Why only deep cycle marine batteries at Walmart

... and that's exactly what they are doing, adding more lead, not (necessarily) more fragile if comparing two starter batteries. They do weigh more.

To quote the car battery faq:


that small in stature battery with high cold crank [amps] will have many very thin lead plates just to get the necessary surface area to make that big cold crank number. It will have the lower volume of electrolyte to provide the cooling necessary for long life and the greater capacity to run the [electrical] systems on the car. All of those thin plates will corrode away and fail long before expected putting the high performance battery's life below that of the lower CCA rated battery with the lower cost. Your best rule-of-thumb is, if it meets the OEM (Original Equipment Manufacturers) recommendation, buy it. Look for the highest reserve capacity [RC] battery at the correct CCA (Cold Cranking Amps)."
 
^ The fundamental misconception is assuming that a lower CCA starter battery of the same type and group size, is going to have thicker plates. Manufacturers aren't seeking to give you more life and increase build cost with more lead per plate in their lower tier starter battery. They do not have the goal of filling the space with as much lead per plate as possible when optimizing the design for lower retail price. It is invalid to assume more plates or more surface area per plate, means they need to be thinner, when the lower tier battery didn't need them to be thicker and cost more either, to meet their rating.

It is a different situation if you want to contrast a starter battery against a combo or deep cycle, then sure, expect thicker plates, but not on a budget starter battery.
 
@Donald Out of curiosity, is there a way to tell which batteries at WM are made by East Penn? I know that the last time I bought a battery at Sam's Club, it said East Penn on it, but I haven't looked at WM batteries in probably close to 20 years (back at that time they said china on them). The battery in the 1996 K1500 is 6 years old as of last month, so it may be nearing the end (East Penn labeled "Duracell" purchased September 2016).
If there is a way to tell which ones are East Penn, I will see if the ones here in West Texas are made by them.
Thank you
 
@Donald Out of curiosity, is there a way to tell which batteries at WM are made by East Penn? I know that the last time I bought a battery at Sam's Club, it said East Penn on it, but I haven't looked at WM batteries in probably close to 20 years (back at that time they said china on them). The battery in the 1996 K1500 is 6 years old as of last month, so it may be nearing the end (East Penn labeled "Duracell" purchased September 2016).
If there is a way to tell which ones are East Penn, I will see if the ones here in West Texas are made by them.
Thank you
Pretty sure the serial number stamped/molded on the top has “EP” in it if it’s East Penn made.
 
Pretty sure the serial number stamped/molded on the top has “EP” in it if it’s East Penn made.
Yes that's it. The battery in the picture does indeed have a serial number printed on a sticker that starts with an EP.
Thank you @bullwinkle and @Donald , I appreciate the info. I will check WM's batteries next time I'm in there and see if they have the EP.
 
So I guess the answer is the starting will have many thinner plates and deep cycle will have fewer thicker plates and dual purpose is in the middle?

Get a battery that has as thick plates as possible but still has enough MCA to start the engine. But newer engines with electronic ignition and fuel injection start easily and quickly. Not a lot of cranking needed.
 
So I guess the answer is the starting will have many thinner plates and deep cycle will have fewer thicker plates and dual purpose is in the middle?

Get a battery that has as thick plates as possible but still has enough MCA to start the engine. But newer engines with electronic ignition and fuel injection start easily and quickly. Not a lot of cranking needed.
Seems like a heavier battery is a good way to gauge plate thickness-more lead=stronger (but lower CCA).
 
So I guess the answer is the starting will have many thinner plates and deep cycle will have fewer thicker plates and dual purpose is in the middle?

Get a battery that has as thick plates as possible but still has enough MCA to start the engine. But newer engines with electronic ignition and fuel injection start easily and quickly. Not a lot of cranking needed.
Forget the "plates". Get the largest group size that will, physically, fit the battery compartment. Measure the compartment, then, measure your prospective battery. The battery Height will often be the limiting dimension. See if you can fit a group 31, if no, then try to fit a smaller group 29,etc.,etc,.etc. AGM is best as it lets you avoid maintenance. Go to a boat dealer, if you wish. This ain't hard.
 
I have 3 batteries and would need to replace them all at once if I went to AGM. $308 each at NAPA.
Yep, AGMs are expensive. So, then, just get the largest group size that fits your battery compartment in a, conventional, water cell battery. You still get the benefits of larger Battery; Larger capacity (check before buying). Fwiw Exide's were never good for me. Hope this helps you get a longer lasting battery.
 
Boat batteries tend to sit for long periods of time. They also tend to get cranked on allot and run down when dirty carbs act up in the middle of the lake. Car batteries don't deal with that kind of abuse very well hence the marine category of batteries.

Personally, reserve capacity seems more important than CCA.
 
Lead antimony batteries are much more tolerant of deep discharges than lead calcium starter batteries used in automotive applications. Their big downside is that they offgas more and require watering which is one reason for the switch to lead calcium in car starter batteries. Any battery labeled maintenance free is lead calcium and is not a true deep cycle.
 
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