Deep cycle battery definition: Deep cycle batteries are designed to provide a long period of sustained power output.

Deep cycle batteries are ideal for applications that require a quick start, such as:

Golf cart

Motorhome (RV) accessories

Motor boat trolling motor

wheelchair

This is compared to a starter battery, which provides a higher current in a shorter train of pulses to start the engine.

Are car batteries deep cycle?

No, a car battery is a starter battery. Starting the battery requires an initial high current to start the engine. Once the engine starts, the alternator takes over the car's power needs. The car starting battery is installed, and the car battery is not deep cycle, that is, the starter and deep cycle are similar in that they are lead acid batteries. So they use the same chemicals to generate electricity.

So, how do lead-acid batteries work?

Components of lead-acid (deep cycle and starting) batteries include:

Lead plate (negative electrode and positive lead oxide electrode)

Electrolyte solution (water and sulfuric acid)

In short, when lead sulfate ions move from the negative plate to the positive plate, the lead-acid deep cycle battery generates electricity.

Illustration showing lead acid battery assembly

Lead-acid batteries generate electricity by the movement of ions between the plates

What is the difference between a starter battery and a deep cycle battery?

We have determined that, at a basic level, starter batteries and deep-cycle batteries work the same way.

But key differences remain, and let's take a look at them.

Sheet thickness

Deep cycle batteries have thicker plates. This helps them to discharge repeatedly and deeply to provide extended power. Why? Each discharge uses up some of the material on the electrode. Therefore, having a thicker plate allows for more cycling, as the process can be repeated over and over again.

Plate thickness of deep cycle battery and starter battery

The pad of a deep-cycle battery is thicker than the starter battery

Starting the battery, on the other hand, requires a lot of current to start the engine. So they switched to thin sheets. This helps increase the surface area of the chemical reaction that produces electricity.

Discharge depth

Another difference is how much each battery can discharge. Deep-cycle batteries can discharge 45 to 100 percent before they need to be recharged. But most manufacturers recommend that batteries discharge only about 50% to extend battery life. Discharging more than 50% will reduce the number of battery cycles. This shortens the battery life. In contrast, starter batteries discharge only a tiny fraction - typically 2 to 5 percent - each time they are used.