What LiFePO4 Means
LiFePO4 stands for lithium iron phosphate. It is a lithium-ion chemistry that uses iron and phosphate in the positive electrode, instead of the cobalt or nickel blends found in many other lithium cells. In everyday buying language, a LiFePO4 battery is a lithium pack built on this chemistry. Buyers often search for the term when they want lithium performance for solar storage, backup power or mobile equipment, with a stable thermal profile and a long working life.
The chemistry is widely used in energy storage because it offers a stable voltage plateau and good tolerance for repeated charge and discharge cycles. Its energy density per kilogram is lower than some other lithium chemistries, which is why LiFePO4 is most common where weight is less critical than cycle life and safety.
Nominal Voltage per Cell and per Pack
A single LiFePO4 cell has a nominal voltage of about 3.2 V. The pack voltage is the number of cells connected in series multiplied by the cell voltage. This simple rule explains most of the voltage classes in the market:
| Pack configuration | Cells in series | Nominal pack voltage | Typical use |
|---|---|---|---|
| 4S | 4 | 12.8 V | 12 V class solar and backup systems |
| 8S | 8 | 25.6 V | 24 V class storage and mobile power |
| 16S | 16 | 51.2 V | 48 V class home storage and mobile batteries |
The charge end voltage is around 3.65 V per cell. For a 4S pack that means about 14.6 V, for an 8S pack about 29.2 V and for a 16S pack about 58.4 V. These are the values used by most chargers and inverters set for LiFePO4. A charger set to a lead-acid profile can apply a different voltage and should be checked before connection.
Cycle Life: What the Number Means
Cycle life is often quoted as a single figure, but the number only has meaning when the test conditions are known. A cycle usually means one full charge and one full discharge. The result depends on depth of discharge, charge and discharge current, temperature and the end-of-life capacity. For example, a pack that is discharged to 80 percent of its rated capacity each day will age differently from one discharged to 50 percent.
YueQi catalog pages cite cycle life figures of more than 2,000 cycles on some 12.8V models and more than 6,000 cycles on some home storage models. These figures are different in test basis and are to be confirmed in writing for each model before they are used in a quotation or a warranty. A buyer should ask for the test condition, the end-of-life definition and the capacity retention at that point.
The Role of the BMS
The battery management system is the control layer of a LiFePO4 pack. It balances the cells, measures voltage, current and temperature and disconnects the pack when a limit is reached. Typical protection items include over-charge, over-discharge, over-current, short circuit and temperature events. The catalog lists several of these functions for YueQi packs. The exact list varies by model, so the BMS protection document should be requested for each product.
- Cell balancing keeps all cells within a narrow voltage band over time
- Temperature limits protect the cells during charging in cold conditions and during high heat
- Communication ports let the inverter or monitoring system read state of charge and alarms
Sizing a LiFePO4 Pack
To size a pack, start from the daily energy need, then add a margin for losses and for the depth of discharge the system will use. Energy in watt-hours equals nominal voltage multiplied by capacity in amp-hours. A 12.8 V, 100 Ah pack stores 1,280 Wh. A 51.2 V, 200 Ah pack stores 10,240 Wh. Usable energy is usually lower than the rated energy because the BMS keeps a reserve.
When the load has a high peak, check the continuous discharge current, not only the energy figure. A pack that stores enough energy can still fail to supply a motor start or a short high-current load if the current rating is too low. Confirm the continuous and peak ratings with the supplier before you finalize the system.
Common Questions From Buyers
- Can LiFePO4 replace lead-acid in an existing system? Often yes, but the charger profile, the BMS communication and the inverter settings need review first.
- Do I need a special charger? A charger with a LiFePO4 profile is recommended, because the charge voltage is different from lead-acid.
- Can packs be connected in parallel? Some models list parallel connection in the catalog. The number of units and the wiring method must be confirmed for each pack.
- Is LiFePO4 safe for indoor installation? Installation location depends on the local code, the housing rating and the system design. Confirm with a qualified installer.
Storage Conditions and Routine Checks
LiFePO4 packs are easy to look after, but a few routine practices help them keep their capacity. Store a pack in a dry, ventilated place and avoid long periods at full charge or at empty. Many suppliers recommend a partial state of charge for long storage, and the exact figure should come from the datasheet. Keep the terminals clean and tight, and check the enclosure for damage or corrosion at each service visit. Periodic checks of the BMS log, if the system provides one, show the cell voltage spread and the temperature history, which are useful early indicators of a problem.
Summary for Importers and Product Teams
LiFePO4 is a practical chemistry for storage projects that need stable voltage and a long working life. The key steps are simple: match the pack voltage to the system, read the cycle life with its test condition, check the BMS protection list and confirm the continuous current. YueQi offers LiFePO4 packs in several voltage classes, and each specification is confirmed in writing before it is used in a commercial document.
Next step
Send your application, target specification and estimated quantity with your inquiry, and we will confirm matching products, samples and document requirements in writing. See the product lines or request a quote.