Difference Between Starter Batteries and Deep Cycle Batteries
Without delving too deeply into the science of the matter, it is still very important to know the differences between deep cycle batteries and so-called starter batteries, which are often referred to as automotive batteries. Deep cycle batteries are what we use in our electric golf carts where automotive batteries are going to be used in gas golf carts.
The first thing to know is that these batteries may have similar capacities, but they have different designs which creates the differences in how they perform. If you swap roles – pulling power from a starter battery so that it drains the power to low levels – you will shorten the life of that battery. And, this works the other way, too. If you use a deep cycle battery as a starter battery, you could be harming your battery.
The differences in function are simple, but the differences illustrate why you need to use the right battery for the right purpose.
The Function of Starter Batteries
Starter batteries, also called SLI (starting, lighting, ignition) batteries are designed to provide a large surge of power all at once, because they have to get your starter engaged and your starter has to turn the engine over even when it is cold. On paper, that would seem like a one-time function that would allow you to use the battery to run the radio, the electric windows and the inboard electronics etc – so what’s the big deal if you drain it a little?
But the big deal in draining a starter battery is that people don’t just turn on their car engine’s once a day. They stop at the store and need a full battery to get them back on the road. Then they stop at another store. Then they stop at the movie theater. The list goes on and on.
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Each time you stop, you need a full battery to ensure your engine can start again. As such, starter batteries only use 1-3 percent of their power to get the car started and right away the alternator starts to recharge them so they are quickly and fully charged when you need them.
If you have a weak battery in the middle of winter and you stop somewhere, you can imagine the results. That’s why starter batteries are like Boy Scouts: Always prepared. They can’t be half discharged and do what they have to do.
Likewise, the battery in your gas golf cart is designed to provide power to your starter which turns the engine and recharges the battery to provide power for accessories and keep the battery charged for the next time of use.
The Function of Deep Cycle Batteries
Deep-cycle batteries are just the opposite. They are designed for long, slow power outputs, just the type of thing you need to listen to the radio for an hour or two. These batteries don’t mind being fully drained and recharged again and again. That’s their purpose in life. And, to be frank, they don’t always have the quick punch that can turn over a cold, gas golf cart engine.
That is why deep cycle batteries are so perfect for electric golf carts. Electric golf carts drain the most energy while accelerating. With that in mind, the quicker the acceleration, the chance for long term battery degradation is increased. However, energy used in an electric golf cart is much less since the efficiency in a gas unit is tremendously higher. With electric golf carts and cars, close to 100% of the energy used is delivered to wheels. That is why the quiet and speedy Tesla can outpace most sports cars in the 0-60mph category. In a gas golf cart, the energy delivered via gas is only around 30% efficiency. Most of the energy is lost in the mechanical delivery of energy through the use of belts, gears, and the drivetrain.
So, you might ask, what about a battery that can do both. The answer to that is yes, we really did put a man on the moon, so, yes, we have developed dual-purpose batteries. However, unless you want to spend more money for them, you are better off being aware of the task at which your battery will be doing. Electric golf carts get deep cycle batteries and not automotive batteries. Gas golf carts get automotive batteries and not deep cycle batteries.