AUXILIARY POWER SUPPLY DEVICE

PROBLEM TO BE SOLVED: To provide an auxiliary power supply device which is capable of stably starting an engine under a state where a battery voltage is low and reducing burdens upon a step-up circuit and a battery by stepping up the battery voltage.SOLUTION: An auxiliary power supply device 1 comprises: a step-up circuit 4 which steps up an input voltage from a battery; a step-up control part 5 which controls a step-up operation of the step-up circuit 4; and a START voltage detection part 6 which detects the input voltage from the battery. The step-up control part 5 starts the step-up operation in a case where the input voltage detected by the START voltage detection part 6 rises and the input voltage becomes higher than a first voltage, and stops the step-up operation in the case where the input voltage detected by the START voltage detection part 6 falls and the input voltage becomes lower than a second voltage, the second voltage being lower than the first voltage.SELECTED DRAWING: Figure 1 【課題】バッテリー電圧を昇圧することにより、バッテリー電圧が低い状態下でエンジンを安定して始動させることができ、かつ、昇圧回路およびバッテリーへの負担が少ない補助電源装置を提供する。【解決手段】補助電源装置１は、バッテリーからの入力電圧を昇圧する昇圧回路４と、昇圧回路４の昇圧動作を制御する昇圧制御部５と、バッテリーからの入力電圧を検出するＳＴＡＲＴ電圧検出部６を備え、昇圧制御部５は、ＳＴＡＲＴ電圧検出部６が検出した入力電圧の上昇時に、当該入力電圧が第１電圧より高くなったときに昇圧動作を開始させ、ＳＴＡＲＴ電圧検出部６が検出した入力電圧の降下時に、当該入力電圧が第２電圧より低くなったときに昇圧動作を停止させ、前記第２電圧は前記第１電圧よりも低い。【選択図】図１