Glossary of Battery terms and definitions:
battery capacity: the total number of amp hours that can be removed from a fully-charged battery or cell at a specified discharge rate.
battery: a device that converts chemical energy contained in its active materials directly into electrical energy by means of an electrochemical reaction.
blocking diode: a solid-state electrical device planed in circuit between the module and the battery when the voltage of the battery is higher than that of the module (i.e. at night)
cell (battery): the smallest unit or section of a battery that can store electrical energy and is capable of providing a current to an external load.
cycle life: of a battery, the number of cycles it is expected to last before being reduced to 80% of its rated capacity
cycle: one discharge and charge period of a battery
deep discharge battery: a type of battery that is not damaged when a large portion of its energy capacity is repeatedly removed (i.e. motive batteries).
depth of discharge: a measure in percentage of the amount of energy removed from the battery during a cycle.
discharge: the removal of electric energy from a battery
dry cell battery: can be made of alkaline cells, consisting of common dry cell carbon or zinc, of types "AA" "AAA", "C", "D" (most common torch/flashlight battery), others used for radios, cassette players, various other small appliances. A dry cell battery contains electrolytes that are in the form of paste rather than liquid.
ni-cad battery: a nickel cadmium (ni-cad) battery. NiCad batteries have been used to power small electronic devices for a number of years. They are rechargeable, have higher energy densities than lead-acid batteries, and have higher energy densities that lead-acid batteries. Rarely used for PV applications for a variety of reasons including reduction in recharge voltage, the so-called "memory effect", among others. [for further reading see: http://www.pfa.org.uk/ni-cad.htm].
shallow discharge batteries: batteries designed to supply high power for a short duration (e.g. automotive batteries); taking too much energy out of these batteries before recharging them is likely to damage the plates inside.
storage: any system by which energy is stored. Storage generally includes batteries, although more advanced storage systems can include heat pumps or water reservoirs.
trickle charge: a low current charge. When the batteries are fully charged, some charge controllers reduce the energy from the module to the battery to a trickle charge so that the batteries are not overcharged, but so that they still get enough current to overcome self-discharge. For more information, check out these sites: http://www.windsun.com/Batteries/batterie.htm