Replacing your car battery is a common DIY task, but maintaining your vehicle’s computer memory during the process is crucial. An Obd2 Battery Saver is a tool designed for this purpose, but using it correctly is essential to avoid electrical issues. If you’re a Lexus owner, particularly of an RX model, or anyone looking for clarity on using an OBD2 battery saver, this guide is for you. We’ll address common questions and concerns to ensure a smooth and safe battery replacement experience.
Understanding OBD2 Battery Savers
What is an OBD2 Battery Saver?
An OBD2 battery saver, also known as a memory saver, is a device that provides a temporary power supply to your car’s electronic control unit (ECU) when you disconnect the main battery. This prevents the loss of important settings like radio presets, seat positions, alarm systems, and anti-theft codes. It utilizes the OBD2 (On-Board Diagnostics II) port in your vehicle to supply this power.
Why Use an OBD2 Battery Saver?
Without a battery saver, disconnecting your car battery can lead to:
- Loss of Radio Presets and Settings: You’ll have to reprogram your favorite radio stations and audio settings.
- Resetting of Navigation System: Navigation settings and saved destinations may be lost.
- ECU Reset: The ECU might lose learned settings, potentially affecting engine performance and fuel efficiency until it relearns.
- Alarm System Issues: Your car alarm might be triggered or require reprogramming.
- Inconvenience: Overall, it saves you time and hassle by preserving your car’s personalized settings.
Connecting Your OBD2 Battery Saver – Step-by-Step Guide
One of the main points of confusion is the correct sequence for connecting an OBD2 battery saver. Let’s clarify the process:
Order of Connection: Clips vs. OBD2 Port
There are two common methods described, leading to uncertainty:
-
Method 1: Connect Clips to Slave Battery First: Some instructions suggest connecting the crocodile clips of the battery saver to a spare (slave) battery before plugging the OBD2 connector into your car’s OBD2 port.
-
Method 2: Connect OBD2 Port First: Others recommend plugging the battery saver into the OBD2 port in your car first, and then connecting the clips to the slave battery.
Which method is correct? While both methods can work, connecting the clips to the slave battery first is generally recommended for safety. This ensures a stable power source is established before making the OBD2 connection to your vehicle’s sensitive electronic system. This minimizes the risk of voltage fluctuations or spikes when initially connecting to the OBD2 port.
Here’s the Recommended Procedure:
- Prepare your slave battery: Ensure your slave battery is fully charged and in good condition.
- Connect the crocodile clips: Attach the red (positive) clip to the positive terminal of the slave battery and the black (negative) clip to the negative terminal.
- Plug into the OBD2 port: Carefully locate your car’s OBD2 port (often under the dashboard on the driver’s side) and firmly plug in the OBD2 connector of the battery saver.
- Verify connection: Check the battery saver’s indicator light or display to confirm it’s receiving power from the slave battery and providing it to the OBD2 system.
- Replace your car battery: Now you can safely disconnect and remove your car’s main battery and install the new one, knowing your vehicle’s memory is being preserved.
Power Considerations: Doors and Electrical Systems
Another common concern is whether opening doors or operating electrical systems while the battery saver is in place can cause issues.
Should you avoid opening doors or using powered circuits? Yes, it’s generally advisable to minimize the use of any electrical components while the battery saver is connected. While the OBD2 battery saver provides a small current to maintain memory, it’s not designed to power the car’s entire electrical system.
- Minimize power draw: Avoid operating power windows, headlights, interior lights, the radio, or the hatch/trunk if it’s power-operated.
- Doors: It’s best to keep doors closed if possible. However, if you need to access the interior, do so quickly and avoid leaving doors open for extended periods. In practical terms, having the driver’s door or hatch slightly ajar while working is usually acceptable, but avoid fully opening and closing them repeatedly.
Safety and Best Practices
Avoiding Electrical Damage
Concerns about damaging electrical components with battery savers are valid. Most reported issues stem from accidental short circuits, specifically the positive and negative crocodile clips coming into contact.
Safety Tips to Prevent Damage:
- Secure connections: Ensure the crocodile clips are firmly attached to the correct terminals of the slave battery and cannot easily slip off.
- Prevent shorts: Be extremely careful to prevent the positive and negative clips from touching each other or any grounded metal parts of the car while they are connected to the slave battery and especially when connected to the OBD2 port. Insulate the clips if necessary to prevent accidental contact.
- Use a reliable battery saver: Choose a reputable brand of OBD2 battery saver. Low-quality or faulty devices could potentially cause voltage irregularities.
- Monitor voltage: Some battery savers have voltage displays. Monitor this to ensure a stable voltage is being supplied.
OBD2 Port Location Challenges
As you mentioned, the OBD2 port location in some vehicles, like Lexus models, can be quite inconvenient.
Tips for Locating and Accessing the OBD2 Port:
- Consult your owner’s manual: The manual will show the exact location of the OBD2 port in your Lexus RX.
- Use a mirror and light: If the port is hard to see, use a small mirror and a flashlight or your phone’s light to locate it.
- Be patient: Take your time and carefully maneuver to connect the OBD2 plug without forcing it.
Disconnecting the Battery Saver
Once you have installed your new car battery, the final step is disconnecting the battery saver.
Order of Disconnection
Similar to the connection process, there’s a question of the correct order for disconnection:
Does it matter if you disconnect the clips first or the OBD2 connector first? Again, disconnecting the OBD2 connector last is slightly safer.
Recommended Disconnection Procedure:
- Disconnect OBD2 port: Carefully unplug the OBD2 connector from your car’s OBD2 port.
- Disconnect crocodile clips: Remove the crocodile clips from the slave battery terminals, starting with the negative (black) clip, then the positive (red) clip.
This sequence minimizes the chance of any voltage spikes or shorts as you disconnect the external power source.
Conclusion
Using an OBD2 battery saver is a straightforward way to preserve your car’s settings during battery replacement. By following these steps and safety precautions, you can confidently replace your Lexus RX battery or any other vehicle’s battery without losing important memory settings. Remember to prioritize safety, double-check connections, and take your time. If you’re ever unsure or uncomfortable working with your car’s electrical system, it’s always best to consult a professional mechanic.
