DC - direct current.

DOD - depth of discharge.

DT - dual terminal.

DVM - Digital voltmeter. See voltmeter.

Deep-Cycle Battery - A battery that is designed to withstand repetitive discharges to a 20% depth of discharge or more and to continue providing its rated capacity after hundreds of cycles. Deep-cycle batteries are often used in marine/RV and industrial applications.

Deep Cycling - The process of drawing a high percentage of a battery's capacity (deep discharging) and recharging it to full capacity.

Deep Discharge - The discharge of the battery to below the specified cutoff voltage before the battery is replaced or recharged.

Depth of Discharge (DOD) - The percent of rated capacity to which a cell or battery is discharged. It is the reciprocal of a battery's state of charge. Example: a battery that has a depth of discharge of 45% has a state of charge of 55%.

Digital Voltmeter (DVM) - See voltmeter.

Diode - A semiconductor device that acts like a one-way valve for current. Today's alternators use diodes to rectify current.

Direct Current (DC) - An electrical current that flows in one direction only. A battery delivers direct current, discharging the battery, and is recharged with direct current.

Discharged - The state of a battery when it has less than a 100% state of charge. Levels of discharge are shown in the Open-Circuit-Voltage Chart.

Discharging - The withdrawal of electrical energy from a cell or battery, usually to operate connected equipment. A battery is discharging when it delivers current.

Discharge Rate - The rate at which current is drawn from a battery, usually expressed in amps.

Drain - Withdrawal of current from a cell or battery. Often referred to as discharging. See also Average Drain and Initial Drain.

Dry Battery - A battery in which the electrolyte is immobilized, being either in the form of a paste or absorbed into the separator material.

Dry-Cell Battery - A cylindrical-cell battery, typically nonrechargeable and disposable, such as a standard alkaline, heavy-duty or general-purpose battery. See also Cell.

Dual-Alloy Battery - See Low-Maintenance Battery.

Dual-Terminal Battery - An automotive battery with top terminals and side terminals.

Duty Cycle - The time duration and use frequency during which a battery is drained. It is affected by such factors as charge and discharge rates, depth of discharge, length of cycle, and length of time in standby mode.