Testing Your Car Battery is More Important than Ever

Published May 2, 2018 

Even if drivers think their car battery is performing well, it’s important to get it tested, said ACDelco Battery Product Manager John Munsell.

Years ago, if a car had a weak battery, the car would be ‘slow to crank.’ Thanks to low viscosity oils, gear reduction starter motors, direct fuel injection and electronic spark control, new vehicles are much easier to start than older models.

Even with a weak battery, it still takes three seconds or less of cranking to start your car.

With increased demands on car batteries and cars not providing tell-tale signs of weakness, Munsell encourages drivers to ask service providers to test battery conductance on vehicles, particularly if they are charging devices regularly.

Skipping the battery conductance test can leave drivers at risk of needing a tow or a jumpstart down the road. When going to your local shop or dealer, simply ask the technician to test your battery. 

Reserve Capacity an Important Consideration When Powering Up Devices

“Reserve capacity extends the life of batteries, which is important if drivers regularly plug in multiple devices such as phones, laptops, or tablets into their cars, trucks or crossovers or if they have built-in Wi-Fi,” Munsell said.

Batteries are made up of thin plates that provide cold cranking capacity (what gets your car started) and thicker plates that provide reserve capacity (what powers your accessories and modules/computers that stay “alive” in key off mode).

The combination of the two is the sweet spot you are looking for in terms of what you need. ACDelco advises that you check with your manufacturer requirements to determine what batteries carry the ideal amount of each that your car needs.

ACDelco provides some of the highest reserve capacity batteries on the market, accommodating for vehicles that are packed with technology such as the new Traverse, Acadia or Enclave or specialized vehicles such as police cars, fire trucks, ambulances, and taxi cabs, which typically have equipment that require significant battery power. 

Watch for Battery Choice with Start/Stop Technology

There are two dominant battery types on the market: Flooded Lead Acid (flooded) and Absorbed Glass Mat (AGM).

With Start/Stop technology, the engine stops when you step on the brake, but many things continue to run on battery power such as the air conditioning blower motor, navigation and lights. When you pull your foot off the brake, the engine starts back up. You might move another 50 feet, hit the brake and then you do it all over again. Vehicles with Start/Stop technology require an AGM battery. AGM batteries are characterized by being charge receptive (they can start up with low state of charge). They are also able to recharge quickly.

Flooded batteries cannot be used on vehicles with start/stop technology. Flooded batteries typically need higher voltage to charge and do not charge back up as quickly as AGMs.

If you put a flooded battery on a vehicle with start/stop technology, once it starts the Start/Stop cycle, the battery plates will begin to disintegrate.

“You are asking it to do too much,” Munsell said. “You are expecting it to run consistently and charge up with the lower voltage that it takes to charge an AGM battery. And because it takes more power to charge, it will never fully charge back up. It will be working extra hard and it will go into a death spiral.”

Choosing the right battery for your vehicle

While AGM batteries are increasingly popular, they are not the answer for all vehicles, Munsell added.

“A car with an AGM battery can start up at a deeper state of discharge, they are very charge receptive and can handle the Start/Stop cycle without a tremendous amount of wear and tear.

When choosing a battery, it is important that choices be guided by original equipment specifications, Munsell added.

“Shops installing a replacement battery should always replace “like with like,” keeping in mind that it is critical for batteries to be able to power accessories AND start a car,” Munsell added.

Customers should consult with their dealer or local ACDelco Professional Service Center to determine what their vehicle requires based on manufacturer requirements and lifestyle.

Because batteries aren’t one-size fits all and choosing the wrong one can cause headaches – and expense – down the road, here are some guidelines to keep in mind:

  • Replacing an AGM with a flooded battery in a vehicle with Start/Stop vehicle technology could lead to battery failure in 4-6 months.
  • The regulated voltage control in vehicles with Stop/Start is calibrated to lower charging requirements of AGM batteries.
  • Along the same lines, using an AGM battery in a vehicle that has regulated voltage control calibrated for a flooded battery will lead to overcharging.
  • An AGM battery that’s exposed to excessive under-hood heat could also become over-charged and vent electrolyte as gas.  If this happens the battery dries out and ceases to function.

For more information on finding the right battery, ACDelco recommends visiting your local ACDelco Professional Service Center, GM dealership or the ACDelco website.

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