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How Do You Wire Two 12 Volt Batteries Together

In many applications—from recreational vehicles to solar power systems—it’s often necessary to increase electrical capacity or voltage beyond what a single 12-volt battery can provide. Wiring two 12-volt batteries together is a practical solution, whether you’re aiming to double the battery capacity while maintaining the same voltage (parallel connection) or increase the voltage to 24 volts while maintaining the same capacity (series connection). This guide provides detailed instructions on how to achieve both, ensuring safety and efficiency in your setup.

Understanding Battery Configurations

  1. Parallel Connection: Links batteries to increase capacity (amp-hours, Ah) while the voltage remains the same.
  2. Series Connection: Increases voltage while keeping capacity constant.

Tools and Equipment Needed

  • Two identical 12-volt batteries
  • High-quality battery cables
  • Cable connectors
  • Wrenches
  • Protective gear (gloves, goggles)
  • Wire brush (for cleaning terminals)

Step-by-Step Guide to Wiring in Parallel

Objective: To double the capacity (Ah) while maintaining the voltage at 12 volts.

  1. Prepare the Area: Ensure the area is clean and dry. Lay out your tools and batteries for easy access.
  2. Install Cables: Attach a battery cable from the positive terminal of the first battery to the positive terminal of the second battery. Repeat this with the negative terminals.
  3. Secure Connections: Use wrenches to tighten the cable connectors. Ensure there is a good contact to prevent potential electrical resistance.
  4. Final Inspection: Double-check all connections for tightness and correct alignment. Ensure no tools or metal objects are left that could create a short circuit.

Step-by-Step Guide to Wiring in Series

Objective: To increase the system voltage to 24 volts while maintaining the capacity.

  1. Setup: Position the batteries close to each other for a clean setup.
  2. Connect in Series: Attach a battery cable from the positive terminal of the first battery to the negative terminal of the second battery. The free negative terminal of the first battery and the free positive terminal of the second battery will now act as the output terminals of your 24-volt battery system.
  3. Secure and Inspect: Tighten all connections securely and inspect the setup for any potential issues like loose cables or misalignments.

Safety Precautions

  • Always wear protective gear when working with batteries.
  • Ensure that all metal tools and objects are away from the battery terminals to avoid shorts.
  • Work in a ventilated area, especially when handling lead-acid batteries.

Testing Your Setup

Once your batteries are connected, it’s essential to test the setup with a multimeter to ensure correct voltage and polarity. This step is crucial to avoid damage to electrical components powered by the batteries.

Maintenance Tips

  • Regularly check and clean battery terminals to prevent corrosion.
  • Ensure connections remain tight and cables are undamaged.
  • Monitor battery voltage and health periodically to maintain performance.

Why Choose Himax Electronics?

Opting for Himax Electronics when setting up your battery systems offers numerous benefits:

  • Reliability: Our products are tested rigorously to meet high standards of durability and performance.
  • Expert Support: Himax Electronics provides expert advice and support, helping you choose the right products and configurations for your needs.
  • Innovative Solutions: We offer the latest in battery technology and integration solutions, ensuring your systems are efficient and up-to-date.


Wiring two 12-volt batteries together, whether in parallel or series, is an effective way to enhance your energy system’s capacity or voltage. By following these detailed instructions and adhering to safety guidelines, you can ensure a successful setup. For all your battery needs, consider Himax Electronics, where quality meets innovation and customer satisfaction.