A lead-acid battery can only delivery just over 2v per cell, hence why they have 6 in series (chambers) making up a typical battery of this type.
To increase the cranking power (amps) you don’t increase the cells as such, you increase the surface area of lead plates exposed to the chemical discharging reaction. If you stick two batteries in parallel, then you’ve increased that ampage without increasing the volts at all. A large battery therefore has more cranking power than a small battery. 
The battery being charged or not depends upon the reversible chemistry between lead, lead oxide, lead sulphate, sulphuric acid, and even the water plays an important part two, as does keeping the plates covered in solution right to the top. 
If you put tap water into a car battery, the mineral contaminants in tap water cause some of the sulphate ions to react with things like dissolved calcium creating calcium sulphate (plaster of paris) which not only won’t dissolve, but flakes off the plates as well, depleting the solution of sulphate ions and therefore the lead sulphate. The plates get covered in crap as well, making it harder to fully re-charge the battery in future. 
This contamination makes the chemical reactions of sulphate ions more difficult, because the main reaction taking place is the total dissolving of the lead plates over time, rather than the building up of the spongy PbSO4 which is what is supposed to happen. I believe the optimum concentration of acid is about 1 part concentrate to 2 parts distilled water. Optium in that one has a very strong electrolyte and a maxed-out number of SO4 ions in solution, which need to flow freely if the battery is to be re-charted on a regular basis without plate deterioation. 
A lead-acid battery in good condition has spongy lead oxide on the plates, and a very clean solution of dilute (with distilled water) sulphuric acid around it.
Concentrated sulphuric acid won’t work, as this is a oily liquid (called ‘Oleum’ or ‘Oil of Vitriol’) that actually contains hardly any water at all!
What little water there is in it is a contaminant from concentrated H2SO4 being hygroscopic, and drawing moisture out of the air!
This makes street-available oleum about 97-99% sulphuric acid, and is often a contaminated-looking buff colour rather than the pure as melted snow colour that 100% acid should be. The concentrate also has a density (specific gravity if you prefer) over double that of water, so 16,000 litres of it would weigh over 32 tonnes! 