INTRODUCTION
Batteries are an essential part of any automotive system. Without batteries, your car's operations would be terribly hampered. This would range from the engine management system not functioning properly.
Batteries come in the capacities and specifications.
Some are rated 12volts, and so.....amp/hr; while others are 24volts.
The choice of battery depends on the application in ?; and whether your choice would be a dry celled one.
Dry celled batteries, are low in maintenance, and sometimes to determine the state of charge(SOC), does not require the use of hygrometers to determine their specific gravity/density. It has indicators on the top of the battery, indicating the state of the health.
For instance, GREEN means the battery's is a stable state of health; RED means the battery's weak, and needs to be recharged; WHITE means the battery is totally dead, and no matter how its recharged, it would never hold a charge.

BATTERY DYNAMICS
I would not be going into the technicalities of battery chemistry, but would rather employ a layman's explanation.
Further details on battery dynamics can be checked on google, and other search engines.
Batteries comprises of electrolytes (what some people call battery water, or acid water); cells, cathodes and anodes, responsible for the transfer of electrons from the anode to the cathode(electrolysis). Pls if I'm wrong, would want to be corrected here.

PROBLEMS OF BATTERIES(CAR)
*Weak cells. With time, the cells of batteries go weak. So, if you've got a battery, that's stayed for years, the cells of the batteries are bound not to hold a charge. Although, this depends o. the brand, and capacity of the battery.
*accumulation of carbon deposits on the battery terminal post. When batteries work, they discharge vapors through the positive battery terminals, in order to escape excessive build up of electrolyte temperatures, etc.
This causes low available voltage at components and sensors that require them, and also faulty battery terminals.
This applies to both dry and wet cell batteries.

BATTERY MAINTENANCE
*Battery terminals with carbon deposits, should be washed with water, to dissolve the deposits. In some instances where the terminals are excessively corroded the terminates, and iron smooth brush could be used to remove such deposits.
*Do not use wrong tools, like pliers, to try and tighten a battery terminal post, or a hammer to smash through them. This would cause the battery posts to distort from it's position, and with time, acid vapours begins to corrode the post(s).
Use appropriate tools. For instance, use a 10mm Allen socket, or otherwise, to loosen or tighten the terminals.
So, the next time you take your car for battery maintenance issues, or fault, endure the battery man does not use inappropriate tools for the job. Right tools for the right hob, saves tremendous time, and money.
*check the batteries state of charge, either monthly, or as required by the manufacturer.
This is done, if your car has a wet celled battery, the specific density is always checked, and compared to a set standard(specification). Say, 0.99, or 1.00. If it distorts from the standard, you're in the process if getting another battery, or recharging it to a full state of charge.
For dry celled batteries, the indicators can be monitored to inform you in their state if charge(SOC).

CHOOSING A BATTERY. DRY OR WET CELLED.
The choice of a battery in my view, depends on the what you WANT.
From experience, I have come to realise that wet celled batteries, do retain tremendous amount of charge, than even the so-called dry celled ones.
Remember, the cars our fathers drove, in the 70s, and 80s. They've all got wet celled u. them. And those batteries have being found to last much linger than the dry celled ones. Though the maintenance cost of such batteries, were a little bit more than the dry celled, but it gave those (babas), value for money. If I may ask. Why do you guys think even in thus time and age, manufacturer in the USA, and eben Europe, prepare wet celled batteries in the various cars they export to our country.

CONCLUSION
Batteries are an essential part of an automobile system. Without it, you're grounded. Choosing the right battery for your application, should depend on the manufacturers specifications, and capacity.
Modifying a battery for your application, also depends on the components amperage requires, and wire gauges.
You too, can maintain your car's battery, saving you some BUCKS.

PS: Figure 1: Corroded wet celled battery post
Figure 2: Maintained battery post; washed with water, and grease applies to stop corrosion