Can I charge a lithium battery with a lead-acid charger? This is a question that we often receive from our customers.

 The answer is not recommended. It is not recommended to use lead acid charger for an extended period as it can affect the performance and lifespan of lithium iron phosphate batteries.

Let's dive in to see why and how to properly charge LiFePO4 batteries.

Part 1: LiFePO4 Battery Charging Logic

The material characteristics of the LiFePO4 battery determine that its charging curve is obviously different from that of a lead-acid battery. Compared with a lead-acid battery, the LiFePO4 battery has a simpler charging process and mode. Therefore, it is recommended to select LiFePO4 for your charging mode.

1.1 LiFePO4 Battery Charging Mode

Picture source: Power Queen

CC (Constant Current) Phase (T1)

In the beginning, a discharged battery will be charged with a constant current and voltage will be climbing steadily until reaching the constant voltage setpoint which varies for different charging methods.

CV (Constant Voltage) Phase (T2)

The battery maintains a constant voltage during this phase while the current gradually decreases to 2A (0.02C) which is also known as tail current. At this point, the charging is cut of and the battery is fully charged.

1.2 Lead Acid Battery Charging Mode

Bulk / Boots Phase (T1)

In the beginning, a discharged battery will be charged with maximum current and voltage will be climbing steadily until reaching the absorption voltage setpoint. (This phase is basically equivalent to the CC phase of LiFePO4 battery charging.)

Absorption Phase (T2)

The battery reaches the absorption voltage setpoint and holds the voltage constant while the current gradually decreases until the battery is becoming full (within 10-20%). Generally, absorption will not exceed 3 hours to prevent overcharging. (This phase is basically equivalent to the CV phase of LiFePO4 battery charging.)

Float Phase (T3)

After the absorption stage, the voltage of the battery will reduce to the float voltage setpoint and the current will also reduce to a low maintenance mode to prevent the battery from discharging and offsetting any self-discharge. Heavier battery discharge may set the controller back to Bulk/Boosts or Absorption to replenish energy lost while energy is available. (LiFePO4 battery does not have this charging phase.)

Part 2: 3 Recommended Ways to Charge LiFePO4 Batteries

Power Queen recommends three reliable charging methods for LiFePO4 batteries: utilizing LiFePO4 battery chargers, generators, and solar panels.

1.Utilizing LiFePO4 Battery Chargers

Using LiFePO4 battery chargers is the most efficient and convenient method to charge LiFePO4 batteries. These chargers are specifically designed for LiFePO4 chemistry, ensuring optimal charging performance and safety.

They provide the correct voltage and current levels required for efficient charging without causing any harm to the battery cells. LiFePO4 battery chargers often come with advanced features such as overcharge protection, temperature monitoring, and automatic shut-off, further enhancing the longevity and safety of the batteries.

Please consult the table below for information regarding the voltage specifications of various LiFePO4 battery packs and systems.

Charging Tips

1. Connect the charger to the battery before connecting it to the grid power in case of sparks.
2. It’s recommended to disconnect the charger from the battery after fully charging.

2.Generator / Alternator

In situations where electricity is not readily available, such as during outdoor activities or in remote locations, generators can be an excellent option for charging LiFePO4 batteries.

When utilizing an alternator or generator to charge your LiFePO4 battery, it is crucial to ensure compatibility between the charging voltage and current and your battery's specifications. Adding a DC-to-DC charger between the battery and the generator is necessary if the alternator or generator supports DC output.

This setup ensures that the LiFePO4 battery receives the appropriate charging conditions and prevents any potential damage.

Power Queen's LiFePO4 batteries can be charged using an alternator or generator, providing a flexible charging option for various power sources.

3.Solar Power

Harnessing the power of the sun, solar panels offer a renewable and sustainable way to charge LiFePO4 batteries. Solar energy is converted into electrical energy through photovoltaic cells present in solar panels. This energy can then be used to charge the batteries directly or stored in a separate energy storage system for later use. When selecting solar panels for charging LiFePO4 batteries, it's crucial to consider factors such as wattage, efficiency, weather conditions, and installation requirements. Additionally, using a charge controller is advisable to prevent overcharging and optimize the charging process.

A 12V 100Ah LiFePO4 battery can use the 300W solar panels to charge, the battery can be fully charged in one day (with effective sunshine 4.5hrs/day).

Moreover, there are also detachable variants available, such as Power Queen portable solar panels, which boast a convenient foldable design accompanied by a portable carrying case. These panels do not necessitate any complex installation procedures and can be effortlessly set up in no time.

Part 3: Charge LiFePO4 Battery In Winter

LiFePO4 batteries can be safely charged within a temperature range of 0°C to 45°C (32°F to 113°F).

To ensure optimal charging in winter, consider following these guidelines:

• Charge indoors or in a temperature-controlled environment to minimize extreme temperature fluctuations.
• Pre-warm the battery before charging if it has been exposed to very low temperatures.
• Use a charger specifically designed for LiFePO4 batteries or one that offers adjustable charging settings suitable for colder conditions.
• Monitor the battery's temperature during charging to prevent it from exceeding the recommended range.
• Avoid overcharging by using chargers with appropriate safety features like overcharge protection or automatic shut-off.

Power Queen 12V 100Ah Smart has the low temperature cutting-off protection. The smart BMS enables the built-in low-temp protection to cut off the charging and avoid damage when charged at a temp below 32°F. If any need to charge the battery under low temp charging protection, push the button to cancel the protection and charge the battery for emergency use.

Power Queen also has self-heating series for cold winter day. Power Queen LifePO4 Self-Heating Battery meets the upgrade self-heating function based on the previous battery. When the charging temperature falls below 41°F/5°C, the self-heating function will be automatically activated. Heating will stop when the temperature reaches 50°F/10°C, and then the battery will be normally charged. No fear of winter coming.

Part 4: How Long Does it Take to Charge Lithium Batteries? 

The charging time for LiFePO4 lithium batteries can vary depending on several factors, including the battery capacity, charging current, and the state of charge when starting the charging process. However, as a general estimate, LiFePO4 batteries typically take around 2 to 6 hours to reach a full charge.

It's important to note that the charging time can be influenced by the charger's specifications and capabilities. Some chargers may provide faster charging rates, allowing LiFePO4 batteries to reach their full capacity more quickly.

To determine the precise charging time for a specific LiFePO4 lithium battery, it is recommended to refer to the manufacturer's guidelines or documentation. These resources usually provide information about the recommended charging current, estimated charging times, and any specific considerations or precautions for an optimal charging process.

Note: Take 12V 100Ah mini LiFePO4 battery as example

Remember that charging LiFePO4 batteries within the manufacturer's recommended limits, using compatible chargers, and monitoring the battery temperature during the charging process are essential to ensure efficient and safe charging while maintaining the battery's longevity.

Conclusion

In conclusion, we do not recommend you charge LiFePO4 batteries with lead acid charger for it could cause damage to the LiFePO4 batteries. The LiFePO4 battery charger is a better choice. Can also learn how to store LiFePO4 battery to extend its lifespan.

Power Queen provides high-quality LiFePO4 deep cycle batteries and battery chargers, if you have any questions, feel free to contact us at service@ipowerqueen.com

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