SLI - A starting-lighting-and-ignition battery.

Sealed Battery - A maintenance-free battery with nonremovable vent caps.

Secondary Battery - Any battery that is designed to be recharged, such as lead-acid, NiCad and nickel-metal-hydride batteries.

Self-Discharge - The discharge that occurs in a battery while it is not in use. The higher the temperature, the greater the rate of self-discharge.

Self-Discharge Rate - The rate at which a cell or battery loses its capacity when standing idle.

Separator - An insulative divider between the positive (+) plates and negative (-) plates of an element that allows the flow of current to pass through it and prevents positive (+) and negative (-) electrodes from touching and creating a short circuit. Interstate's lead-acid batteries generally use polyethylene separators.

Series Circuit - A circuit in which the current has only one path to follow. In this configuration, two batteries of equal rating are wired together positive (+) to negative (-). In series, the battery voltage increases while the RC and CCA remain the same as the weakest individual battery.

Series/Parallel Circuit - A circuit in which some of the terminals are connected in series to increase total voltage, and some are connected in parallel to increase total capacity. The amount of voltage and capacity depends on the exact number of series and parallel connections.

Service Life - The length of time a battery can be used in a given application.

Shelf Life - The amount of time a cell or battery will retain a specified percent of its rated capacity, typically under ambient storage conditions. Interstate's superior rotation service ensures that batteries are fresh on the shelf.

Short Circuit - An unwanted electrical connection between a negative (-) ground and a positive (+) source. A short circuit in a battery cell may be permanent enough to discharge the cell and render the battery useless.

Silver-Oxide Battery - A small, nonrechargeable battery used in devices such as watches and calculators.

Slow Charging - Charging at a rate of about 5-10% of a battery's rated capacity. Example: 50 AH battery x 10% = 5-amp charge.

Smart Battery - A battery with internal circuitry designed to communicate information, such as capacity remaining, to the user or to other parts of the application's circuit.

Smart Charger - A charger that fully discharges a NiCad battery and/or an NiMH battery before recharging it to prevent a memory effect from occurring.

Solenoid - (1) A term used to mean coil or inductor. (2) A type of relay that switches the starter current "off" in an automobile after the engine engages.

Specialty Battery - Any battery other than an SLI battery.

Specific Gravity - In a lead-acid battery, the weight of sulfuric acid compared to the weight of an equal volume of pure water.

Standby - A backup power supply. See also Float Charge and Uninterrupted Power Supply.

Standby Time - The number of hours a cell phone can be left "on" and unused before its battery's capacity is depleted. See also Talk Time.

Starting Battery - A starting-lighting-and-ignition battery (SLI).

Starting-Lighting-and-Ignition Battery (SLI) - A battery primarily used to start a vehicle and to provide power for lights and accessories. SLI batteries include automotive, deep-cycle and heavy-duty commercial starting batteries.

State of Charge - The condition of a battery in terms of rated capacity remaining at a given point in time. See also Open-Circuit-Voltage Chart, Specific-Gravity Chart and Depth of Discharge.

Stratification - A condition in which the concentration of acid is greater at the bottom of the battery than at the top. Normally caused by continued undercharging.

Sulfation - The accumulation of lead sulfates on the plates of a lead-acid battery. When enough plate area has sulfated, the battery will not be able to provide enough current and will normally need to be replaced.

Switch - A mechanical device used for opening and closing a circuit.