Almost all of today’s car batteries are "maintenance-free." However, your battery should be load-tested annually once it is 2 years old if you live in a warmer climate, or 4 years old if you live in a colder climate. Doing so tests its ability to hold voltage while being used, and the results will let you know when it’s time to start shopping.
In addition, it is a good practice to check the terminals to ensure that the connectors are tight and free from corrosion.
Car batteries typically last from three to five years, according to AAA, spanning from 58 months or more in the farthest northern regions of the U.S., down to less than 41 months in the most southern regions.
The battery’s age is also a strong indicator that it’s time to consider a replacement. The date can be found on a sticker affixed to the top or side of the battery. A battery made in October 2022 will have a numeric code of 10/22 or an alphanumeric code of K-1. "A" is for January, "B" is for February, and so on (the letter "I" is skipped).
It is important to choose a battery with the longest free-replacement period you can get. A battery’s warranty is measured in two figures: the free-replacement period and the prorated period- which allows only partial reimbursement. A code of 24/84, for example, indicates a free-replacement period of 24 months and a prorated warranty of 84 months. But the amount you’ll be reimbursed usually drops off pretty quickly once you’re in the pro-rated period.
Car batteries come in two basic varieties: the more traditional maintenance-free and the more advanced absorbed glass mat (AGM).
Batteries once required drivers to periodically top off the water in the electrolyte solution, the liquid inside that is the battery’s power source. Modern maintenance-free batteries consume far less water than traditional “flooded cell” ones. Low-maintenance batteries retain their fluid for the life of the battery, and the caps on these models aren’t meant to be removed. There are still some batteries that can be topped off with distilled water; properly maintained, these may last longer in hot climates.
A lead-acid battery will generally cost significantly less than an absorbed glass mat battery. However, it will not hold a charge for as long and is less able to tolerate a deep discharge.
Absorbed Glass Mat (AGM)
AGMs are built to better stand up to repeated draining and recharging cycles than standard batteries. They are becoming standard equipment in more cars because modern features such as fuel-saving stop-start systems, electronic safety and convenience features, and power outlets for mobile electronics all increase the demand for power.
Although AGM batteries do vent gasses, most are re-absorbed by the mat and require only a small side vent attached to a drain tube for any gasses they may expel. (Note- This is a good feature for the Challenger whose battery is located in the trunk). AGM batteries can be recharged as much as 15% faster than a lead-acid or gel battery, and peak voltage can be as high as 14.7 volts. Float phase voltage is in between the gel and lead-acid units, at 13.6 volts.
One premium type of AGM battery is the Optima. Each of its 2.11-volt cells have their tightly stacked plates rolled into cylinders, with additional grid reinforcement applied to the outside of each stack. This explains their odd-shaped cases that look like three or six separate cylindrical batteries bolted to each other. Its Spiral Cell Technology delivers a high level of power in the first five seconds of a vehicle’s start cycle. Optima claims to have the most potent five-second starting power on the market and provides 15 times more vibration resistance than cheaper wet cell batteries.
AGMs can cost 40 to 100% more than highly rated conventional batteries. Consider buying one if you sometimes don’t use your vehicle for long periods and the battery loses its charge. An AGM battery can better tolerate a deep discharge, and it is more likely to fully recover if it is accidentally drained.
Get the Right Fit
Car batteries come in many sizes. Make sure you get the right size and terminal locations (or type) for your vehicle. It’s important to choose the right one to ensure that it fits securely and provides sufficient power. If the terminals are in the wrong place, your car’s cables might not reach or they might not fit securely. Check your owner’s manual or an in-store fit guide. Many retailers will install the battery free of charge.
The sizes for top terminal batteries are 24/24F, 35, 47(H5), 48(H6), H7, 49(H8), 51R and 65. The Challenger takes a Group Code H7(94R) size It is vented to avoid any fumes because of its enclosed trunk location. Its dimensions are 12 3/8 length x 6 7/8 width x 7 ½ height. (Note- The group code is a unique identifier for the battery group and is used by the Battery Council International (BCI). The code is a combination of letters and numbers and are used to ensure the battery size will be the best fit for a specific vehicle.
Cold-cranking amps CCA is a rating that measures a battery’s ability to start an engine in cold temperatures, specifically at 0°F for 30 seconds while maintaining a voltage of at least 7.2 volts for a 12-volt battery or 14.4 volts for a 24-volt battery.
The higher the CCA rating, the more power the battery can deliver in cold temperatures. However, it’s important to note that you don’t necessarily need the highest CCA rating available. The rate of CCA required to start your engine depends on several factors, such as the size of your engine, the circuit resistance, the viscosity of your engine oil, the temperature, and the loads of accessories you have in your vehicle. An excellent battery rating for the Challenger would be 790-800 CCA.
Reserve capacity indicates how long a battery can run a vehicle if the alternator charging system fails. It’s also a measure of how long you can accidentally leave the headlights on and still get the car started without needing a jump-start. To test reserve capacity, engineers measure how long it takes a fully charged battery to be discharged down to 10.5 volts, which is considered to be fully discharged. At that level, the car will be unable to start without a jump-start. About 1½ hours of power is average. Higher-scoring models can supply power well past 2 hours.
Battery life is measured by repeatedly discharging and recharging each battery about 3,000 times at a test temperature of about 167° F for 15 weeks or until performance drops to unacceptable levels. This simulates the hot under-hood conditions a battery can face during the summer, the hardest time of year for batteries because of the heat. Frequent high temperatures are very tough on batteries, increasing plate corrosion and more quickly vaporizing the electrolyte needed for current. Long life is especially important if you make many short trips that don’t allow much time for recharging. The higher the score, the longer the battery will be reliable.
Battery Manufacturers and Retailers
Most aftermarket car batteries sold in the U.S. are made by three companies that build them for retailers: Johnson Controls (supplies more than half of the market), Stryten and East Penn.
They are sold under various names and built to the specifications of retailers, so performance can vary. Most stores will test, install, and match a battery to your car’s needs. Here are the major brands: AC Delco, AutoCraft, Bosch, Die Hard, Duracell, Duralast, Everstart, Interstate, NAPA, Optima and Super Start.
DIY Challenger Battery Replacement- H7(94R)
See: Vented Battery Replacement | Dodge Challenger Forum