A car battery replacement can lead to the loss of important vehicle settings, radio presets, and even learned engine parameters. A Memory Saver Obdii device provides continuous power to the vehicle’s electrical system, preventing this data loss. While commercial memory savers are available, a simple and effective one can be built at home with readily available components. This guide provides a step-by-step approach to constructing your own memory saver OBDII.
Building Your Own Memory Saver OBDII
This memory saver utilizes a 12V DC power supply to maintain power to the vehicle’s computer through the OBDII port while the battery is disconnected. Here’s a breakdown of the components and assembly:
Parts List:
- 12V DC 2A mains powered regulated power supply
- 16 pin OBDII empty male plug with shell for cable entry (or an old OBDII clone dongle)
- Two 470 ohm 1/8w resistors (for LEDs)
- One 3mm green LED
- One 3mm red LED
- One 3A diode (e.g., 1N540)
Assembly:
The provided image illustrates the connections. Solder the red LED positive lead to pin 16 of the OBDII plug (battery positive). Connect the red LED’s negative lead to a 470-ohm resistor, then to the positive terminal of the 12V power supply. The green LED positive lead connects to the power supply’s negative terminal through a 470-ohm resistor. Connect both LED negative leads and the diode cathode (negative side with the band) to pin 4 of the OBDII plug (chassis ground). The diode anode (positive) connects to the negative terminal of the power supply. This diode protects the circuit from reverse voltage.
Using Your Memory Saver OBDII
Procedure:
- Prepare the Vehicle: Turn off all accessories (lights, radio, etc.).
- Connect the Memory Saver: Plug the memory saver into the OBDII port. Only the red LED should illuminate, indicating a connection to the car’s battery.
- Power Down the Vehicle: Turn off the ignition and ensure all doors and windows are closed. Do not use the remote locking key fob. Wait approximately 5 minutes for the vehicle’s systems to go into sleep mode.
- Power the Memory Saver: Plug the power supply into a wall outlet. Both the red and green LEDs should now be lit.
- Disconnect the Battery: Carefully disconnect the negative battery terminal first, followed by the positive terminal. Avoid touching the terminals together.
- Replace the Battery: Install the new battery, connecting the positive terminal first, then the negative terminal.
- Remove the Memory Saver: Unplug the memory saver’s power supply from the wall outlet and then disconnect the memory saver from the OBDII port.
- Verify Success: Turn on the ignition. If warning lights behave normally (e.g., the steering wheel warning light doesn’t stay illuminated), the memory saver has functioned correctly.
This simple DIY memory saver OBDII can save you time and frustration by preserving your vehicle’s settings during a battery replacement. Remember to always exercise caution when working with electrical systems. While this design incorporates a basic level of protection, a fuse in line with the positive lead from the power supply is recommended for added safety.
