The structural difference between deep-cycle and cranking lead–acid 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. The thicker battery plates resist corrosion through extended
charge and discharge cycles. Deep-cycle lead–acid batteries generally fall into two distinct categories;
flooded and
valve-regulated lead–acid (
FLA and
VRLA), with the VRLA type further subdivided into two types,
absorbent glass mat (AGM) and
gel. The reinforcement of absorbed glass mat separators helps to reduce damage caused by spilling and jolting vibrations. 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.
Flooded The term
flooded is used because this type of battery contains a quantity of
electrolyte fluid so that the plates are completely submerged. The electrolyte level should be above the tops of the plates which serves as a reservoir to make sure that water loss during charging does not lower the level below the plate tops and cause damage. Flooded batteries will decompose some water from the electrolyte during charging, so regular maintenance of flooded batteries requires inspection of electrolyte level and addition of water. Major modes of failure of deep-cycle batteries are loss of the active material due to shedding of the plates, and
corrosion of the internal grid that supports active material. The capacity of a deep-cycle battery is usually limited by electrolyte capacity and not by the plate mass, to improve life expectancy. OPzS batteries are a type of deep-cycle battery commonly used for
backup power systems and renewable energy applications. OPzS is recommended for storing energy from intermittent supplies, such as wind and solar supplies for
off-grid use.
OPzV batteries OPzV stands for , meaning
stationary tubular plate, sealed. ==New technologies==