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Memory Savers: The Tool You Need When Changing Your Car’s Battery

DIY, Workspaces & Tools  /   /  By Gary Lieber

Sooner or later, the time will come when your car’s battery will need to be replaced.  Automobile batteries typically last about four to five years before they stop holding a charge. Pay attention to when the starter is not turning over as fast as it did before. If it turns out that you need a new battery, keep this in mind: using a “memory saver” can save you time, money, and keep your car’s computers running with the correct data they need to properly operate its complex systems.

Today’s cars run on a network of computers—controlling the engine, brakes, air bags, infotainment systems, and so on. Each computer stores information about your car’s performance and your driving characteristics in what is known as VRAM (or volatile random access memory).  When you remove the battery, there’s a chance that you might lose that information.

Your car will relearn some of that information over time, but it also might have to be reprogrammed if you don’t use a memory saver.

What Is a Memory Saver?

A memory saver is simply a connector with a small battery that has just enough voltage and current to keep all of the computer memory alive while the main battery is being changed. The connector plugs into the car’s cigarette lighter, or the OBDII connector.

The steps to use a memory saver are easy.

  • Before the main battery is disconnected, make sure the car is turned off. Then plug the memory saver—with its small battery attached into the cigarette lighter or the OBDII connector. The OBDII connector is located under the driver’s side of the dashboard on the steering column.
  • Next, remove the old battery, making sure that the positive battery wire is not touching the car’s body. (I usually put the positive battery connector in a plastic bag. Then, install the new battery, and attach the connectors.
  • Finally, unplug the memory saver from the car. That’s all.
Memory saver that plugs into the cigarette lighter.

Memory saver that plugs into the cigarette lighter.

Your car will start up with the fresh new battery, and your clock will keep the time, your favorite radio stations—and most importantly, your car’s dashboard will not become a Christmas tree of warning and fault lights.

Types of Memory Savers

The cheapest and easiest memory saver is a cable that has a connection for a 9V battery, and a plug for the cigarette lighter.  Simply plug in the cable with the 9V battery attached into your car, change the battery, and remove the memory saver when done. The only caveat to this type of memory saver is that it only works with cars that have a cigarette lighter that is still powered when the car is turned off.  Unfortunately, cars built in the last 15 years or so almost universally have cigarette lighters that only work when the car is running.  Avoid this type of memory saver if that’s the case.

A memory saver that accesses the OBD2 port.

A memory saver that accesses the OBD2 port.

If your car does not have an “unswitched” cigarette lighter, then use the other type of memory saver—the one that plugs into your car’s OBDII diagnostic plug. This cable plugs into the OBDII port on one side and a battery on the other side.  There are several types of battery connections for this type of memory saver, but the best ones are used with compact lithium-ion jumpstart batteries.

Both of these types of memory savers are available with a variety of battery connectors, including some with wall adapters, alligator clips, or built-in rechargeable batteries. Regardless, a memory saver is a smart buy.  Go to eBay Motors to check out a full selection of automotive memory savers.

About the Author

Gary Lieber is a regular contributor to the eBay Motors Blog, Clean Fleet Reports,, and He likes to modify his cars by adding features that are unique to the marque. His Porsche 911 is a multiple Concours winner including Top 911 at Porsche Parade in 2005 and 2015. His Volkswagen GTI has been tricked out with engine management upgrades and style enhancements not commonly available on this side of the pond.

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