Short answer: a pack commonly called 48 V often uses 13 lithium-ion cells in series (13S), while a 51.2 V LiFePO4 pack commonly uses 16 cells in series (16S). Parallel groups are then added to reach the required capacity and current. Final voltage limits must match the exact chemistry, cell model, BMS and charger.
Series cells determine voltage
Series connection adds cell voltage. A simplified calculation is:
Nominal pack voltage = nominal cell voltage x series count
| Example chemistry | Common series count | Approximate nominal pack voltage |
|---|---|---|
| 3.6 V lithium-ion | 13S | 46.8 V, commonly marketed as 48 V |
| 3.2 V LiFePO4 | 16S | 51.2 V |
Parallel cells determine capacity and current
Parallel connection adds capacity. If a 5 Ah cell is used in four parallel positions, the simplified nominal capacity is 20 Ah. Total cell count equals the series count multiplied by the parallel count.
| Configuration | Total cells | Simplified example |
|---|---|---|
| 13S4P | 52 | 48 V-class lithium-ion pack |
| 13S10P | 130 | Higher-capacity 48 V-class pack |
| 16S1P | 16 | 51.2 V LiFePO4 pack using large prismatic cells |
Energy calculation
A simplified energy estimate is nominal voltage multiplied by amp-hour capacity. For example, 51.2 V x 100 Ah equals 5.12 kWh nominal energy. Usable energy depends on configured voltage limits, load, temperature and system efficiency.
Design checks before assembly
- Use matched cells of the same model and batch.
- Confirm maximum charge and minimum discharge voltage.
- Size the BMS, conductor and protection devices for the load.
- Provide mechanical restraint, insulation and temperature monitoring.
- Use a charger approved for the chemistry and series count.
- Have high-energy battery systems reviewed by a qualified professional.
See our assembled battery packs, LiFePO4 cells and BMS components.
Frequently asked questions
Is a 13S pack exactly 48 V?
No. The term 48 V is a nominal system class. Actual pack voltage changes with state of charge and depends on the cell chemistry.
Why is LiFePO4 often listed as 51.2 V?
Sixteen 3.2 V nominal LiFePO4 cells in series produce a nominal voltage of 51.2 V.
Can I increase capacity by adding parallel cells?
Parallel groups increase capacity and current-sharing capability, but the interconnection, protection, BMS and thermal design must be engineered for the new configuration.