LiFePO4 Battery Calculator
LiFePO4, or lithium iron phosphate, is one of the most popular lithium battery types for solar storage, RV systems, marine setups, backup power, and many EV applications. It is popular because it combines long cycle life, strong safety, high efficiency, and high usable capacity in one battery chemistry.
This calculator estimates LiFePO4 battery voltage, nominal energy, usable energy, runtime under load, cell count, and recommended pack class. It gives you a quick way to size a battery for common 12V, 24V, and 48V systems without needing to work through all the formulas manually.
Short answer: A LiFePO4 battery uses 3.2V nominal cells, typically allows about 80% to 90% usable depth of discharge, and usually delivers far more cycles than lead acid. That makes it a common choice for daily-cycle battery systems.
LiFePO4 Runtime & Sizing Calculator
Estimate pack voltage, usable Wh, runtime, and approximate LiFePO4 pack size from system voltage, Ah, load, DoD, and efficiency
LiFePO4 Key Specs
Nominal Voltage
LiFePO4 cells are typically rated at 3.2V nominal, which is the basis for common 12V, 24V, and 48V pack calculations.
Charge Range
Full charge is commonly around 3.65V per cell, while common lower cutoff guidance is around 2.5V per cell.
Cycle Life
LiFePO4 batteries are often rated in the 2000 to 5000 cycle range, with higher life possible under lighter depth of discharge.
Efficiency
LiFePO4 systems are known for high efficiency, commonly modeled around 97% to 99% in practical storage discussions.
Common LiFePO4 Battery Sizes
| Battery Class | Series Cells | Nominal Voltage | Common Capacities |
|---|---|---|---|
| 12V LiFePO4 | 4S | 12.8V | 100Ah, 200Ah |
| 24V LiFePO4 | 8S | 25.6V | 100Ah, 200Ah |
| 48V LiFePO4 | 16S | 51.2V | 100Ah, 200Ah, 300Ah |
These system classes are the most common starting points for LiFePO4 battery sizing. In practice, many solar and storage products sold as 12V, 24V, or 48V are actually 12.8V, 25.6V, and 51.2V nominal when based on LiFePO4 cells.
How the Math Works
The core formulas are straightforward. Nominal battery energy is pack voltage multiplied by battery capacity in amp-hours, usable energy applies depth of discharge and efficiency, and runtime is usable watt-hours divided by the load in watts.
For example, a 12.8V 100Ah LiFePO4 battery has 1280Wh nominal energy. At 80% usable DoD and 98% system efficiency, usable energy is about 1003.5Wh, which would run a 300W load for about 3.35 hours.
Practical warning: Runtime estimates assume an average steady load. Real runtime changes with inverter losses, surge loads, low-temperature performance, BMS cutoffs, cable losses, and how conservative the system is about usable depth of discharge.
Why LiFePO4 Is Popular
Solar Storage
LiFePO4 is widely used in solar because it handles repeated daily cycling much better than lead acid in many systems.
Backup Power
Its high usable capacity and high efficiency make it attractive for home backup, UPS, telecom, and off-grid energy storage.
Mobile Power
RVs, boats, vans, and portable power systems often use LiFePO4 because it offers strong cycle life with a relatively flat voltage curve.
EV and Industrial
LiFePO4 is also common in electric mobility and industrial applications where long life and thermal stability matter.
Practical rule: Use 80% usable DoD as a conservative LiFePO4 planning number unless the battery manufacturer clearly specifies a different routine operating window.