Using a memory saver when disconnecting your car battery prevents the loss of important vehicle settings. However, not all power sources are suitable for this task. Using a high-current power supply like a jump starter to maintain power to the OBD2 port while disconnecting the battery is extremely dangerous and can lead to battery explosions or severe burns. A safer option is a low-current battery charger, like a NOCO G3500, with a maximum output of 3.5 amps. This will provide sufficient power without the risk of serious damage if a short circuit occurs. Even a small, 1-amp power supply can effectively maintain the vehicle’s settings. With a low-current supply, an accidental short will simply cause a voltage drop, preventing harm.
While jump starters like the NOCO GB40 can provide substantial power, their safety mechanisms are designed for jump-starting a dead battery, not maintaining system power. They require a certain load to enable their output, and connecting them to a minimal load, like the OBD2 port (typically around 70 mA), can lead to unpredictable behavior. The override function, while enabling power delivery in these situations, significantly increases the risk of damage in this application.
If you’ve experienced a total system failure after attempting to use a memory saver, you likely blew a fuse. Many vehicles have a 7.5-amp fuse protecting the OBD2 port’s 12v line. While a blown fuse might trigger a fault code, a complete system shutdown is less common. Start by checking your battery connections for secure contact. Use a voltmeter to measure the voltage directly at the battery posts, and then again on the terminals a short distance from the posts. A healthy battery should read around 12.6 volts in both locations. If you have a significant voltage drop, this indicates a problem with the battery connections or the battery itself. Inspecting and tightening connections, or even replacing corroded terminals, might resolve the issue.
