When I was a poor college student I always bought the Wal-Mart batteries because they would reliably fail shortly before warranty expiration in the cold where I live. So I could buy the battery once and never have to again!
Personally I like the Die-Hard Gold line of battery, but my camaro currently has a "Fleet Farm" branded one in it now, as the Sears here didn't have any Golds that fit it when I wanted to replace the one that came with the car (it was cracked). I think the Optima's also seem to be a pretty popular option though.

 

optima yellow top.

 

I have Interstate in 4 out of 5 vehicles, Dually has two of them, and garden tractor included. No problems here. Three of them are over 5 years old and still good.

The key to good battery life is a good recharge, meaning good voltage and good amount of time for recharging, and using them. Keep them exercised by using a heavy load, ie, cranking. This action keeps them from sulphating, a growth between the plates reducing the battery capacity.

 

I have WalMart batteries in both my Camaro SS & RS and no issues, they have a good warranty policy too, if you have an issue, bring it back and see what can be done (purchase date dependent) -- check the date code on the battery before buying and get the freshest one, also get the one that fits with the most power -- CCA/reserve, etc.

If you're really asking "where's the beef", look into EnerSys Odyssey 75/86 battery:

http://www.camarohomepage.com/project/part4.htm



"The best choice in batteries for a performance car is the Odyssey, made by EnerSys Energy Products in Missouri. Popular among racers with high compression engines, car audio enthusiasts, diesel pick-up owners, off-roaders whose trucks have winches and those who will pay extra for a battery with long service life, the Odyssey has earned a solid reputation in the niche market that is premium car batteries. Admittedly, an Odyssey battery is not cheap, but they are a high-value product because of their durability has them capable of outlasting just about everything else on the market of comparable size and cold cranking amp (CCA) rating.

Some batteries provide enormous cranking power–others, deep cycle reserve power. EnerSys designs its products to do both. How so? One reason are flat plates made of pure lead rather than lead alloy. Pure lead plates can be made thinner, so more of them fit into the battery. Lots of plates mean more surface area and that means more power, up to two times that of some conventional batteries.

Odysseys are capable of providing five-second cranking pulses far in excess of their CCA ratings and that's often, two-to-three times the pulse rating of equally-sized conventional batteries, even at low temperatures. Odyssey's can handle deep cycles, too--as many as 400 charge-discharge cycles to 80% discharge.



The 75/86 has a CCA rating of 730-amp, a 5-sec. pulse hot cranking amp rating of 1230 and a hot cranking amp rating of 815. It's reserve capacity is 100 minutes.

Rugged construction, Absorbed Glass Mat (AGM) design, vibration-resistant welded, intercell connections and tough, corrosion-resistant, tin-plated brass terminals combine to give the Odyssey Battery reliability and durability such that they have a 3-10 year service life. Further, the AGM design prevents spills, even when installed on its side. Unlike conventional batteries, Odysseys can be stored for up to two years and still be returned to full power.

The particular Odyssey (PN PC1230DT) we put in the Tom Henry RS is a dual terminal unit which EnerSys calls a "Group 75/86 battery". It has top terminals (typical of a 75) and the side terminals (typical of an 86) used in GM cars from the late-'60s to the mid-'00s. It's rated at 730 cold (30-sec. at 0°F) cranking amps and 1230 "starting pulse" amps (5-sec. at 68°F). This unit weighs 45.5 lbs, 10.2 lbs more than the O.E. Delco we took out. There are no free lunches. The Odyssey's extra plates cost some mass"

 

Pretty much all batteries (Interstate, Wal-mart, Autozone, Optima, Advance, O'Reillys, possibly Napa) are all made by Johnson Controls, but they do sport their own "level" of quality. Interstate is their top OE type batteries. Optima is their top aftermarket battery, and the rest fit into different tier levels of quality.

I used to have a Wal-mart battery and it worked just fine for me. I ended up trading up to an Advance Gold series battery because the Wal-mart one left me stranded after jumping a girls battery down at school and because the warranty was better (1 year on the Wally, 3 year + 5 year pro-rated on the Gold). I did end up charging and testing the old battery and it actually ended up being good. My manager took it home with him and used it in his Bravada and it's still in now.

 

Johnson Controls is literally behind my house lol.

I just put my 5th walmart Everstart in mine in 2.5 yrs. First one came in car and this is #4 we've exchanged. I've never had to pay anything and mine have 3 yr warranties. Still, very inconvenienced. Battery was a little over 9 volts and had dead cell. Alternator isn't even a month old from rebuild. Brought battery home, tested 12.6 volts. Car cranked right up. Ran it about 5 mins and then had to run to inlaws. Didn't drive it as we've had flooding and I don't drive it in downpours. Came home about 4 hours later and it tests 12.4. Don't know if that's normal or not. It jumps to little over 14volts when it's running.

 

Also see:
Top Car battery Reviews | Best Car battery

In the Group 75 batteries, only these were recommended, but the selection tested was not very large, only 8 in this group:

Type Cost Rating
Interstate Mega-Tron II MT-75 7 $110 71
EverStart MAXX-75N (North) 6 $80 69 <-- the WalMart one
DieHard Gold 50575 (South) 1 $105 68


Most aftermarket car batteries sold in the United States are made by three companies that build them for retailers: Johnson Controls, which supplies more than half of the market, Exide, 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 the right battery to your car’s needs. Here are the major brands and where they are sold:

AutoCraft
Available at a variety of Advance Auto Parts stores across the country.

Bosch
Available at Pep Boys.

DieHard
Available at Sears and Kmart automotive centers.

Duralast
Sold at AutoZone.

EverStart
Available at Walmart stores.

Interstate
Available at a number of auto parts stores, repair shops, and online.

Kirkland Signature
Sold exclusively through the Costco warehouse club. Membership to the store is required before you purchase.

NAPA
Sold through NAPA auto-parts stores.

Nascar Select
Sold through NAPA auto-parts stores.

 

If you have a bad or weak alternator, it will also prematurely wear out your battery... Had it happen, not fun

 

Batteries take time for recharging. Twelve point four could mean the time for recharge may not have been enough.
You might take a voltage reading referenced to battery neg post, from both the alt BATT stud and at battery pos post. The difference between the two, alt being higher, should no more than 0.4 volt.

If more difference, you may want to disconnect battery, maybe place a charger on it as you disconnect both ends of each battery cable and wire brush them and the spot they touch. Anything you do to reduce the difference will improve recharge power.

Make sure there are no broken strands in the cables.
If clamp-on battery terminals are used, replace the cable with a molded terminal.
You also might want to check quiescent current with the Camaro sitting. Insert the DMM as an ammeter between a cable and battery, the meter will read current drawn as the car sits. Should be under 80 milliamperes - 0.080 amps. Anything more might mean some troubleshooting is needed in finding the culprit. Engine PCM, Body CM, and radio will draw power for retention of learning charactistics and clock & radio presets. Might even try to set the alarm to see if Camaro 'goes to sleep' and draws less current, something below 40 milliamps?
I don't suspect so, but hey, it's worth a shot.

 

They offer the Everstart Maxx 75N on their website but not our store. We've been getting 75S. Wonder if there's a difference in the 2 as far a reliability or durability.

Walmart blamed the 4 week old alternator. The blamed the battery at alt shop.