Deep Cycle Batteries

Repco offers a comprehensive selection of high-quality deep cycle batteries from trusted brands including Century, Optima, and Repco’s own range. Deep cycle batteries are specifically designed to deliver consistent, long-lasting power for applications such as caravans, recreational vehicles, boats, and off-grid solar systems, ensuring dependable performance when you need it most.

What is a deep cycle battery?

A deep cycle battery is a type of lead-acid or lithium-based battery specifically designed to provide a steady amount of power over a long period. Unlike regular starter car batteries, which deliver short bursts of high current to start engines, deep cycle batteries are built to be discharged deeply before being recharged. This characteristic makes them well-suited for applications requiring sustained energy draw, such as in recreational vehicles, marine systems, solar energy storage, and automotive auxiliary power systems. In automotive contexts, deep cycle batteries power accessories independently of the engine's primary battery or supply power for extended use when the engine is off.

How to test a deep cycle battery

Testing a deep cycle battery involves checking its voltage, specific gravity (for flooded lead-acid types), and load capacity. First, use a voltmeter to measure the battery’s open-circuit voltage, a fully charged 12-volt deep cycle battery typically reads about 12.6 to 12.8 volts. Next, if the battery is flooded type, measure the electrolyte specific gravity with a hydrometer to assess charge state and health, values around 1.265 indicate full charge. You can also perform a load test by applying a discharge equivalent to the battery’s rated current for a set period and observing the voltage drop. If the voltage falls below a certain threshold during this test, the battery may be failing. Regular testing ensures reliable performance and early detection of issues.

How to charge a deep cycle battery

Charging a deep cycle battery should be done using a charger designed for deep cycle applications and matched to the battery’s chemistry, whether lead-acid or lithium. For lead-acid types, a multi-stage charger is preferred as it prevents overcharging and extends battery life. The charging process generally involves bulk charge, absorption, and float stages. The bulk stage rapidly replenishes charge, absorption maintains near-full voltage while repairing charge capacity, and float keeps the battery topped-up without damage. Lithium deep cycle batteries require chargers with specific voltage and current profiles to maintain safety and efficiency. Avoid using standard automotive starter battery chargers, as these do not provide the appropriate charging profile and can reduce battery longevity.

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

The main difference lies in their design purpose and construction. Regular automotive batteries, often called starter batteries, are designed to deliver a high burst of current for a short period to start an engine. They have many thin plates to maximise surface area for quick power delivery but are not meant for deep discharges. Deep cycle batteries, on the other hand, have thicker plates and denser active material, allowing them to be discharged to a much greater extent without damaging the battery. This makes them ideal for continuous power delivery over hours rather than seconds. Using a starter battery in deep cycle applications will lead to premature failure, while using a deep cycle battery for starting is less efficient due to lower cold cranking amps.

Which is better, a deep cycle or a lithium battery?

The choice between a deep cycle lead-acid battery and a lithium battery depends on application, budget, and performance requirements. Lithium batteries typically offer advantages such as lighter weight, higher energy density, faster charging, longer cycle life, and better efficiency under deep discharge conditions. They are especially useful in modern automotive setups where weight reductions and extended auxiliary power are priorities, such as in campervans or off-grid vehicles. However, lithium batteries generally have a higher upfront cost and may require compatible chargers and battery management systems. Traditional lead-acid deep cycle batteries remain popular due to lower cost, widespread availability, and proven reliability in harsh conditions. For users who need dependable power with minimal investment, lead-acid is practical, for those prioritising performance and longevity, lithium offers clear benefits.

Find the Right Deep Cycle Battery at Repco

Find the right deep cycle battery at Repco and get out and enjoy the great outdoors. Whether you need an AGM battery for your caravan or deep cycle batteries to connect to your camping solar setup, we have a number of quality deep cycle batteries to choose from. Designed to be durable, reliable, and with the capacity for long-term storage, a deep cycle battery will excel in a wide range of applications requiring portable battery power.