Can we connect lead acid and lifepo4 batteries in parallel


Can We Connect Lead Acid and LiFePO4 Batteries in Parallel? Understanding the Risks and Strategies

Mixing different types of batteries, such as lead acid and LiFePO4 (Lithium Iron Phosphate), in a parallel setup is a topic that sparks considerable debate among experts and enthusiasts alike. While theoretically possible, combining these batteries in practice involves numerous challenges and risks. This article explores the feasibility and considerations of such configurations, with insights on how Himax Electronics provides solutions to enhance safety and efficiency.

The Challenges of Mixing Battery Types

  1. Voltage Differences:
    1. Nominal Voltage Discrepancy: Lead acid batteries typically have a nominal voltage of about 2.1 volts per cell (12.6 volts for a 6-cell battery when fully charged), whereas LiFePO4 batteries usually have a nominal voltage of 3.2 volts per cell (about 12.8 volts for a 4-cell configuration). This slight difference can create imbalance during charging and discharging.
  2. Charging Characteristics:
    1. Charge Voltage: Lead acid and LiFePO4 batteries require different charging voltages, which complicates the charging process when connected in parallel.
    2. Charging Curve: LiFePO4 batteries charge differently than lead acid, often requiring a constant current/constant voltage (CC/CV) charge method which doesn’t align with the typical constant voltage charging of lead acid batteries.
  3. Discharge Rates and Capacity:
    1. Different Discharge Profiles: The batteries discharge at different rates. When connected in parallel, this can lead to one type discharging faster than the other, potentially leading to ‘voltage dragging’ or over-discharging of the slower-discharging battery.
    2. Capacity Variation: If the batteries have different capacities, it can further complicate the energy balance between them.
  4. Age and Condition:
    1. Battery Health: Mixing old and new batteries, or batteries in different states of health, can lead to reduced performance and lifespan.

Risks Involved

  • Safety Risks: Imbalances in charging and discharging can lead to safety issues such as overheating, which may result in battery damage or failure.
  • Reduced Efficiency: The overall system efficiency may be compromised due to the energy losses from managing imbalances.
  • Shortened Lifespan: Each battery type could degrade faster due to stress from operating outside optimal conditions.


Best Practices and Alternatives

  • Separate Battery Systems: Instead of connecting them in parallel, maintaining separate systems for each battery type is usually safer and more efficient.
  • Use of a Battery Management System (BMS): For setups that must mix battery types, using a sophisticated BMS can help manage the charging and discharging processes to minimize risks.

How Himax Electronics Can Help

Himax Electronics provides advanced battery management solutions that can assist in setups involving multiple battery chemistries:
  • Custom BMS Solutions: Himax designs BMS solutions that can handle complex scenarios, including mixed-battery setups, ensuring each battery operates within its safe parameters.
  • Expert Consultation: Himax offers expertise in energy storage solutions, helping clients design systems that are both safe and efficient, tailored to their specific needs.
  • Safety Enhancements: By implementing Himax’s cutting-edge technology, users can mitigate the risks associated with connecting different battery types in parallel.



While connecting lead acid and LiFePO4 batteries(Lifepo4 battery) in parallel is not generally recommended due to the significant differences in their charging and discharging characteristics, it can be technically feasible with the right controls and systems in place. Himax Electronics is committed to providing the technology and support needed to tackle such complex setups safely and effectively.
For those looking to explore advanced battery configurations or needing specific solutions for mixed battery types, contacting Himax Electronics can provide the necessary guidance and technology to ensure optimal performance and safety.