Whoever took over my soapbox, I gotta have it back. I need to rant about people without technical backgrounds misusing and abusing language by taking specific terminology out of context and misapplying it while acting as if they actually know what they're talking about, both in general and as it applies to motor vehicle batteries. In the process, they manage to create meaningless buzzwords that only create confusion.
Let's begin by applying an appropriately descriptive phrase to the batteries that existed 50 years ago: Open-Cell Flooded Wet-Cell Lead-Acid Motor Vehicle Batteries. This is a concise phrase that precisely describes a type of battery that was developed in the 1800s and is still available and in common use today. If you can open the caps on your battery and add water, you have an open-cell battery. Flooded refers to a type of construction and wet-cell refers to the type of electrolyte used. Lead-acid encompasses a very, very large range of batteries, of which motor vehicle batteries are just a small segment.
Marketers and salespeople apparently decide this phrase was too long and cumbersome so they tried to shorten it. Take any one of the adjectives, combine it with battery, and you're automatically referring to much more than just one type of battery. (**** it, I had to add "motor vehicle" to the phrase because, without it, I'd be including the same type of battery with uses other than motor vehicles.)
Those people would be just as well off just calling them "cheap" or "old-fashioned" batteries and arguably would do a better job of identifying exactly what they're talking about.
The adjective "gel" is another buzzword that's been so misused and misapplied it's been rendered virtually meaningless. (Whenever you run across "gel," just substitute "blah-blah-blah" -- you'll get just as much out of the discussion.)
A few years back, marketers ballyhoo'ed "gel" as the latest and greatest innovation in battery technology. This was just more dross because gel-cell batteries were manufactured as far back as the 1930s, primarily for use in military field radios and similar equipment.
To paraphrase an old military cliche, if you can't inform them, bury them in bull****. (Personally, I prefer "if you can't convince them, bury them in paperwork," although I have used the first one when dealing with especially obnoxious, ignorant individuals.)
Currently, you rarely hear any mention of "gel" in the motor vehicle field, with the possible exception of salespeople who neglected to update their buzzword vocabulary. The relative rarity of the adjective may be due to marketers realizing people tended to "turn off their ears" whenever they heard it. Alternatively, they may have dropped it when they realized, based on negative customer feedback, that gel batteries were just a more expensive yet less suitable alternative to standard "old-fashioned" batteries.
It's worth noting that Optima, on their website, recommends avoiding any battery chargers that mention "gel," including those that have gel/ACM settings. This is because these chargers tend to shorten battery life through inappropriate charging profiles.
Most gel batteries are the same as old-fashioned flooded batteries in terms of construction and operation. The only significant difference is the electrolyte is gelified by adding fumed silica, turning the electrolyte into a thick gelatin-like material. This thickened electrolyte impedes the flow of ions, making them less than ideal as starting batteries because they can't provide the quick, high amp surge needed by the starter to crank the engine. They also have less capacity than the same size flooded batteries.
Most importantly, from an expense perspective, gel batteries require a special well-regulated, stabilized charging system. Without significant changes, standard automobile charging systems are likely to damage gel batteries and drastically shorten their life span.
These shortcomings forced most gel battery manufacturers to withdraw from the automobile market and focus on electronic applications for which gel batteries are better suited and that can provide the kind of charging system they need.
Oh,yeah, I forgot to mention โฆ flooded and gel batteries are both lead-acid batteries. The electrochemical processes that allow them to collect, store, and release electricity are identical for both types.
A third type, absorbed glass mat (AGM) batteries, are also lead-acid batteries, with same internal electrochemical processes as the first two types. The AGM batteries differ from flooded and, to a lesser extent, gel batteries primarily in their design and construction.
Internally, flooded and most gel batteries have lead plates suspended in liquid or gelified electrolyte, consisting mostly of diluted sulfuric acid. AGM batteries use a fiberglass mat, saturated with electrolyte, to keep the lead plates separated. Because to the large openings in the glass mats, AGM batteries allow a greater, more rapid flow of ions than gel batteries, approaching that of flooded batteries.
Both gelified and absorbed glass mat electrolyte inhibits the formation of lead sulfate that leads to battery death. One major drawback of flooded batteries is the formation, shedding, and accumulation of lead sulfate, called shredding. These also do a much better job of keeping the plates from coming into physical contact, which causes cell(s) to be shorted out, rendering the battery useless.
The internal construction of some AGM battery use flat lead plates kept separate from each other by the absorbed glass mat. Some AGM batteries (e.g., Optima) use alternating layers of lead plate and fiberglass mat wound into a cylinder, which arguably seems to result in a more efficient battery.
While they are distinctly different, "gel" and "AGM" is sometimes (often?) incorrectly used interchangeably to describe particular batteries. For example, one amazon.com offering describes an Optima battery as being a "Sealed Gel Battery," with no mention of AGM. After looking up that particular battery on Optima's web site, I discovered it's really an AGM battery.
We've already established gel batteries are, in general, not suitable for our needs. I'd avoid any battery that's described as being a gel battery, regardless of whether the label is incorrect or not. If a company loses potential sales due to incorrect description, it their loss. If it really is an AGM and I want that particular battery, I'd find somewhere else, with a correct description, to buy it.
Another batch of terms that often cause confusion is "maintenance free," "sealed," and similar descriptions. (In this area, applying "dry" to automobile batteries really, really irritates me because it's totally bogus. "Dry" is only appropriate for the batteries that you use in flashlights, portable electronics, and children's toys.)
First of all, NO lead acid battery is truly sealed. Under certain conditions, ALL lead acid batteries will release flammable hydrogen and acidic gasses. For this reason, manufacturers are legally required to provide a means of venting these gases into the atmosphere and preventing, in particular, hydrogen gas from building up into an explosive concentration.
The correct term for "maintenance free" batteries is valve-regulated lead acid (VRLA) batteries. These batteries have valves that prevent the gases from being released unless pressure exceeds a certain limit. This actually extends the battery's life by keeping the gases inside the battery when they can be recombined into the chemicals the battery needs to work.
To the best of my knowledge, all gel and AGM batteries are also VRLA batteries. There is no technical or economic reasons for producing non-VRLA version of these types of battery. In particular, there is very little, if any, market demand for non-VRLA versions.
Likewise, almost all flooded batteries are produced in VRLA form nowadays. A few manufacturers still produce and sell some non-VRLA flooded batteries, primarily for old farts that insist on being able to perform old-fashioned maintenance. (I am an old fart but not part of this group โฆ some innovations make life less complicated, especially when a relatively small added expense results in significant improvements over tradition.)
Actually, non-VRLA batteries are marketed to large operations with robust maintenance procedures that seek extend the life of their investment beyond that offered by VRLA technology. (I'm just one old fart who doesn't want to spend the time on the regular routine maintenance required by non-VRLA batteries โฆ guaranteed I'd get busy, forget, and murder the battery.)
Some manufacturers claim their VRLA batteries can be mounted in orientations other than upright. Reliable manufacturers that offer this capability install multiple VRLA vents so that at least one valve can release excess pressure. Other manufacturers have a ****ty legal department, have a marketing department that doesn't listen to their technologists, or don't care about possible civil suits.
Easiest is to simply mount the battery in an upright orientation. If you have to use another orientation, make sure yourself that the battery has a viable vent for that orientation. (As far as I know, there are no batteries that are suitable for upside-down orientation.)
I think I've cut through all the mysterious jargon and provided what you need to know to choose the battery that suits you best. If not, please post questions and I'll try to answer them.
To summarize, flooded and AGM batteries both do well in our applications and your choice boils down to your financial resources.
In my next post on this subject, I'll look at differences that have an actual bearing on which battery is best for you. I'll also look at what causes premature battery death and what you can do to keep from murdering your battery before its time. (As a teaser, every battery should last at least as long as its warranty period and it's reasonably possible to extend its life span to as much as two or three times the length of the warranty.)
1970 Explorer Class A on a 1969 Dodge M300 chassis with 318 cu. in. (split year)
1972 Executive Class A on a Dodge M375 chassis with 413 cu. in.
1973 Explorer Class A on a Dodge RM350 (R4) chassis with 318 engine & tranny from 1970 Explorer Class A