It is best to use a dedicated LiFePO4 battery charger to charge LiFePO4 battery. High quality LiFePO4 chargers ensure high performance and long battery life.
The characteristics of LiFePO4 battery cells
The essence of LiFePO4 battery charging is to charge LiFePO4 battery cells. So it is necessary to understand the charging characteristics of LiFePO4 battery cells.
According to the specification of LF280K, we can list the following characteristics:
- Standard charge/discharge current: 0.5C/0.5C(What does “C” mean)
- Charge/discharge cutoff voltage. 3.65V/2.5V
- Maximum continuous charge/discharge current: 1C/1C
- Maximum pulse charge/discharge current (30s): 2C/2C
- Recommended SOC range: 10%/90%.
- Charging temperature. 0 ℃～55 ℃
- Cycle life at 25 ℃: more than 6000 times
Let’s take another look at the cycle life test environment.
“under 300kgf pressure, 30 minutes rest after standard charging, discharging at (25±2) ℃ with a current of 0.5C(A) to 2.5V cutoff, then start the next cycle, end.
Then the next cycle is started and the capacity is reduced to 80% of the initial capacity. (The number of cycles is defined as the cycle life of the battery”
Please note that a pressure of 300kgf is mentioned here, which is to prevent the LiFePO4 battery cells from expanding themselves. If you DIY LiFePO4 battery pack, you should do compression on the cells. Please refer to the previous post for details: How to Compress LiFePO4 Battery Cells?
This means that with the proper charge profiles, we will have the opportunity to get more than 6000 cycles of life.
LiFePO4 charge profiles
LiFePO4 batteries can be charged using either 1-stage profile charging or 2-stage profile charging.
1-stage profile charging is constant current charging (CC), also called bulk stage.
2-stage profile charging is constant current charging first and switch to constant voltage charging when battery’s capacity is nearly full(CC-CV).
1-stage profile charging can charge the battery’s capacity up to 97%.
2-stage profile charging can charge the battery’s capacity to 100%.
1-stage profile charging parameters – CC
Charge with a constant current until the battery reaches termination voltage.
Recommended charge current: ≤0.5C
Termination voltage for different system:
|Termination Voltage||14V – 14.6V||28V – 29.2V||42V – 43.8V||56V – 58.4V|
2-stage profile charging parameters – CC-CV
2 steps charging.
Step 1 – Charge with a constant current until the battery reaches absorption voltage.
Step 2 – Hold absorption voltage until charge reduces to termination current.
Recommended charge current: ≤0.5C
Absorption voltage for different system:
|Absorption Voltage||14V – 14.6V||28V – 29.2V||42V – 43.8V||56V – 58.4V|
When charge current reduces to under 0.05C, means the battery already be fully charged, then stop charging.
Is it possible to use a lead-acid battery charger?
You can use lead-acid to charge LiFePO4 battery. However, there are two issues to be aware of here:
1, Extended charging time
Lead-acid battery chargers will reduce the current output as the battery voltage increases. This will result in longer charging times.
2, Cannot fully charge the battery
When the battery voltage reaches 13.1V, the lead-acid battery charger has almost no current output. So the lead-acid charger cannot charge the LiFePO4 battery to 14.6 V(The full charge voltage of LiFePO4 battery is 14.6 V ).
Will the use of other types of chargers damage LiFePO4 batteries?
If you have a BMS with charge protection in your battery pack, it will protect the battery from damage.
When should I charge?
You can charge your LiFePO4 batteries after each use or when they have been discharged up to 80% DOD (20% SOC).
What is the temperature range for charging LiFePO4 batteries?
LiFePO4 batteries can be safely charged between 0°C to 45°C (-32°F to 113°F). Do not charge below 0°C (-32°F) without heating, as this can damage the battery.
Can I fully discharge a LiFePO4 battery?
Although LiFePO4 batteries can be discharged to 100% of their capacity. To optimize the performance of your LiFePO4 battery, achieve a higher cycle life, and avoid the BMS disconnecting the battery, we recommend limiting the discharge to 80% capacity.
If the BMS disconnects the battery due to low voltage, at 100% depth of discharge, remove the load and recharge with a LiFePO4 charger to reactivate the BMS.
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