I don't know crap about Turbo Regals - but this I might know something about.

I happen to sell batteries - albeit slightly larger ones.
www.Alpha.com
Any significant out-gassing - if you will, mainly occurs at discharge.
Discharges on automotive batteries happen relatively seldom - i.e. starting
Yes - there is some out gassing at what we refer to as float voltage, (car running) but it is generally not considered significant.
Also, an automotive battery is designed to have a relatively shallow depth of discharge. DOD in the trade jargon is an all important specification.
It then determines how much power must be put back into the battery to get it to a full state of charge.
When you have to do a heavy recharge, you are pumping more power back into the battery, and you will use more water- i.e. out gas (split the water molecule into hydrogen and oxygen)
So again, not a hugely significant amount of recharge should occur under normal operating condtions.
And if you consider the duty cycle, the car is only running for a relatively short period vs the time it is off.
Hence, even float voltages, and any slight out gassing; are minimized.
"Typical" float voltage for a lead acid cell is = 2.35 volts per cell. x 6 cells
Guess how much voltage? = 14.1V
Different manufacturers may recommend slightly different float voltages - but I would guess in the automotive world - they are based upon a range of voltages
In the industrial world - we can set the microprocessor based chargers to output exactly what we want.
EDIT - WE4Mateo - you asked about one of those volt booster situations.
So I would assume it is modifying the regulator on the alternator to produce a higher output.
You then are "floating" your battery at a higher voltage.
Now, basically, once your battery is fully charged, any additional voltage does nothing (good) for the battery. But my thinking, and I would have to run this by my guys, is that this would be a slight equivalent to what we call "boost charging" or equalize charging.
This is referred to as "gassing voltage" - or typically about 14.4 volts
Where you for a period of time, give the battery a higher voltage.
I can tell you from my years of experience in the battery world - this will shorten your battery life, slightly, as you will produce more out gassing. And generally speaking, you have no way to add more water to your battery since it is "sealed"
To give you an anecdotal example - you can watch a normal battery under float voltage just lazily bubble every now and then.
But put it on equalize, and you see a significant increase in bubbles ; i.e. outgassing. Loss of water. While most automotive batteries have designed into the cases a margin of error for electrolyte level, once you expose the plates to air, you lose (significant) battery capacity.
We have had clients screw up and leave their chargers on equalize mode, only to come back (many months later mind you) - and find their batteries dry.
Extreme example I know. What happens to an auto battery at 16 or 17 volts for a relaltively shorter period of time I can not answer at the moment.
It can get alot more technical as to what a higher voltage is doing to the plates and such - but for now - I think that is good.
How would a Hawker style with immobilized Gel type electrolyte respond to higher float voltages I couldn't say without doing more research.
As to Enerysys, and their competitors promoting the new technologies.
It's kind of funny - since it is actually an old technology.
Based more upon using a pure lead positive plate vs an PbAntimony or PbCalcium positive plate.
And sometimes wound in a spiral for more surface area in a smaller footprint. (Energy density)
In the industrial world - we refer to that as a Plante' (plaan-tay) plate. Reference Gaston Plante', and the first battery types using pure lead.
Plante was used for years before being replaced with more commercially advantageous grid alloys. But it has its advantages - mainly much longer life of the grid and higher discharge rates.
Cost or ease of manufacturing is not one of them
One advantage of using a thixotropic gel is the immobilization of the electrolyte. So these batteries do not need to be placed in an upright position.
Also, since they are less sensitive to higher temperatures, because unlike Absorbed Glass Mat (AGM) type batteries, they tend not to "dry out" as much - they have a longer life span.
However, between a pure lead grid and the gel electrolyte vs a AGM style VRLA or traditional wet cell - there is pretty hefty price premium.
Add those positive features to the marketing hype - and I've seen these batteries sell for 2 - 3X the price of a traditional wet cell. Again - in the automotive world - cost is "almost" everything.
But it is your basic VRLA battery, but instead of using absorbed glass mats (AGM) and alloy grids, it has a pure lead grid and thixotropic gel as an electrolyte.
In an auto - my GN auto for instance - I like some of these for the "energy density"- power vs weight or size ratio; - i.e. weight savings.
In the automtoive world - muscle car or new OEM - it's all about weight.
Now the cool batteries are the ones being used for the Start/ Stop systems.
By the way - the picture title says Exploded battery - which is BS.
They seldom, if ever - explode.
What they do do is enter a state called "thermal runaway" - which when the plates contact each other (short circuit) or separators dry out. After your battery has become "too gassy"
