Home, Automotive Repair Library, Auto Parts, Accessories, Tools & Equipment, Manuals & Books, Car BLOG, Links, Index

Car Battery FAQs

by Larry Carley copyright AA1Car.com

How long should a car battery last?

Average battery life for a conventional wet cell lead-acid car battery is about four to five years, and can be as short as three years in hot climates. Battery life can be reduced if the battery is run down frequently, chronically undercharged, or subjected to extreme vibration (driving on rough roads). AGM batteries usually last up to 6 years or longer.

How can I tell if a battery is good or bad?

Load testing a battery or using an electronic battery tester to check the condition of your battery will tell you if it is good or bad. If your battery fails either type of test, it needs to be replaced.

What type of replacement battery should I buy?

You can replace your battery with a conventional wet cell battery car battery, or an AGM battery.

The Cold Cranking Amp (CCA) rating of the new battery should be the same or higher than your old battery.

Who Makes Car Batteries?

Most lead-acid 12-volt car batteries that are marketed in the U.S. are made by:

Clarios, LLC (bought Johnson Controls battery division in 2019)

Stryten Manufacturing (bought Exide batteries in 2020 after Exide filed bankrupcy)

East Penn Mfg. Co. (DEKA)

All of these manufacturers sell their batteries under various brand names to vehicle manufacturers and aftermarket retailers. Brands made by Clarios (formerly Johnson Controls) include AC Delco, Interstate, DieHard, Duralast and Optima. NAPA batteries are made by East Penn. Walmart batteries are supplied by both Clarios or Stryten.

Can I install a marine battery in my car?

Marine batteries are designed for deep discharge cycles and for lower amperage output. They are not well suited for vehicle applications unless a vehicle is seldom driven and does not require a lot of amps for cranking or other electrical accessories.

How should I dispose of my old car battery?

Car batteries contain lead (a toxic heavy metal) and acid. They should always be recycled. Most retail outlets and repair facilities that sell batteries will accept your old battery for recycling. If you do not give them your old battery for recycling, they may charge a deposit fee to encourage you to recycle your old battery.

How much does a car battery cost?

It depends on the cranking capacity of the battery (CCA rating), the type of battery (conventional or AGM) and the warranty on the battery. The higher the CCA rating and/or the longer the warranty period, the higher the price. AGM batteries also cost up to 25 percent more than conventional batteries. New batteries typically sell for $70 to $200.

Can I replace an AGM battery with a less expensive conventional battery?

You can, but you probably should not. AGM batteries are longer lived and often have higher amperage ratings than a comparable conventional battery. AGM batteries are often used in vehicles with idle stop-start systems.

Are all car batteries rated at 12 volts?

Yes, for most starting and basic electrical systems. A fully charged 12 volt battery will actually read about 12.65 volts. Back in the 1950s and early 1960s, some cars have 6 volt batteries and electrical systems. Hybrid vehicles have a separate high voltage battery that may range from 48 volts up to 300 volts or higher depending on the application.

How hard is it to replace a battery?

A car battery is heavy, but it is usually fairly simple to replace. The positive and negative cables are disconnected from the old battery, then the bracket or clamps that hold the battery on its tray are loosened to remove the battery. The new battery can then be placed on the tray, tightened down and reconnected to the positive and negative cables. On late model vehicles with electronic modules, it is highly recommended to use a "battery saver" or external power supply attached to the electrical system to maintain voltage to the electronics while the battery is being replaced. This will preserve learned memory settings in the electronics.

Are car batteries dangerous?

A 12-volt car battery cannot shock you. However, car batteries emit hydrogen gas when they are charging. Hydrogen gas is very explosive. A spark nearby could cause the battery to explode. Caution should be used when jump starting a dead battery for this reason. Never connect both jumper cables to the battery itself. Connect the positive jumper cable to the battery, but make the negative cable connection to a ground on the vehicle away from the battery to reduce the risk of an explosion. Also, wear eye protection and gloves while handling or changing a battery and void contact with any acid that spills from the battery. Never attempt to jump start a frozen battery.

Are all car batteries lead-acid?

Most stock production 12 volt cranking batteries are lead acid (conventional or AGM), but some racing batteries may be lithium-ion. Hybrid batteries can be nickel metal hydride (older first generation hybrids), but most are high voltage lithium-ion.

What is the difference between an AGM battery and a conventional battery?

AGM stands for Absorbed Glass Mat. It is a type of battery cell construction that used a paste rather than liquid acid electrolyte between the cell plates. AGM batteries cannot spill because there is no liquid to spill, and they are typically longer lived because of their unique construction. AGM batteries are also slightly lighter, charge faster and can deep cycle with less risk of battery damage.

What is the Difference Between a Car Battery, a RV Battery and a Marine Battery?

Car batteries are designed to deliver a large surge of current for a short period of time for starting the engine. A car battery will typically have a Cold Cranking Amp (CCA) rating of 600 to 800 amps for reliable cold weather starting. Once the engine starts, the battery just serves as a voltage reservoir for the charging system as the alternator takes over the job of supplying the vehicle's electrical needs.

Marine batteries and RV batteries are designed to provide less initial current flow but for longer periods of time. In other words, they typically have a lower cranking rating (500 marine cranking amps) but a high amp-hour and reserve capacity rating so they can provide a steady flow of current for a longer period of time. Marine and RV-batteries are also designed to handle deep discharging better than a regular car battery, and to hold their charge longer when the battery is unused for long periods of time. For maximum life, regular car batteries have to be maintained at or near full charge and degrade if left in a discharged condition for a long period of time.

That said, some owners of vintage cars and classic muscle cars that are driven infrequently and may set in a garage unused for weeks or months at a time may find installing an RV battery or marine battery better suits their needs than a regular car battery.