Lead-acid batteries or “starting batteries,” as they are also called, are the oldest rechargeable batteries in existence and the first used for commercial use. They have dominated the market for over 100 years, ever since their invention in the 1850s by Gaston Plante, a French engineer, and continue to weave their magic to this day. The surge of new batteries in the market has not lessened their importance.
Today, lead-acid are cost-effective and their ability to supply high surge currents, makes them the most viable option for use in cars and other motor vehicles, as they meet the requirement of the high current that automobile starter motors need.
How lead-acid batteries work
Car batteries are used to start diesel or gasoline engines, as they provide the electricity needed for starter motors, ignition, lights and other electronic features. Most of the car batteries are lead-acid batteries and the energy is produced through a chemical process that involves lead, lead oxide and a liquid electrolyte solution.
Plates of lead and lead oxide sit in the electrolyte solution that is made up of a small percentage of sulfuric acid and more of water. This causes a chemical reaction and electrons are released, which are all routed through conductors in the battery to generate the electricity needed for the car.
When lead batteries are discharged, sulfuric acid forms on the lead plates, and when they are recharged again, this sulfuric acid on the plates breaks back into its constituent lead and lead oxide.
Some car batteries need maintenance in the form of adding water. It was during the 1970s that maintenance-free sealed lead-acid batteries were developed and they can be used in any position, sideways or upside down without the risk of acid leakage.
>> READ MORE: How to repair and recondition your lead-acid batteries
The liquid electrolyte is gelled into separators and sealed. Safety valves are used to allow venting during charging, discharging and other atmospheric pressure changes. Currently, there are two lead-acid systems used, the small sealed lead-acid (SLA) and the larger valve-regulated lead-acid (VRLA).
The newer type of sealed lead-acid batteries are the Absorbed Glass Mat batteries (AGM) that are maintenance free and the plates are mounted in such a way that they can withstand extensive vibration and shock. The hydrogen emission from cars using these batteries is less than 4% and self-discharge is extremely low at 1-3% per month.
This gives them long storage before the need to recharge. These batteries are more expensive than the flooded lead-acid batteries (liquid electrolyte), but because of their durability, they are the preferred version for high performance cars rather than the flooded variety.
One of the best things about lead-acid batteries is their self-discharge, which is one of the best on rechargeable batteries at about 40% per year, in comparison with nickel-cadmium that self-discharges in three months.
In conclusion, lead-acid batteries are a perfect choice for cars as they are inexpensive, reliable and provide dependable service, durable when used appropriately, and they have the lowest self-discharge rate among rechargeable batteries.