Last updateTue, 17 Oct 2017 5pm

On The Road

Make sure to buy the right battery for your vehicle


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 the shop recommended seemed expensive. I am curious if you agree the shop was trying to sell him something he really doesn’t need?

A: It sounds as though this shop may not have explained to your friend why it 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 while the voltage is measured.

A battery’s voltage needs to be at or above 9.7 volts. If it measures below 9.7 volts, 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 will perform the battery check and if it is low, advise customers to install a new battery before they are stranded.

During the winter, for example, it is important to know that a battery that operates well at 80 F outside temperature can produce only half of its output at 0 F, so it is important to check a battery before traveling in a cold climate.

As for the expense, batteries come in all shapes, sizes and quality levels. Generally, 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 “one size fits all.”

Many of today’s new vehicles require specific batteries and may not run correctly if the wrong battery is installed. These batteries are expensive. Plates, which are inside the battery, determine 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.

Finally, the battery must be installed correctly. The cables that connect the battery to the vehicle must be free of corrosion and connected properly. Connecting the cables in reverse order can damage the vehicle’s computers.

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 email McCord at This email address is being protected from spambots. You need JavaScript enabled to view it.

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