What does S mean on a LiPo battery?

S stands for cells in series. A 4S battery has four lithium-polymer cells wired in series, so their voltages add. Each cell is nominally 3.7 V, making a 4S pack nominally 14.8 V.

What voltage is a fully charged LiPo cell?

A fully charged LiPo cell is 4.2 V. Multiply by the cell count for the pack: a 4S pack reaches 16.8 V at full charge. Charging above 4.2 V per cell is dangerous and can cause a fire.

What is LiPo storage voltage?

Store LiPo cells at about 3.8 V each (3.7 to 3.85 V is fine). Leaving packs fully charged or fully drained for long periods damages them. A 4S pack should be stored at around 15.2 V.

How low can I safely discharge a LiPo?

Do not take cells below about 3.5 V under load or 3.0 V at rest. Sustained discharge below 3.0 V per cell permanently damages the pack. Most FPV pilots land at around 3.5 V per cell to preserve battery life.

Why does cell count matter for my drone?

Higher cell counts deliver more voltage, which spins motors faster and produces more power for the same current. A 6S setup is more efficient than 4S at the same power because it draws less current, but motors and electronics must be rated for the higher voltage.

Drone Battery Cell Count & Voltage Calculator

LiPo batteries are rated by their cell count in series (the S number), and each cell behaves the same regardless of pack size. This tool multiplies the standard per-cell voltages by your cell count so you know exactly what nominal, charged, storage, and minimum voltages to expect.

How it works

Cells in series add their voltages, so every pack figure is a per-cell value times the cell count:

nominal      = 3.70 V × cells
full charge  = 4.20 V × cells
storage      = 3.80 V × cells
min (resting)= 3.00 V × cells
land target  = 3.50 V × cells

These per-cell values are the industry standard for lithium-polymer chemistry. A 4S pack is therefore 14.8 V nominal, 16.8 V charged, 15.2 V stored, and should never rest below about 12.0 V.

Tips and notes

Always set your flight controller’s low-voltage alarm using the per-cell land target (around 3.5 V) rather than a fixed pack voltage, so the same setting works across battery sizes. Never charge above 4.2 V per cell, never store packs fully charged, and balance-charge so all cells stay within about 0.05 V of each other. Higher-S packs are more efficient at a given power because they pull less current, but every component — ESC, motors, flight controller — must be rated for the higher voltage before you step up.