saturation of 94%-97%, the water loss value is increased by 10% based on the calculated value of formula (four), which is:

[0031] The above-mentioned rapid test method for water loss of lead-acid battery, in step b, for different battery exhaust structures and reaction heat effects, the corresponding gas collection mode is selected, taking a 12V 6-cell battery as an example, there are four kinds of gas collection modes, which are:

[0032] Gas collection mode 1: a concentrated exhaust port is designed on the battery cover, which can collect the gas of 6 single cells at the same time, and the gas collection volume is V 1a ;

[0033] Gas collection mode 2: two concentrated exhaust ports are designed on the battery cover, each exhaust port collects the gas of 3 single cells, and during the test, gas can be collected from any one of the concentrated exhaust ports, and the gas collection volume is V 2a ;

[0034] Gas collection mode 3: no concentrated exhaust port is designed on the battery cover, and the battery shell is 1x6 structure, and the gas is collected from 1#, 2#, 3# three single cells or 4#, 5#, 6# three single cells, and the gas collection volume is V 3a ;

[0035] Gas collection mode 4: no concentrated exhaust port is designed on the battery cover, and the battery shell is 2x3 structure, and the gas is collected from any one of 1#, 3#, 4#, 6# four single cells, and the gas is collected from any one of 2#, 5# two single cells, and the gas collection volume is V 4a ;

[0036] The quick testing method of water loss of the lead-acid battery, in the step c, the collected gas amount V is recorded according to four kinds of gas collecting modes na , the collected gas amount V of the whole battery is calculated respectively a , for the gas collecting mode 1: V a =V 1a , for the gas collecting mode 2: V a =2V 2a , for the gas collecting mode 3: V a =2V 3a , for the gas collecting mode 4: V a =3V 4a .

[0037] The quick testing method of water loss of the lead-acid battery, in the step e, the gas collecting time t is different according to different battery types, when the battery is a flooded battery, the gas collecting time t is 0.5h, when the battery is a valve regulated battery with AGM separator saturation of 94-97%, the gas collecting time t is 1.5h.

[0038] The quick testing method of water loss of the lead-acid battery, the gas collecting device comprises a gas guide pipe, a measuring cylinder and a support, one end of the gas guide pipe is sealingly connected with a concentrated exhaust port on the battery, the other end is inserted into the measuring cylinder, the measuring cylinder is fixed on the support in an inverted manner, the measuring cylinder is filled with water, and the height h of the measuring cylinder immersed in the water is less than or equal to 20mm.

[0039] The quick testing method of water loss of the lead-acid battery, when the battery does not have a concentrated exhaust port, the gas collecting device further comprises a plastic cup, the plastic cup is open at both top and bottom, the lower opening covers an exhaust plug on the battery, the plastic cup is sealed with the battery cover by sealing glue, and the upper opening serves as a single cell exhaust port and is connected with one end of the gas guide pipe, the other end of the gas guide pipe is inserted into the measuring cylinder.

[0040] The present application has the following advantages:

[0041] The present application converts the long time and small amount of mass change under the overcharged state of the battery into a short time and large amount of volume change for measurement, selects the corresponding gas collecting mode and calculates the corresponding collected gas amount according to different battery exhaust structures and reaction heat effects, converts the gas volume and the mass of electrolytic water through the Faraday electrolysis law and the ideal gas state equation, provides a quick testing method of water loss of the lead-acid battery, the required test period is shortened from 500h to 24h (the temperature balance of 24h is not included), the equipment is simple, a large range and high precision electronic scale is not required, and the method is a supplementary testing method of the water loss of the lead-acid battery, and is more suitable for the rapid screening and evaluation of carbon materials in parallel samples in the field of lead-acid battery research. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 Battery gas collection device structure corresponding to the gas collection method 1 of the present application;

[0043] Figure 2 Battery gas collection device structure corresponding to the gas collection method 2;

[0044] Figure 3 Battery gas collection device structure corresponding to the gas collection method 3;

[0045] Figure 4 Battery gas collection device structure corresponding to the gas collection method 4.

[0046] In the figure: 1, plastic cup; 2, gas guide pipe; 3, measuring cylinder; 4, support. DETAILED DESCRIPTION

[0047] According to GB / T 5008.1-2013 test, the water loss of the battery includes the following two aspects:

[0048] (1) Electrolyte water loss under overcharge: electrolyte water loss is a side reaction of overcharge reaction. In the later stage of battery charging, with the electrode polarization, the terminal voltage of the battery gradually rises, when the terminal voltage of the battery exceeds 2.3V, the side reaction of water electrolysis begins to occur, when the positive electrode reaches 70% of the charging capacity, electrode reaction ① occurs on the positive electrode, and oxygen evolution reaction begins; when the negative electrode reaches 90% of the charging capacity, electrode reaction ② occurs on the negative electrode, and hydrogen evolution reaction begins.

[0049] H2O—2e — →2H + +1 / 2O2↑ ①

[0050] 2H + +2e — →H2↑ ②

[0051] (2) Gas permeation and evaporation of battery shell: the standard requires that the test environment temperature is 40℃±2℃, and the battery laboratory generally uses water bath constant temperature method to achieve it, the battery is immersed in water more than 80%, at this time the gas permeation and evaporation amount through the battery shell is very small and can be ignored.

[0052] For the flooded battery, the water loss test process described above is in a stable state of positive and negative electrode potential, and the gas bubbles are evenly released during gas collection, so it has the condition of rapid test, and the gas collection time is set to 0.5h.

[0053] For the valve-regulated battery with AGM separator saturation of 94%-97%, in addition to the positive electrode reaction ① and negative electrode reaction ② described above, the oxygen generated by the positive electrode is transmitted to the negative electrode surface through diffusion in the liquid phase, or in the form of gas phase through the pole group to the negative electrode surface, combined with the negative electrode metal lead, and the oxygen recombination reaction ③ occurs, and further reacts with the acid to regenerate water, and the reaction ④ occurs.

[0054] O2+2Pb→2PbO ③

[0055] PbO+H + +HSO4 — →PbSO4+H2O ④

[0056] The oxygen circulation reaction of the valve-regulated battery ensures that the battery does not need to be added with water during use and can reach the service life. The oxygen recombination efficiency is closely related to the saturation degree of the AGM separator in the electrode group. Due to the difference in design and used materials, the saturation degree of the AGM separator allows certain process deviation between different batteries, at different stages of the service life of the same battery, and between different cells of the same battery. Therefore, the oxygen recombination efficiency has certain difference. Generally, with the increase of overcharge amount, the gas evolution amount gradually increases. Through experimental research, the water loss value of the valve-regulated battery with the AGM separator saturation degree of 94%-97% is increased by 10% based on the water loss value calculated for the flooded battery, and the result is closer to the actual data. Due to the difference in thermal effect between the edge cell and the middle cell, the oxygen recombination efficiency of the middle cell is slightly higher than that of the edge cell. However, due to the small water loss of the valve-regulated battery, the water loss test period is relatively short compared with the service life. Therefore, the water loss test process of the valve-regulated battery can be simplified as a process of stable increase of the oxygen recombination efficiency and the gas evolution amount. Due to the occurrence of the oxygen recombination reaction, the positive and negative electrode potentials are always fluctuated within a limited range, and the amounts of evolved hydrogen and oxygen are also changed. Therefore, compared with the flooded battery, the gas collection period is slightly longer. When the gas collection time is set to 1.5h, the test data is closer to the actual data.

[0057] Based on the above analysis, the water loss amount of the battery in the test process is converted from the conventional long-time, small amount of mass change to the large amount of volume change in the short time of the present application. The evolved oxygen and hydrogen are collected by the drainage gas collection method. The flooded battery is collected for 0.5h, and the valve-regulated battery with the AGM separator saturation degree of 94%-97% is collected for 1.5h. According to the ideal gas state equation: The gas collection amount under the experimental environment is converted to the gas collection amount under the standard state. Based on this, the gas collection amount of 500h is calculated. The gas volume and the mass of electrolytic water are converted by the Faraday's law of electrolysis and the ideal gas state equation, and the mass of electrolytic water is calculated.

[0058] Under the standard state, the 1Ah of charge of the storage battery is all used for electrolytic water, and the theoretical gas evolution amount is 684mL / Ah. The electrochemical equivalent of water is calculated to be 0.336g / Ah by the Faraday's law of electrolysis, and the conversion between the mass and the volume of electrolytic water is performed.

[0059] The present application is further described below in conjunction with examples.

[0060] Example 1

[0061] Take 5 6-QW-180 batteries (flooded batteries), respectively test 20h rate capacity, and fully charged. Observe that the battery has two concentrated exhaust port, using the way 2, see Figure 2 , directly into the gas guide tube on one of the concentrated exhaust port, the battery together with the gas guide tube placed in 40℃±2℃ water bath, requires the battery immersed in water more than 80%, the amount of water-filled cylinder 3, and its immersed in water height h = 20 mm. Temperature balance for 24h, 12h pre-charge at constant voltage 14.4V±0.05V, start to collect gas, record t = 0.5h of gas collection V 2a1 = 168, V 2a2 = 160, V 2a3 = 174, V 2a4 = 170, V 2a5 = 164 (mL), calculate the whole battery gas collection V a1 = 2V 2a1 = 336, V a2 = 2V 2a2 = 320, V a3 = 2V 2a3 = 348, V a4 = 2V 2a4 = 340, V a5 = 2V 2a5 = 328 (mL), V a into equation (four) The water loss is calculated as: G1 = 0.86, G2 = 0.82, G3 = 0.89, G4 = 0.87, G5 = 0.84 (g / Ah), the average water loss is 0.86 g / Ah.

[0062] Example 2

[0063] Take 5 6-QFLZ-220 batteries (AGM separator saturation of 94%-97% valve regulated battery), respectively test 20h rate capacity, and fully charged. Observe that the battery has no concentrated exhaust port, and the battery shell is 2x3 structure, using the way 4, 2# and 4# two single cell gas collection. See Figure 4 , the exhaust plug is covered with a plastic cup 1, the plastic cup and the battery cover are sealed by sealing glue, the upper opening is used as a single cell exhaust port, connected with the gas guide tube 2 one end, the other end of the gas guide tube 2 is inserted into the graduated cylinder 3, the battery together with the gas guide tube is placed in 40℃±2℃ water bath, the battery is required to be immersed in water more than 80%, the graduated cylinder 3 is filled with water, and its immersed in water height h = 20 mm. Temperature balance for 24h, 12h pre-charge at constant voltage 14.4V±0.05V, start to collect gas, record t = 1.5h of gas collection V4a1 =148, V 4a2 =152, V 4a3 =136, V 4a4 =144, V 4a5 =156 (mL), calculate the total gas intake V of the entire battery. a1 =3V 4a1 =444, V a2 =3V 4a2 =456, V a3 =3V 4a3 =408, V a4 =3V 4a4 =432, V a5 =3V 4a5 =468 (mL), V a Formula for calculating water loss in valve-regulated batteries with AGM separator saturation of 94%-97% (Part 5) The calculated water losses are as follows: G V1 =0.34, G V2 =0.35, G V3 =0.31, G V4 =0.33, G V5 =0.36 (g / Ah), and the average water loss is calculated to be 0.34 g / Ah.

[0064] Comparative Example 1

[0065] Take any 6-QW-180 battery (flooded battery), test its 20-hour rate capacity, and fully charge it. Then wipe the battery surface clean, dry it, and weigh it, recording W1 as 45.065 kg. Place it in a water bath at 40℃±2℃ and charge it at a constant voltage of 14.4V±0.05V for 500 hours. Wipe the battery surface clean, dry it, and weigh it, recording W2 as 44.908 kg. Calculate the water loss W = (45.065-44.908) / 180 = 0.87 g / Ah.

[0066] Comparative Example 2

[0067] Take any 6-QFLZ-220 battery (a valve-regulated battery with AGM separator saturation of 94%-97%), test its 20-hour rate capacity, and fully charge it. Then wipe the battery surface clean, dry it, and weigh it, recording W1 as 66.231 kg. Place it in a water bath at 40℃±2℃ and charge it at a constant voltage of 14.4V±0.05V for 500 hours. Wipe the battery surface clean, dry it, and weigh it, recording W2 as 66.158 kg. Calculate the water loss W = (66.231-66.158) / 220 = 0.33 g / Ah.

[0068] The test results of the examples and the comparative examples of the present application show that the water loss of example 1 tested by the method of the present application is 0.86 g / Ah, the water loss of comparative example 1 tested by the traditional method is 0.87 g / Ah; the water loss of example 2 is 0.34 g / Ah, and the water loss of comparative example 2 is 0.33 g / Ah. The test data of the present application is close to the test data of the traditional method, which shows that the data of the present application is effective, and the test period is shortened from 500 h to 24 h.

Claims

1. A rapid test method for water loss in lead-acid batteries, characterized in that: The water loss of the battery is calculated based on the volume of gas produced by the battery. The test method includes the following steps: a. Test the battery's 20-hour rate capacity and fully charge it; b. Select the appropriate gas collection method and install a gas collection device for different battery exhaust structures and reaction heat effects. Place the battery equipped with the gas collection device in a 40℃±2℃ water bath, and immerse the battery in water to a height of more than 80% of the total height of the battery. c. After 24 hours of temperature equilibration, perform a 12-hour pre-charge at a constant voltage of 14.4V ± 0.05V, then proceed to the gas collection stage and record the gas collection volume V. na , where n is the gas collection method number, n = 1, 2, 3 or 4, calculate the total gas collection volume V of the entire battery. a ; d. Calculate the gas volume V under standard conditions. n V a Substituting into the ideal gas law (I): (one) In the formula: V n Corrected gas volume (mL); V a The volume of gas collected (mL); T r Standard temperature: 293K; T a The ambient temperature is 40℃. P a The ambient atmospheric pressure is kPa, and the laboratory ambient atmospheric pressure is close to the standard atmospheric pressure. Therefore, P a =P r ; P r Standard atmospheric pressure: 101.3 kPa; Calculations yielded: V n =0.936V a ; e. Calculate the gas collection volume V and water loss of the battery over 500 hours: During the test, the gas collection time was t. The gas collection volume at time t was converted into the gas collection volume V over 500 hours. The gas collection volume V over 500 hours was obtained by calculating using the following formula (II): (two) Based on the gas collection rate V over 500 hours, the mass G of the electrolyzed water is calculated using the following formula (iii). (three) In equation (iii), 0.336: the electrochemical equivalent of water calculated using Faraday's law of electrolysis, in g / Ah; 684: Under standard conditions, the theoretical gas evolution rate of a battery that is fully used for water electrolysis when 1 Ah of electricity is charged into it, in mL / Ah. Based on the obtained mass G of electrolyzed water, the water loss value W is calculated using the following formula (iv), with units of g / Ah. (Four) In equation (iv), C n This refers to the battery's rated capacity.

2. The rapid test method for water loss in lead-acid batteries according to claim 1, characterized in that: In step e, when the test battery is a valve-regulated battery with an AGM separator saturation of 94%-97%, the water loss value is increased by 10% based on the value calculated in equation (iv), specifically: (five).

3. The rapid test method for water loss in lead-acid batteries according to claim 2, characterized in that: In step b, a corresponding gas collection method is selected based on different battery venting structures and reaction heat effects. Taking a 12V battery with 6 individual cells as an example, there are four gas collection methods, specifically: Gas collection method 1: The battery cover is designed with a centralized exhaust port, which can collect gas from 6 individual cells simultaneously, with a gas collection volume of V. 1a ; Gas collection method 2: The battery cover is designed with two centralized exhaust ports, each collecting gas from three individual cells. During testing, gas can be collected from any one of the centralized exhaust ports, with a collection volume of V. 2a ; Gas collection method 3: The battery cover does not have a centralized exhaust port, and the battery casing has a 1×6 structure. Gas is collected from three cells (1#, 2#, 3#) or three cells (4#, 5#, 6#), with a collection volume of V. 3a ; Gas collection method 4: Since there is no centralized exhaust port on the battery cover and the battery casing has a 2×3 structure, gas is collected from any one of the four cells (1#, 3#, 4#, and 6#), and simultaneously, gas is collected from any one of the two cells (2# and 5#). The gas collection volume is V. 4a .

4. The rapid test method for water loss in lead-acid batteries according to claim 3, characterized in that: In step c, the gas collection volume V is recorded according to the four gas collection methods. na Calculate the gas collection volume V of the entire battery. a Gas collection method 1: V a =V 1a For gas collection method 2: V a =2V 2a For gas collection method 3: V a =2V 3a For gas collection method 4: V a =3V 4a .

5. The rapid test method for water loss in lead-acid batteries according to claim 4, characterized in that: In step e, the gas collection time t varies depending on the type of battery. When the battery is a flooded battery, the gas collection time t is 0.5h; when the battery is a valve-controlled battery with an AGM separator saturation of 94%-97%, the gas collection time t is 1.5h.

6. The rapid test method for water loss in lead-acid batteries according to claim 5, characterized in that: The gas collection device includes a gas guide pipe (2), a measuring cylinder (3) and a bracket (4). One end of the gas guide pipe (2) is sealed to the centralized exhaust port on the battery, and the other end is inserted into the measuring cylinder (3). The measuring cylinder (3) is fixed upside down on the bracket (4). The measuring cylinder (3) is filled with water, and the height of its immersion in the water is h≤20mm.

7. The rapid test method for water loss in lead-acid batteries according to claim 6, characterized in that: When the battery does not have a centralized exhaust port, the gas collection device also includes a plastic cup (1). The plastic cup (1) has openings at both the top and bottom. The lower opening covers the exhaust plug on the battery. The plastic cup is sealed to the battery cover with sealant. The upper opening serves as a single-cell exhaust port and is connected to one end of the gas guide tube (2). The other end of the gas guide tube (2) is inserted into the measuring cylinder (3).

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