Battery pack having tension bar

1. A battery pack, comprising:

a plurality of battery modules, each having two secondary battery cells, a module frame and a cooling fin;

end plates provided at both sides of a battery module assembly configured by assembling the plurality of battery modules;

a front circuit assembly electrically connected to electrode leads formed at the plurality of battery modules included in the battery module assembly;

a rear circuit assembly electrically connected to electrode leads formed at the plurality of battery modules included in the battery module assembly;

a tension bar configured to fix the end plates by using protrusions formed at the end plates;

a front cover configured to cover front portions of the front circuit assembly and the battery module assembly not to be exposed outwards; and

a rear cover configured to cover rear portions of the rear circuit assembly and the battery module assembly not to be exposed outwards.

2. The battery pack according to claim 1 ,

wherein the battery module is any one of a parallel-type module in which electrode leads having the same polarity formed at two secondary battery cells are exposed in the same direction and a series-type module in which electrode leads having the same polarity formed at two secondary battery cells are exposed in different directions, and

wherein the battery module assembly includes the parallel-type module and the series-type module simultaneously.

3. The battery pack according to claim 2 ,

wherein the battery module assembly includes six battery modules.

4. The battery pack according to claim 3 ,

wherein the battery module assembly includes four parallel-type modules and two series-type modules.

5. The battery pack according to claim 4 ,

wherein the battery modules are arranged from one side to the other side in the order of a parallel-type module, a series-type module, a parallel-type module, a parallel-type module, a series-type module and a parallel-type module.

6. The battery pack according to claim 5 ,

wherein the front circuit assembly and the rear circuit assembly are configured to electrically connect three secondary battery cells in parallel and electrically connect four unit sets, in which the three secondary battery cells are electrically connected in parallel, in series.

7. The battery pack according to claim 1 ,

wherein the battery module assembly includes an absorption pad respectively interposed between the battery modules.

8. The battery pack according to claim 7 ,

wherein the absorption pad is made of ethylene propylene diene monomer (EPDM) rubber.

9. The battery pack according to claim 1 ,

wherein the battery pack further includes an insulation sheet interposed between the battery module assembly and the end plate.

10. The battery pack according to claim 1 ,

wherein the front circuit assembly includes a connector for coupling with an external measurement device.

11. The battery pack according to claim 1 ,

wherein a thread is formed at the protrusion formed on the end plate,

wherein a groove corresponding to the protrusion is formed at the tension bar, and

wherein the end plate and the tension bar are fixed using a nut.

12. The battery pack according to claim 1 ,

wherein the tension bar is respectively connected to a front upper portion, a front lower portion, a rear upper portion and a rear lower portion of the battery module assembly.

13. The battery pack according to claim 1 ,

wherein the front cover includes an electrode terminal electrically connected to the front circuit assembly, and

wherein the electrode terminal is exposed at an outer surface of the front cover.

14. A battery operating system, comprising:

a battery pack defined in claim 1 ; and

a load configured to receive power from the battery pack.

15. The battery operating system according to claim 14 ,

wherein the load is an electric-driven unit or a portable device.