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GLOSSARY OF TERMS FOR SEALED LEAD-ACID BATTERIES - CONTINUED

DISCHARGE RATE The term to express the magnitude of discharge current. When assuming discharge current and time to discharge cut-off voltage t hours, this discharge is called t hour rate (tHR) discharge, and the current is called t-hour rate discharge current. When time t is minutes instead of hours, tMR is used.

INTERNAL RESISTANCE The resistance within a battery: it is the total of individual resistances of the electrolyte and the positive and negative plates. Internal resistance is simply measured with the current four-terminal method (1,000 Hz) and expressed in the composite value of resistance component and capacitor component.

DUTY CYCLE TEST Test of batteries in ordinary use including charge, discharge and rest.

INTERNAL SHORT-CIRCUIT Touching of the positive and negative plates within a cell.

ELECTROLYTE The medium which serves to conduct ions in the electrochemical reactions in batteries. The lead-acid battery adopts diluted sulfuric acid as the electrolyte.

LIFE The time period until a cell/battery loses its expected characteristics.

ENERGY DENSITY Energy available per unit Approx. mass or unit volume of a cell/ battery. Energy density is expressed in Wh/ kg or Wh/l.

The system in which a constant voltage is contin- uously applied to a battery connected to a rectifier in parallel with a load to maintain the battery in charged state: on occurrence of power failure or load variation, the battery supplies power to the load without any short break.

GAS RECOMBINATION ABILITY Capability of a battery to recombine (or absorb) internally generated oxygen gas at the negative plate. The greater this capability is, the larger the available charge current.

HIGH RATE DISCHARGE A very rapid discharge of a battery. (In many cases it means discharging at approx. 1 CA or higher rate.)

INTERNAL PRESSURE The pressure within a sealed battery. Internal pressure of a battery is increased by oxygen gas which is generated from the positive plate at the end of charging.

LOW MAINTENANCE Low maintenance means that no watering nor equalizing charge is required in operating batteries.

LOW-VOLTAGE CUT-OFF A circuitry designed to discontinue discharge of a battery at a predetermined voltage level.

MALE TAB The metallic pieces which are attached to a SLA battery as the terminals.

MEMORY EFFECT A phenomenon where a temporary drop of discharge voltage is observed during deep discharge of an alkaline rechargeable battery which has been subjected to shallow charge/discharge. Cycles or trickle charging over long time.

NEGATIVE PLATE The battery electrode into which a current from the external circuit flows during discharging. The negative plate has lower electric potential than the positive plate to the electrolyte. The negative plate is incorporated with connection parts such as the electrode pole.

RATED CAPACITY A nominal value of capacity of a cell/battery, which is a measure of electric capability. Rated capacity is rather approximate compared with rated capacity.

Sealed Lead-Acid Handbook, Page 74

January 2000

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