Whether you need to jumpstart a car, learn how to choose a battery or find out how to store one, just take a tour through Battery Basics and you'll be ready to go.


The standard automotive battery in today's vehicles is 12 volts. Each battery has six cells with 2.1 volts. A car battery is considered fully charged at 12.6 volts

When a battery drops voltage, even a small amount, it makes a big difference. For instance, when a battery drops from 12.6 to 12.0 volts, its power drops from 100% to 25%. At 12.4 volts, a car battery is 75% charged. At 12.2 volts, it's 50% charged.*

A car battery is considered charged at 12.4 volts or higher. It is considered discharged when it's at 12.39 volts or less.

Voltage is produced by a chemical reaction. Inside a battery there are positive and negative lead plates that sit in a liquid called electrolyte solution. Electrolyte solution is a mixture of water and sulfuric acid.

When this solution interacts with the lead plates, there's a chemical reaction. This chemical reaction creates pressure that we call "voltage."

The pressure (voltage) pushes the current out of the battery's negative terminal through the "load", the equipment drawing the power. The current returns through the positive terminal.


To achieve the chemical reaction that creates voltage in an automotive battery, the electrolyte solution inside the battery must have the correct mix of water and sulfuric acid. As you know, when a car battery is at 12.6 volts, it's charged at 100 percent.

At 12.6 volts, the electrolyte solution is 65 percent water and 35 percent sulfuric acid. This is the ideal combination!

Sometimes electrolyte "breaks down" and the acid moves onto the plates. So, there's less acid in the water. Whenever the percentage of acid in the solution decreases, the charge drops.

Cranking Power

As the temperature drops, the cranking power required by the car increases. However, as more cranking power is used, the amount of battery power available decreases.

Cold Cranking Amps (CCA) is critical for good cranking ability. It refers to the number of amps a battery can support for 30 seconds at 0°F until the battery voltage drops to unusable levels. For example, a 12 volt battery with 600 CCAs means the battery will provide 600 amps for 30 seconds at 0°F before the voltage falls to 7.20 volts (six cells). The higher the CCA, the more powerful the cranking ability.

If you live in a cold climate, you should consider the CCA rating when choosing a battery. If you live in a very hot climate, you don't need as much CCA.

Selecting the Right Battery

How do you know which battery is right for your vehicle?

Here are some quick tips to help you make the right choice.

Check your vehicle manual for the original equipment manufacturer's recommendations for:
  • Battery group size
  • Cold cranking amps (CCA)
  • Reserve capacity (RC) for your vehicle
Battery group size indicates the battery size that will best fit the physical dimensions of your vehicle. Many vehicles can accommodate more than one group size.

CCA is critical for good cranking ability. It's the number of amps a battery can support for 30 seconds at a temperature of 0 degrees F until the battery voltage drops to unusable levels. A 12V battery with a rating of 600 CCA means the battery will provide 600 amps for 30 seconds at 0 degrees before the voltage falls to 7.20 V (six cells).

RC helps to power your vehicle's electrical system if the alternator fails. It indicates the battery's "staying power" -- how many minutes the battery can supply ample power without falling below the minimum voltage needed to run your vehicle.

In general for both CCA and RC, the higher the number the better. HOWEVER, if you live in a cold climate, the CCA rating should be an important consideration in choosing a battery. Conversely, if you live in a high heat climate, you don't need as much CCA.

If you're looking for a deep cycle battery for marine or RV use, you must consider:

  • The type of equipment to be powered
  • The current (amps) needed to run the equipment
  • The number of hours you'll be using the equipment
Multiply the Amps by the Hours to determine the Amp Hours, or AH, required.


Current Draw (Amps)




AMP Hours







Trolling Motor






Fish Locator













Look for a battery that will deliver the required amount of AH for the specified time and voltage. For a safety cushion, increase the number of AH by 20%. To add AH, connect batteries in parallel. To add voltage, connect batteries in a series.

Be careful of products that display only ratings such as Hot Cranking Amps (HCA) or Cranking Amps (CA)

Products that display HCA or CA ratings are tested at higher temperatures, in the case of HCA — 80 degrees — so the resulting numbers appear higher. (CAs are tested at 30°F.) Since these batteries are not as powerful as you might think, what looks like a "bargain" may end up costing you money. Make sure you are comparing apples to apples when looking at ratings. The CCA and RC are the best measure of a battery's true power.

Check for freshness

Learn to interpret battery date codes. Or ask your retailer to make sure you purchase the "freshest" battery available. A battery that has been sitting on the shelf for extended periods can lose some of its charge and may not provide the performance you need during its first use. Long term performance probably won't be compromised however, as the battery can be returned to its original levels of performance with either in-vehicle charging or by using an external charger.

Look for a hassle free warranty

  • Is the warranty nationwide so you can obtain service wherever you are?
  • How long is the free replacement period?
  • After that time, will you be reimbursed for a portion of the battery's cost on a prorated basis?
Consider value as well as price

You might want to get professional advice from your mechanic or retailer at your local parts store before you buy.

Purchase a new battery before your existing one fails

Before you take a long trip, or when you're having your car serviced, have your battery tested. It could save you a lot of time and money down the road.

img   img   img   img   img   img   img   img   img