LiFePO4 Charge Voltage Table
Complete voltage reference for charging LiFePO4 batteries at the cell and pack level. Use this table to configure charge controllers, BMS units, and solar charge regulators.
Cell-Level Voltage Reference
Each LiFePO4 cell has a nominal voltage of 3.2V. The charge voltage range is 2.5V (minimum) to 3.65V (maximum). The table below shows voltage at each stage of the charge cycle.
| Stage | Cell Voltage | Approx. SOC | Notes |
|---|---|---|---|
| Minimum (empty) | 2.50V | 0% | BMS cutoff — do not discharge below this |
| Nominal | 3.20V | ~50% | Flat plateau region |
| Full (resting) | 3.40V | 100% | Typical resting voltage after full charge |
| Charge limit (CC) | 3.65V | 100% | Maximum charge voltage — do not exceed |
Pack Voltage Table
Pack voltage is the cell voltage multiplied by the number of cells in series (S count). The table below shows charge voltages for common pack configurations.
| Pack Configuration | Nominal Voltage | Min Voltage | Max Charge Voltage | Typical Float |
|---|---|---|---|---|
| 4S (12V) | 12.8V | 10.0V | 14.6V | 13.6V |
| 8S (24V) | 25.6V | 20.0V | 29.2V | 27.2V |
| 16S (48V) | 51.2V | 40.0V | 58.4V | 54.4V |
| 7S (24V alt) | 22.4V | 17.5V | 25.55V | 23.8V |
Voltage values are per string. Parallel strings share the same voltage. Always use a BMS for cell balancing.
LiFePO4 Charge Profile
LiFePO4 uses a CC-CV (Constant Current, Constant Voltage) charge profile. During the CC phase, the charger supplies a constant current while voltage rises. When voltage reaches 3.65V per cell, the charger switches to CV mode and holds voltage constant while current tapers.
CC Phase (Bulk)
Charger delivers constant current (e.g., 0.5C). Voltage rises from ~3.0V to 3.65V per cell. This phase charges the battery from ~0% to ~90% SOC. Duration depends on charge rate and capacity.
CV Phase (Absorb)
Charger holds 3.65V per cell. Current tapers as the battery approaches full. When current drops to ~0.05C, the battery is considered fully charged. This phase takes 30–60 minutes at typical charge rates.
Unlike lead-acid, LiFePO4 does not require a float charge. Once fully charged, the BMS typically disconnects the charger. Some systems use a reduced maintenance voltage (3.38–3.42V per cell) to compensate for self-discharge during storage.
Common Mistakes
Using Lead-Acid Charge Voltages
Lead-acid chargers use 14.4V absorb and 13.5V float for 12V systems. LiFePO4 needs 14.4–14.6V max charge and does not use float. Using lead-acid settings undercharges LiFePO4.
Exceeding 3.65V Per Cell
Charging above 3.65V per cell causes lithium plating on the anode, which permanently damages the cell and can create safety hazards. Always set the BMS charge limit to 3.65V or below.
Skipping the BMS
Without a BMS, individual cells can be overcharged or overdischarged. Cell imbalance grows over time, leading to premature capacity loss and potential safety risks. Always use a BMS.
Charging at Too High a Rate
Try It
Use the Charging Time Calculator to estimate charge time based on your charger current and battery capacity.
Open Charging Time CalculatorFrequently Asked Questions
What is the typical charge voltage for LiFePO4 cells?
A single LiFePO4 cell has a nominal voltage of 3.2V and a maximum charge voltage of 3.65V. For a 12V pack (4 cells in series), the charge voltage range is 14.4–14.6V. For a 24V pack, it is 28.8–29.2V. For a 48V pack, it is 57.6–58.4V.
What is the float voltage for LiFePO4?
LiFePO4 does not require a traditional float charge like lead-acid. Once the battery reaches its maximum charge voltage (3.65V per cell), the BMS typically disconnects the charger. Some systems use a reduced voltage of 3.38–3.42V per cell for maintenance, but this is not standard practice.
How does charge voltage affect battery life?
Charging to a higher voltage (e.g., 3.65V vs 3.55V per cell) provides slightly more capacity but accelerates calendar aging. Charging to a lower voltage (e.g., 3.50V per cell) reduces capacity by 5–10% but can significantly extend cycle life. Many BMS units allow configurable charge voltage limits.
Can I charge LiFePO4 with a lead-acid charger?
Not reliably. Lead-acid chargers use a different voltage profile (bulk, absorb, float) that does not match LiFePO4 requirements. The float voltage of a lead-acid charger (13.5–13.8V) is too low to fully charge LiFePO4, and the absorb voltage may be too high. Use a charger specifically designed for LiFePO4.