Energy level conversion circuit for portable energy storage apparatus

An energy level conversion circuit for a portable energy storage apparatus, comprising:

• a motherboard circuit comprising a female connector circuit having a plurality of female connectors to connect a plurality of sub-board circuits through the female connector circuit, wherein each of the plurality of sub-board circuits receive direct current (DC) power, convert the DC power to a preset energy level and output the converted DC power to the motherboard circuit;
• and
• the each of the plurality of sub-board circuits comprising a male connector circuit connected to a corresponding female connector of the female connector circuit, a transformer, and a switching circuit including a plurality of switching transistors,
• wherein the plurality of switching transistors is coupled between the male connector circuit and the transformer and is on/off when receiving a pair of switching pulses applied from the motherboard circuit,
• wherein the transformer transforms the DC power to a transformed power and the transformer is connected to receive the pair of switching pulses, and
• wherein when each of the plurality of the switching transistor is on/off, the transformed power is outputted through a pair of transformer tap connection terminals of a secondary side of each of the plurality of female connectors.