Deep Cycle Battery

Deep cycle battery

Definition

A deep-cycle battery is a lead-acid battery designed to be regularly deeply discharged using most of its capacity. In contrast, starter batteries (e.g. most automotive batteries) are designed to deliver short, high-current bursts for cranking the engine, thus frequently discharging only a small part of their capacity. While a deep-cycle battery can be used as a starting battery, the lower "cranking current" implies that an oversized battery may be required.

A deep-cycle battery is designed to discharge between 45% and 75% of its capacity, depending on the manufacturer and the construction of the battery. Although these batteries can be cycled down to 20% charge, the best lifespan vs cost method is to keep the average cycle at about 45% discharge.[1] There is an indirect correlation between the depth of discharge (DOD) of the battery, and the number of charge and discharge cycles it can perform.[2]

 

Structure

Deep-cycle lead-acid batteries generally fall into two distinct categories; flooded (FLA) and valve-regulated lead-acid (VRLA), with the VRLA type further subdivided into two types, Absorbed Glass Mat (AGM) and Gel. The reinforcement of absorbed glass mat separators helps to reduce damage caused by spilling and jolting vibrations.[3] Further, flooded deep-cycle batteries can be divided into subcategories of Tubular-plated Opzs or flat plated. The difference generally affects the cycle life and performance of the cell. The structural difference between deep-cycle batteries and cranking batteries is in the lead battery plates. Deep cycle battery plates have thicker active plates, with higher-density active paste material and thicker separators. Alloys used for the plates in a deep cycle battery may contain more antimony than that of starting batteries.[4] The thicker battery plates resist corrosion through extended charge and discharge cycles.

Applications

Cathodic protection, which might include marine use

Other marine use, especially on a sailboat lacking power generation capability, generally smaller vessels

Trolling motors for recreational fishing boats

Industrial electrically-propelled forklifts and floor sweepers

Motorized wheelchairs

Off-grid energy storage systems for solar power or wind power, especially in small installations for a single building or motorhome

Power for instruments or equipment at remote sites

Recreational vehicles

Traction batteries to propel vehicles, such as golf carts, and other highway electric vehicles

Traffic signals

Uninterruptible power supply ('UPS'), usually for computers and associated equipment, but also sump pumps

Audio equipment, similarly to a UPS but also in certain 'clean power' devices to supply clean DC power isolated from the public electric supply for inversion to AC to maximize audio signal reproduction