Li-Ion 4S to 5V

244

02:59:41

Attempting to figure out methods of dropping and regulating power.

Power Source : Li-Ion 4S4P Pack
~Cell Voltage Nominal: 3.7V
~Cell Current Max: 2A
~Pack Voltage Min: 12V
~Pack Voltage Nominal: 14.8V
~Pack Voltage Max: 16.8V
~Pack Current Max: 8A

Test Load Lamps
(1) 5V .5A  2.5W
(2) 5V 1A 5W
(3) 5V 3A 15W
(4) 5V 10A 50W

Overall Goal: Efficiently modify the Li-Ion power to a constant 5V, assuming various load current requirements.  Understand variations in methodology based on load current requirements. 

Ultimate Goal:  Adjust output from 4S1P to a constant 5V with a maximum draw of 3A

Top Left SPDT: Select voltage min\max
Top Left SPST: Main Power
Top Right SPDTx3: Load Selection

Circuit should only be changed between Terminal A of the Relay to the left, and Input Terminal on the first SPDT Switch on the right.

published 5 years ago

NarWhale

5 years ago

Ahh... I see the problem now... I can't test things like ICs in EveryCircuit, so I can't experiment with things like the LM7805. Damn... well, it had to be possible before linear voltage regulators were packaged.

NarWhale

5 years ago

Resistors aren't the way... most are .25W, so I would need twelve 47Ω resistors in parallel to equal about 4Ω of resistance and withstand 3A. This only provides 5V at the pack max voltage of 16.8V. I think this would also waste about 6V, so would only be like 65% efficient... if I actually understand this all correctly.

NarWhale

5 years ago

Zener Diodes don't seem to work for me... most likely because I don't understand how they are supposed to be used in general, or how to configure them in EveryCircuit. Also, I think they wouldn't withstand 3A of current.

NarWhale

5 years ago

Resistors used as a voltage divider would also not work since the resistors would still likely only be .25W and because this would not result in a constant 5V

NarWhale

5 years ago

Changed layout so it was easier to mess with

tony_j

4 years ago

you want to build a DC-DC Buck converter. Circuits available on here.

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