Lead storage battery

Abstract

To provide a lead storage battery capable of lowering an initial internal resistance value.SOLUTION: A lead storage battery includes: a battery case having a cell chamber; an electrode plate group stored in the cell chamber; and an electrolyte injected into the cell chamber. The electrode plate group has a laminate having a separator disposed between multiple alternating positive and negative electrode plates. The positive electrode plate has a positive electrode current collector plate including a grid-shaped portion and a positive electrode mix held in the grid-shaped portion. The positive electrode mix is porous. In a pore size distribution measured by subjecting the positive electrode mix to a mercury porosimeter, a proportion of pores having a diameter of 0.1 μm or more and 4.0 μm or less is 70% or more. In a graph showing a log differential pore volume distribution obtained by subjecting the positive electrode mix to the mercury porosimeter, a proportion of pores having a diameter of 0.4 μm or more and 2.0 μm or less and the log differential pore volume of 0.05 mL / g or more and 0.10 mL / g or less is 10% or more and 20% or less.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a lead-acid battery. [Background technology]

[0002] A flooded lead-acid battery, which is a typical lead-acid battery, includes a battery case having a cell chamber, a plate group housed in the cell chamber, and an electrolyte injected into the cell chamber. The plate group has a laminate including a plurality of alternatingly arranged positive and negative plate plates and separators arranged between the positive and negative plate plates.

[0003] The positive electrode plate has a positive electrode current collector including a lattice portion, a positive electrode mixture (a mixture containing a positive electrode active material) held by the lattice portion, and a layer of the positive electrode mixture is formed on both plate surfaces of the lattice portion.The negative electrode plate has a negative electrode current collector including a lattice portion, and a negative electrode mixture (a mixture containing a negative electrode active material) held by the lattice portion, and a layer of the negative electrode mixture is formed on both plate surfaces of the lattice portion. The positive electrode plate has a positive electrode current collector including a lattice portion, a positive electrode lug protruding upward from the lattice portion in the vertical direction of the battery case, and a positive electrode mixture (a mixture containing a positive electrode active material) held by the lattice portion, and the negative electrode plate has a negative electrode current collector including a lattice portion, a negative electrode lug protruding upward from the lattice portion in the vertical direction of the battery case, and a negative electrode mixture held by the lattice portion.

[0004] The positive electrode lug is disposed at a position offset to one side from the center of the width direction of the grid portion (a direction perpendicular to both the up-down direction of the battery case and the stacking direction of the stack), and the negative electrode lug is disposed at a position offset to the other side from the center of the width direction of the grid portion. The electrode plate group further has a positive electrode strap and a negative electrode strap that respectively connect the lugs of the multiple positive and negative electrode plates. Dilute sulfuric acid is used as the electrolyte. Such flooded lead-acid batteries are widely used as automobile batteries and the like.

[0005] The performance required for lead-acid batteries used in conventional engine vehicles was mainly related to starting performance, capacity, etc. However, in recent years, as charge-controlled vehicles and idling-stop vehicles have become mainstream, the performance required for lead-acid batteries has changed, and battery designs suitable for controlling charge-controlled vehicles and idling-stop vehicles are now required. When a charge-controlled vehicle or an idling-stop vehicle is driven after being left unused for a long period of time, the idling stop may not be performed. One of the reasons for this phenomenon is that when the vehicle is left unused for a long period of time, gas is generated from the positive and negative plates due to self-discharge, causing the internal resistance of the lead-acid battery to increase and become high. In idling-stop vehicles, idling stop is controlled based on the internal resistance value of the lead-acid battery, so it is essential that the lead-acid battery for idling-stop vehicles be controlled so that the internal resistance does not rise above a certain value.

[0006] Generally, the main factors that determine the initial internal resistance of a lead-acid battery immediately after manufacture are the mass of the lead components used in the battery, such as the straps, poles, and terminals (bushings), and the number of positive and negative plates included in the plate group, i.e., factors that are caused by the battery design, and it is essential to consider these design items in order to keep the initial internal resistance low. On the other hand, in lead-acid batteries, it is difficult to prevent self-discharge from occurring when the battery is left stationary, and self-discharge continues to occur during the period from battery manufacture to installation in the vehicle (actually, until the battery is driven and charging / discharging control begins), and the generated gas may accumulate inside the battery, causing the battery's internal resistance to continue to rise. When this happens, even though the battery itself is almost fully charged and in a healthy state, the internal resistance alone is high, so the vehicle determines that the "charge state is insufficient" or that the "battery itself is degraded," and control is put into place to stop the idling stop system itself, which means that there is a possibility of an intermittent "failure to stop idling."

[0007] Effective means for solving these problems include increasing the weight of lead parts such as straps and poles to reduce the initial internal resistance.Furthermore, various battery designs, such as increasing the number of positive and negative plates included in the plate group and the amount of mixture (mixture containing active material) held in the positive and negative plates, can be used to increase the battery reaction area, making it difficult for gas generated from the positive and negative plates to remain inside the battery and easy to efficiently release it to the outside of the battery. However, increasing the number of positive and negative plates contained in the lead components or plate group, and the amount of mixture held in the positive and negative plates, naturally leads to an increase in the weight of the lead-acid battery itself, which is contrary to the design concept of recent vehicles that require improved fuel efficiency.

[0008] In response to this, Patent Document 1 describes a method of suppressing an increase in the internal resistance of a lead-acid battery by controlling the diameter and pore volume of the pores of the active material held on the current collector. Specifically, the average diameter of the pores of the positive electrode active material is set to 0.07 μm or more and 0.20 μm or less, and the porosity of the positive electrode active material is set to 30% or more and 50% or less. This makes it difficult for gas generated in the positive electrode plate to remain inside the battery and makes it easier to efficiently release it outside the battery, thereby suppressing an increase in internal resistance. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2020-53296 A Summary of the Invention [Problem to be solved by the invention]

[0010] The lead-acid battery described in Patent Document 1 has room for improvement in terms of keeping the initial internal resistance low. An object of the present invention is to provide a lead-acid battery capable of keeping the initial internal resistance value low. [Means for solving the problem]

[0011] In order to solve the above problems, one aspect of the present invention provides a lead-acid battery having the following configurations (1) to (4). (1) A battery comprising a battery case having a cell chamber, a plate assembly housed in the cell chamber, and an electrolyte injected into the cell chamber. The plate assembly has a laminate formed by disposing a separator between a plurality of alternatingly arranged positive and negative plate sheets, and by alternately arranging the bag-shaped separator housing the positive plate and the negative plate. The positive plate has a positive electrode current collector including a lattice portion, and a positive electrode mixture (a mixture containing a positive electrode active material) held in the lattice portion. The negative plate has a negative electrode current collector including a lattice portion, and a negative electrode mixture (a mixture containing a negative electrode active material) held in the lattice portion. (2) The positive electrode mixture is porous. (3) In the pore size distribution measured by using a mercury porosimeter for the positive electrode mixture, the proportion of pores having a diameter of 0.1 μm or more and 4.0 μm or less is 70% or more. (4) In a graph showing a log differential pore volume distribution obtained by subjecting the positive electrode mixture to a mercury porosimeter, the proportion of pores existing in a range having a diameter of 0.4 μm or more and 2.0 μm or less and a log differential pore volume of 0.05 mL / g or more and 0.10 mL / g or less is 10% or more and 20% or less. Effect of the Invention

[0012] According to the lead-acid battery of the present invention, it is expected that the initial internal resistance value can be kept low. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram illustrating a flooded lead-acid battery according to an embodiment of the lead-acid battery of the present invention, with the lid removed from the battery case. [Diagram 2] FIG. 2 is a partial cross-sectional view of the flooded lead-acid battery of FIG. 1. [Diagram 3] 1 is a graph showing the log differential pore volume distribution of a positive electrode mixture constituting the flooded lead-acid battery No. 1 of the examples. [Figure 4]1 is a graph showing the log differential pore volume distribution of a positive electrode mixture constituting a flooded lead-acid battery No. 2 of the embodiment. [Diagram 5] 1 is a graph showing the log differential pore volume distribution of a positive electrode mixture constituting a flooded lead-acid battery No. 3 of the embodiment. [Figure 6] 1 is a graph showing the log differential pore volume distribution of a positive electrode mixture constituting a flooded lead-acid battery No. 4 of the embodiment. [Figure 7] 1 is a graph showing the log differential pore volume distribution of a positive electrode mixture constituting a flooded lead-acid battery No. 5 of the examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, the embodiments of the present invention will be described, but the present invention is not limited to the embodiments shown below. In the embodiments shown below, technically preferable limitations are imposed for carrying out the present invention, but these limitations are not essential requirements for the present invention.

[0015] [Overall battery configuration] As shown in Fig. 1, the flooded lead-acid battery of the embodiment has a monoblock-type battery case 1, a lid (not shown), and six electrode plate groups 2. The shape of the battery case 1 is a rectangular parallelepiped, and the battery case 1 has a pair of first walls 11 formed on a pair of long sides of a rectangle forming a bottom surface, and a pair of second walls 12 formed on a pair of short sides. The interior of the battery case 1 is divided into six cell chambers 4 by five partition walls 13 parallel to the second walls 12. One electrode group 2 is disposed in each of the six cell chambers 4, and an electrolyte is poured into each cell chamber 4. The electrolyte is dilute sulfuric acid with a specific gravity of 1.28 to 1.30 (calculated at 20°C). Although not shown, the tops of all of the cell chambers 4 are closed by fixing lids to the battery case 1. As shown in FIG. 1, the direction in which the cell chambers 4 are arranged is the X direction, and the direction perpendicular to this is the Y direction.

[0016] 2, the electrode plate group 2 has a laminate 6, and the laminate 6 is composed of a plurality of positive electrode plates 10 and negative electrode plates 20 arranged alternately, and separators 30 arranged between the positive electrode plates 10 and the negative electrode plates 20. The laminate 6 is formed by arranging the negative electrode plates 20 and bag-shaped separators housing the positive electrode plates 10 alternately. The number of positive electrode plates 10 constituting the laminate 6 may be the same as the number of negative electrode plates 20, or may be greater than the number of negative electrode plates 20. In this example, the number of positive electrode plates 10 is one less than the number of negative electrode plates 20.

[0017] The positive electrode plate 10 is composed of a positive electrode current collector and a positive electrode mixture (a mixture containing a positive electrode active material), and the positive electrode current collector has a rectangular lattice portion and an ear protruding from one side of the rectangle forming the lattice portion, and the positive electrode mixture is held in the lattice portion. In FIG. 2, the lattice portion holding the positive electrode mixture is indicated by reference numeral 101, and the ear of the positive electrode plate 10 is indicated by reference numeral 120. The ear 120 of the positive electrode plate 10 is disposed at a position shifted to one side from the center in the width direction of the lattice portion (the direction perpendicular to the paper surface of FIG. 2, the Y direction in FIG. 1). The positive electrode plate 10 will be described in detail later.

[0018] The negative electrode plate 20 is composed of a negative electrode current collector and a negative electrode mixture (a mixture containing a negative electrode active material), and the negative electrode current collector has a rectangular lattice portion and an ear protruding from one side of the rectangle forming the lattice portion, and the negative electrode mixture is held in the lattice portion. In Fig. 2, the lattice portion holding the negative electrode mixture is indicated by reference numeral 201, and the ear of the negative electrode plate 20 is indicated by reference numeral 220. The ear 220 of the negative electrode plate 20 is disposed at a position shifted from the center in the width direction of the lattice portion (the direction perpendicular to the paper surface of Fig. 2, the Y direction in Fig. 1). The laminate 6 is housed in the cell chamber 4 with the lamination direction aligned along the X direction and with the plate surfaces of the positive electrode plates 10 and the negative electrode plates 20 aligned along the up-down direction of the cell chamber 4.

[0019] Each plate group 2 further has a positive electrode strap 71, a negative electrode strap 72, and a positive electrode intermediate pole 71a and a negative electrode intermediate pole 72a rising from the positive electrode strap 71 and the negative electrode strap 72, respectively. The positive electrode strap 71 and the negative electrode strap 72 connect the lugs 120 of the multiple positive electrode plates 10 and the lugs 220 of the multiple negative electrode plates 20 constituting the stack 6 at different positions in the width direction of the positive electrode plates 10 and the negative electrode plates 20 (the direction that becomes the Y direction when inserted into the cell chamber). The plate groups 2 arranged in the cell chambers at both ends in the cell arrangement direction each have a positive electrode pole 8 and a negative electrode pole 9 that serve as external terminals.

[0020] The positive electrode intermediate pole 71a and the negative electrode intermediate pole 72a of the adjacent cell chambers 4 are resistance welded to electrically connect the adjacent cells in series. The positive electrode pole 8 and the negative electrode pole 9 are formed on the positive electrode strap 71 and the negative electrode strap 72 via small pieces 71b and 72b, respectively. The positive electrode pole 8 and the negative electrode pole 9 penetrate the lid and are exposed to the outside.

[0021] [Regarding positive and negative plates] [Positive electrode current collector, negative electrode current collector] The positive electrode current collector constituting the positive electrode plate 10 is formed by gravity casting using a Pb-Ca-Sn alloy. The negative electrode current collector constituting the negative electrode plate 20 is formed by continuous casting using a Pb-Ca-Sn alloy. Other manufacturing methods for the positive electrode current collector and the negative electrode current collector include a punching method for a rolled lead alloy plate and an expanding method using a rolled lead alloy plate.

[0022] [Method of manufacturing positive and negative electrode plates] The positive electrode mixture and the negative electrode mixture are filled in the openings of the lattice parts of the positive electrode current collector plate and the negative electrode current collector plate, and are also present in layers on both plate surfaces of the lattice parts. The positive electrode mixture and the negative electrode mixture are formed on the lattice parts of each current collector plate, for example, as follows. First, necessary additives (polypropylene fiber, polyethylene fiber, conductive carbon, etc.) are added to the lead powder and mixed by dry mixing, then water is added and kneaded to obtain a water paste, and sulfuric acid is added to this water paste and kneaded to prepare a paste for the positive electrode and a paste for the negative electrode. At this time, organic shrink-proofing agents such as lignin, which are often used as additives for the negative electrode, may be added at the same time as water because they are water-soluble. Next, the obtained positive electrode paste and negative electrode paste are filled into the openings of each grid-shaped portion, and then aging and drying processes are performed to obtain a pre-chemical positive electrode plate and a pre-chemical negative electrode plate. Furthermore, by assembling these into a flooded lead-acid battery and then performing battery container formation, a positive electrode mixture and a negative electrode mixture are formed in each grid-shaped portion.

[0023] [Porosity and pore size distribution of positive electrode mixture] The positive electrode mixture of the positive electrode plate constituting the flooded lead-acid battery of the embodiment is porous and has a porosity of 30% to 50%. In addition, in a pore size distribution measured by subjecting the positive electrode mixture to a mercury porosimeter, the proportion of pores having a diameter of 0.1 μm to 4.0 μm is 70% or more. Furthermore, in a graph showing a log differential pore volume distribution obtained by subjecting the positive electrode mixture to a mercury porosimeter, the proportion of pores existing in a range having a diameter of 0.4 μm to 2.0 μm and a log differential pore volume of 0.05 mL / g to 0.10 mL / g is 10% to 20%.

[0024] The porosity and pore size distribution of the positive electrode mixture can be adjusted, for example, by controlling the temperature during formation. As a method for adjusting the positive electrode mixture of the positive plate constituting the flooded lead-acid battery of the embodiment to the above porosity and pore distribution, a method of placing the flooded lead-acid battery before formation in a water tank with the water temperature adjusted to 40°C and performing battery container formation while adjusting the electrolyte temperature in the battery to 60°C can be mentioned. The method of placing the flooded lead-acid battery before formation in a water tank with the water temperature adjusted to 30°C and performing battery container formation while adjusting the electrolyte temperature in the battery to 40°C cannot adjust to the above pore size distribution.

[0025] [Action, effect] In the flooded lead-acid battery of the embodiment, the pore size distribution of the positive electrode mixture is such that in the pore size distribution measured by subjecting the positive electrode mixture to a mercury porosimeter, the proportion of pores having a diameter of 0.1 μm or more and 4.0 μm or less is 70% or more, and in a graph showing the log differential pore volume distribution obtained by subjecting the positive electrode mixture to a mercury porosimeter, the proportion of pores existing in the range of diameters of 0.4 μm or more and 2.0 μm or less and log differential pore volumes of 0.05 mL / g or more and 0.10 mL / g or less is 10% or more and 20% or less. As a result, the flooded lead-acid battery of the embodiment can keep the initial internal resistance lower than one that does not satisfy the above configuration.

[0026] In addition, the porosity of the positive electrode mixture of the positive plate is 30% or more and 50% or less, which is a preferable configuration in terms of the utilization rate of the active material and the battery life. If the porosity of the positive electrode mixture is less than 30%, sulfuric acid does not easily penetrate into the positive electrode mixture, and the utilization rate of the active material becomes insufficient. On the other hand, if the porosity of the positive electrode mixture is more than 50%, the density of the active material is too low, and the required life may not be obtained. In the present embodiment, a flooded lead-acid battery is described, but the lead-acid battery of the present invention may be a valve regulated lead-acid battery. EXAMPLES

[0027] [Preparation of test battery] As flooded lead-acid batteries having the same structure as the flooded lead-acid battery of the embodiment, flooded lead-acid batteries of Samples No. 1 to No. 5 having the configurations shown below were fabricated in pairs. The flooded lead-acid batteries of samples No. 1 to No. 5 were flooded lead-acid batteries with a 20-hour rate capacity of 64 Ah, Q-85 (D23 size), and nominal voltage of 12 V, and all had the same configuration except that the temperature conditions for battery container formation were changed as shown in Table 1.

[0028] Specifically, it was prepared by the following method. First, positive and negative current collectors were made of Pb-Ca-Sn alloys. The positive current collector was produced by a book mold casting method, and the negative current collector was produced by a continuous casting method. Next, the lattice part of the positive electrode current collector was filled with a paste of a mixture (positive electrode mixture) containing a positive electrode active material prepared by a normal method, and aged and dried to obtain a positive electrode plate (positive electrode filled plate) before chemical formation. Also, the lattice part of the negative electrode current collector was filled with a paste of a mixture (negative electrode mixture) containing a negative electrode active material prepared by a normal method, and aged and dried to obtain a negative electrode plate (negative electrode filled plate) before chemical formation.

[0029] Next, the unconverted negative plates were placed in a polyethylene separator bag, and eight separators containing unconverted negative plates and seven unconverted positive plates were alternately stacked to obtain a laminate. Next, a cast-on-strap (COS) casting device was used to form straps, intermediate poles, and terminal poles on the unconverted positive and negative plates of each laminate, obtaining six electrode plate groups. Next, the six obtained electrode plate groups were placed in each of the six cell chambers of a monoblock-type battery case made of polypropylene.

[0030] After that, the intermediate poles between adjacent cell chambers were resistance-welded, the battery case and the lid were heat-welded, and the terminals were welded in the usual manner. Next, aluminum sulfate octadecahydrate (Al2(SO4)3·18H2O) was added to dilute sulfuric acid with a specific gravity of 1.230 (calculated at 20°C) to obtain an electrolyte with an aluminum ion concentration of 0.1 mol / L and a specific gravity of 1.240 (calculated at 20°C). This electrolyte was then poured into each cell chamber through each of the filling holes on the lid. Next, the filling holes were closed with filling plugs to assemble an unformed flooded lead-acid battery.

[0031] Thereafter, for Samples No. 1 to No. 3, the unformed flooded lead-acid batteries were placed in a water tank with the water temperature adjusted to 40° C., and the container was formed with 230% current while adjusting the temperature of the electrolyte in the battery to 60° C. In this way, the positive and negative electrode filled plates were used as positive and negative plates, and flooded lead-acid batteries Samples No. 1 to No. 3 with electrolyte specific gravity of 1.29 (20° C. converted value) were obtained. For Samples No. 4 and No. 5, the unformed flooded lead-acid batteries were placed in a water tank with the water temperature adjusted to 30°C, and the battery tank was formed with 230% current while adjusting the electrolyte temperature inside the battery to 40°C. As a result, the positive and negative filled plates were used as the positive and negative plates, and flooded lead-acid batteries Samples No. 4 and No. 5 were obtained, in which the specific gravity of the electrolyte was 1.280 (converted value at 20°C).

[0032] [Testing and Evaluation] <Measurement of pores in positive electrode mixture> Each of the obtained flooded lead-acid batteries (fully charged state) of Samples No. 1 to No. 5 was immediately disassembled, and the plate group was removed from the cell chamber (third cell chamber) adjacent to the cell chamber (first cell chamber) in which the plate group having the positive terminal pole was stored. The positive plate stored in the bag-shaped separator located in the center of the removed plate group was removed, and the positive electrode mixture held in the lattice-shaped part of the positive electrode current collector was scraped off and crushed to obtain a powdered measurement sample for each sample.

[0033] The obtained samples were subjected to a mercury porosimeter (Shimadzu AutoPore IV 9500) to measure the pore size distribution of the positive electrode mixture. In addition, a graph of the log differential pore volume distribution was obtained. These graphs are shown in Figures 3 to 7. Figures 3 to 7 correspond to the graphs of samples No. 1 to No. 5, respectively. From the measurement results of the pore size distribution, the percentage of pores with diameters of 0.1 μm to 4.0 μm and the average pore size were examined. In addition, from each graph of the obtained log differential pore volume distribution, the percentage of pores existing in the range of diameters of 0.4 μm to 2.0 μm and log differential pore volumes of 0.05 mL / g to 0.10 mL / g was examined. Furthermore, the porosity of each obtained sample was examined.

[0034] <Internal resistance measurement> Each of the remaining integral flooded lead-acid batteries of Samples 1 to 5 obtained was left to stand in an atmosphere at a temperature of 25° C. for 48 hours without being disassembled, and then the internal resistance value was measured.

[0035] These results are shown in Table 1 together with the conditions for forming the battery container and the pore structure of the positive electrode mixture.

[0036] [Table 1]

[0037] As can be seen from the results in Table 1, the flooded lead-acid batteries No. 1 to No. 3 satisfying the configuration of the present invention had low internal resistance values ​​of 4.20 mΩ or less after being left standing for 48 hours, whereas the flooded lead-acid batteries No. 4 to No. 5 not satisfying the configuration of the present invention had high internal resistance values ​​of 4.41 mΩ or more after being left standing for 48 hours. [Explanation of symbols]

[0038] 1 battery case 11 The first wall of the battery case 12 The second wall of the battery case 13 Battery case bulkhead 2 Plate group 30 Separator 4 Cell Room 6 Laminate 10 Positive electrode plate 101 The grid-like portion of the positive electrode current collector plate in which the positive electrode mixture is held 120 Positive electrode collector plate lug 20 Negative plate 201 The grid-shaped portion of the negative electrode current collector plate holding the negative electrode mixture 220 Negative electrode current collector lug 71 Positive strap 72 Negative strap 71a Positive electrode intermediate pole 72a Negative intermediate pole 8 Positive terminal 9 Negative terminal

Claims

1. The battery includes a battery case having a cell chamber, a plate group housed in the cell chamber, and an electrolyte injected into the cell chamber; the electrode plate group has a laminate in which a separator is disposed between a plurality of alternately arranged positive electrode plates and negative electrode plates, The positive electrode plate includes a positive electrode current collector including a lattice portion and a positive electrode mixture held by the lattice portion, The negative electrode plate includes a negative electrode current collector including a lattice portion and a negative electrode mixture held by the lattice portion, The positive electrode mixture is porous, In a pore size distribution measured by a mercury porosimeter for the positive electrode mixture, the proportion of pores having a diameter of 0.1 μm or more and 4.0 μm or less is 70% or more; A lead-acid battery, in which in a graph showing a log differential pore volume distribution obtained by subjecting the positive electrode mixture to a mercury porosimeter, the proportion of pores existing in a range having a diameter of 0.4 μm or more and 2.0 μm or less and a log differential pore volume of 0.05 mL / g or more and 0.10 mL / g or less is 10% or more and 20% or less.

2. In a pore size distribution measured by a mercury porosimeter for the positive electrode mixture, the ratio of pores having a diameter of 0.1 μm or more and 4.0 μm or less is 70% or more and 75% or less; 2. The lead-acid battery according to claim 1, wherein in a graph showing a log differential pore volume distribution obtained by subjecting the positive electrode mixture to a mercury porosimeter, the proportion of pores existing in a range having a diameter of 0.4 μm or more and 2.0 μm or less and a log differential pore volume of 0.05 mL / g or more and 0.10 mL / g or less is 14% or more and 17% or less.

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