Different Kinds of Car Batteries
The range of car batteries today are a lot different compared to your twenty or thirty years ago. Then, most cars would have been using the common lead-acid type of car battery.
Today, while the lead-acid battery is still common, the car battery industry is looking to the future with a range of new lead free batteries.
Why are the lead-acid batteries still popular? It's simply down to cost. While they are definitely not the greenest of items, they are relatively cheap to produce, have a known reliability cycle and as they are "low-tech" can be manufactured anywhere. The downsides (apart from the lack of green credentials), are that they require regular maintenance (topping up and checking), and require precautions when handling (as the generic term implies, they are filled with a dilute acid). Plus there is also the issue of disposal, with both the lead and the acid requiring specific recycling techniques.
One of the newer kinds of car battery is the Sealed or Valve Regulated (AGM) battery. Instead of using lead, these use a glass matt to separate the cells. Another type uses Gel Packs, which holds the sulphuric acid in a powder mix. The benefits of these batteries is as they are sealed, there is no chance of accidental leakage, plus when recycling time comes, no lead to worry about.
Another trend is a steady move away from the conventional lead acid car batteries to newer calcium type batteries. Calcium car batteries still use lead and sulphuric acid but also have calcium incorporated into their plates, which makes them more efficient that the standard older type lead-acid batteries. An important thing to make note of though, is that if you have an old battery charger, it may not work on the newer calcium batteries.
While a standard battery charger may maintain a calcium battery if it is not discharged, it cannot fully charge it. So if you have a fully discharged calcium car battery, you either need to buy a specific calcium battery charger, or go to your garage that should have one.