Surely if the battery is a 100ah you will only get the same amount of power out of it, wether it is a LiPo gel or lead acid, or NiCad, the only difference is the weight and size of the actual battery. Or am I total wrong
That as you imply is what 100AH or any quoted AH value for a "12volt" battery is, the specification of the amount of energy it holds.
Having said that is what it holds, holding, and the ability to yield though are not the same as what it ought to be asked to provided and around those subjects there are large differences, technology to technology, product to product.
The sensible amount of what energy they hold to what they ought to be used to provide being the Achillies heel of lead acid batteries in general. Typically, a LA vehicle starter battery, whilst able to supply a high momentary cranking current is quickly damaged by being asked to provide much of the overall energy it holds; I would hazard a figure of draining it by around just 30% draining frequently becomes quite life shortening.
Comparatively, a good [ as real not simply labelled] traction or leisure battery, then the figure moves to about a 50% drain as a sensible usage level to limit the amount taken.
Really super, and mega expensive traction batteries can yield a bit more, but the limit never gets near what the battery holding value states. Unlike starter batteries, typically traction batteries are more easily damaged by providing high momentary engine cranking currents; there are offerings that try to do both duties.
Here the Lithium based technologies score on two fronts, one they can yield more of what they hold without damage, and that damage is not so damaging, nor the time left drained as damaging.
My own opinion is that "the jury is out" about the actual levels the various lithium technologies ought to yield of their held capacity, it's certainly better than the LA equivalents, and they seem able to provide both the high cranking current, and low current roles.
I am personally still unsure quite the damage level a deep drain causes, or in contrast to LA how damaging actually fully charging is. My e-bike, though of 2016 vintage the charging guidance is to work between 80% fully charged and 20% left, plus don't store, fully charged and if over a month charge to only 60%.
If these figures, the 80% to 20% are correct it gives the usable as 60%, but with the proviso of the damage for the over draining occasions being far less of a life limiting impact than with the LA battery.
I accept 2016 is a lifetime ago, and in the 7 years both the technology and level of understanding of lithium-based batteries could well have developed.
If and when I need a new caravan or motorhome I don't doubt I will go the lithium route, but with kit specifically aligned to match it, not as of now where I would fit a lithium with mains and solar charging that is for LA, Gell.
My Gell lasted 11 years of nearly all off grid caravanning, but was always on charge in storage and generally not used to power the mover. [I keep a traction battery at home for doing that higher current mover use].
So come change time I replaced like with like.