Lexus Rx400H 12V Battery Replacement: Tips And Guide

Lexus RX 400H 20062009 Hybrid Car Battery Pack Replacement
Lexus RX 400H 20062009 Hybrid Car Battery Pack Replacement from


Welcome to our blog post on replacing the 12V battery in the Lexus RX400h! In this article, we will provide you with helpful tips and a step-by-step guide on how to replace the 12V battery in your Lexus RX400h. As the years go by, it’s common for the battery in hybrid vehicles to start losing its efficiency. So, if you’ve noticed any signs of a weakening battery or if it’s been more than five years since you last replaced it, it’s time to consider a replacement.

Signs of a Weakening Battery

Before we dive into the replacement process, let’s quickly go over some common signs that indicate it’s time to replace your Lexus RX400h’s 12V battery. These signs include:

  • Dimming headlights and interior lights
  • Difficulty starting the vehicle
  • Frequent jump-starting
  • Malfunctioning electronics

If you’ve experienced any of these issues, it’s highly likely that your 12V battery needs to be replaced.

Step-by-Step Guide

Step 1: Safety First

Prior to replacing the battery, ensure that the vehicle is parked on a flat surface and the engine is turned off. It’s also recommended to wear safety gloves and goggles to protect yourself from any potential hazards.

Step 2: Locate the Battery

The 12V battery in the Lexus RX400h is located in the trunk, on the right-hand side. Open the trunk and remove any necessary covers or panels to access the battery.

Step 3: Disconnect the Negative Terminal

Using a wrench or pliers, loosen the nut on the negative terminal of the battery. Once loose, carefully remove the negative cable from the terminal and set it aside. Take extra caution not to let the cable touch any metal surfaces.

Step 4: Disconnect the Positive Terminal

Similar to the negative terminal, loosen the nut on the positive terminal and remove the cable from the battery. Be cautious not to touch any metal surfaces with the cable.

Step 5: Remove the Battery

With the cables disconnected, carefully lift the battery out of its compartment. Be mindful of its weight and handle it with care to prevent any spills or damage.

Step 6: Prepare the New Battery

Before installing the new battery, ensure that it is the correct size and specifications for your Lexus RX400h. Remove any protective covers or packaging from the new battery.

Step 7: Install the New Battery

Place the new battery into the compartment, making sure that it is secure. Reconnect the positive terminal first, followed by the negative terminal. Tighten the nuts on both terminals to ensure a secure connection.

Step 8: Test the Battery

Once the new battery is installed, turn on your Lexus RX400h and check if all electrical components are functioning properly. This will help verify that the replacement was successful.

Step 9: Properly Dispose of the Old Battery

Dispose of the old battery responsibly by taking it to a recycling center or an authorized battery disposal facility. Do not discard it in regular household waste.

Step 10: Maintenance Tips

To prolong the life of your new battery, consider the following maintenance tips:

  • Regularly check the battery’s terminals for corrosion and clean if necessary
  • Drive your Lexus RX400h regularly to keep the battery charged
  • Avoid leaving electrical components on when the vehicle is turned off

By following these tips, you can ensure the longevity and optimal performance of your new 12V battery.


Replacing the 12V battery in your Lexus RX400h is a straightforward process that can be accomplished with some basic tools and precautions. By following our step-by-step guide and practicing proper maintenance, you can enjoy a reliable and efficient electrical system in your vehicle. Remember, if you’re unsure or uncomfortable with the replacement process, it’s always best to consult a professional mechanic.