Battery pack for driving electric motor of compact engine starting device, engine starting device driven by the battery pack, and manual working machine having the engine starting device

A battery pack for driving a compact electric motor of a compact engine starting device mounted on a working machine comprising a compact electric motor, a power accumulating portion in which power of the compact electric motor is transmitted in a power accumulating direction through a highly speed reducer mechanism, and a power transmitting portion for transmitting accumulated force of the power accumulating portion to a crankshaft of an engine, wherein

• the battery pack is provided therein with a lithium-based secondary battery comprising at least two cells, a normal protection circuit comprising a self-discharge preventing circuit and an overcurrent preventing circuit, and further provided with a protection circuit comprising an electronic circuit comprising at least an overcharge preventing circuit (B), an overdischarge inhibit circuit (A) and a start switch relay circuit, which are connected to the lithium-based secondary battery, wherein
• a total discharging amount of the lithium-based secondary battery in the battery pack is 500 to 2000 mAh, and charging voltage per one cell is 3.0 to 4.2 V, and wherein
• a maximum discharge current of the lithium-based secondary battery in the battery pack is set to 10 to 60 A, and discharge is automatically stopped when a predetermined continuous discharge time set in accordance with set maximum discharge current elapsed.