Last updateTue, 19 Sep 2017 5pm

On The Road

It's better to buy a new battery sooner rather than later


Q: A friend of mine said he brought his car to a new shop that recommended a new battery for his car. However, he chose not to buy it because his car still starts and runs with no hesitation, and the battery they recommended seemed expensive. I am curious if you agree that the shop was just trying to sell him something he really doesn’t need.

A: It sounds as if the person at this shop may not have explained to your friend why he or she was making this recommendation. What your friend should know is that batteries deteriorate over time from normal use, and the condition of a battery should be checked regularly as part of a complete automotive service.

This is easily done by performing a load test on the battery using a special piece of equipment that is connected to the battery. This equipment applies an electrical load to the battery for 15 seconds, at which time the voltage of the battery is measured. A healthy battery’s voltage needs to be at or above 9.7 volts. If the voltage measures below 9.7, the battery is considered unreliable and may fail to start the vehicle at any time.

It is also important to know that a weak battery causes the vehicle charging system to work harder than designed and will result in the alternator failing sooner, which is a much more expensive repair than replacing the battery.

A competent repair/service facility performs the battery check for its customers and advises them to install new batteries before they become stranded somewhere. During the winter, for example, it is important to know that a healthy battery at 80 F outside temperature has only half of its output at 0 F, so check a battery before traveling in any cold climate.

As for the expense, batteries come in all shapes, sizes and quality levels. In general, the lower the cost of the battery, the shorter the service life. It is important to purchase a battery that matches your vehicle’s manufacturer-recommended size and power. There is no such thing as “one size fits all.” What is inside the battery, called “plates,” dictates the quality; the size and number of plates in a battery determine how many amps it can deliver, as well as its service life, its warranty and its price.

Last but not least, the battery needs to be installed correctly. The cables that connect the battery to the vehicle must be free of corrosion and connected properly. If the cables are connected to the battery in reverse order, the vehicle’s computers will be damaged.

So, yes, even if your friend’s vehicle still starts and runs, the battery could be on its last legs – and a good-quality, long-lasting battery will cost more.

Warren McCord is an ASE certified master technician and owner of Dean’s Automotive Inc., 2037 Old Middlefield Way, Mountain View. For more information, call 961-0302 or e-mail This email address is being protected from spambots. You need JavaScript enabled to view it..

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