JP2014130759A - Knapsack type power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a knapsack type power supply by which temperature distribution of a secondary battery becomes uniform.SOLUTION: A knapsack type power supply comprises: a battery assembly having a plurality of secondary battery cells; a substrate controlling the battery assembly; heat uniformizing means provided between the battery assembly and the substrate; a case part housing the battery assembly, the substrate, and the heat uniformizing means; and a knapsack part attached to the case part.

Description

  The present invention relates to a back-fed power source that is equipped with a secondary battery and supplies electric power to a power tool.

  Conventionally, in an electric tool powered by a motor or the like, not only a tool used by connecting an AC commercial power source or a DC constant voltage power source, but also an electric tool capable of mounting a secondary battery has been widely used. Yes. In power tools using secondary batteries, so-called cordless power tools, the demand for larger battery capacities is increasing due to the expansion of the types and applications of power tools. Only battery packs that are directly attached to the tool body In addition, a battery holster that houses a secondary battery and can be worn on the waist is known (see, for example, Patent Document 1).

Japanese Utility Model Publication No. 7-3983

  However, the battery holster that can be worn on the operator's waist has a limit on the number of secondary batteries that can be worn, and the portable power source for power tools and the like has a larger capacity than the battery holster, such as the backpack type. There is a demand for commercial power supplies.

  In this case, a large-capacity power source such as a back-loading type has a plurality of secondary battery units (for example, lithium ion secondary batteries) arranged in parallel and accommodated in order to increase the capacity. Further, in the technical field where a high current output is required, it is required to use a secondary battery having a low internal resistance in order to reduce heat generation of the secondary battery due to the internal resistance.

With the above-described configuration, a large-capacity power source such as a backpack type may cause temperature variation for each battery unit as compared with a conventional small-capacity battery pack. In addition, a large-capacity power source such as a back load type outputs a large current and is expected to be used continuously for a long time, so the amount of heat generated by the secondary battery also increases. Therefore, a slight difference in the characteristics of the battery units constituting the large capacity power source tends to increase with use.

  Furthermore, in this technical field, a secondary battery having a characteristic that the temperature rises during charging or discharging is employed. Secondary batteries generally have a tendency to increase the output current because the activation inside the battery increases as the temperature rises. In a secondary battery whose temperature rises during discharge, the temperature and output current have a positive correlation. doing. For this reason, once a temperature difference occurs between the secondary batteries, the difference may spread.

  Due to such temperature variation of the secondary battery, the life of the battery unit also varies. The power storage capacity of the large-capacity power supply is limited by the battery unit having the secondary battery whose heat generation is extremely shortest.

  Therefore, the variation in temperature of the secondary battery constituting the large-capacity power supply is a problem that becomes more serious as the number of power supply cells increases or the capacity increases. Sufficient measures are required to put the power supply into practical use.

  In view of such circumstances, the present invention intends to provide a back-fed power source in which the temperature distribution of the secondary battery is uniform.

  In order to achieve the above object, the present invention provides a battery assembly including a plurality of secondary battery cells, a substrate for controlling the battery assembly, and a heat equalization provided between the battery assembly and the substrate. There is provided a back-type power source comprising means, a case part for accommodating the battery set, the substrate, and the heat equalizing means, and a back-side part attached to the case part.

  According to such a configuration, it becomes possible to make the temperature distribution of the secondary battery cells close to be uniform, and as a result, the capacity of the backpack type power source can be secured for a longer period of time.

  The battery set includes a plurality of cell units each including a plurality of secondary battery cells, and the heat equalization unit includes a parallel connection unit that electrically connects the cell units in parallel. Preferably, the resistance value of the entire current path connecting each of the cell units and the substrate is equal in the at least two cell units. According to such a configuration, it becomes possible to equalize the amount of current output from each cell unit, and the amount of heat generated by each cell unit can be made close to uniform.

  The parallel connection unit includes a plurality of conductive plates that connect at least two cell units in parallel, and a plurality of lead wires that connect the plurality of conductive plates and the substrate, and the plurality of conductive plates. The resistance values of the plurality of lead wires are preferably equal. According to such a configuration, it becomes possible to equalize the amount of current output from each cell unit, and the amount of heat generated by each cell unit can be made close to uniform.

In the parallel connection portion, it is preferable that a sum of a resistance value of a positive current path connecting the cell unit and the substrate and a resistance value of a negative current path is equal in the at least two cell units. According to this configuration, the temperatures of at least two cell units can be made closer to each other.
It is preferable that at least one of a switch for cutting off a circuit or a fuse is provided between the battery set and the substrate.
The substrate further includes a switching element that switches between supply and disconnection of power from a plurality of cell units, and a heat insulating member is provided as the heat uniformizing unit between the switching element and the battery set. It is preferable. According to such a configuration, it is possible to suppress the heat generated from the switching element from moving to the battery set, and thus it is possible to make the temperature distribution of the secondary battery cells closer to uniform.

  The plurality of cell units include at least a first cell unit and a second cell unit, and the substrate is provided between the first cell unit and the second cell unit. Is preferred. According to such a configuration, the cell units can be connected by the conductive members having substantially the same resistance value with a simple configuration. Moreover, it becomes possible to make the temperature distribution of each secondary battery cell close to uniform using the heat dissipation effect of the substrate.

  Preferably, the substrate is composed of at least two substrates, and each of the at least two substrates is provided on a side surface of the cell unit. According to such a configuration, it is possible to make the temperature distribution of each secondary battery cell closer to uniform using the heat dissipation effect of the at least two substrates.

The battery set includes a plurality of cell units each including a plurality of secondary battery cells, and the heat equalization unit includes a parallel connection unit that electrically connects the cell units in parallel. Is composed of a first cell unit housed in the upper part of the case part and a second cell unit housed in the case part lower than the first cell unit, and the parallel connection part is It is preferable that the resistance value of the entire current path connecting the first cell unit and the substrate is larger than the resistance value of the lead wire connected to the second cell unit. According to this configuration, the amount of heat generated by each cell unit can be adjusted by the resistance value of the lead wire, and the temperature distribution of the secondary battery cells can be made more uniform.
The battery set includes at least three cell units including a plurality of secondary battery cells, and the heat equalization unit includes a parallel connection unit that electrically connects the cell units in parallel, and the plurality of cells. The unit includes a first cell unit placed at an end inside the case portion, a second cell unit placed at the other end inside the case portion, the first cell unit, and a second cell unit. The parallel connection portion has a resistance value of an entire current path connecting the third cell unit and the substrate, the first and second cell units being placed between the cell units. It is preferable that the resistance value of the entire current path connecting the second cell unit and the substrate is larger. According to such a configuration, the temperature distributions of the three cell units can be made closer to each other.
It is preferable that the heat equalizing means has a heat diffusing member, and the heat diffusing member is provided in at least a part of the periphery of the battery set. The heat diffusing member is preferably provided on a side surface of the battery set. According to such a configuration, it becomes possible to make the temperature distribution of the battery set closer to uniform.
Preferably, the case portion is formed of a material having a higher thermal conductivity than the backpack portion, and the heat diffusion member is in thermal contact with the case portion and transfers heat to the case portion. According to such a configuration, the temperature distribution of the battery set can be made closer to uniform using the case portion.

  According to the back load type power supply of the present invention, it becomes possible to reduce the uneven temperature distribution of a large number of secondary battery cells mounted on the power supply, and the ability of the back load type power supply for supplying power to the power tool is ensured for a long time. can do.

The perspective view which shows the external appearance of the backpack type power supply of this Embodiment. The front view which shows the structure inside the case part of this Embodiment. The side view which shows the structure inside the right end part of the case part of this Embodiment. The side view which shows the structure inside the left end part of the case part of this Embodiment. The front view which shows the structure inside the case part of the left end part of the backpack type power supply of a modification.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 exemplifies an overview of a backpack type power supply according to this embodiment, and a detailed configuration is omitted.

  As shown in FIG. 1, the backpack-type power source 1 according to the present embodiment is in a state in which a case portion 12 housing a plurality of battery cells 51 (see FIG. 2) housed therein is carried by a backpack portion 13. , For supplying power to electric tools (including small work tools such as chainsaws, blowers, brush cutters, lawn mowers, etc. used outdoors in agriculture, gardens, streets, etc.) connected via the power cable 32 It is. In the present embodiment, as illustrated in FIG. 1, tools 2A, 2B, etc. used for drilling or screw tightening via a connector 31, a power cable 32, and an adapter 33 connected to the lower part of the backpack type power source. Connected to. As shown in FIG. 2, the backpack-type power source 1 includes a case portion 12 having a box shape, a backpack portion 13, and an operation switch 14.

  The backpack 13 has a backpack and a shoulder belt, and the user carries the backpack power source 1 by putting the shoulder belt on the shoulder.

  The case portion 12 is preferably a hard case material having sufficient strength to work with the electric tool, and at least the internal space portion is formed of a non-conductive material. As such a material, a metal whose surface is insulated by coating or the like, a nonconductive resin, or the like is preferable. If the structure for holding the secondary battery or the like inside is a hard material, the exterior of the case portion 12 may be made of a soft material (cloth or the like made of a fibrous material).

  As shown in FIG. 2, in the present embodiment, a total of 80 lithium ion secondary battery cells (hereinafter referred to as battery cells) 51 are provided in the case portion 12 as an example. In detail, in the case part 12, the cell unit 52 (upper 10) comprised of a total of 20 battery cells 51 in which 10 battery cells 51 connected in series in the left-right direction were connected in parallel in two rows in the vertical direction. 4 units 52A to 52D) in order. Each cell unit 52 extends in the left-right direction, and the plurality of cell units 52 are arranged in the up-down direction. There are a total of 80 battery cells exemplified in the present embodiment, and each battery cell 51 is a lithium ion secondary battery cell 51 having a rating of 3.6 volts, and the power source has a rating of 36 volts as a whole.

The case unit 12 is provided with a main switch 59. The main switch 59 is an element that is in a part of the power supply path from the cell unit 52 to the tools 2A, 2B, etc. having different rated voltages, and can shut off the output to the outside.
As an example, in the present embodiment, the substrate 60 is mounted on the upper part of the cell unit 52A, and monitors the overdischarge / overcharge of the entire back negative power source 1 and each cell unit 52 to charge / discharge. A circuit for controlling is mounted. The substrate 60 has FETs 61A and 61B, and the FETs 61A and 61B are used in a control circuit or a circuit for monitoring overdischarge and overcharge. In the present embodiment, as an example, the FETs 61 </ b> A and 61 </ b> B are used as interrupting elements that stop discharging and charging when each cell unit 52 is overdischarged and overcharged. In addition, a heat insulating sheet 65 is provided as a heat insulating member at a place where the FETs 61A and 61B are provided on the lower surface of the substrate 60 (the surface facing the cell unit 52). The size of the heat insulating sheet 65 is at least larger than that of the FETs 61A and 61B at a portion in contact with the battery cell 51, such as in the front-rear and left-right directions. Although an example in which two FETs 61A and 61B are provided on the substrate 60 is shown, the number of FETs is not necessarily limited to two. Also in this case, the heat insulating sheet 65 having a size that allows sufficient thermal separation from the battery cell 51 in the front-rear and left-right directions from each FET is provided on the substrate 60. In the example of FIG. 2, a single heat insulating sheet 65 is provided collectively for the FETs 61 </ b> A and 61 </ b> B, but a protective sheet 65 may be provided individually. In the present invention, “heat insulation” means “to reduce heat transfer”, and any material that can be intentionally inserted to prevent heat transfer between the FET and the battery cell 51. Can be adopted. As an example, the material constituting the heat insulating sheet 65 is preferably a resin material or a porous material having a low thermal conductivity.

  A metal plate 56 is provided at the end of each battery cell 51 of each cell unit 52. These metal plates 56 are connected so that one cell unit has a configuration in which 10 battery cells 51 are arranged in parallel in two in the vertical direction and in series in the horizontal direction.

  As shown in FIGS. 2 and 3, two substantially linear metal plates 571 (571 </ b> A, 571 </ b> B) and two lead wires 581 (581 </ b> A, 581 </ b> B) are provided on the right end side of the cell unit 52. . As shown in FIGS. 2 and 4, two substantially linear metal plates 572 (572A, 572B) and two lead wires 582 (582A, 582B) are provided on the left end side of the cell unit 52. It has been. The lengths of the two lead wires 581 are substantially equal to each other, and the lengths of the two lead wires 582 are also equal to each other. Accordingly, the resistance values of the two lead wires 581 are equal to each other, and the resistance values of the two lead wires 582 are also equal to each other.

  As shown in FIG. 2, the metal plate 571A connects the plus side terminals of the cell units 52A and 52B in parallel, and the metal plate 571B connects the plus side terminals of the cell units 52C and 52D in parallel. In addition, one end of each of the lead wires 581A and 581B is connected to a central portion in the vertical direction of the metal plates 571A and 571B, respectively, and the other end is connected to one terminal of the substrate 60 at one point. Thereby, the metal plates 571A and 571B are connected in parallel.

  The metal plate 572A connects the minus side terminals of the cell units 52A and 52B in parallel, and the metal plate 572B connects the minus side terminals of the cell units 52C and 52D in parallel. In addition, one end of each of the lead wires 582A and 582B is connected to a central portion in the vertical direction of the metal plates 572A and 572B, respectively, and the other end is connected to one terminal of the switch 59 at one point. Thereby, the metal plates 572A and 572B are connected in parallel. Accordingly, the four cell units 52 are connected in parallel.

  In the present embodiment, each cell unit 52 and two connection points on the main body side (in this embodiment, one terminal on the substrate 60 to which the lead wires 581A and 581B are connected, and the lead wires 582A and 582B are connected. The metal plates 571, 572, and the two wires so that the resistance between the terminals of the switch 59 (hereinafter referred to as wiring resistance) is equal in all cell units including the contact resistance at each point. The resistance values of the lead wires 581 and 582 are set equal to each other. Here, “equal to each other” does not require that the difference in resistance value between the connection points is completely zero. For example, the resistance value is sufficiently smaller than the internal resistance value of the battery cell 51 or the battery cell unit 52. Any difference that does not substantially affect the variation in the temperature rise is acceptable. In the present embodiment, as an example, a battery cell 51 having an internal resistance of about 20 mΩ is employed. In addition, the present embodiment is only one preferable example, and the metal plates 571 and 572 have a configuration in which each path resistance value from each cell unit to the connection point on the main body side such as the control board is equal. And the lead wires 581 and 582 do not have to have the same resistance value. When the interruption switch 59 or a fuse is interposed in the path, the combined resistance of the entire path including the interruption switch 59 is As long as the units are equal, wiring may be shared by one wiring for a portion where the path is common in each unit, for example, from the switch 59 for blocking to the control board.

  The back-type power source 1 is a large-capacity power source, and the output current value also increases. In the present embodiment, as an example, it is assumed that a large current of about 5 A is output from each cell unit 52. Since such a large current flows, there is a concern that the variation in the temperature of the cell unit 52 increases as the amount of heat generated from each cell unit 52 increases. Further, if a difference in wiring resistance occurs due to a difference in wiring path length, a difference occurs in the output current from each cell unit, resulting in a large variation in the amount of heat generated in the cell unit.

For example, as a comparative example, the positive terminal and the negative terminal of four cell units 52 are connected in parallel with one metal plate, and connected to two connection points on the main body side at the upper end or lower end of the metal plate. In this case, the wiring resistances of the four cell units 52 cannot be made equal. In such a case, a difference in wiring resistance of about 200 mΩ occurs as an example between a cell unit near the connection point and a cell unit far from the connection point. Further, as described above, the battery cell 51 made of a lithium ion battery has a small internal resistance, and the battery cell employed in the present embodiment has an internal resistance of about 20 mΩ.

Therefore, in these large current / low internal resistance systems, the contribution of the wiring resistance cannot be ignored. Due to the difference in the wiring resistance, the temperature difference of the battery cell unit 52 is 10 in the comparative example. It may occur on the order of ~ 20 ° C. On the other hand, in the present embodiment, the metal plates 571 and 572 are each divided into two parts, and the two lead wires 581 having the same length and the two lead wires 582 having the same length are used as 4 Two cell units 52 are connected in parallel. For this reason, the wiring resistance of each cell unit 52 becomes equal. Therefore, the current output from each cell unit 52 is also equal, and the heat generation amount of each cell unit 52 can be made uniform.

  In the present embodiment, a heat insulating sheet 65 is provided on the lower surface of the substrate 60 (the surface facing the cell unit 52) where the FETs 61A and 61B are provided. In the substrate 60, the FETs 61A and 61B are main heat sources. Therefore, by providing the heat insulating sheet 65, it is possible to prevent the heat generated from the FETs 61A and 61B from moving to the cell unit 52 side. Thereby, it is possible to prevent the temperature of the cell unit 52A adjacent to the FETs 61A and 61B, specifically, the battery cell 51 in the cell unit 52A and the battery cell 51 adjacent to the FETs 61A and 61B from rising.

  The backpack type power supply according to the present invention is not limited to the above-described embodiments, and various modifications and improvements can be made within the scope described in the claims.

  For example, in the above embodiment, two metal plates 571 and 572 are provided, but the number of metal plates 571 and 572 is not limited to two. For example, the same number of metal plates 571 and 572 as each cell unit, four in the example of this embodiment, are prepared, and each metal plate 571 and 572 is connected to one corresponding cell unit 52, and each metal unit The plates 571 and 572 may be connected by four lead wires 581 and 582. Also in this case, the lengths (resistance values) of the four lead wires 581 are equal, and the lengths (resistance values) of the four lead wires 582 are equal. In addition, one metal plate 571, 572 is connected to each cell unit in the same manner as in the comparative example (one common to each cell unit), and one metal plate is connected to one lead wire at the lower end. The other metal plate may be connected to one lead wire at the upper end. In this case, the path length on each of the positive electrode side and the negative electrode side differs for each cell unit, but the sum of the path lengths on the positive electrode side and the negative electrode side, that is, the total wiring resistance viewed from the connection point on the main body side is Will be equal throughout.

  In the above embodiment, the substrate 60 is provided above the cell unit 52A. However, the position where the substrate 60 is provided is not limited to the upper portion. For example, you may provide between the cell unit 52B and the cell unit 52C, ie, in the intermediate part of the four cell units 52. FIG. In this case, a heat insulating sheet may be provided so as to cover not only the lower surface of the substrate 60 but also the upper surfaces of the FETs 61A and 61B. According to such a configuration, the length of the lead wire 581 that connects the metal plate 571 and the substrate 60 can be shortened while being equal. The switch 59 may also be arranged so that its vertical position is close between the cell unit 52B and the cell unit 52C. According to such a configuration, the lengths of the lead wires 582 can be made even shorter while being equal. In addition to providing the substrate 60 between the cell unit 52B and the cell unit 52C, a substrate may be provided between the other cell units 52, and the battery tab of the cell unit 52 may be provided in the front-rear direction of the case portion. You may provide between the metal plate 56 used as (electrode) and a case part. Also in this case, the length of the lead wire 581 can be made shorter than when the substrate 60 is provided above the cell unit 52A.

  Further, the substrate 60 may be divided into a plurality of parts and arranged around the cell unit 52. For example, the substrate 60 may be divided into two and arranged on the front side and the rear side of the cell unit 52 (front side and back side in FIG. 2), right and left, top and bottom, respectively. According to such a configuration, the heat generated from the cell unit 52 and the heat generated from the FETs 61A and 61B can be dispersed and made uniform using the above. Note that the number of divisions of the substrate 60 may be two or more.

  In the above embodiment, the lengths of the lead wires 581 and 582 are made equal, and the wiring resistance is made uniform, so that the heat generation of each cell unit 52 is made uniform. On the other hand, when the number of battery cells 51 and cell units constituting the cell unit 52 is increased and the density of the battery cells is increased, a portion where the secondary batteries are concentrated due to heat generation of each secondary battery, that is, a case portion. The temperature of the cell 51 located at the center of the cell tends to be higher than the temperature of the cell 51 located at the end in the left-right direction and the up-down direction. Further, since the heat generated from each cell 51 rises to the upper part of the case part 12, the cell unit 52 (for example, 52A) arranged at the upper part tends to be higher than the lower cell unit 52 (for example, 52D). is there. In this way, when temperature deviation occurs in the cell unit due to a reason different from the wiring resistance, the wiring of different path lengths is used so that the wiring resistance is different so as to correct the temperature deviation of the cell unit. It is good.

For example, in the configuration in which the wiring length is uniform, when the temperature of the upper cell unit 52A rises, the wiring length of the lead wires 581A and 582A connected to the upper metal plates 571A and 572A is reduced. You may make it longer than the length of the wiring of the lead wires 581B and 582B connected to the side metal plates 571B and 572B. As a result, the resistance of the lead wires 581A and 582A becomes larger than the resistance of the lead wires 581B and 582B, and the current flowing through the lead wires 581A and 582A decreases. Therefore, the heat generation amounts of the upper cell units 52A and 52B and the lead wires 581A and 582A are smaller than the heat generation amounts of the lower cell units 52C and 52D and the lead wires 581B and 582B, respectively.

Similarly, using the above-described four lead wires 581 and a modification using the four lead wires 582, the lengths of the lead wires 581 and 582 are set to the upper side (the side connected to the cell unit 52A). ) From the upper side to the lower side, and the wiring resistance of the cell unit 52 may be reduced from the upper side to the lower side. Further, in order to change the wiring resistance, the length of the lead wires 581 and 582 is not changed, but the wiring material may be changed, or a separate balance resistance element may be inserted. Note that which cell unit 52 is likely to rise in temperature may vary depending on the number of cell units 52 and the structure of the case portion 12. Therefore, the resistance values of the lead wires 581 and 582 are not limited to the relationship that changes in order from the top, and if the temperature of the cell unit in the central part increases, the path resistance value of the cell unit located in the central part. For example, the resistance value of the lead wires 581 and 582 corresponding to the cell unit 52 that generates a large amount of heat may be relatively increased.

  Further, the entire battery cell 51 or the cell unit 51 or the heat generated from the specific battery cell 51 or the substrate 60 (FET 61A, 61B, etc.) is diffused to the other battery cells or the entire cell unit 52, or A part of the substrate 60 or the substrate 60 may be covered with a heat diffusing material such as a heat diffusion member such as a heat conductive sheet. This makes it possible to mitigate the temperature rise of the battery cell 51 provided at a position where the temperature is likely to rise, and also diffuses the heat generated from the substrate 60 or the like throughout the cell unit 52, thereby The temperature of the entire 52 can be made uniform. The heat diffusion member preferably covers at least a part of the side surface of the battery cell 51 so as to surround the periphery of the battery set such as the battery cell 51 or the cell unit 51.

  Further, the entire case part 12 or at least a part close to the cell unit 52 and the substrate 60 is made of a material having high thermal conductivity, such as metal, and the heat of the cell unit 52 and the substrate 60 is transferred to the case part 12. You may make it conduct. At this time, the cell unit 52 or the substrate 60 and the case portion 12 may be brought into direct contact with each other, or may be brought into contact with each other through the above-described heat diffusion member. Alternatively, a chassis made of metal or the like having a high thermal conductivity may be provided inside the case portion 12, and the heat of the cell unit 52 may be conducted to the chassis. Also at this time, the cell unit 52 and the chassis may be brought into direct contact with each other or may be brought into contact with each other through the above-described heat diffusion member. Further, the contact with the case portion 12 and the chassis is a structure in which the contact is made through an insulating member (insulating sheet, resin, etc.) having a thickness that does not substantially hinder heat transfer. Also good.

  Further, as shown in FIG. 5, the cell units 52 may be rotated 90 degrees in the arrangement direction so that the cell units 52 extend in the vertical direction and are arranged in the horizontal direction. In this case, the substrate 60 is provided on the left side of the leftmost cell unit 52 as an example. According to this configuration, the space 70 formed between the cell units 52 serves as an air flow path. For this reason, the air heated by the cell unit 52 easily moves upward through the space 70, efficiently dissipates the heat generated from the cell unit 52, and suppresses the specific cell unit 52 from being heated excessively. Can do. In addition, the position of the substrate 60 in the configuration can be arranged not only on the left side of the cell unit 52 but also at an arbitrary position such as the upper end and the lower end as in the above embodiment. Moreover, when providing the heat-diffusion member mentioned above, it is suitable to make the arrangement | positioning which does not disturb the flow path of air.

DESCRIPTION OF SYMBOLS 1 Back type power supply 12 Case part 13 Back side part 52 Cell unit 571,572 Metal plate 581,582 Lead wire 60 Board | substrate

Claims (13)

A battery set including a plurality of secondary battery cells;
A substrate for controlling the battery set;
Thermal uniformizing means provided between the battery set and the substrate;
A case portion for housing the battery set, the substrate, and the heat equalizing means;
A backpack-type power source comprising a backpack attached to the case. The battery set has a plurality of cell units composed of a plurality of secondary battery cells,
The heat equalizing means has a parallel connection part for electrically connecting each cell unit in parallel,
2. The back-type power supply according to claim 1, wherein the parallel connection portion has a resistance value of an entire current path connecting each of the cell units and the substrate equal in the at least two cell units. The parallel connection part is:
A plurality of conductive plates connecting at least two cell units in parallel;
A plurality of lead wires connecting the plurality of conductive plates and the substrate;
3. The back-type power source according to claim 2, wherein the resistance values of the plurality of conductive plates are equal and the resistance values of the plurality of lead wires are equal.   The parallel connection unit is characterized in that the sum of the resistance value of the positive current path connecting the cell unit and the substrate and the resistance value of the negative current path is equal in the at least two cell units. Then, the backpack type power supply according to claim 2.   The backpack type power supply according to any one of claims 1 to 4, wherein at least one of a switch or a fuse for interrupting a circuit is provided between the battery set and the substrate. The substrate further includes a switching element that switches between supply and disconnection of power from a plurality of cell units,
The backpack type power supply according to any one of claims 1 to 5, wherein a heat insulating member is provided as the heat uniformizing means between the switching element and the battery set. The plurality of cell units includes at least a first cell unit and a second cell unit,
The backpack type power supply according to any one of claims 2 to 6, wherein the substrate is provided between the first cell unit and the second cell unit. The substrate is composed of at least two substrates,
The back-type power supply according to any one of claims 2 to 6, wherein each of the at least two substrates is provided on a side surface of the cell unit. The battery set has a plurality of cell units composed of a plurality of secondary battery cells,
The heat equalizing means has a parallel connection part for electrically connecting each cell unit in parallel,
The plurality of cell units are configured by a first cell unit accommodated in an upper part of the case part and a second cell unit accommodated in the case part lower than the first cell unit,
The parallel connection portion is characterized in that a resistance value of an entire current path connecting the first cell unit and the substrate is larger than a resistance value of a lead wire connected to the second cell unit. The backpack type power supply according to claim 1. The battery set includes at least three cell units including a plurality of secondary battery cells,
The heat equalizing means has a parallel connection part for electrically connecting each cell unit in parallel,
The plurality of cell units include a first cell unit placed at an end portion inside the case portion, a second cell unit placed at the other end inside the case portion, and the first cell. A third cell unit placed between the unit and the second cell unit;
In the parallel connection portion, the resistance value of the entire current path connecting the third cell unit and the substrate is greater than the resistance value of the entire current path connecting the first and second cell units and the substrate. The back-type power supply according to claim 1, wherein   11. The backpack according to claim 1, wherein the heat equalizing means includes a heat diffusing member, and the heat diffusing member is provided on at least a part of the periphery of the battery set. Power supply.   The backpack power source according to claim 11, wherein the heat diffusion member is provided on a side surface of the battery set.   The case portion is formed of a material having a higher thermal conductivity than the backpack portion, and the heat diffusion member is in thermal contact with the case portion and transfers heat to the case portion. The backpack type power supply according to any one of claims 11 and 12.

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