Search for a "24V lithium battery" and you'll find packs labelled 25.6V, 25.2V and 25.9V. A "48V" pack might say 51.2V, 46.8V or 51.8V. The numbers aren't marketing: they come straight from the cell chemistry and the number of cells in series. Getting them right matters, because your controller, charger and low-voltage cut-off all care about the real voltage window, not the class name.
Nominal voltage comes from the cell
A lithium battery pack is a set of cells connected in series (to add voltage) and in parallel (to add capacity). The pack's nominal voltage is simply the cell's nominal voltage times the number of cells in series.
| Chemistry | Nominal per cell | Typical full charge per cell | Typical discharge cut-off per cell |
|---|---|---|---|
| LiFePO4 (LFP) | 3.2V | 3.6–3.65V | about 2.5–2.8V |
| NMC lithium-ion | 3.6–3.7V | 4.2V | about 2.75–3.0V |
| Lead-acid (for comparison) | 2.0V | about 2.4V while charging | about 1.75V |
Exact limits depend on the cell's datasheet and on how conservatively the pack is designed. Running closer to the limits gives more usable energy; staying inside them gives more margin and longer life.
Common LiFePO4 pack voltages
| Voltage class | Cells in series | Nominal | Typical full charge | Typical charger output |
|---|---|---|---|---|
| 12V | 4S | 12.8V | 14.4–14.6V | 14.6V |
| 24V | 8S | 25.6V | 28.8–29.2V | 29.2V |
| 36V | 12S | 38.4V | 43.2–43.8V | 43.8V |
| 48V | 16S | 51.2V | 57.6–58.4V | 58.4V |
| 60V | 20S | 64.0V | 72–73V | 73V |
| 72V | 24S | 76.8V | 86.4–87.6V | 87.6V |
A 12.8V LFP pack lines up well with 12V lead-acid systems: four LFP cells sit close to six lead-acid cells across most of the discharge. That's why LFP is the usual choice for lead-acid replacement, although the charger profile and low-voltage cut-off still need checking. For a side-by-side comparison, see LiFePO4 vs lead-acid for industrial equipment.
Common NMC pack voltages
| Voltage class | Cells in series | Nominal (3.6V/cell) | Full charge (4.2V/cell) |
|---|---|---|---|
| 12V | 3S | 10.8–11.1V | 12.6V |
| 24V | 7S | 25.2V | 29.4V |
| 36V | 10S | 36V | 42V |
| 48V | 13S | 46.8V | 54.6V |
| 48V | 14S | 50.4–51.8V | 58.8V |
NMC packs swing over a wider voltage range than LFP from full to empty. A 13S NMC pack runs from about 54.6V at full charge down to about 39V at cut-off, while a 16S LFP pack spends most of its discharge between about 52V and 50V. Your controller must accept the whole window.
Why the voltage window matters more than the label
- Motor controllers and DC-DC converters have minimum and maximum input voltages. A controller that's happy with a 48V lead-acid battery may not accept the 58.4V a 16S LFP pack reaches at full charge, or the low voltage of a 13S NMC pack near empty.
- Low-voltage cut-offs set for lead-acid often shut equipment down early or too late on lithium. The BMS should be the final protection, but the equipment's own cut-off should be set to the pack.
- Chargers must match the chemistry and series count. A 14.6V charger suits a 4S LFP pack; a 12.6V charger suits a 3S NMC pack. Using the wrong one undercharges the pack or trips its protection. Lead-acid chargers with equalization or float stages aren't suitable for lithium. Our lithium battery charger catalog is organized by chemistry, series count and output voltage for this reason.
Capacity and energy
Amp-hours (Ah) tell you charge capacity at the pack's voltage. Watt-hours (Wh) tell you energy, and that's the fairer comparison between packs of different voltages:
Energy (Wh) = nominal voltage (V) × capacity (Ah)
- 12.8V × 100Ah = 1,280 Wh
- 25.6V × 100Ah = 2,560 Wh
- 51.2V × 100Ah = 5,120 Wh
A 51.2V 100Ah pack stores four times the energy of a 12.8V 100Ah pack. When you compare quotes, compare Wh and the usable voltage window, not just Ah.
LFP's flat voltage curve
LiFePO4 holds an almost constant voltage through most of its discharge. That's good for equipment, which sees steady voltage until the pack is nearly empty. It also means voltage alone is a poor fuel gauge for LFP. A good BMS estimates state of charge by counting current in and out, and recalibrates when the pack reaches full charge. If your equipment rarely fully charges, raise it early so the BMS and charging routine can be designed around it. See battery management systems for custom packs.
Picking a voltage class for new equipment
- Higher voltage, lower current. For the same power, doubling the voltage halves the current, which reduces conductor size, connector rating and losses. That's why larger AGVs, industrial vehicles and storage systems move to 48V-class and higher.
- Safety and design rules change with voltage. Higher-voltage systems need more attention to insulation, spacing and protection. Check the standards your market requires at your chosen voltage before you commit.
- Component availability. Motors, controllers, chargers and DC-DC converters are easiest to source at standard classes: 12V, 24V, 36V, 48V and up.
Quick reference
- "12V lithium" usually means 12.8V LFP (4S) or 10.8–11.1V NMC (3S).
- "24V lithium" usually means 25.6V LFP (8S) or 25.2V NMC (7S).
- "48V lithium" usually means 51.2V LFP (16S), or 46.8V (13S) or 51.8V (14S) NMC.
- Always design to the full voltage window from full charge to cut-off, not the nominal number.
Find a pack by voltage
Browse reference designs by voltage class: 12V, 24V, 36V, 48V, 72V, 96V and 144V. If none fits your controller's window, we'll design one that does. Lithium Battery Company has designed and built custom lithium battery packs since 2014, with hundreds of thousands produced for OEM programs. Catalog packs start at 10 units and custom packs at 25.
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Frequently asked questions
Why is a 24V lithium battery rated 25.6V?
A 24V-class LiFePO4 pack has eight 3.2V cells in series, so its nominal voltage is 8 × 3.2V = 25.6V. A 24V-class NMC pack usually has seven cells and is rated about 25.2V.
Is a 51.2V battery the same as a 48V battery?
It's a 48V-class battery. A 51.2V LiFePO4 pack has 16 cells in series and charges to about 58.4V, so check that your controller and charger accept that full voltage window.
What charger voltage does a 12.8V LiFePO4 battery need?
A 12.8V (4S) LiFePO4 pack is normally charged at about 14.4–14.6V with a charger designed for LFP, not a lead-acid charger with equalization or float stages.
How do I calculate a lithium battery's energy in watt-hours?
Multiply the nominal voltage by the capacity in amp-hours. For example, 51.2V × 100Ah = 5,120 Wh.