Deep-cycle batteries and car batteries are both lead-acid batteries but have internal design differences that make one better suited for certain applications over the other. Car batteries have thinner plates that allow high bursts of current for starting an engine but cannot provide sustained power, while deep-cycle batteries have thicker plates for consistent low-level power over extended periods. Though they can be interchanged, using the wrong type can damage it and reduce effectiveness.

1. DEEP CYCLE VS. CAR BATTERY
Boney Maundu
Can I use a deep cycle battery for my car?
Can I use a car battery for solar?
Are they interchangeable?

2. What battery should you use for your car? Can I use the same for solar? Will one work in place of the other?
Choosing the right battery for your car or solar application is crucial because the wrong battery could not only
provide insufficient power but also fail in extreme temperatures, resulting in unwanted costs and losses in
productivity.
A conventional automobile battery and a deep-cycle battery are the two common types of batteries, and which one
you choose will depend on its intended use and application. Although they both have a similar outer appearance,
they differ internally in terms of operation and design.
Difference between a Regular Car Battery and a Deep-Cycle Battery
Both deep-cycle batteries and car batteries are lead-acid batteries have the same basic elements and function in the
same way. They have an electrolyte fluid, which is often acid, and negative and positive terminals. Simply explained,
current flows between the negative and positive contacts with the help of the electrolyte fluid.
Internally, each type of battery has a different design. The strength of the electricity the battery will generate and
how long it will take for the battery to drain are both influenced by the quantity of electrolyte fluid and the size of
the metallic elements.
Car Battery
A regular car battery generates electricity in short sharp bursts, which are then used to crank start a vehicle's engine.
From this point on, the alternator takes over and recharges the battery so only a small portion of the battery’s
capacity is used. In this way a car battery is able to last longer as it’s not meant to be completely discharged and
recharged unlike a deep-cycle battery.
Car batteries have thinner lead grids and active material to maximize the metallic plate’s surface area, which help
deliver the large amounts of initial current. They are, however, not suitable for providing sustained, consistent levels
of power for long periods. However, they cannot deliver constant, sustained levels of power over an extended
period of time.
A car battery usually has two ratings;
 Cold Cranking Amps (CCA): It’s a rating that defines the battery’s ability to start an engine in cold
temperatures. It’s the number of amps the battery can generate at 0 degrees Celsius (or 32 degrees
Fahrenheit) for 30 seconds while retaining a voltage above 7.2 volts. The higher the CCA rating, the greater
the starting power of the battery.
 Reserve Capacity (RC): The amount of time the battery can deliver 25 amps while keeping its voltage above
10.5 volts. For instance, if a battery has an RC of 150, it can supply 25 amps for 150 minutes before the voltage
drops to 10.5 volts.
The charging methods of a regular battery and a deep-cycle battery are different. A regular car battery only
discharges the battery about 2 to 4% each time it’s used to crank an engine, after which the vehicle’s alternator
recharges it. Throughout its entire lifespan, the battery might never lose more than 25% of its charge. This means
it’s not meant for manual recharging, which could significantly reduce its lifespan.

3. Deep-Cycle Battery
Deep-cycle batteries, on the other hand, produce a lower but consistent amount of current rather than a short burst
of high current, which is enough to power a motor or a load for a long time. This is why they are used to power an
electric vehicle for a sustained period.
They have thicker metallic elements compared to car batteries, and these thicker metal plates allow the battery to
release electricity more consistently with a lower current draw over sustained periods.
Additionally, they’re able to withstand repeated charge and discharge cycles, which would normally damage a car
battery.
Typically, a deep-cycle battery will have almost three times the reserve capacity of a car battery, so they can provide
sustained energy for longer, but they can only generate about half the cold cranking amps of a car battery, so they
are not as ideal for starting a car, especially in cold temperatures.
A deep-cycle battery should ideally run until it’s completely discharged, after which it's recharged. This discharge and
recharge cycle can repeat hundreds of times.
Which one is more powerful?
In a nutshell, it depends on the application. A battery with a higher CCA generates a large amount of current to start
a vehicle's engine, so a car battery is powerful in this regard. On the other hand, a higher reserve capacity battery
can generate sustained levels of energy for a long period of time, which is where deep-cycle batteries have an edge.
Are the batteries interchangeable?
Technically, since they have the same elements, they can be interchanged, though it’s not advisable. The thin metal
plates of a car battery are not designed for extended use, and in fact, they can warp after sustained current draw.
Deep-cycle batteries can be run to exhaustion.
Though there are dual-purpose batteries on the market that are both deep-cycle and can be used to provide short
bursts of large current, they’re just not as aptly suited for a specific function as either deep-cycle or car batteries
because of the internal design differences in both types.
----