LiFePO4 Battery Calculator
Size and estimate runtime for LiFePO4 batteries, one of the safest and longest-lasting lithium chemistries. Calculate stored energy, usable energy, and expected runtime for 12V, 24V, and 48V LiFePO4 battery systems.
LiFePO4 Size and Runtime Tool
Enter your LiFePO4 battery voltage, capacity, load, and usable depth of discharge to estimate total energy, usable energy, and expected runtime.
Calculate LiFePO4 Battery Performance
This calculator is designed for lithium iron phosphate batteries commonly used in solar, RV, marine, backup power, and off-grid systems.
Calculation Results
These results show total energy, usable energy, and runtime for the LiFePO4 battery setup entered above.
Educational Estimates Only: Real LiFePO4 performance depends on BMS limits, inverter efficiency, discharge rate, temperature, charging profile, cell quality, and battery age. Always verify with manufacturer datasheets for critical systems.
LiFePO4 Battery Basics
LiFePO4 stands for lithium iron phosphate, a lithium battery chemistry widely used where safety, long lifespan, and deep usable capacity matter.
LiFePO4 batteries are one of the most popular lithium battery types for solar power, RV systems, boats, backup power, and off-grid storage. They are known for strong thermal stability, long cycle life, lower fire risk than some other lithium chemistries, and a flat voltage curve during discharge. These strengths make them especially attractive for users who want reliable daily cycling and safer long-term energy storage.
A single LiFePO4 cell has a nominal voltage of about 3.2V. A typical 12V LiFePO4 battery uses four cells in series for a nominal pack voltage of 12.8V. Larger systems commonly use 8 cells for 25.6V or 16 cells for 51.2V, which are often referred to as 24V and 48V packs in the battery market.
LiFePO4 batteries also provide much more usable capacity than lead-acid batteries. While many lead-acid systems are sized around 50 percent usable depth of discharge, LiFePO4 systems are often designed around 80 to 90 percent usable depth of discharge without the same severe lifespan penalty. This means a lithium battery with the same nominal capacity often delivers more practical energy in everyday use.
Battery energy is calculated by multiplying voltage by amp-hours. For example, a 12.8V 100Ah LiFePO4 battery stores about 1280Wh or 1.28kWh. A 12.8V 200Ah battery stores 2560Wh or 2.56kWh, and a 51.2V 100Ah battery stores 5120Wh or 5.12kWh. These are common reference sizes for comparing off-grid battery systems.
When estimating runtime, start with usable energy rather than total nameplate capacity. If a 12.8V 100Ah battery is used at 85 percent depth of discharge, usable energy is about 1088Wh. A 200W load would then run for about 5.4 hours in ideal conditions before efficiency losses and real-world derating are considered.
LiFePO4 facts
- Nominal 3.2V per cell.
- 12.8V nominal for 12V pack.
- 80–90% usable depth of discharge is common.
- Typical cycle life: 2000–5000 cycles.
Common LiFePO4 builds
| Battery build | Energy |
|---|---|
| 12V 100Ah | 1.28kWh |
| 12V 200Ah | 2.56kWh |
| 48V 100Ah | 5.12kWh |
Why LiFePO4 is safer
LiFePO4 chemistry is widely recognized for better thermal stability than many other lithium chemistries. That does not make it risk-free, but it is one of the main reasons it is preferred for home storage, RVs, and mobile battery systems.
LiFePO4 vs lead acid
LiFePO4 usually wins on cycle life, usable capacity, charging efficiency, and weight. Lead-acid still has a lower upfront cost in many cases, but it generally offers much less usable energy from the same rated Ah capacity.
Where LiFePO4 is used
These batteries are common in solar systems, camper vans, golf carts, electric mobility, trolling motors, home backup systems, and off-grid cabins because they combine light weight with long service life.
Why BMS protection matters
A battery management system protects LiFePO4 cells from overcharge, over-discharge, short circuit, and excessive current. No LiFePO4 pack should be sized or installed without considering its BMS limits.
Frequently Asked Questions
These are common questions about LiFePO4 battery sizing, runtime, and how this chemistry compares with lead acid.
What is LiFePO4?
LiFePO4 means lithium iron phosphate, a lithium battery chemistry known for safety, long cycle life, and stable performance. It is widely used in solar, RV, marine, and backup battery systems.
Is LiFePO4 better than lead acid?
Yes for lifespan, weight, charging efficiency, and usable capacity. Lead-acid batteries often allow only about 50 percent usable discharge, while LiFePO4 batteries are often designed around 80 to 90 percent usable depth of discharge.
What is the nominal voltage of a LiFePO4 cell?
A LiFePO4 cell has a nominal voltage of about 3.2V. This is why 4-cell packs are about 12.8V, 8-cell packs are about 25.6V, and 16-cell packs are about 51.2V.
How do I calculate LiFePO4 battery energy?
Multiply battery voltage by amp-hours to get watt-hours. For example, 12.8V × 100Ah = 1280Wh. Divide by 1000 if you want the answer in kWh.
How do I calculate LiFePO4 runtime?
First calculate usable watt-hours, then divide by the load in watts. Usable watt-hours are the battery voltage × amp-hours × usable DoD percentage.
How much energy is in a 12V 100Ah LiFePO4 battery?
A typical 12.8V 100Ah LiFePO4 battery stores about 1280Wh, which equals 1.28kWh.
How much energy is in a 12V 200Ah LiFePO4 battery?
A typical 12.8V 200Ah LiFePO4 battery stores about 2560Wh, which equals 2.56kWh.
How much energy is in a 48V 100Ah LiFePO4 battery?
A typical 51.2V 100Ah LiFePO4 battery stores about 5120Wh, which equals 5.12kWh.
What usable depth of discharge is common for LiFePO4?
Many users plan around about 80 to 90 percent usable DoD. The exact recommendation depends on the battery brand, BMS settings, and desired lifespan.
How many cycles can LiFePO4 batteries last?
Typical LiFePO4 batteries are often rated for about 2000 to 5000 cycles, though some premium models may exceed that under favorable conditions.
Why is LiFePO4 considered safer?
LiFePO4 has stronger thermal and chemical stability than many other lithium chemistries. This reduces the risk of overheating and is one reason it is widely chosen for energy storage and mobile battery applications.
Can I use LiFePO4 for solar storage?
Yes. LiFePO4 is one of the most common battery chemistries for solar systems because it handles cycling well, charges efficiently, and offers long service life.
Does a LiFePO4 battery need a BMS?
Yes. A proper BMS is essential to protect the cells and enforce safe charge and discharge limits. It is a critical part of every LiFePO4 battery pack.
Is this calculator exact?
No. It provides educational estimates using nominal voltage and user-entered DoD. Real runtime changes with temperature, inverter losses, discharge rate, and battery condition.
Plan LiFePO4 Power with Confidence
Use this calculator to estimate LiFePO4 battery energy and runtime, then compare it with our other tools to size your solar, RV, marine, or backup battery system more accurately.
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