Small Deep Cycle Battery-Introduction, Charger And Cycle Life

Sep 17, 2020   Pageview:119

Have you ever wondered why there are different kinds of batteries? Well, the answers are straightforward; Batteries vary according to different manufactures and also their application. There are batteries used for small appliances like powering radios, televisions, etc. Others are used to power heavy machinery like aircraft and ships.

Some of these devices require a steady supply of power for an extended period. For instance, the battery of a trolling motor should supply electricity for an extended time. Also, the current should always be steady. This is where the deep cycle batteries come into play. Let us look at some of the features of deep cycle batteries.

What is the smallest deep cycle battery?

A deep small deep cycle battery is a battery that is constructed for long-use applications. It regularly discharges using most of its capacity. Depending on manufactures and construction, a deep cycle battery can discharge up to 80% of its capacity before being charged.

It differs significantly from the starter or automotive batteries, which gives only part of their capacity in a short, high current discharge for cranking the engine.

Applications of deep cycle batteries include:

  • Trolling motors

  • Traction batteries to power vehicles

  • Uninterrupted power supply (UPS)

  • Sailboats which generally fail due to lack of proper charging

  • Traffic signals

  • Forklifts.

Deep cycle batteries are constructed with thick active plates having thicker separators and high-density active paste material. Moreover, they come in different sizes and types.

The types include:

?Valve regulated Lead-acid battery


Valve-regulated lead-acid battery is subdivided into Absorbed Glass Mat (AGM) and Gel. The differences in these types dramatically affect performance and cycle life.

Flooded deep cycle batteries are most common where the plates are completely submerged in an electrolyte solution. They often require an inspection to check the level of electrolyte, ensuring it is above the plates.

Valve regulated lead-acid battery, also termed a sealed lead-acid battery, is a limited amount of electrolyte in a paste. Therefore these batteries can be installed in a different orientation. They also require less maintenance

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Does a small deep cycle battery need a special charger?

A special charger is needed to charge these kinds of batteries to full capacity. A wrong charger may damage the battery or take long to charge it fully. Imagine your boat fails in the middle of the sea! You will need this special charger to bring up your battery to full capacity. Using ordinary chargers will mean spending hours in the sea before a full charge is attained.

This unique charger's advantage is that it protects against overcharging as it charges the battery in phases. A deep cycle battery is not made for rapid charging and excess heat. Standard chargers produce excess heat in the course of charging. Thus, affecting the battery lifespan and performance characteristics.

The special charger allows more current to flow into the battery when it is deeply discharged. It then slows down the current amount as the battery nears full capacity, thus ensuring a longer battery life.

The phases that the special charger has is divided into three. At the start of charging, we have the Bulk Charging Phase. Here the highest charge current and voltage are applied to restore the charge. After this is the Absorption Charge Phase, where a constant charge voltage is maintained. But, current drops, until the battery charge reaches about 90% of its capacity.

The last phase of charging is termed as the float phase. In this phase, the applied voltage and current declines until the battery is fully charged. All these charging phases ensure optimum charging and, at the same time, increase the lifespan of the small deep cycle battery.

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How long will a small deep cycle battery last?

A deep cycle battery generally has a longer lifespan if correct charging procedures are followed. They are constructed to withstand large numbers of deep discharge and recharging cycles. A typical example is a deep cycle battery used in trolling motors where the battery is designed to deliver low amounts of current over a long period and, at the same time, discharging to a deeper level.

Its depth of discharge influences the lifespan of the battery. A typical cycle of a small deep cycle battery will start at 100% capacity in most instances. The battery's discharge will fall from 25% to 50% before being charged to full capacity again.

An essential thing to note here is that a battery that discharges to a minimum of between 50% and 55% regularly tend to have a longer lifespan. Frequent low discharges say between 10-15% of a small deep cycle battery harms the battery's lifespan.

Also, the lifespan of a small deep cycle battery is influenced by the following factors:

  • Temperature- the voltage and chemical reactions inside the battery is affected by temperature, hot or cold.

  • Usage - Overloading a deep cycle battery will drain it faster, and the desired lifespan is drastically reduced.

  • Quality of the battery- Depending on the manufacturer, the deep cycle battery's quality will differ. A standard battery will guarantee a longer lifespan.

  • According to the manufacturer's instructions, maintenance- service and battery maintenance can aid in the battery's increasing lifespan. Though Valve regulated lead-batteries are commonly referred to as maintenance-free, battery manufacturers’ advocate for scheduled maintenance and servicing.

For a 12-volt Gel or AGM batteries, the lifespan is up to 6 years if proper maintenance is kept. It can take around 500 full cycles of being discharged way below 20% and recharge to full capacity.

For a 2-volt Gel, the lifespan can go as far as 15 years and take around 1000 full cycles when discharging below 20 % of full charge.

It has been found that flooded deep cycle batteries are the most reliable and functions well in hot environments. They can function for 20 years if well maintained.


The use of small deep cycle batteries is widening due to its various merits. Their performance characteristics outcompete the starter or automotive batteries. Deep cycle batteries will have more extended durability compared to regular batteries. Lastly, small deep cycle batteries are environmentally friendly; thus, many people have opted to purchase them.

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