Series and Parallel Cells

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Battery packs are often described in ‘S’ and ‘P’, for example 6S1P or 3S2P are two common battery pack configurations. Both of these examples are actually made up of the same number of single cells and they both have the same available energy in Wh [ Energy(Wh) = Voltage(V) x Capacity (Ah) ], they are however 2 very different batteries:

The ‘S’ is simply the number of series cells within the battery pack and the ‘P’ is the number of parallel cells.

A 6S1P battery pack contains 6 cells in series with 1 parallel string:

A 3S2P battery pack contains 3 cells in series with 2 parallel strings:

When cells are placed in series, the output voltage increases proportionally. When cells are placed in parallel the maximum charge/discharge current and capacity in Ah increases proportionally.

For high power applications it is generally preferable to increase the voltage of a battery pack in order to reduce the resistive power loss associated with running a system at a high current:

Power Loss (W) = Current(A) x Current(A) x Resistance (Ω)

For lower power devices it is often optimal to choose a lower voltage pack to more closely match the typical voltages of components within the application circuitry, such as microcontrollers and sensors. Resistive power loss at low current levels is usually not significant.