What's the difference between normal and deep-cycle batteries?

If you're an audio nut you will have no doubt heard of deep-cycle batteries. Most normal and deep-cycle batteries are lead-acid cells and use exactly the same chemistry for their operation. The difference is in the way that the batteries optimize their design. Normal car battery A normal car battery is designed to provide a very large amount of current for a short period of time. This surge of current is needed to turn the engine over during starting. Once the engine starts the alternator provides all the power that the car needs so a car battery may go through its entire life without ever being drained more than 20 percent of its total capacity. Used in this way a normal car battery can last a number of years. To achieve a large amount of current a normal car battery uses thin plates in order to increase its surface area. Deep-cycle battery A deep-cycle battery is designed to provide a steady amount of current over a long period of time. They can still provide a surge when needed ...  more